int main(int argc,char *argv[])
{
comedi_t *it;
- int chan=0;
lsampl_t data;
-
+
it=comedi_open("/dev/comedi0");
- comedi_data_read(it,subdev,chan,range,aref,& data);
+ comedi_data_read(it,subdev,chan,range,aref,&data);
printf("%d\n",data);
</CODE></BLOCKQUOTE>
</P>
-<P>Should be understandable. Open the device, get the data,
+<P>Should be understandable: open the device, get the data,
print it out. This is basically the guts of <CODE>demo/inp.c</CODE>,
without error checking or fancy options.
-Compile it using </P>
+Compile it using</P>
<P>
<BLOCKQUOTE><CODE>
<PRE>
</H2>
-<P>If you selected an analog input subdevice, you should notice
+<P>If you selected an analog input subdevice, you probably noticed
that the output of <CODE>tut1</CODE> is a number between
0 and 4095, or 0 and 65535, depending on the number of bits
in the A/D converter. Comedi samples are <B>always</B> unsigned,
input, and Comedi allows you to select which of these to
use. This parameter is called the "range parameter", since
it specifies the "input range" for analog input (or "output range"
-analog output.) The range parameter represents both the gain
+for analog output.) The range parameter represents both the gain
and the unipolar/bipolar aspects.</P>
<P>Comedi keeps the number of available ranges and the largest
sample value for each subdevice/channel combination. (Some
<PRE>
#include <stdio.h> /* for printf() */
#include <comedi.h> /* also included by comedilib.h */
-#include <comedilib.h> /* for comedi_get() */
+#include <comedilib.h> /* 'cuz we're using comedilib */
int subdev = 0; /* change this to your input subdevice */
int chan = 0; /* change this to your channel */
{
comedi_t *cf;
int chan=0;
- int data;
+ lsampl_t data;
int maxdata,rangetype;
double volts;
rangetype=comedi_get_rangetype(cf,subdev,chan);
- data=comedi_get(cf->fd,subdev,chan,range,aref);
+ comedi_data_read(cf->fd,subdev,chan,range,aref,&data);
volts=comedi_to_phys(data,rangetype,range,maxdata);
</CODE></BLOCKQUOTE>
</P>
-<P>By now, the <CODE>comedi_read_data()</CODE> line looks a little archaic, using
-the UNIX file descriptor cf->fd instead of just cf. (By the
-way, somewhere in the heart of <CODE>comedi_open()</CODE> is the line
-<CODE>cf->fd=open(filename,O_RDWR)</CODE>.) Well, there isn't one good
-replacement, since it highly depends on your application
-what additional features you might want in a <CODE>comedi_get()</CODE>
-replacement. But this is the topic of a different section.</P>
-
<HR>
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<TITLE>Comedi Documentation: Application-specific functions</TITLE>
+ <LINK HREF="comedilib-6.html" REL=next>
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+<A HREF="comedilib-6.html">Next</A>
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<HR>
<P>Many data acquisition devices have the capability to directly
control acquisition using either an on-board timer or an external
triggering input. Comedi commands are used to control this kind
-of acquisition. The same structure (comedi_cmd) used to control
-acquisition is used to query the capabilities of a device.</P>
+of acquisition. The
+<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A> structure is
+used to control acquisition and query the capabilities of a device
+(see also
+<A HREF="comedilib-6.html#comedi_command">comedi_command()</A>,
+<A HREF="comedilib-6.html#comedi_command_test">comedi_command_test()</A>, and
+<A HREF="comedilib-6.html#comedi_get_cmd_src_mask">comedi_get_cmd_src_mask()</A>).</P>
<P>Commands specify a particular data acquisition sequence, which
is comprised of a number of scans. Each scan is comprised of
a number of conversions, which usually corresponds to a single
the start and end of each scan, and each conversion is called an
event.</P>
<P>Each of these 5 types of events are caused by a triggering
-source. The source types are:</P>
+source, specified through the *_src members of the
+<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A> structure. The source types are:</P>
<P>
<UL>
-<LI>TRIG_NONE don't ever cause event</LI>
-<LI>TRIG_NOW cause event to occur immediately</LI>
-<LI>TRIG_FOLLOW (see notes below)</LI>
-<LI>TRIG_TIME cause event to occur at a particular time</LI>
-<LI>TRIG_TIMER cause event to occur repeatedly at a specific rate</LI>
-<LI>TRIG_COUNT cause event when count reaches specific value</LI>
-<LI>TRIG_EXT external signal causes event</LI>
-<LI>TRIG_INT internal signal causes event</LI>
+<LI>TRIG_NONE: don't ever cause an event</LI>
+<LI>TRIG_NOW: cause event to occur immediately</LI>
+<LI>TRIG_FOLLOW: see notes below</LI>
+<LI>TRIG_TIME: cause event to occur at a particular time</LI>
+<LI>TRIG_TIMER: cause event to occur repeatedly at a specific rate</LI>
+<LI>TRIG_COUNT: cause event when count reaches specific value</LI>
+<LI>TRIG_EXT: external signal causes event</LI>
+<LI>TRIG_INT: internal signal causes event</LI>
+<LI>TRIG_OTHER: driver-specific meaning</LI>
</UL>
</P>
+<P>For every trigger, there is a corresponding
+argument (the *_arg members of the
+<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A>
+structure) whose meaning depends on the type of trigger. The meanings
+of the arguments are as follows:</P>
+
<P>Not all triggers are applicable to all events. Supported triggers
for specific events depends significantly on your particular
-device. In addition, for every trigger type, there is a cooresponding
-argument that specifies the rate, the count, which external signal,
-etc.</P>
-<P>TRIG_FOLLOW is a special type of trigger for scan_begin events that
-triggers on the next lower level trigger, in this case, the trigger
-for convert events. It may or may not be supported. Later, it may
-also be used for start events if you want to chain multiple commands.</P>
-<P>In particular, scan_end events will almost always be triggered on
-TRIG_COUNT, with the argument being the number of channels in the
-scan. (Actually, samples in the scan, since on most boards you can
-measure a single channel multiple times in a scan.) Also, until
-otherwise supported, start events can only be TRIG_NOW.</P>
-
+device.</P>
+<P>TRIG_NONE is typically used only as a stop_src. The arg for TRIG_NONE
+is reserved and should be set to 0.</P>
+<P>TRIG_NOW is most often used as a start_src. The arg for TRIG_NOW is
+the number of nanoseconds between when the command is issued and when
+the event should occur. In the case of using TRIG now as a start_src,
+it indicates a delay between issuing the command and the start of
+acquisition. Most drivers only support a delay of 0.</P>
+<P>TRIG_FOLLOW is a special type of trigger for events that trigger on
+the completion of some other, logically connected event. The argument
+is reserved and should be set to 0. When used
+as a scan_begin_src, it indicates that a trigger should occur as a
+logical continuation of convert events. This is done in order to
+properly describe boards that do not have separate timers for
+convert and scan_begin events. When used as a start_src for analog
+output subdevices, it indicates that conversion of output samples
+should begin when samples are written to the buffer.</P>
+<P>TRIG_TIME is reserved for future use.</P>
+<P>TRIG_TIMER is most often used as a convert_src, a scan_begin_src, or
+both. It indicates that triggers should occur at a specific rate.
+The argument specifies the interval between triggers in nanoseconds.</P>
+<P>TRIG_COUNT is used for scan_end_src and stop_src. It indicates that
+a trigger should occur when the specified number of corresponding
+lower-level triggers (convert and scan_begin, respectively) occur.
+The argument is the count of lower-level triggers.</P>
+<P>TRIG_EXT can be useful as any of the trigger sources. It indicates
+that an external digital line should be used to trigger the event.
+The exact meaning of digital line is device-dependent. Some devices
+have one dedicated line, others may allow generic digital input
+lines to be used. The argument indicates the particular external
+line to use as the trigger.</P>
+<P>TRIG_INT is typically used as a start_src. This trigger occurs when
+the application performs an INSN_INTTRIG instruction. Using TRIG_INT
+is a method by which the application can accurately record the time of
+the start of acquisition, since the parsing and setup time of a
+particular command may be significant. The argument associated with
+TRIG_INT is reserved and should be set to 0.</P>
+<P>TRIG_OTHER can be useful as any of the trigger sources. The exact
+meaning of TRIG_OTHER is driver-specific, and implements a feature
+that otherwise does not fit into the command interface. Configuration
+of TRIG_OTHER features are done by INSN_CONFIG insns. The argument
+is reserved and should be set to 0.</P>
+
+<P>The chanlist member of the
+<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A>
+structure should point to an array whose number of elements is specificed by chanlist_len
+(this will generally be the same as the scan_end_arg).
+The chanlist specifies the sequence of channels and gains (and analog references)
+that should be stepped through for each scan. The elements of the chanlist array
+should be initialized by packing the channel, range and reference information
+together with the
+<A HREF="comedilib-6.html#CR_PACK">CR_PACK(channel, range, aref)</A> macro.</P>
+<P>The final member of the
+<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A> structure is 'flags'.
+The following flags are valid, and can be bitwise-or'd together.</P>
+<P>
+<UL>
+<LI>TRIG_BOGUS: do the motions??</LI>
+<LI>TRIG_DITHER: enable dithering??</LI>
+<LI>TRIG_DEGLITCH: enable deglitching??</LI>
+<LI>TRIG_RT: ask driver to use a hard real-time interrupt handler. This will
+reduce latency in handling interrupts from your data aquisition hardware. It can
+be useful if you are sampling at high frequency, or if your hardware has a small onboard
+fifo. You must have a real-time kernel (RTAI or RTLinux) and must compile
+comedi with real-time support or this flag will do nothing.</LI>
+<LI>TRIG_CONFIG: perform configuration, not triggering.</LI>
+<LI>TRIG_WAKE_EOS: some drivers will change their behaviour when this flag is set,
+trying to transfer data at the end of every scan (instead of, for example, passing
+data in chunks whenever the board's onboard fifo is half full). This flag
+may degrade a driver's performance at higher frequencies.</LI>
+<LI>TRIG_WRITE: write to bidirectional devices. Could be useful in principle, if someone
+wrote a driver that supported commands for a digital i/o device that could do either
+input or output.</LI>
+</UL>
+There are also a few flags that indicate how timing arguments should be rounded
+if the hardware cannot achieve the exact timing requested.
+<UL>
+<LI>TRIG_ROUND_NEAREST: round to nearest supported timing period, the default.</LI>
+<LI>TRIG_ROUND_DOWN: round period down.</LI>
+<LI>TRIG_ROUND_UP: round period up.</LI>
+<LI>TRIG_ROUND_UP_NEXT: this one doesn't do anything, and I don't know what it was intended
+to do??</LI>
+</UL>
+</P>
<HR>
-Next
+<A HREF="comedilib-6.html">Next</A>
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- <META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
- <TITLE>Comedi Documentation: Comedilib reference</TITLE>
+ <META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.7.4">
+ <TITLE>Comedi Documentation: Libcomedi Reference</TITLE>
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</HEAD>
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<HR>
-<H2><A NAME="s6">6. Comedilib reference</A></H2>
+<H2><A NAME="s6">6.</A> <A HREF="comedilib.html#toc6">Libcomedi Reference</A></H2>
-<P>Reference of structures:
+
+
+<H2><A NAME="ss6.1">6.1 Constants and Macros</A>
+</H2>
+
+
+
+<H3><A NAME="CR_PACK"></A> CR_PACK(channel, range, aref)</H3>
+
+
+<P>undocumented</P>
+
+<H3>RANGE_LENGTH() <I>(deprecated)</I></H3>
+
+<P>
+<A NAME="RANGE_LENGTH"></A> </P>
+<P><CODE>RANGE_LENGTH(rangetype)</CODE></P>
+
+<P>Rangetype values are library-internal tokens that represent an
+array of range information structures. These numbers are primarily
+used for communication between the kernel and library.</P>
+
+<P>The RANGE_LENGTH() macro returns the length of the array that is
+specified by the rangetype token.</P>
+
+<P>The RANGE_LENGTH() macro is deprecated, and should not be used in
+new applications. It is scheduled to be removed from the header
+file at version 1.0. Binary compatibility may be broken for version
+1.1.</P>
+
+
+
+<H2><A NAME="ss6.2">6.2 Data Types and Structures</A>
+</H2>
+
+
+<H3><A NAME="comedi_t"></A> comedi_t</H3>
+
+<P>The data type <CODE>comedi_t</CODE> is used to represent an open Comedi
+device. A valid <CODE>comedi_t</CODE> pointer is returned by a successful
+call to <CODE>comedi_open()</CODE>, and should be used for subsequent
+access to the device.
+It is a transparent type, and pointers to type <CODE>comedi_t</CODE>
+should not be dereferenced by the application.</P>
+
+
+
+<H3><A NAME="sampl_t"></A> sampl_t</H3>
+
+<P>The data type <CODE>sampl_t</CODE> is one of the generic types used to represent
+data values in libcomedi. It is used in a few places where a shorter
+data type is useful, but is limited to 16 bits on the i386 architecture.</P>
+
+
+
+<H3><A NAME="lsampl_t"></A> lsampl_t</H3>
+
+<P>The data type <CODE>lsampl_t</CODE> is one of the generic types used to represent
+data values in libcomedi. It is currently defined to be <CODE>unsigned int</CODE>.</P>
+
+
+
+
+
+<H3><A NAME="comedi_trig_struct"></A> comedi_trig_struct <I>(deprecated)</I></H3>
+
+
+<P>The <CODE>comedi_trig</CODE> structure</P>
<P>
<BLOCKQUOTE><CODE>
<PRE>
-typedef struct comedi_t_struct comedi_t;
+struct comedi_trig_struct{
+ unsigned int subdev; /* subdevice */
+ unsigned int mode; /* mode */
+ unsigned int flags;
+ unsigned int n_chan; /* number of channels */
+ unsigned int *chanlist; /* channel/range list */
+ sampl_t *data; /* data list, size depends on subd flags */
+ unsigned int n; /* number of scans */
+ unsigned int trigsrc;
+ unsigned int trigvar;
+ unsigned int trigvar1;
+ unsigned int data_len;
+ unsigned int unused[3];
+}
+</PRE>
+</CODE></BLOCKQUOTE>
+</P>
+<P>The <CODE>comedi_trig</CODE> structure is a control structure used by the
+COMEDI_TRIG ioctl, an older method of communicating
+instructions to the driver and hardware. Use of comedi_trig is
+deprecated, and should not be used in new applications.</P>
+
+<P>This structure is defined as part of the Comedi kernel interface.</P>
+
-typedef struct{
- double min;
- double max;
- unsigned int unit;
-}comedi_range;
+<H3><A NAME="comedi_sv_t"></A> comedi_sv_t</H3>
-typedef struct comedi_sv_struct{
+
+<P>
+<BLOCKQUOTE><CODE>
+<PRE>
+struct comedi_sv_struct{
comedi_t *dev;
unsigned int subdevice;
unsigned int chan;
/* range policy */
int range;
int aref;
-
+
/* number of measurements to average (for ai) */
int n;
lsampl_t maxdata;
-}comedi_sv_t;
+}
</PRE>
</CODE></BLOCKQUOTE>
-<P>
-<H2><A NAME="ss6.1">6.1 comedi_loglevel()</A>
-</H2>
+</P>
+<P>The <CODE>comedi_sv_t</CODE> structure is used by the <CODE>comedi_sv_*()</CODE>
+functions to provide a simple method of accurately measuring
+slowly varying inputs. See the relevant section for more
+details.</P>
-<P>
-<P>int comedi_loglevel(int loglevel);
-<P>
-<P>
-<P>This function affects the output of debugging and error messages
-from comedlib. By increasing the loglevel, additional debugging
-information will be printed. This function returns the previous
-loglevel. Some debugging information will only be printed if
-comedilib was compiled with this debugging information included.
-The loglevel can also be affected by the environment
-variable COMEDI_LOGLEVEL. The meaning of the loglevels is as
-follows:
-<P>COMEDILIB_LOGLEVEL=0
-<P>Comedilib prints nothing.
-<P>COMEDILIB_LOGLEVEL=1 (default)
-<P>Comedilib only prints error messages when there is a
-self-consistency error.
-<P>COMEDILIB_LOGLEVEL=2
-<P>Comedilib prints an error message whenever an invalid
-parameter is passed to comedilib.
-<P>COMEDILIB_LOGLEVEL=3
-<P>Comedilib prints an error message whenever an error is generated
-in the comedilib library or is generated in the C library when
-called by comedilib.
-<P>COMEDILIB_LOGLEVEL=4
-<P>Comedilib prints a lot of debugging messages.
-<P>
-<P>
-<P>
-<H2><A NAME="ss6.2">6.2 comedi_open</A>
-</H2>
-<P>
-<P>comedi_t *comedi_open(char *fn);
-<P>Opens a comedi device specified by the filename fn. Returns NULL
-on error. Returns a handle that is given as a parameter to other
-comedilib functions.
-<P>You are not supposed to have access to the structure comedi_t.
-<P>void comedi_close(comedi_t *it);
-<P>Closes a device previously opened by comedi_open().
-<P>void comedi_perror(const char *s);
-char *comedi_strerror(int errnum);
-int comedi_errno(void);
-<P>When a comedilib function fails, it usually returns -1 or
-NULL, depending on the return type. An internal library
-variable stores an error number, which can be retrieved with
-<CODE>comedi_errno()</CODE>. This error number can be
-converted to a human-readable form by the functions
-<CODE>comedi_perror()</CODE> and <CODE>comedi_strerror()</CODE>.
-<P>These functions are intended to mimic the behavior of the
-standard C library functions <CODE>perror()</CODE>,
-<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
-comedilib functions sometimes return an error that is generated
-inside the C library; the comedi error message in this case
-is the same as the C library.
-<P>The function <CODE>comedi_perror()</CODE> prints an error
-message to stderr. The error message consists of the
-argument string, a colon, a space, a description of the error
-condition, and a new line.
-<P>The function <CODE>comedi_strerror()</CODE> returns a pointer to a
-character string
-describing the comedilib error <CODE>errnum</CODE>. The persistence
-of the returned pointer is undefined, and should not be trusted
-after the next comedilib call. An unrecognized error number will
-return a pointer to the string "undefined error", or similar.
-<P>The function <CODE>comedi_errno()</CODE>
-returns an integer describing the most recent comedilib error. This
-integer may be used as the <CODE>errnum</CODE> parameter for
-<CODE>comedi_strerror()</CODE>.
-<P>
-<P>
-<H2><A NAME="ss6.3">6.3 comedi_fileno()</A>
-</H2>
-<P>
-<P>int comedi_fileno(comedi_t *it);
-<P>The function <CODE>comedi_fileno</CODE>
-returns the integer descriptor for the handle <CODE>it</CODE>. If
-<CODE>it</CODE> is an invalid <CODE>comedi_t</CODE> pointer, the function
-returns -1 and sets the appropriate comedilib error value.
-<P>
-<P>
-<P>
-<H2><A NAME="ss6.4">6.4 comedi_get_n_subdevices()</A>
-</H2>
+<H3><A NAME="comedi_cmd"></A> comedi_cmd</H3>
-<P>
-<P>int comedi_get_n_subdevices(comedi_t *it);
-<P>The function <CODE>comedi_get_n_subdevices</CODE> returns the
-number of subdevices associated with the comedi descriptor
-<CODE>it</CODE>, or -1 if there is an error.
-<P>
-<P>
-<H2><A NAME="ss6.5">6.5 comedi_get_version_code()</A>
-</H2>
-<P>
-<P>int comedi_get_version_code(comedi_t *it);
-<P>The function <CODE>comedi_get_version_code()</CODE> returns the
-version code of the currently running comedi module. The version
-code is of the form 0x010203, which is the version code for
-version 1.2.3.
-<P>
-<P>
-<H2><A NAME="ss6.6">6.6 comedi_get_driver_name()</A>
-</H2>
+<P>undocumented</P>
-<P>
-<P>char *comedi_get_driver_name(comedi_t *it);
-<P>The function <CODE>comedi_get_driver_name</CODE> returns a pointer
-to a string containing the name of the driver being used by comedi
-for the comedi device represented by <CODE>it</CODE>. This pointer is
-valid until the comedi descriptor <CODE>it</CODE> is closed. This
-function returns NULL if there is an error.
-<P>
-<P>
-<H2><A NAME="ss6.7">6.7 comedi_get_board_name()</A>
-</H2>
+<P>Related functions are described in section XXX.</P>
-<P>
-<P>char *comedi_get_board_name(comedi_t *it);
-<P>The function <CODE>comedi_get_board_name</CODE> returns a pointer
-to a string containing the name of the device. This pointer is
-valid until the comedi descriptor <CODE>it</CODE> is closed. This
-function returns NULL if there is an error.
-<P>
-<P>
-<H2><A NAME="ss6.8">6.8 comedi_get_subdevice_type()</A>
-</H2>
+<P>This structure is defined as part of the Comedi kernel interface.</P>
-<P>
-<P>int comedi_get_subdevice_type(comedi_t *it,unsigned int subdevice);
-<P>The function <CODE>comedi_get_subdevice_type()</CODE> returns an
-integer describing the type of subdevice that belongs to the comedi
-device <CODE>it</CODE> and has the index <CODE>subdevice</CODE>. The
-function returns -1 is there is an error.
-<P>Valid subdevice types are:
-<P>
-<UL>
-<LI><CODE>COMEDI_SUBD_UNUSED</CODE>
-Subdevice has no functionality, i.e., a place-holder.</LI>
-<LI><CODE>COMEDI_SUBD_AI</CODE> Analog input</LI>
-<LI><CODE>COMEDI_SUBD_AO</CODE> Analog output</LI>
-<LI><CODE>COMEDI_SUBD_DI</CODE> Digital input</LI>
-<LI><CODE>COMEDI_SUBD_DO</CODE> Digital output</LI>
-<LI><CODE>COMEDI_SUBD_DIO</CODE>
-Digital input/output. Channels are configurable as to whether they
-are inputs or outputs.</LI>
-<LI><CODE>COMEDI_SUBD_COUNTER</CODE> Counter</LI>
-<LI><CODE>COMEDI_SUBD_TIMER</CODE> Timer</LI>
-<LI><CODE>COMEDI_SUBD_MEMORY</CODE>
-Memory, e.g., EEPROM or dual-ported RAM</LI>
-<LI><CODE>COMEDI_SUBD_CALIB</CODE>
-Calibration DACs</LI>
-<LI><CODE>COMEDI_SUBD_PROC</CODE>
-Processor or DSP</LI>
-</UL>
-<P>
-<P>
-<P>
-<H2><A NAME="ss6.9">6.9 comedi_find_subdevice_by_type()</A>
-</H2>
-<P>
-<P>int comedi_find_subdevice_by_type(comedi_t *it,int type,unsigned int start_subdevice)
-<P>The function <CODE>comedi_find_subdevice_by_type</CODE> tries to
-locate a subdevice belonging to comedi device <CODE>it</CODE>,
-having type <CODE>type</CODE>, starting with the subdevice
-<CODE>start_subdevice</CODE>. If it finds the requested subdevice,
-it returns its index. If it does not locate the requested
-subdevice, it returns -1 and sets the comedi error number to
-"subdevice not found". If there is an error, the function
-returns -1 and sets the appropriate error.
-<P>For subdevice types, see the manual page for the function
-<CODE>comedi_get_subdevice_type()</CODE>.
-<P>
-<P>
-<H2><A NAME="ss6.10">6.10 comedi_get_n_channels()</A>
-</H2>
+<H3><A NAME="comedi_insn"></A> comedi_insn</H3>
-<P>
-<P>
-<P>int comedi_get_n_channels(comedi_t *it,unsigned int subdevice);
-<P>The function <CODE>comedi_get_n_channels()</CODE> returns the number
-of channels of the subdevice belonging to the comedi device <CODE>it</CODE>
-and having index <CODE>subdevice</CODE>. This function returns -1 on error.
-<P>
-<P>
-<H2><A NAME="ss6.11">6.11 comedi_get_maxdata()</A>
-</H2>
-<P>
-<P>lsampl_t comedi_get_maxdata(comedi_t *it,unsigned int subdevice,unsigned int chan);
-<P>The function <CODE>comedi_get_maxdata()</CODE> returns the maximum
-valid data value for channel <CODE>chan</CODE> of subdevice
-<CODE>subdevice</CODE> belonging to the comedi device <CODE>it</CODE>
-This function returns 0 on error.
-<P>
-<P>
-<H2><A NAME="ss6.12">6.12 comedi_get_rangetype()</A>
-</H2>
+<P>undocumented</P>
-<P>
-<P>int comedi_get_rangetype(comedi_t *it,unsigned int subdevice,unsigned int chan);
-<P>The function <CODE>comedi_get_rangetype()</CODE> returns an integer
-that represents the number of range specifications available for a
-particular channel, as well as a conversion table to convert sample
-values to/from physical units. The macro
-<CODE>RANGE_LENGTH(rangetype)</CODE>
-can be used to determine the number of range specifications for a given
-range type.
-<P>
-<P>
-<H2><A NAME="ss6.13">6.13 comedi_get_range()</A>
-</H2>
+<P>Related functions are described in section XXX.</P>
-<P>
-<P>comedi_range * comedi_get_range(comedi_t *it,unsigned int subdevice,unsigned int chan,unsigned int range);
-<P>The function <CODE>comedi_get_range</CODE> returns a pointer to a
-comedi_range structure that contains information that can be used to
-convert sample values to or from physical units. The pointer is valid
-until the comedi device <CODE>it</CODE> is closed. If there is an
-error, NULL is returned.
-<P>
-<P>
-<H2><A NAME="ss6.14">6.14 comedi_trigger()</A>
-</H2>
+<P>This structure is defined as part of the Comedi kernel interface.</P>
-<P>
-<P>int comedi_trigger(comedi_t *it,comedi_trig *trig);
-<P>The function <CODE>comedi_trigger()</CODE> instructs comedi to
-perform the command specified by the trigger structure
-<CODE>trig</CODE>. Results depend on the particular command
-being issued. If there is an error, -1 is returned.
-<P>Complete information about comedi commands is given in the
-manual page comedi(8).
-<P>double comedi_to_phys(lsampl_t data,comedi_range *rng,lsampl_t maxdata);
-lsampl_t comedi_from_phys(double data,comedi_range *rng,lsampl_t maxdata);
-<P>The functions <CODE>comedi_to_phys()</CODE> and
-<CODE>comedi_from_phys()</CODE> convert sample values to/from physical
-units. The parameter <CODE>rng</CODE> represents the conversion
-information to use, and the parameter <CODE>maxdata</CODE> represents
-the maximum possible data value for the channel that the data was read/
-will be written to.
-<P>
-<P>
-<P>
-<H2><A NAME="ss6.15">6.15 comedi_data_read()</A>
+
+
+<H3><A NAME="comedi_range"></A> comedi_range</H3>
+
+
+<P>undocumented</P>
+
+
+
+<H2><A NAME="ss6.3">6.3 Functions</A>
</H2>
-<P>
-<P>int comedi_data_read(comedi_t *it,unsigned int subd,unsigned int chan,
-unsigned int range,unsigned int aref,lsampl_t *data);
-int comedi_data_write(comedi_t *it,unsigned int subd,unsigned int chan,
-unsigned int range,unsigned int aref,lsampl_t data);
-<P>These functions read or write a single sample on the channel that
+
+
+<H3><A NAME="comedi_close"></A> comedi_close()</H3>
+
+
+<P><CODE>void comedi_close(comedi_t *it);</CODE></P>
+
+<P>Closes a device previously opened by comedi_open().</P>
+
+<P>The return type of this function will change to <CODE>int</CODE>, in
+order to match <CODE>fclose</CODE>.</P>
+
+<P>Source: <CODE>/lib/comedi.c</CODE></P>
+
+
+<H3><A NAME="comedi_command"></A> comedi_command()</H3>
+
+
+<P><CODE>int comedi_command(comedi_t *it, comedi_cmd *cmd);</CODE></P>
+<P>undocumented</P>
+<P>Source: <CODE>/lib/comedi.c</CODE></P>
+
+
+<H3><A NAME="comedi_command_test"></A> comedi_command_test()</H3>
+
+
+<P><CODE>int comedi_command_test(comedi_t *it, comedi_cmd *cmd);</CODE></P>
+<P>undocumented</P>
+<P>Source: <CODE>/lib/comedi.c</CODE></P>
+
+
+<H3><A NAME="comedi_data_read"></A> comedi_data_read()</H3>
+
+
+<P><CODE>int comedi_data_read(comedi_t *it,unsigned int subd,unsigned int chan,
+unsigned int range,unsigned int aref,lsampl_t *data);</CODE></P>
+
+<P>Reads a single sample on the channel that
is specified by the comedi device <CODE>it</CODE>, the
subdevice <CODE>subd</CODE>, and the channel <CODE>chan</CODE>.
-For the operation,
+For the A/D conversion (if appropriate),
the device is configured to use range specification
<CODE>range</CODE> and (if appropriate) analog reference type
<CODE>aref</CODE>. Analog reference types that are not supported
-by the device are silently ignored.
-<P>The function <CODE>comedi_data_read()</CODE> reads one data value from
-the specified channel and places the
+by the device are silently ignored.</P>
+
+<P><CODE>comedi_data_read()</CODE> reads one data value from
+the specified channel and places the
data value that is read in the location pointed to by
-<CODE>data</CODE>.
-<P>The function <CODE>comedi_data_write()</CODE> writes the data value
+<CODE>data</CODE>.</P>
+
+<P>On sucess, <CODE>comedi_data_read()</CODE> returns 0. If there is an
+error, -1 is returned.</P>
+
+<P>Valid analog reference numbers are:</P>
+<P>
+<UL>
+<LI>AREF_GROUND Reference to analog ground</LI>
+<LI>AREF_COMMON Reference to analog common</LI>
+<LI>AREF_DIFF Differential reference</LI>
+<LI>AREF_OTHER Board-specific meaning</LI>
+</UL>
+</P>
+<P>Valid data values returned by these function is an unsigned integer
+less than or equal to <CODE>maxdata</CODE>, which is channel-dependent.
+Conversion of these data value to physical units can be performed
+by <CODE>
+<A HREF="#comedi_to_phys">comedi_to_phys()</A></CODE>.</P>
+<P>Source: <CODE>/lib/data.c</CODE></P>
+
+
+<H3>comedi_data_write()</H3>
+
+
+<P><CODE>int comedi_data_write(comedi_t *it,unsigned int subd,unsigned int chan,
+unsigned int range,unsigned int aref,lsampl_t data);</CODE></P>
+
+<P>Writes a single sample on the channel that
+is specified by the comedi device <CODE>it</CODE>, the
+subdevice <CODE>subd</CODE>, and the channel <CODE>chan</CODE>.
+For the D/A conversion (if appropriate), the device is
+configured to use range specification
+<CODE>range</CODE> and (if appropriate) analog reference type
+<CODE>aref</CODE>. Analog reference types that are not supported
+by the device are silently ignored.</P>
+<P><CODE>comedi_data_write()</CODE> writes the data value
specified by the argument <CODE>data</CODE> to
-the specified channel.
-<P>On sucess, these functions return 0. If there is an error, -1 is
-returned.
-<P>Valid analog reference numbers are:
+the specified channel.</P>
+<P>On sucess, <CODE>comedi_data_write()</CODE> returns 0. If there is an error, -1 is
+returned.</P>
+<P>Valid analog reference numbers are:</P>
<P>
<UL>
<LI>AREF_GROUND Reference to analog ground</LI>
<LI>AREF_DIFF Differential reference</LI>
<LI>AREF_OTHER Board-specific meaning</LI>
</UL>
+</P>
<P>Valid data values used by these functions is an unsigned integer
less than or equal to <CODE>maxdata</CODE>, which is channel-dependent.
-Conversion of these data values to physical units can be performed
-by <CODE>comedi_to_phys()</CODE> and <CODE>comedi_from_phys()</CODE>.
-<P>
-<P>
-<P>
-<H2><A NAME="ss6.16">6.16 comedi_sv_init()</A>
-</H2>
+Conversion of physical units to these data value can be performed
+by <CODE>
+<A HREF="#comedi_from_phys">comedi_from_phys()</A></CODE>.</P>
+<P>Source: <CODE>/lib/data.c</CODE></P>
-<P>
-<P>
-<BLOCKQUOTE><CODE>
-<PRE>
-int comedi_sv_init(comedi_sv_t *it,comedi_t *dev,unsigned int subd,unsigned int chan);
-int comedi_sv_update(comedi_sv_t *it);
-int comedi_sv_measure(comedi_sv_t *it,double *data);
-</PRE>
-</CODE></BLOCKQUOTE>
-<P>The special functions <CODE>comedi_sv_*()</CODE> are designed to
-make it easy to accurately measure slowly varying analog inputs.
-A slowly
-varying input is one that is effectively constant over the course
-of approximately 100 A/D conversions. However, since these
-conversions can sometimes be pre-empted by scheduling, for most
-purposes, a slowly varying signal should be effectively constant
-for greater than 20 ms (the default Linux timeslice).
-<P>By averaging many A/D conversions of a relatively constant
-signal, it is possible to get a better measurement of the signal
-than a single A/D conversion. In general, the uncertainty of the
-measurement decreases as the square root of the number of samples.
-This is limited by the rate that which the signal varies, and
-ultimately by the spurious free dynamic range of the A/D converter.
-<P>
-<P>
-<P>
-<H2><A NAME="ss6.17">6.17 comedi_get_timer()</A>
-</H2>
+
+<H3>comedi_dio_bitfield();</H3>
+
+<P><CODE>int comedi_dio_bitfield(comedi_t *it,unsigned int subd,unsigned
+int write_mask,unsigned int *bits);</CODE></P>
+
+<P>The function <CODE>comedi_dio_bitfield()</CODE> allows multiple channels to
+be read simultaneously from a digital input or digital I/O device.
+The parameter <CODE>write_mask</CODE> and the value pointed to by <CODE>bits</CODE>
+are interpreted as bit fields, with the least significant bit
+representing channel 0. For each bit in <CODE>write_mask</CODE> that is
+set, the cooresponding bit in <CODE>*bits</CODE> is written to the digital
+output channel. Each digital input channel is read, and the result
+placed in the approprate bits in <CODE>*bits</CODE>.</P>
+
+<P>The current implementation reads and writes bits using separate
+system calls, which is not ideal. When the kernel driver supports
+simultaneous reading/writing, this will be fixed in the library.</P>
+
+<P>It should be noted that it is not possible to access channels
+greater than 31 using this function.</P>
+
+<P>Source: <CODE>/lib/dio.c</CODE></P>
+
+
+
+<H3>comedi_dio_config()</H3>
+
+<P><CODE>int comedi_dio_config(comedi_t *it,unsigned int subd,unsigned
+int chan,unsigned int dir);</CODE></P>
+
+<P>The function <CODE>comedi_dio_config</CODE> configures individual channels
+in a digital I/O subdevice to be either input or output, depending
+on the value of parameter <CODE>dir</CODE>. Depending on the capabilities
+of the hardware device, multiple channels may be affected by
+a single call to <CODE>comedi_dio_config</CODE>.</P>
+
+<P>Valid directions are:
+<UL>
+<LI> COMEDI_INPUT</LI>
+<LI> COMEDI_OUTPUT</LI>
+</UL>
+</P>
+<P>Source: <CODE>/lib/dio.c</CODE></P>
+
+
+
+<H3>comedi_dio_read()</H3>
+
+<P><CODE>int comedi_dio_read(comedi_t *it,unsigned int subd,unsigned int
+chan,unsigned int *bit);</CODE></P>
+
+<P>The function reads the status of channel <CODE>chan</CODE> belonging to the digital
+input subdevice <CODE>subd</CODE> of device <CODE>it</CODE>. The result, 0 or 1, is stored
+in bit. Returns -1 on failure.</P>
+
+<P>This function is equivalent to <CODE>comedi_data_read(it,subd,chan,0,0,bit)</CODE>.</P>
+
+<P>Source: <CODE>/lib/dio.c</CODE></P>
+
+
+<H3>comedi_dio_write()</H3>
+
+<P><CODE>int comedi_dio_write(comedi_t *it,unsigned int subd,unsigned
+int chan,unsigned int bit);</CODE></P>
+
+<P>The function writes the value of <CODE>bit</CODE>, 0 or 1, to channel <CODE>chan</CODE>,
+belonging to the digital output device <CODE>subd</CODE> of device <CODE>it</CODE>. Returns
+-1 on failure.</P>
+
+<P>Source: <CODE>/lib/dio.c</CODE></P>
+
+
+<H3>comedi_fileno()</H3>
+
+
+<P><CODE>int comedi_fileno(comedi_t *it);</CODE></P>
+
+<P>The function <CODE>comedi_fileno</CODE>
+returns the integer descriptor for the handle <CODE>it</CODE>. It
+is equivalent to the standard function <CODE>fileno</CODE>. If
+<CODE>it</CODE> is an invalid <CODE>comedi_t</CODE> pointer, the function
+returns -1 and sets the appropriate libcomedi error value.</P>
+<P>Source: <CODE>/lib/comedi.c</CODE></P>
+
+
+
+<H3>comedi_find_range()</H3>
+
+
+<P><CODE>int comedi_find_range(comedi_t *it, unsigned int subdevice, unsigned
+int chan, unsigned int unit, double min, double max);</CODE></P>
+
+<P>The function <CODE>comedi_find_range</CODE> tries to
+locate the optimal (smallest) range for the channel <CODE>chan</CODE>
+belonging to a <CODE>subdevice</CODE> of the comedi device <CODE>it</CODE>,
+that includes both <CODE>min</CODE> and <CODE>max</CODE> in <CODE>units</CODE>.
+If it finds a matching range, it returns its index. If no
+matching range is available, it returns -1.</P>
+
+<P>Valid units are:</P>
+<P>
+<UL>
+<LI>UNIT_volt</LI>
+<LI>UNIT_mA</LI>
+<LI>UNIT_none</LI>
+</UL>
+</P>
+<P>Source: <CODE>/lib/range.c</CODE></P>
+
+
+
+<H3><A NAME="comedi_errno"></A> comedi_errno()</H3>
+
+<P><CODE>int comedi_errno(void);</CODE></P>
+
+<P>The function <CODE>comedi_errno()</CODE>
+returns an integer describing the most recent comedilib error. This
+integer may be used as the <CODE>errnum</CODE> parameter for
+<CODE>
+<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.</P>
+<P>When a libcomedi function fails, it usually returns -1 or
+NULL, depending on the return type. An internal library
+variable stores an error number, which can be retrieved with
+<CODE>comedi_errno()</CODE>. This error number can be
+converted to a human-readable form by the functions
+<CODE>
+<A HREF="#comedi_perror">comedi_perror()</A></CODE>
+and <CODE>
+<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.</P>
+<P>These functions are intended to mimic the behavior of the
+standard C library functions <CODE>perror()</CODE>,
+<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
+libcomedi functions sometimes return an error that is generated
+by the C library; the Comedi error message in this case
+is the same as the C library.</P>
+<P>Source: <CODE>/lib/error.c</CODE></P>
+
+
+
+<H3>comedi_find_subdevice_by_type()</H3>
+
+
+<P><CODE>int comedi_find_subdevice_by_type(comedi_t *it,int type,unsigned int
+start_subdevice);</CODE></P>
+
+<P>The function <CODE>comedi_find_subdevice_by_type</CODE> tries to
+locate a subdevice belonging to comedi device <CODE>it</CODE>,
+having type <CODE>type</CODE>, starting with the subdevice
+<CODE>start_subdevice</CODE>. If it finds the requested subdevice,
+it returns its index. If it does not locate the requested
+subdevice, it returns -1 and sets the comedi error number to
+"subdevice not found". If there is an error, the function
+returns -1 and sets the appropriate error.</P>
+
+<P>For subdevice types, see the manual page for the function
+<CODE>
+<A HREF="#comedi_get_subdevice_type">comedi_get_subdevice_type()</A></CODE>.</P>
+<P>Source: <CODE>/lib/get.c</CODE></P>
+
+
+
+<H3><A NAME="comedi_from_phys"></A> comedi_from_phys()</H3>
+
+
+<P><CODE>lsampl_t comedi_from_phys(double data, comedi_range *rng,
+lsampl_t maxdata);</CODE></P>
+<P>Converts data given in physical units (<CODE>data</CODE>) into sample values
+(lsampl_t, between 0 and maxdata). The parameter <CODE>rng</CODE>
+represents the conversion information to use, and the parameter
+<CODE>maxdata</CODE> represents the maximum possible data value for the
+channel that the data will be written to.</P>
+
+<P>Source: <CODE>/lib/range.c</CODE></P>
+
+
+
+<H3>comedi_get_board_name()</H3>
+
+
+<P><CODE>char *comedi_get_board_name(comedi_t *it);</CODE></P>
+<P>The function <CODE>comedi_get_board_name</CODE> returns a pointer
+to a string containing the name of the device. This pointer is
+valid until the comedi descriptor <CODE>it</CODE> is closed. This
+function returns <CODE>NULL</CODE> if there is an error.</P>
+<P>Source: <CODE>/lib/get.c</CODE></P>
+
+
+<H3><A NAME="comedi_get_cmd_src_mask"></A> comedi_get_cmd_src_mask()</H3>
+
+
+<P><CODE>int comedi_get_cmd_src_mask(comedi_t *dev, unsigned int subdevice,
+comedi_cmd *cmd);</CODE></P>
+<P>undocumented</P>
+<P>Source: <CODE>/lib/cmd.c</CODE></P>
+
+
+<H3>comedi_get_driver_name()</H3>
+
+
+<P><CODE>char *comedi_get_driver_name(comedi_t *it);</CODE></P>
+<P>The function <CODE>comedi_get_driver_name</CODE> returns a pointer
+to a string containing the name of the driver being used by comedi
+for the comedi device represented by <CODE>it</CODE>. This pointer is
+valid until the comedi descriptor <CODE>it</CODE> is closed. This
+function returns <CODE>NULL</CODE> if there is an error.</P>
+<P>Source: <CODE>/lib/get.c</CODE></P>
+
+
+
+<H3>comedi_get_maxdata()</H3>
+
+
+<P><CODE>lsampl_t comedi_get_maxdata(comedi_t *it,unsigned int
+subdevice,unsigned int chan);</CODE></P>
+
+<P>The function <CODE>comedi_get_maxdata()</CODE> returns the maximum
+valid data value for channel <CODE>chan</CODE> of subdevice
+<CODE>subdevice</CODE> belonging to the comedi device <CODE>it</CODE>
+This function returns 0 on error.</P>
+<P>Source: <CODE>/lib/get.c</CODE></P>
+
+
+
+<H3>comedi_get_n_channels()</H3>
+
+
+<P><CODE>int comedi_get_n_channels(comedi_t *it,unsigned int subdevice);</CODE></P>
+<P>The function <CODE>comedi_get_n_channels()</CODE> returns the number
+of channels of the subdevice belonging to the comedi device <CODE>it</CODE>
+and having index <CODE>subdevice</CODE>. This function returns -1 on error.</P>
+<P>Source: <CODE>/lib/get.c</CODE></P>
+
+
+
+<H3>comedi_get_n_ranges()</H3>
+
+
+<P><CODE>int comedi_get_n_ranges(comedi_t *it,unsigned int subdevice, unsigned int
+chan);</CODE></P>
+<P>The function <CODE>comedi_get_n_ranges()</CODE> returns the number
+of ranges of the channel <CODE>chan</CODE> belonging to the <CODE>subdevice</CODE>
+of the comedi device <CODE>it</CODE>. This function returns -1 on error.</P>
+<P>Source: <CODE>/lib/range.c</CODE></P>
+
+
+
+<H3>comedi_get_n_subdevices()</H3>
+
+
+<P><CODE>int comedi_get_n_subdevices(comedi_t *it);</CODE></P>
+<P>The function <CODE>comedi_get_n_subdevices</CODE> returns the
+number of subdevices associated with the comedi descriptor
+<CODE>it</CODE>, or -1 if there is an error.</P>
+<P>Source: <CODE>/lib/get.c</CODE></P>
+
+
+
+<H3>comedi_get_range()</H3>
+
+
+<P><CODE>comedi_range * comedi_get_range(comedi_t *it,unsigned int subdevice,unsigned int chan,unsigned int
+range);</CODE></P>
+<P>The function <CODE>comedi_get_range</CODE> returns a pointer to a
+comedi_range structure that contains information that can be used to
+convert sample values to or from physical units. The pointer is valid
+until the comedi device <CODE>it</CODE> is closed. If there is an
+error, NULL is returned.</P>
+<P>Source: <CODE>/lib/get.c</CODE></P>
+
+
+<H3>comedi_get_rangetype() <I>deprecated</I></H3>
+
+
+<P><CODE>int comedi_get_rangetype(comedi_t *it,unsigned int subdevice,unsigned int
+chan);</CODE></P>
+<P>The function <CODE>comedi_get_rangetype()</CODE> returns an integer
+that represents the number of range specifications available for a
+particular channel <CODE>chan</CODE> of the subdevice <CODE>subdevice</CODE>, as well as a conversion table to convert sample
+values to/from physical units.</P>
+<P>The macro
+<CODE>RANGE_LENGTH(rangetype)</CODE>
+can be used to determine the number of range specifications for a given
+range type.</P>
+
+<P>This function is deprecated and should not be used in new code.</P>
+<P>Source: <CODE>/lib/get.c</CODE></P>
+
+
+<H3><A NAME="comedi_get_subdevice_type"></A> comedi_get_subdevice_type()</H3>
+
+
+<P><CODE>int comedi_get_subdevice_type(comedi_t *it,unsigned int subdevice);</CODE></P>
+<P>The function <CODE>comedi_get_subdevice_type()</CODE> returns an
+integer describing the type of subdevice that belongs to the comedi
+device <CODE>it</CODE> and has the index <CODE>subdevice</CODE>. The
+function returns -1 is there is an error.</P>
+<P>Valid subdevice types are:</P>
<P>
+<UL>
+<LI><CODE>COMEDI_SUBD_UNUSED</CODE>
+Subdevice has no functionality, i.e., a place-holder.</LI>
+<LI><CODE>COMEDI_SUBD_AI</CODE> Analog input</LI>
+<LI><CODE>COMEDI_SUBD_AO</CODE> Analog output</LI>
+<LI><CODE>COMEDI_SUBD_DI</CODE> Digital input</LI>
+<LI><CODE>COMEDI_SUBD_DO</CODE> Digital output</LI>
+<LI><CODE>COMEDI_SUBD_DIO</CODE>
+Digital input/output. Channels are configurable as to whether they
+are inputs or outputs.</LI>
+<LI><CODE>COMEDI_SUBD_COUNTER</CODE> Counter</LI>
+<LI><CODE>COMEDI_SUBD_TIMER</CODE> Timer</LI>
+<LI><CODE>COMEDI_SUBD_MEMORY</CODE>
+Memory, e.g., EEPROM or dual-ported RAM</LI>
+<LI><CODE>COMEDI_SUBD_CALIB</CODE>
+Calibration DACs</LI>
+<LI><CODE>COMEDI_SUBD_PROC</CODE>
+Processor or DSP</LI>
+</UL>
+</P>
+<P>Source: <CODE>/lib/get.c</CODE></P>
+
+
+<H3>comedi_get_timer() <I>(deprecated)</I></H3>
+
+
+<P><CODE>int comedi_get_timer(comedi_t *it,unsigned int subdev, double
+freq,unsigned int *trigvar, double *actual_freq);</CODE></P>
+
+<P>The function <CODE>comedi_get_timer</CODE> converts the frequency <CODE>freq</CODE>
+to a number suitable to send to the driver in a <CODE>comedi_trig</CODE>
+structure. This function remains for compatibility with very
+old versions of Comedi, that converted sampling rates to timer
+values in the libary. This conversion is now done in the kernel,
+and every device has the timer type <CODE>nanosec_timer</CODE>, indicating
+that timer values are simply a time specified in nanoseconds.</P>
+
+<P>This function is deprecated and should not be used in new applications.</P>
+
+<P>Source: <CODE>/lib/timer.c</CODE></P>
+
+
+<H3>comedi_get_version_code()</H3>
+
+
+<P><CODE>int comedi_get_version_code(comedi_t *it);</CODE></P>
+
+<P>The function <CODE>comedi_get_version_code()</CODE> returns the
+version code of the currently running comedi module. The version
+code is of the form 0x01072b, which is the version code for
+version 1.7.43.</P>
+
+<P>This function is of limited usefulness. A typical mis-application
+of this function is to use it to determine if a certain feature is
+supported. If the application needs
+to know of the existence of a particular feature, an existence
+test function should be written and put in the libcomedi source.</P>
+<P>Source: <CODE>/lib/get.c</CODE></P>
+
+
+<H3>comedi_loglevel()</H3>
+
+
+<P><CODE>int comedi_loglevel(int loglevel);</CODE></P>
+
+<P>This function affects the output of debugging and error messages
+from libcomedi. By increasing the loglevel, additional debugging
+information will be printed. This function returns the previous
+loglevel. Error messages and debugging are printed to the
+stream <CODE>stderr</CODE>. The loglevel can also be affected by the
+environment variable COMEDI_LOGLEVEL.</P>
+
+<P>In order to conserve resources, some debugging information is
+disabled when libcomedi is compiled.</P>
+
+<P>The meaning of the loglevels is as follows:</P>
<P>
-<BLOCKQUOTE><CODE>
-<PRE>
-int comedi_get_timer(comedi_t *it,unsigned int subdev,double freq,unsigned int *trigvar,
- double *actual_freq);
-</PRE>
-</CODE></BLOCKQUOTE>
-<P>
-<P>
+<UL>
+<LI><CODE>COMEDILIB_LOGLEVEL=0</CODE>
+
+Comedilib prints nothing.
+</LI>
+<LI><CODE>COMEDILIB_LOGLEVEL=1</CODE> (default)
+
+Comedilib only prints error messages when there is a
+self-consistency error (i.e., internal bug).
+</LI>
+<LI><CODE>COMEDILIB_LOGLEVEL=2</CODE>
+
+Comedilib prints an error message when an invalid
+parameter is passed to comedilib.
+</LI>
+<LI><CODE>COMEDILIB_LOGLEVEL=3</CODE>
+
+Comedilib prints an error message whenever an error is generated
+in the comedilib library or is generated in the C library when
+called by comedilib.
+</LI>
+<LI><CODE>COMEDILIB_LOGLEVEL=4</CODE>
+
+Comedilib prints a lot of debugging messages.
+</LI>
+</UL>
+</P>
+<P>Bugs: Libcomedi doesn't currently have much debugging information.</P>
+<P>Source: <CODE>/lib/error.c</CODE></P>
+
+
+<H3>comedi_open()</H3>
+
+
+<P><CODE>comedi_t *comedi_open(char *filename);</CODE></P>
+<P>Opens a comedi device specified by the filename <CODE>filename</CODE>.
+Returns NULL on error. On sucess, it returns a handle that is
+given as a parameter to other libcomedi functions.</P>
+
+<P>You are not supposed to have access to the internals of the
+<CODE>comedi_t</CODE> structure.</P>
+<P>Bugs: Not strictly identical to <CODE>fopen</CODE></P>
+<P>Source: <CODE>/lib/comedi.c</CODE></P>
+
+
+
+<H3><A NAME="comedi_perror"></A> comedi_perror()</H3>
+
+
+<P><CODE>void comedi_perror(const char *s);</CODE></P>
+<P>When a comedilib function fails, it usually returns -1 or
+NULL, depending on the return type. An internal library
+variable stores an error number, which can be retrieved with
+<CODE>
+<A HREF="#comedi_errno">comedi_errno()</A></CODE>.
+This error number can be
+converted to a human-readable form by the functions
+<CODE>comedi_perror()</CODE>
+and <CODE>
+<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.</P>
+<P>These functions are intended to mimic the behavior of the
+standard C library functions <CODE>perror()</CODE>,
+<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
+comedilib functions sometimes return an error that is generated
+inside the C library; the comedi error message in this case
+is the same as the C library.</P>
+<P>The function <CODE>comedi_perror()</CODE> prints an error
+message to stderr. The error message consists of the
+argument string, a colon, a space, a description of the error
+condition, and a new line.</P>
+<P>Bugs: Does not support internationalization.</P>
+<P>Source: <CODE>/lib/error.c</CODE></P>
+
+
+
+<H3><A NAME="comedi_strerror"></A> comedi_strerror()</H3>
+
+
+<P><CODE>*comedi_strerror(int errnum);</CODE></P>
+<P>When a comedilib function fails, it usually returns -1 or
+NULL, depending on the return type. An internal library
+variable stores an error number, which can be retrieved with
+<CODE>
+<A HREF="#comedi_errno">comedi_errno()</A></CODE>. This error number can be
+converted to a human-readable form by the functions
+<CODE>
+<A HREF="#comedi_perror">comedi_perror()</A></CODE>
+and <CODE>comedi_strerror()</CODE>.</P>
+<P>These functions are intended to mimic the behavior of the
+standard C library functions <CODE>perror()</CODE>,
+<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
+comedilib functions sometimes return an error that is generated
+inside the C library; the comedi error message in this case
+is the same as the C library.</P>
+<P>The function <CODE>comedi_strerror()</CODE> returns a pointer to a
+character string
+describing the comedilib error <CODE>errnum</CODE>. The persistence
+of the returned pointer is undefined, and should not be trusted
+after the next libcomedi call. An unrecognized error number will
+return a pointer to the string "undefined error", or similar.</P>
+<P>Bugs: Does not support internationalization.</P>
+<P>Source: <CODE>/lib/error.c</CODE></P>
+
+
+
+<H3>comedi_sv_init()</H3>
+
+
+<P><CODE>int comedi_sv_init(comedi_sv_t *sv,comedi_t *dev,unsigned int subd,
+unsigned int chan);</CODE></P>
+
+<P><CODE>comedi_sv_init</CODE> initializes the slow varying comedi structure
+<CODE>sv</CODE> of the device <CODE>dev</CODE>, the subdevice <CODE>subd</CODE> (analog input) and
+the channel <CODE>chan</CODE>.
+The slow varying comedi structure <CODE>sv</CODE> of type <CODE>
+<A HREF="#comedi_sv_t">comedi_sv_t</A></CODE>
+specifies the signal measurement. The default number of averaged
+samples is 100. Returns zero on success, -1 on error.</P>
+<P>Bugs: comedi_sv_* was very poorly designed.</P>
+<P>Source: <CODE>/lib/sv.c</CODE></P>
+
+
+
+<H3>comedi_sv_update()</H3>
+
+
+<P><CODE>int comedi_sv_update(comedi_sv_t *sv);</CODE></P>
+<P>The function <CODE>comedi_sv_update</CODE> updates the slow varying comedi structure
+<CODE>sv</CODE>.
+Returns zero on success, -1 on error.</P>
+<P>Source: <CODE>/lib/sv.c</CODE></P>
+
+
+
+<H3>int comedi_sv_measure()</H3>
+
+
+<P><CODE>int comedi_sv_measure(comedi_sv_t *it,double *data);</CODE></P>
+<P><CODE>comedi_sv_measure</CODE> measures the slow variing signal. The measurement
+is specified by the slow varying comedi structure <CODE>sv</CODE>, the result is
+stored in <CODE>data</CODE>.
+On success returns the number of samples, -1 on error.</P>
+<P>Source: <CODE>/lib/sv.c</CODE></P>
+
+
+
+<H3><A NAME="comedi_to_phys"></A> comedi_to_phys()</H3>
+
+
+<P><CODE>double comedi_to_phys(lsampl_t data, comedi_range *rng,
+lsampl_t maxdata);</CODE></P>
+<P>Converts data given in sample values (lsampl_t, between 0 and
+maxdata) into physical units (double). The parameter <CODE>rng</CODE>
+represents the conversion information to use, and the parameter
+<CODE>maxdata</CODE> represents the maximum possible data value for the
+channel that the data was read.</P>
+<P>Source: <CODE>/lib/range.c</CODE></P>
+
+
+
+<H3>comedi_trigger() <I>(deprecated)</I></H3>
+
+
+<P><CODE>int comedi_trigger(comedi_t *it,comedi_trig *trig);</CODE></P>
+<P>The function <CODE>comedi_trigger</CODE> instructs comedi to
+perform the command specified by the
+<A HREF="#comedi_trig_struct">trigger structure</A> <CODE>trig</CODE>. Results depend on
+the particular command being issued. If there is an
+error, -1 is returned.</P>
+<P>Lifetime: removal at 1.0.</P>
+<P>Source: <CODE>/lib/comedi.c</CODE></P>
+
+
+
+<H3><A NAME="comedi_get_subdevice_flags"></A> comedi_get_subdevice_flags()</H3>
+
+
+<P><CODE>int comedi_get_subdevice_flags(comedi_t *dev, unsigned int subdevice);</CODE></P>
+
+<P>This function returns a bitfield describing the capabilities of the
+specified subdevice. If there is an error, -1 is returned.</P>
+
+<P>The bits are:</P>
<P>
+<UL>
+<LI>SDF_BUSY subdevice is running a command</LI>
+<LI>SDF_BUSY_OWNER subdevice is running a command started by
+the file descriptor used by <CODE>dev</CODE>.</LI>
+<LI>SDF_LOCKED subdevice is locked</LI>
+<LI>SDF_LOCKED_OWNER subdevice is locked by the file descriptor used
+by <CODE>dev</CODE>.</LI>
+<LI>SDF_MAXDATA maximum data values are channel dependent</LI>
+<LI>SDF_FLAGS channel flags are channel dependent</LI>
+<LI>SDF_RANGETYPE range types are channel dependent</LI>
+<LI>SDF_MODE0 deprecated</LI>
+<LI>SDF_MODE1 deprecated</LI>
+<LI>SDF_MODE2 deprecated</LI>
+<LI>SDF_MODE3 deprecated</LI>
+<LI>SDF_MODE4 deprecated</LI>
+<LI>SDF_CMD subdevice supports commands</LI>
+<LI>SDF_READABLE subdevice can be read from</LI>
+<LI>SDF_WRITEABLE subdevice can be written to</LI>
+<LI>SDF_RT deprecated</LI>
+<LI>SDF_GROUND subdevice is capable of ground analog reference</LI>
+<LI>SDF_COMMON subdevice is capable of common analog reference</LI>
+<LI>SDF_DIFF subdevice is capable of differential analog reference</LI>
+<LI>SDF_OTHER subdevice is capable of other analog reference</LI>
+<LI>SDF_DITHER subdevice recognizes dither flag</LI>
+<LI>SDF_DEGLITCH subdevice recognizes deglitch flag</LI>
+<LI>SDF_MMAP deprecated</LI>
+<LI>SDF_RUNNING subdevice is acquiring data (i.e., command has not
+completed)</LI>
+<LI>SDF_LSAMPL subdevice uses samples of type lsampl_t (otherwise
+sampl_t)</LI>
+<LI>SDF_PACKED subdevice uses bitfield samples (otherwise it uses
+one sample per channel)</LI>
+</UL>
+</P>
+
+
+
+<P>The bit definitions are part of the Comedi kernel interface.</P>
+
+
+
+<H3><A NAME="comedi_range_is_chan_specific"></A> comedi_range_is_chan_specific()</H3>
+
+
+<P><CODE>int comedi_range_is_chan_specific(comedi_t *dev,unsigned int subdevice);</CODE></P>
+
+<P>If each channel of the specified subdevice has a different range
+specification, this function returns 1. Otherwise, this function
+returns 0. On error, this function returns -1.</P>
+
+
+
+<H3><A NAME="undocumented"></A> Undocumented functions</H3>
+
+
+
<P>
+<UL>
+<LI>comedi_maxdata_is_chan_specific()</LI>
+<LI>comedi_get_buffer_size()</LI>
+<LI>comedi_get_max_buffer_size()</LI>
+<LI>comedi_set_buffer_size()</LI>
+<LI>comedi_set_max_buffer_size()</LI>
+<LI>comedi_do_insnlist()</LI>
+<LI>comedi_do_insn()</LI>
+<LI>comedi_lock()</LI>
+<LI>comedi_unlock()</LI>
+<LI>comedi_get_cmd_src_mask()</LI>
+<LI>comedi_get_cmd_generic_timed()</LI>
+<LI>comedi_cancel()</LI>
+<LI>comedi_command()</LI>
+<LI>comedi_command_test()</LI>
+<LI>comedi_poll()</LI>
+<LI>comedi_get_buffer_contents()</LI>
+<LI>comedi_mark_buffer_read()</LI>
+<LI>comedi_get_buffer_offset()</LI>
+<LI>comedi_set_global_oor_behavior()</LI>
+</UL>
+</P>
+
+
<HR>
Next
<A HREF="comedilib-5.html">Previous</A>
<HR>
<H1>Comedi Documentation</H1>
-<H2>David Schleef, <CODE>ds@stm.lbl.gov</CODE></H2>
+<H2>David Schleef <CODE>ds@stm.lbl.gov</CODE>,
+Frank Hess <CODE>fmhess@uiuc.edu</CODE></H2>
<P>
<H2><A NAME="toc1">1.</A> <A HREF="comedilib-1.html">Introduction</A></H2>
<P>
<H2><A NAME="toc5">5.</A> <A HREF="comedilib-5.html">Application-specific functions</A></H2>
+<P>
+<H2><A NAME="toc6">6.</A> <A HREF="comedilib-6.html">Libcomedi Reference</A></H2>
+
<HR>
<A HREF="comedilib-1.html">Next</A>
Previous
+++ /dev/null
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
-<HTML>
-<HEAD>
- <META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.7.4">
- <TITLE>Comedi Documentation: Libcomedi Reference</TITLE>
-
- <LINK HREF="comedilib_reference.html#toc1" REL=contents>
-</HEAD>
-<BODY>
-Next
-Previous
-<A HREF="comedilib_reference.html#toc1">Contents</A>
-<HR>
-<H2><A NAME="s1">1.</A> <A HREF="comedilib_reference.html#toc1">Libcomedi Reference</A></H2>
-
-
-
-<H2><A NAME="ss1.1">1.1 Constants and Macros</A>
-</H2>
-
-
-
-
-<H3>RANGE_LENGTH() <I>(deprecated)</I></H3>
-
-<P>
-<A NAME="RANGE_LENGTH"></A> </P>
-<P><CODE>RANGE_LENGTH(rangetype)</CODE></P>
-
-<P>Rangetype values are library-internal tokens that represent an
-array of range information structures. These numbers are primarily
-used for communication between the kernel and library.</P>
-
-<P>The RANGE_LENGTH() macro returns the length of the array that is
-specified by the rangetype token.</P>
-
-<P>The RANGE_LENGTH() macro is deprecated, and should not be used in
-new applications. It is scheduled to be removed from the header
-file at version 1.0. Binary compatibility may be broken for version
-1.1.</P>
-
-
-
-<H2><A NAME="ss1.2">1.2 Data Types and Structures</A>
-</H2>
-
-
-<H3><A NAME="comedi_t"></A> comedi_t</H3>
-
-<P>The data type <CODE>comedi_t</CODE> is used to represent an open Comedi
-device. A valid <CODE>comedi_t</CODE> pointer is returned by a successful
-call to <CODE>comedi_open()</CODE>, and should be used for subsequent
-access to the device.
-It is a transparent type, and pointers to type <CODE>comedi_t</CODE>
-should not be dereferenced by the application.</P>
-
-
-
-<H3><A NAME="sampl_t"></A> sampl_t</H3>
-
-<P>The data type <CODE>sampl_t</CODE> is one of the generic types used to represent
-data values in libcomedi. It is used in a few places where a shorter
-data type is useful, but is limited to 16 bits on the i386 architecture.</P>
-
-
-
-<H3><A NAME="lsampl_t"></A> lsampl_t</H3>
-
-<P>The data type <CODE>lsampl_t</CODE> is one of the generic types used to represent
-data values in libcomedi. It is currently defined to be <CODE>unsigned int</CODE>.</P>
-
-
-
-
-
-<H3><A NAME="comedi_trig_struct"></A> comedi_trig_struct <I>(deprecated)</I></H3>
-
-
-<P>The <CODE>comedi_trig</CODE> structure</P>
-<P>
-<BLOCKQUOTE><CODE>
-<PRE>
-struct comedi_trig_struct{
- unsigned int subdev; /* subdevice */
- unsigned int mode; /* mode */
- unsigned int flags;
- unsigned int n_chan; /* number of channels */
- unsigned int *chanlist; /* channel/range list */
- sampl_t *data; /* data list, size depends on subd flags */
- unsigned int n; /* number of scans */
- unsigned int trigsrc;
- unsigned int trigvar;
- unsigned int trigvar1;
- unsigned int data_len;
- unsigned int unused[3];
-}
-</PRE>
-</CODE></BLOCKQUOTE>
-</P>
-<P>The <CODE>comedi_trig</CODE> structure is a control structure used by the
-COMEDI_TRIG ioctl, an older method of communicating
-instructions to the driver and hardware. Use of comedi_trig is
-deprecated, and should not be used in new applications.</P>
-
-<P>This structure is defined as part of the Comedi kernel interface.</P>
-
-
-<H3><A NAME="comedi_sv_t"></A> comedi_sv_t</H3>
-
-
-<P>
-<BLOCKQUOTE><CODE>
-<PRE>
-struct comedi_sv_struct{
- comedi_t *dev;
- unsigned int subdevice;
- unsigned int chan;
-
- /* range policy */
- int range;
- int aref;
-
- /* number of measurements to average (for ai) */
- int n;
-
- lsampl_t maxdata;
-}
-</PRE>
-</CODE></BLOCKQUOTE>
-</P>
-<P>The <CODE>comedi_sv_t</CODE> structure is used by the <CODE>comedi_sv_*()</CODE>
-functions to provide a simple method of accurately measuring
-slowly varying inputs. See the relevant section for more
-details.</P>
-
-
-
-<H3><A NAME="comedi_cmd"></A> comedi_cmd</H3>
-
-
-<P>undocumented</P>
-
-<P>Related functions are described in section XXX.</P>
-
-<P>This structure is defined as part of the Comedi kernel interface.</P>
-
-
-<H3><A NAME="comedi_insn"></A> comedi_insn</H3>
-
-
-<P>undocumented</P>
-
-<P>Related functions are described in section XXX.</P>
-
-<P>This structure is defined as part of the Comedi kernel interface.</P>
-
-
-
-<H3><A NAME="comedi_range"></A> comedi_range</H3>
-
-
-<P>undocumented</P>
-
-
-
-<H2><A NAME="ss1.3">1.3 Functions</A>
-</H2>
-
-
-
-<H3><A NAME="comedi_close"></A> comedi_close()</H3>
-
-
-<P><CODE>void comedi_close(comedi_t *it);</CODE></P>
-
-<P>Closes a device previously opened by comedi_open().</P>
-
-<P>The return type of this function will change to <CODE>int</CODE>, in
-order to match <CODE>fclose</CODE>.</P>
-
-<P>Source: <CODE>/lib/comedi.c</CODE></P>
-
-
-<H3><A NAME="comedi_data_read"></A> comedi_data_read()</H3>
-
-
-<P><CODE>int comedi_data_read(comedi_t *it,unsigned int subd,unsigned int chan,
-unsigned int range,unsigned int aref,lsampl_t *data);</CODE></P>
-
-<P>Reads a single sample on the channel that
-is specified by the comedi device <CODE>it</CODE>, the
-subdevice <CODE>subd</CODE>, and the channel <CODE>chan</CODE>.
-For the A/D conversion (if appropriate),
-the device is configured to use range specification
-<CODE>range</CODE> and (if appropriate) analog reference type
-<CODE>aref</CODE>. Analog reference types that are not supported
-by the device are silently ignored.</P>
-
-<P><CODE>comedi_data_read()</CODE> reads one data value from
-the specified channel and places the
-data value that is read in the location pointed to by
-<CODE>data</CODE>.</P>
-
-<P>On sucess, <CODE>comedi_data_read()</CODE> returns 0. If there is an
-error, -1 is returned.</P>
-
-<P>Valid analog reference numbers are:</P>
-<P>
-<UL>
-<LI>AREF_GROUND Reference to analog ground</LI>
-<LI>AREF_COMMON Reference to analog common</LI>
-<LI>AREF_DIFF Differential reference</LI>
-<LI>AREF_OTHER Board-specific meaning</LI>
-</UL>
-</P>
-<P>Valid data values returned by these function is an unsigned integer
-less than or equal to <CODE>maxdata</CODE>, which is channel-dependent.
-Conversion of these data value to physical units can be performed
-by <CODE>
-<A HREF="#comedi_to_phys">comedi_to_phys()</A></CODE>.</P>
-<P>Source: <CODE>/lib/data.c</CODE></P>
-
-
-<H3>comedi_data_write()</H3>
-
-
-<P><CODE>int comedi_data_write(comedi_t *it,unsigned int subd,unsigned int chan,
-unsigned int range,unsigned int aref,lsampl_t data);</CODE></P>
-
-<P>Writes a single sample on the channel that
-is specified by the comedi device <CODE>it</CODE>, the
-subdevice <CODE>subd</CODE>, and the channel <CODE>chan</CODE>.
-For the D/A conversion (if appropriate), the device is
-configured to use range specification
-<CODE>range</CODE> and (if appropriate) analog reference type
-<CODE>aref</CODE>. Analog reference types that are not supported
-by the device are silently ignored.</P>
-<P><CODE>comedi_data_write()</CODE> writes the data value
-specified by the argument <CODE>data</CODE> to
-the specified channel.</P>
-<P>On sucess, <CODE>comedi_data_write()</CODE> returns 0. If there is an error, -1 is
-returned.</P>
-<P>Valid analog reference numbers are:</P>
-<P>
-<UL>
-<LI>AREF_GROUND Reference to analog ground</LI>
-<LI>AREF_COMMON Reference to analog common</LI>
-<LI>AREF_DIFF Differential reference</LI>
-<LI>AREF_OTHER Board-specific meaning</LI>
-</UL>
-</P>
-<P>Valid data values used by these functions is an unsigned integer
-less than or equal to <CODE>maxdata</CODE>, which is channel-dependent.
-Conversion of physical units to these data value can be performed
-by <CODE>
-<A HREF="#comedi_from_phys">comedi_from_phys()</A></CODE>.</P>
-<P>Source: <CODE>/lib/data.c</CODE></P>
-
-
-
-<H3>comedi_dio_bitfield();</H3>
-
-<P><CODE>int comedi_dio_bitfield(comedi_t *it,unsigned int subd,unsigned
-int write_mask,unsigned int *bits);</CODE></P>
-
-<P>The function <CODE>comedi_dio_bitfield()</CODE> allows multiple channels to
-be read simultaneously from a digital input or digital I/O device.
-The parameter <CODE>write_mask</CODE> and the value pointed to by <CODE>bits</CODE>
-are interpreted as bit fields, with the least significant bit
-representing channel 0. For each bit in <CODE>write_mask</CODE> that is
-set, the cooresponding bit in <CODE>*bits</CODE> is written to the digital
-output channel. Each digital input channel is read, and the result
-placed in the approprate bits in <CODE>*bits</CODE>.</P>
-
-<P>The current implementation reads and writes bits using separate
-system calls, which is not ideal. When the kernel driver supports
-simultaneous reading/writing, this will be fixed in the library.</P>
-
-<P>It should be noted that it is not possible to access channels
-greater than 31 using this function.</P>
-
-<P>Source: <CODE>/lib/dio.c</CODE></P>
-
-
-
-<H3>comedi_dio_config()</H3>
-
-<P><CODE>int comedi_dio_config(comedi_t *it,unsigned int subd,unsigned
-int chan,unsigned int dir);</CODE></P>
-
-<P>The function <CODE>comedi_dio_config</CODE> configures individual channels
-in a digital I/O subdevice to be either input or output, depending
-on the value of parameter <CODE>dir</CODE>. Depending on the capabilities
-of the hardware device, multiple channels may be affected by
-a single call to <CODE>comedi_dio_config</CODE>.</P>
-
-<P>Valid directions are:
-<UL>
-<LI> COMEDI_INPUT</LI>
-<LI> COMEDI_OUTPUT</LI>
-</UL>
-</P>
-<P>Source: <CODE>/lib/dio.c</CODE></P>
-
-
-
-<H3>comedi_dio_read()</H3>
-
-<P><CODE>int comedi_dio_read(comedi_t *it,unsigned int subd,unsigned int
-chan,unsigned int *bit);</CODE></P>
-
-<P>The function reads the status of channel <CODE>chan</CODE> belonging to the digital
-input subdevice <CODE>subd</CODE> of device <CODE>it</CODE>. The result, 0 or 1, is stored
-in bit. Returns -1 on failure.</P>
-
-<P>This function is equivalent to <CODE>comedi_data_read(it,subd,chan,0,0,bit)</CODE>.</P>
-
-<P>Source: <CODE>/lib/dio.c</CODE></P>
-
-
-<H3>comedi_dio_write()</H3>
-
-<P><CODE>int comedi_dio_write(comedi_t *it,unsigned int subd,unsigned
-int chan,unsigned int bit);</CODE></P>
-
-<P>The function writes the value of <CODE>bit</CODE>, 0 or 1, to channel <CODE>chan</CODE>,
-belonging to the digital output device <CODE>subd</CODE> of device <CODE>it</CODE>. Returns
--1 on failure.</P>
-
-<P>Source: <CODE>/lib/dio.c</CODE></P>
-
-
-<H3>comedi_fileno()</H3>
-
-
-<P><CODE>int comedi_fileno(comedi_t *it);</CODE></P>
-
-<P>The function <CODE>comedi_fileno</CODE>
-returns the integer descriptor for the handle <CODE>it</CODE>. It
-is equivalent to the standard function <CODE>fileno</CODE>. If
-<CODE>it</CODE> is an invalid <CODE>comedi_t</CODE> pointer, the function
-returns -1 and sets the appropriate libcomedi error value.</P>
-<P>Source: <CODE>/lib/comedi.c</CODE></P>
-
-
-
-<H3>comedi_find_range()</H3>
-
-
-<P><CODE>int comedi_find_range(comedi_t *it, unsigned int subdevice, unsigned
-int chan, unsigned int unit, double min, double max);</CODE></P>
-
-<P>The function <CODE>comedi_find_range</CODE> tries to
-locate the optimal (smallest) range for the channel <CODE>chan</CODE>
-belonging to a <CODE>subdevice</CODE> of the comedi device <CODE>it</CODE>,
-that includes both <CODE>min</CODE> and <CODE>max</CODE> in <CODE>units</CODE>.
-If it finds a matching range, it returns its index. If no
-matching range is available, it returns -1.</P>
-
-<P>Valid units are:</P>
-<P>
-<UL>
-<LI>UNIT_volt </LI>
-<LI>UNIT_mA</LI>
-<LI>UNIT_none</LI>
-</UL>
-</P>
-<P>Source: <CODE>/lib/range.c</CODE></P>
-
-
-
-<H3><A NAME="comedi_errno"></A> comedi_errno()</H3>
-
-<P><CODE>int comedi_errno(void);</CODE></P>
-
-<P>The function <CODE>comedi_errno()</CODE>
-returns an integer describing the most recent comedilib error. This
-integer may be used as the <CODE>errnum</CODE> parameter for
-<CODE>
-<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.</P>
-<P>When a libcomedi function fails, it usually returns -1 or
-NULL, depending on the return type. An internal library
-variable stores an error number, which can be retrieved with
-<CODE>comedi_errno()</CODE>. This error number can be
-converted to a human-readable form by the functions
-<CODE>
-<A HREF="#comedi_perror">comedi_perror()</A></CODE>
-and <CODE>
-<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.</P>
-<P>These functions are intended to mimic the behavior of the
-standard C library functions <CODE>perror()</CODE>,
-<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
-libcomedi functions sometimes return an error that is generated
-by the C library; the Comedi error message in this case
-is the same as the C library.</P>
-<P>Source: <CODE>/lib/error.c</CODE></P>
-
-
-
-<H3>comedi_find_subdevice_by_type()</H3>
-
-
-<P><CODE>int comedi_find_subdevice_by_type(comedi_t *it,int type,unsigned int
-start_subdevice);</CODE></P>
-
-<P>The function <CODE>comedi_find_subdevice_by_type</CODE> tries to
-locate a subdevice belonging to comedi device <CODE>it</CODE>,
-having type <CODE>type</CODE>, starting with the subdevice
-<CODE>start_subdevice</CODE>. If it finds the requested subdevice,
-it returns its index. If it does not locate the requested
-subdevice, it returns -1 and sets the comedi error number to
-"subdevice not found". If there is an error, the function
-returns -1 and sets the appropriate error.</P>
-
-<P>For subdevice types, see the manual page for the function
-<CODE>
-<A HREF="#comedi_get_subdevice_type">comedi_get_subdevice_type()</A></CODE>.</P>
-<P>Source: <CODE>/lib/get.c</CODE></P>
-
-
-
-<H3><A NAME="comedi_from_phys"></A> comedi_from_phys()</H3>
-
-
-<P><CODE>lsampl_t comedi_from_phys(double data, comedi_range *rng,
-lsampl_t maxdata);</CODE></P>
-<P>Converts data given in physical units (<CODE>data</CODE>) into sample values
-(lsampl_t, between 0 and maxdata). The parameter <CODE>rng</CODE>
-represents the conversion information to use, and the parameter
-<CODE>maxdata</CODE> represents the maximum possible data value for the
-channel that the data will be written to.</P>
-
-<P>Source: <CODE>/lib/range.c</CODE></P>
-
-
-
-<H3>comedi_get_board_name()</H3>
-
-
-<P><CODE>char *comedi_get_board_name(comedi_t *it);</CODE></P>
-<P>The function <CODE>comedi_get_board_name</CODE> returns a pointer
-to a string containing the name of the device. This pointer is
-valid until the comedi descriptor <CODE>it</CODE> is closed. This
-function returns <CODE>NULL</CODE> if there is an error.</P>
-<P>Source: <CODE>/lib/get.c</CODE></P>
-
-
-
-<H3>comedi_get_driver_name()</H3>
-
-
-<P><CODE>char *comedi_get_driver_name(comedi_t *it);</CODE></P>
-<P>The function <CODE>comedi_get_driver_name</CODE> returns a pointer
-to a string containing the name of the driver being used by comedi
-for the comedi device represented by <CODE>it</CODE>. This pointer is
-valid until the comedi descriptor <CODE>it</CODE> is closed. This
-function returns <CODE>NULL</CODE> if there is an error.</P>
-<P>Source: <CODE>/lib/get.c</CODE></P>
-
-
-
-<H3>comedi_get_maxdata()</H3>
-
-
-<P><CODE>lsampl_t comedi_get_maxdata(comedi_t *it,unsigned int
-subdevice,unsigned int chan);</CODE></P>
-
-<P>The function <CODE>comedi_get_maxdata()</CODE> returns the maximum
-valid data value for channel <CODE>chan</CODE> of subdevice
-<CODE>subdevice</CODE> belonging to the comedi device <CODE>it</CODE>
-This function returns 0 on error.</P>
-<P>Source: <CODE>/lib/get.c</CODE></P>
-
-
-
-<H3>comedi_get_n_channels()</H3>
-
-
-<P><CODE>int comedi_get_n_channels(comedi_t *it,unsigned int subdevice);</CODE></P>
-<P>The function <CODE>comedi_get_n_channels()</CODE> returns the number
-of channels of the subdevice belonging to the comedi device <CODE>it</CODE>
-and having index <CODE>subdevice</CODE>. This function returns -1 on error.</P>
-<P>Source: <CODE>/lib/get.c</CODE></P>
-
-
-
-<H3>comedi_get_n_ranges()</H3>
-
-
-<P><CODE>int comedi_get_n_ranges(comedi_t *it,unsigned int subdevice, unsigned int
-chan);</CODE></P>
-<P>The function <CODE>comedi_get_n_ranges()</CODE> returns the number
-of ranges of the channel <CODE>chan</CODE> belonging to the <CODE>subdevice</CODE>
-of the comedi device <CODE>it</CODE>. This function returns -1 on error.</P>
-<P>Source: <CODE>/lib/range.c</CODE></P>
-
-
-
-<H3>comedi_get_n_subdevices()</H3>
-
-
-<P><CODE>int comedi_get_n_subdevices(comedi_t *it);</CODE></P>
-<P>The function <CODE>comedi_get_n_subdevices</CODE> returns the
-number of subdevices associated with the comedi descriptor
-<CODE>it</CODE>, or -1 if there is an error.</P>
-<P>Source: <CODE>/lib/get.c</CODE></P>
-
-
-
-<H3>comedi_get_range()</H3>
-
-
-<P><CODE>comedi_range * comedi_get_range(comedi_t *it,unsigned int subdevice,unsigned int chan,unsigned int
-range);</CODE></P>
-<P>The function <CODE>comedi_get_range</CODE> returns a pointer to a
-comedi_range structure that contains information that can be used to
-convert sample values to or from physical units. The pointer is valid
-until the comedi device <CODE>it</CODE> is closed. If there is an
-error, NULL is returned.</P>
-<P>Source: <CODE>/lib/get.c</CODE></P>
-
-
-<H3>comedi_get_rangetype() <I>deprecated</I></H3>
-
-
-<P><CODE>int comedi_get_rangetype(comedi_t *it,unsigned int subdevice,unsigned int
-chan);</CODE></P>
-<P>The function <CODE>comedi_get_rangetype()</CODE> returns an integer
-that represents the number of range specifications available for a
-particular channel <CODE>chan</CODE> of the subdevice <CODE>subdevice</CODE>, as well as a conversion table to convert sample
-values to/from physical units. </P>
-<P>The macro
-<CODE>RANGE_LENGTH(rangetype)</CODE>
-can be used to determine the number of range specifications for a given
-range type.</P>
-
-<P>This function is deprecated and should not be used in new code.</P>
-<P>Source: <CODE>/lib/get.c</CODE></P>
-
-
-<H3><A NAME="comedi_get_subdevice_type"></A> comedi_get_subdevice_type()</H3>
-
-
-<P><CODE>int comedi_get_subdevice_type(comedi_t *it,unsigned int subdevice);</CODE></P>
-<P>The function <CODE>comedi_get_subdevice_type()</CODE> returns an
-integer describing the type of subdevice that belongs to the comedi
-device <CODE>it</CODE> and has the index <CODE>subdevice</CODE>. The
-function returns -1 is there is an error.</P>
-<P>Valid subdevice types are:</P>
-<P>
-<UL>
-<LI><CODE>COMEDI_SUBD_UNUSED</CODE>
-Subdevice has no functionality, i.e., a place-holder.</LI>
-<LI><CODE>COMEDI_SUBD_AI</CODE> Analog input</LI>
-<LI><CODE>COMEDI_SUBD_AO</CODE> Analog output</LI>
-<LI><CODE>COMEDI_SUBD_DI</CODE> Digital input</LI>
-<LI><CODE>COMEDI_SUBD_DO</CODE> Digital output</LI>
-<LI><CODE>COMEDI_SUBD_DIO</CODE>
-Digital input/output. Channels are configurable as to whether they
-are inputs or outputs.</LI>
-<LI><CODE>COMEDI_SUBD_COUNTER</CODE> Counter</LI>
-<LI><CODE>COMEDI_SUBD_TIMER</CODE> Timer</LI>
-<LI><CODE>COMEDI_SUBD_MEMORY</CODE>
-Memory, e.g., EEPROM or dual-ported RAM</LI>
-<LI><CODE>COMEDI_SUBD_CALIB</CODE>
-Calibration DACs</LI>
-<LI><CODE>COMEDI_SUBD_PROC</CODE>
-Processor or DSP</LI>
-</UL>
-</P>
-<P>Source: <CODE>/lib/get.c</CODE></P>
-
-
-<H3>comedi_get_timer() <I>(deprecated)</I></H3>
-
-
-<P><CODE>int comedi_get_timer(comedi_t *it,unsigned int subdev, double
-freq,unsigned int *trigvar, double *actual_freq);</CODE></P>
-
-<P>The function <CODE>comedi_get_timer</CODE> converts the frequency <CODE>freq</CODE>
-to a number suitable to send to the driver in a <CODE>comedi_trig</CODE>
-structure. This function remains for compatibility with very
-old versions of Comedi, that converted sampling rates to timer
-values in the libary. This conversion is now done in the kernel,
-and every device has the timer type <CODE>nanosec_timer</CODE>, indicating
-that timer values are simply a time specified in nanoseconds.</P>
-
-<P>This function is deprecated and should not be used in new applications.</P>
-
-<P>Source: <CODE>/lib/timer.c</CODE></P>
-
-
-<H3>comedi_get_version_code()</H3>
-
-
-<P><CODE>int comedi_get_version_code(comedi_t *it);</CODE></P>
-
-<P>The function <CODE>comedi_get_version_code()</CODE> returns the
-version code of the currently running comedi module. The version
-code is of the form 0x01072b, which is the version code for
-version 1.7.43.</P>
-
-<P>This function is of limited usefulness. A typical mis-application
-of this function is to use it to determine if a certain feature is
-supported. If the application needs
-to know of the existence of a particular feature, an existence
-test function should be written and put in the libcomedi source.</P>
-<P>Source: <CODE>/lib/get.c</CODE></P>
-
-
-<H3>comedi_loglevel()</H3>
-
-
-<P><CODE>int comedi_loglevel(int loglevel);</CODE></P>
-
-<P>This function affects the output of debugging and error messages
-from libcomedi. By increasing the loglevel, additional debugging
-information will be printed. This function returns the previous
-loglevel. Error messages and debugging are printed to the
-stream <CODE>stderr</CODE>. The loglevel can also be affected by the
-environment variable COMEDI_LOGLEVEL.</P>
-
-<P>In order to conserve resources, some debugging information is
-disabled when libcomedi is compiled.</P>
-
-<P>The meaning of the loglevels is as follows:</P>
-<P>
-<UL>
-<LI><CODE>COMEDILIB_LOGLEVEL=0</CODE>
-
-Comedilib prints nothing.
-</LI>
-<LI><CODE>COMEDILIB_LOGLEVEL=1</CODE> (default)
-
-Comedilib only prints error messages when there is a
-self-consistency error (i.e., internal bug).
-</LI>
-<LI><CODE>COMEDILIB_LOGLEVEL=2</CODE>
-
-Comedilib prints an error message when an invalid
-parameter is passed to comedilib.
-</LI>
-<LI><CODE>COMEDILIB_LOGLEVEL=3</CODE>
-
-Comedilib prints an error message whenever an error is generated
-in the comedilib library or is generated in the C library when
-called by comedilib.
-</LI>
-<LI><CODE>COMEDILIB_LOGLEVEL=4</CODE>
-
-Comedilib prints a lot of debugging messages.
-</LI>
-</UL>
-</P>
-<P>Bugs: Libcomedi doesn't currently have much debugging information.</P>
-<P>Source: <CODE>/lib/error.c</CODE></P>
-
-
-<H3>comedi_open()</H3>
-
-
-<P><CODE>comedi_t *comedi_open(char *filename);</CODE></P>
-<P>Opens a comedi device specified by the filename <CODE>filename</CODE>.
-Returns NULL on error. On sucess, it returns a handle that is
-given as a parameter to other libcomedi functions.</P>
-
-<P>You are not supposed to have access to the internals of the
-<CODE>comedi_t</CODE> structure.</P>
-<P>Bugs: Not strictly identical to <CODE>fopen</CODE></P>
-<P>Source: <CODE>/lib/comedi.c</CODE></P>
-
-
-
-<H3><A NAME="comedi_perror"></A> comedi_perror()</H3>
-
-
-<P><CODE>void comedi_perror(const char *s);</CODE></P>
-<P>When a comedilib function fails, it usually returns -1 or
-NULL, depending on the return type. An internal library
-variable stores an error number, which can be retrieved with
-<CODE>
-<A HREF="#comedi_errno">comedi_errno()</A></CODE>.
-This error number can be
-converted to a human-readable form by the functions
-<CODE>comedi_perror()</CODE>
-and <CODE>
-<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.</P>
-<P>These functions are intended to mimic the behavior of the
-standard C library functions <CODE>perror()</CODE>,
-<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
-comedilib functions sometimes return an error that is generated
-inside the C library; the comedi error message in this case
-is the same as the C library.</P>
-<P>The function <CODE>comedi_perror()</CODE> prints an error
-message to stderr. The error message consists of the
-argument string, a colon, a space, a description of the error
-condition, and a new line.</P>
-<P>Bugs: Does not support internationalization.</P>
-<P>Source: <CODE>/lib/error.c</CODE></P>
-
-
-
-<H3><A NAME="comedi_strerror"></A> comedi_strerror()</H3>
-
-
-<P><CODE>*comedi_strerror(int errnum);</CODE></P>
-<P>When a comedilib function fails, it usually returns -1 or
-NULL, depending on the return type. An internal library
-variable stores an error number, which can be retrieved with
-<CODE>
-<A HREF="#comedi_errno">comedi_errno()</A></CODE>. This error number can be
-converted to a human-readable form by the functions
-<CODE>
-<A HREF="#comedi_perror">comedi_perror()</A></CODE>
-and <CODE>comedi_strerror()</CODE>.</P>
-<P>These functions are intended to mimic the behavior of the
-standard C library functions <CODE>perror()</CODE>,
-<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
-comedilib functions sometimes return an error that is generated
-inside the C library; the comedi error message in this case
-is the same as the C library.</P>
-<P>The function <CODE>comedi_strerror()</CODE> returns a pointer to a
-character string
-describing the comedilib error <CODE>errnum</CODE>. The persistence
-of the returned pointer is undefined, and should not be trusted
-after the next libcomedi call. An unrecognized error number will
-return a pointer to the string "undefined error", or similar.</P>
-<P>Bugs: Does not support internationalization.</P>
-<P>Source: <CODE>/lib/error.c</CODE></P>
-
-
-
-<H3>comedi_sv_init()</H3>
-
-
-<P><CODE>int comedi_sv_init(comedi_sv_t *sv,comedi_t *dev,unsigned int subd,
-unsigned int chan);</CODE></P>
-
-<P><CODE>comedi_sv_init</CODE> initializes the slow varying comedi structure
-<CODE>sv</CODE> of the device <CODE>dev</CODE>, the subdevice <CODE>subd</CODE> (analog input) and
-the channel <CODE>chan</CODE>.
-The slow varying comedi structure <CODE>sv</CODE> of type <CODE>
-<A HREF="#comedi_sv_t">comedi_sv_t</A></CODE>
-specifies the signal measurement. The default number of averaged
-samples is 100. Returns zero on success, -1 on error.</P>
-<P>Bugs: comedi_sv_* was very poorly designed.</P>
-<P>Source: <CODE>/lib/sv.c</CODE></P>
-
-
-
-<H3>comedi_sv_update()</H3>
-
-
-<P><CODE>int comedi_sv_update(comedi_sv_t *sv);</CODE></P>
-<P>The function <CODE>comedi_sv_update</CODE> updates the slow varying comedi structure
-<CODE>sv</CODE>.
-Returns zero on success, -1 on error.</P>
-<P>Source: <CODE>/lib/sv.c</CODE></P>
-
-
-
-<H3>int comedi_sv_measure()</H3>
-
-
-<P><CODE>int comedi_sv_measure(comedi_sv_t *it,double *data);</CODE></P>
-<P><CODE>comedi_sv_measure</CODE> measures the slow variing signal. The measurement
-is specified by the slow varying comedi structure <CODE>sv</CODE>, the result is
-stored in <CODE>data</CODE>.
-On success returns the number of samples, -1 on error.</P>
-<P>Source: <CODE>/lib/sv.c</CODE></P>
-
-
-
-<H3><A NAME="comedi_to_phys"></A> comedi_to_phys()</H3>
-
-
-<P><CODE>double comedi_to_phys(lsampl_t data, comedi_range *rng,
-lsampl_t maxdata);</CODE></P>
-<P>Converts data given in sample values (lsampl_t, between 0 and
-maxdata) into physical units (double). The parameter <CODE>rng</CODE>
-represents the conversion information to use, and the parameter
-<CODE>maxdata</CODE> represents the maximum possible data value for the
-channel that the data was read.</P>
-<P>Source: <CODE>/lib/range.c</CODE></P>
-
-
-
-<H3>comedi_trigger() <I>(deprecated)</I></H3>
-
-
-<P><CODE>int comedi_trigger(comedi_t *it,comedi_trig *trig);</CODE></P>
-<P>The function <CODE>comedi_trigger</CODE> instructs comedi to
-perform the command specified by the
-<A HREF="#comedi_trig_struct">trigger structure</A> <CODE>trig</CODE>. Results depend on
-the particular command being issued. If there is an
-error, -1 is returned.</P>
-<P>Lifetime: removal at 1.0.</P>
-<P>Source: <CODE>/lib/comedi.c</CODE></P>
-
-
-
-<H3><A NAME="comedi_get_subdevice_flags"></A> comedi_get_subdevice_flags()</H3>
-
-
-<P><CODE>int comedi_get_subdevice_flags(comedi_t *dev, unsigned int subdevice);</CODE></P>
-
-<P>This function returns a bitfield describing the capabilities of the
-specified subdevice. If there is an error, -1 is returned.</P>
-
-<P>The bits are:</P>
-<P>
-<UL>
-<LI>SDF_BUSY subdevice is running a command</LI>
-<LI>SDF_BUSY_OWNER subdevice is running a command started by
-the file descriptor used by <CODE>dev</CODE>.</LI>
-<LI>SDF_LOCKED subdevice is locked</LI>
-<LI>SDF_LOCKED_OWNER subdevice is locked by the file descriptor used
-by <CODE>dev</CODE>.</LI>
-<LI>SDF_MAXDATA maximum data values are channel dependent</LI>
-<LI>SDF_FLAGS channel flags are channel dependent</LI>
-<LI>SDF_RANGETYPE range types are channel dependent</LI>
-<LI>SDF_MODE0 deprecated</LI>
-<LI>SDF_MODE1 deprecated</LI>
-<LI>SDF_MODE2 deprecated</LI>
-<LI>SDF_MODE3 deprecated</LI>
-<LI>SDF_MODE4 deprecated</LI>
-<LI>SDF_CMD subdevice supports commands</LI>
-<LI>SDF_READABLE subdevice can be read from</LI>
-<LI>SDF_WRITEABLE subdevice can be written to</LI>
-<LI>SDF_RT deprecated</LI>
-<LI>SDF_GROUND subdevice is capable of ground analog reference</LI>
-<LI>SDF_COMMON subdevice is capable of common analog reference</LI>
-<LI>SDF_DIFF subdevice is capable of differential analog reference</LI>
-<LI>SDF_OTHER subdevice is capable of other analog reference</LI>
-<LI>SDF_DITHER subdevice recognizes dither flag</LI>
-<LI>SDF_DEGLITCH subdevice recognizes deglitch flag</LI>
-<LI>SDF_MMAP deprecated</LI>
-<LI>SDF_RUNNING subdevice is acquiring data (i.e., command has not
-completed)</LI>
-<LI>SDF_LSAMPL subdevice uses samples of type lsampl_t (otherwise
-sampl_t)</LI>
-<LI>SDF_PACKED subdevice uses bitfield samples (otherwise it uses
-one sample per channel)</LI>
-</UL>
-</P>
-
-
-
-<P>The bit definitions are part of the Comedi kernel interface.</P>
-
-
-
-<H3><A NAME="comedi_range_is_chan_specific"></A> comedi_range_is_chan_specific()</H3>
-
-
-<P><CODE>int comedi_range_is_chan_specific(comedi_t *dev,unsigned int subdevice);</CODE></P>
-
-<P>If each channel of the specified subdevice has a different range
-specification, this function returns 1. Otherwise, this function
-returns 0. On error, this function returns -1.</P>
-
-
-
-<H3><A NAME="undocumented"></A> Undocumented functions</H3>
-
-
-
-<P>
-<UL>
-<LI>comedi_maxdata_is_chan_specific()</LI>
-<LI>comedi_get_buffer_size()</LI>
-<LI>comedi_get_max_buffer_size()</LI>
-<LI>comedi_set_buffer_size()</LI>
-<LI>comedi_set_max_buffer_size()</LI>
-<LI>comedi_do_insnlist()</LI>
-<LI>comedi_do_insn()</LI>
-<LI>comedi_lock()</LI>
-<LI>comedi_unlock()</LI>
-<LI>comedi_get_cmd_src_mask()</LI>
-<LI>comedi_get_cmd_generic_timed()</LI>
-<LI>comedi_cancel()</LI>
-<LI>comedi_command()</LI>
-<LI>comedi_command_test()</LI>
-<LI>comedi_poll()</LI>
-<LI>comedi_get_buffer_contents()</LI>
-<LI>comedi_mark_buffer_read()</LI>
-<LI>comedi_get_buffer_offset()</LI>
-<LI>comedi_set_global_oor_behavior()</LI>
-</UL>
-</P>
-
-
-
-
-
-
-
-
-
-
-<HR>
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-Previous
-<A HREF="comedilib_reference.html#toc1">Contents</A>
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-<HR>
-<H2><A NAME="s2">2. Reference Comedilib-0.7.9: types</A></H2>
-
-<P>
-<H2><A NAME="ss2.1">2.1 sampl_t</A>
-</H2>
-
-<P>defined in <CODE>comedi.h</CODE>
-correspond to <CODE>unsigned int</CODE>
-type of the sample data
-<P>
-<P>
-<H2><A NAME="comedi_sv_t"></A> <A NAME="ss2.2">2.2 comedi_sv_t</A>
-</H2>
-
-<P>defined in <CODE>comedilib.h</CODE>
-correspond to <CODE>
-<A HREF="comedilib_reference-3.html#comedi_sv_struct">comedi_sv_struct</A></CODE>
-<P>
-<P>
-<HR>
-<A HREF="comedilib_reference-3.html">Next</A>
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-<HTML>
-<HEAD>
- <META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
- <TITLE>Comedi Documentation: Reference Comedilib-0.7.9: structures</TITLE>
- <LINK HREF="comedilib_reference-4.html" REL=next>
- <LINK HREF="comedilib_reference-2.html" REL=previous>
- <LINK HREF="comedilib_reference.html#toc3" REL=contents>
-</HEAD>
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-<HR>
-<H2><A NAME="s3">3. Reference Comedilib-0.7.9: structures</A></H2>
-
-<P>
-<P>
-<H2><A NAME="comedi_trig_struct"></A> <A NAME="ss3.1">3.1 comedi_trig_struct</A>
-</H2>
-
-<P>
-<P>
-<BLOCKQUOTE><CODE>
-<PRE>
-struct comedi_trig_struct{
- unsigned int subdev; /* subdevice */
- unsigned int mode; /* mode */
- unsigned int flags;
- unsigned int n_chan; /* number of channels */
- unsigned int *chanlist; /* channel/range list */
- sampl_t *data; /* data list, size depends on subd flags */
- unsigned int n; /* number of scans */
- unsigned int trigsrc;
- unsigned int trigvar;
- unsigned int trigvar1;
- unsigned int data_len;
- unsigned int unused[3];
-}
-</PRE>
-</CODE></BLOCKQUOTE>
-<P>
-<P>
-<H2><A NAME="comedi_sv_struct"></A> <A NAME="ss3.2">3.2 comedi_sv_struct</A>
-</H2>
-
-<P>
-<BLOCKQUOTE><CODE>
-<PRE>
-struct comedi_sv_struct{
- comedi_t *dev;
- unsigned int subdevice;
- unsigned int chan;
-
- /* range policy */
- int range;
- int aref;
-
- /* number of measurements to average (for ai) */
- int n;
-
- lsampl_t maxdata;
-}
-</PRE>
-</CODE></BLOCKQUOTE>
-<P>
-<HR>
-<A HREF="comedilib_reference-4.html">Next</A>
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-<HTML>
-<HEAD>
- <META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
- <TITLE>Comedi Documentation: Reference Comedilib-0.7.9: functions</TITLE>
- <LINK HREF="comedilib_reference-3.html" REL=previous>
- <LINK HREF="comedilib_reference.html#toc4" REL=contents>
-</HEAD>
-<BODY>
-Next
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-<A HREF="comedilib_reference.html#toc4">Contents</A>
-<HR>
-<H2><A NAME="s4">4. Reference Comedilib-0.7.9: functions</A></H2>
-
-<P>
-<P>
-<H2><A NAME="ss4.1">4.1 comedi_close()</A>
-</H2>
-
-<P>
-<P><CODE>void comedi_close(comedi_t *it);</CODE>
-<P>Closes a device previously opened by comedi_open().
-<P>Source: <CODE>/lib/comedi.c</CODE>
-<P>
-<H2><A NAME="ss4.2">4.2 comedi_data_read()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_data_read(comedi_t *it,unsigned int subd,unsigned int chan,
-unsigned int range,unsigned int aref,lsampl_t *data);</CODE>
-<P>Reads a single sample on the channel that
-is specified by the comedi device <CODE>it</CODE>, the
-subdevice <CODE>subd</CODE>, and the channel <CODE>chan</CODE>.
-For the operation,
-the device is configured to use range specification
-<CODE>range</CODE> and (if appropriate) analog reference type
-<CODE>aref</CODE>. Analog reference types that are not supported
-by the device are silently ignored.
-<P><CODE>comedi_data_read()</CODE> reads one data value from
-the specified channel and places the
-data value that is read in the location pointed to by
-<CODE>data</CODE>.
-<P>On sucess, <CODE>comedi_data_read()</CODE> returns 0. If there is an error, -1 is
-returned.
-<P>Valid analog reference numbers are:
-<P>
-<UL>
-<LI>AREF_GROUND Reference to analog ground</LI>
-<LI>AREF_COMMON Reference to analog common</LI>
-<LI>AREF_DIFF Differential reference</LI>
-<LI>AREF_OTHER Board-specific meaning</LI>
-</UL>
-<P>Valid data values used by these function is an unsigned integer
-less than or equal to <CODE>maxdata</CODE>, which is channel-dependent.
-Conversion of these data value to physical units can be performed
-by <CODE>
-<A HREF="#comedi_to_phys">comedi_to_phys()</A></CODE>.
-<P>Source: <CODE>/lib/data.c</CODE>
-<P>
-<P>
-<H2><A NAME="ss4.3">4.3 comedi_data_write()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_data_write(comedi_t *it,unsigned int subd,unsigned int chan,
-unsigned int range,unsigned int aref,lsampl_t data);</CODE>
-<P>Writes a single sample on the channel that
-is specified by the comedi device <CODE>it</CODE>, the
-subdevice <CODE>subd</CODE>, and the channel <CODE>chan</CODE>.
-For the operation,
-the device is configured to use range specification
-<CODE>range</CODE> and (if appropriate) analog reference type
-<CODE>aref</CODE>. Analog reference types that are not supported
-by the device are silently ignored.
-<P><CODE>comedi_data_write()</CODE> writes the data value
-specified by the argument <CODE>data</CODE> to
-the specified channel.
-<P>On sucess, <CODE>comedi_data_write()</CODE> returns 0. If there is an error, -1 is
-returned.
-<P>Valid analog reference numbers are:
-<P>
-<UL>
-<LI>AREF_GROUND Reference to analog ground</LI>
-<LI>AREF_COMMON Reference to analog common</LI>
-<LI>AREF_DIFF Differential reference</LI>
-<LI>AREF_OTHER Board-specific meaning</LI>
-</UL>
-<P>Valid data values used by these functions is an unsigned integer
-less than or equal to <CODE>maxdata</CODE>, which is channel-dependent.
-Conversion of physical units to these data value can be performed
-by <CODE>
-<A HREF="#comedi_from_phys">comedi_from_phys()</A></CODE>.
-<P>Source: <CODE>/lib/data.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.4">4.4 comedi_dio_bitfield();</A>
-</H2>
-
-<P>int comedi_dio_bitfield(comedi_t *it,unsigned int subd,unsigned int write_mask,
-unsigned int *bits);
-<P>Source: <CODE>/lib/dio.c</CODE>
-<P>
-<P>
-<H2><A NAME="ss4.5">4.5 comedi_dio_config()</A>
-</H2>
-
-<P><CODE>int comedi_dio_config(comedi_t *it,unsigned int subd,unsigned int chan,unsigned int dir);</CODE>
-<P>The function <CODE>comedi_dio_config</CODE> configures the direction <CODE>dir</CODE> of
-channel <CODE>chan</CODE> belonging to the configurable digital input/output subdevice
-<CODE>subd</CODE> of the device <CODE>it</CODE>. Returns -1 on failure.
-<P>
-<P>Valid directions are:
-<UL>
-<LI> COMEDI_INPUT</LI>
-<LI> COMEDI_OUTPUT</LI>
-</UL>
-<P>Source: <CODE>/lib/dio.c</CODE>
-<P>
-<P>
-<H2><A NAME="ss4.6">4.6 comedi_dio_read()</A>
-</H2>
-
-<P><CODE>int comedi_dio_read(comedi_t *it,unsigned int subd,unsigned int chan,unsigned int *bit);</CODE>
-<P>The function reads the status of channel <CODE>chan</CODE> belonging to the digital
-input subdevice <CODE>subd</CODE> of device <CODE>it</CODE>. The result, 0 or 1, is stored
-in bit. Returns -1 on failure.
-<P>Source: <CODE>/lib/dio.c</CODE>
-<P>
-<P>
-<H2><A NAME="ss4.7">4.7 comedi_dio_write()</A>
-</H2>
-
-<P><CODE>int comedi_dio_write(comedi_t *it,unsigned int subd,unsigned int chan,unsigned int bit);</CODE>
-<P>The function writes the value of <CODE>bit</CODE>, 0 or 1, in channel <CODE>chan</CODE>,
-belonging to the digital output device <CODE>subd</CODE> of device <CODE>it</CODE>. Returns
--1 on failure.
-<P>Source: <CODE>/lib/dio.c</CODE>
-<P>
-<P>
-<H2><A NAME="ss4.8">4.8 comedi_fileno()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_fileno(comedi_t *it);</CODE>
-<P>The function <CODE>comedi_fileno</CODE>
-returns the integer descriptor for the handle <CODE>it</CODE>. If
-<CODE>it</CODE> is an invalid <CODE>comedi_t</CODE> pointer, the function
-returns -1 and sets the appropriate comedilib error value.
-<P>Source: <CODE>/lib/comedi.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.9">4.9 comedi_find_range()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_find_range(comedi_t *it, unsigned int subdevice, unsigned
-int chan, unsigned int unit, double min, double max);</CODE>
-<P>The function <CODE>comedi_find_range</CODE> tries to
-locate the optimal (smallest) range of a channel <CODE>chan</CODE> belonging to a
-<CODE>subdevice</CODE> of the comedi device <CODE>it</CODE>, which includes the data
-range between <CODE>min</CODE> and <CODE>max</CODE> in <CODE>units</CODE> with highest
-precision. If it finds a matching range,
-it returns its index. If no matching range is available, it returns -1.
-<P>Valid units are:
-<P>
-<UL>
-<LI>UNIT_volt </LI>
-<LI>UNIT_mA</LI>
-<LI>UNIT_none</LI>
-</UL>
-<P>Source: <CODE>/lib/range.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="comedi_errno"></A> <A NAME="ss4.10">4.10 comedi_errno()</A>
-</H2>
-
-<P><CODE>int comedi_errno(void);</CODE>
-<P>
-<P>When a comedilib function fails, it usually returns -1 or
-NULL, depending on the return type. An internal library
-variable stores an error number, which can be retrieved with
-<CODE>comedi_errno()</CODE>. This error number can be
-converted to a human-readable form by the functions
-<CODE>
-<A HREF="#comedi_perror">comedi_perror()</A></CODE>
-and <CODE>
-<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.
-<P>These functions are intended to mimic the behavior of the
-standard C library functions <CODE>perror()</CODE>,
-<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
-comedilib functions sometimes return an error that is generated
-inside the C library; the comedi error message in this case
-is the same as the C library.
-<P>The function <CODE>comedi_errno()</CODE>
-returns an integer describing the most recent comedilib error. This
-integer may be used as the <CODE>errnum</CODE> parameter for
-<CODE>
-<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.
-<P>Source: <CODE>/lib/error.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.11">4.11 comedi_find_subdevice_by_type()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_find_subdevice_by_type(comedi_t *it,int type,unsigned int
-start_subdevice);</CODE>
-<P>The function <CODE>comedi_find_subdevice_by_type</CODE> tries to
-locate a subdevice belonging to comedi device <CODE>it</CODE>,
-having type <CODE>type</CODE>, starting with the subdevice
-<CODE>start_subdevice</CODE>. If it finds the requested subdevice,
-it returns its index. If it does not locate the requested
-subdevice, it returns -1 and sets the comedi error number to
-"subdevice not found". If there is an error, the function
-returns -1 and sets the appropriate error.
-<P>For subdevice types, see the manual page for the function
-<CODE>
-<A HREF="#comedi_get_subdevice_type">comedi_get_subdevice_type()</A></CODE>.
-<P>Source: <CODE>/lib/get.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="comedi_from_phys"></A> <A NAME="ss4.12">4.12 comedi_from_phys()</A>
-</H2>
-
-<P>
-<P><CODE>lsampl_t comedi_from_phys(double data, comedi_range *rng, lsampl_t maxdata);</CODE>
-<P>Converts data given in physical units (double) into sample values (lsampl_t, between 0 and maxdata).
-The parameter <CODE>rng</CODE> represents the conversion information to use, and the parameter <CODE>maxdata</CODE> represents
-the maximum possible data value for the channel that the data will be written to.
-<P>Source: <CODE>/lib/range.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.13">4.13 comedi_get_board_name()</A>
-</H2>
-
-<P>
-<P><CODE>char *comedi_get_board_name(comedi_t *it);</CODE>
-<P>The function <CODE>comedi_get_board_name</CODE> returns a pointer
-to a string containing the name of the device. This pointer is
-valid until the comedi descriptor <CODE>it</CODE> is closed. This
-function returns NULL if there is an error.
-<P>Source: <CODE>/lib/get.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.14">4.14 comedi_get_driver_name()</A>
-</H2>
-
-<P>
-<P><CODE>char *comedi_get_driver_name(comedi_t *it);</CODE>
-<P>The function <CODE>comedi_get_driver_name</CODE> returns a pointer
-to a string containing the name of the driver being used by comedi
-for the comedi device represented by <CODE>it</CODE>. This pointer is
-valid until the comedi descriptor <CODE>it</CODE> is closed. This
-function returns NULL if there is an error.
-<P>Source: <CODE>/lib/get.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.15">4.15 comedi_get_maxdata()</A>
-</H2>
-
-<P>
-<P><CODE>lsampl_t comedi_get_maxdata(comedi_t *it,unsigned int subdevice,unsigned int
-chan);</CODE>
-<P>The function <CODE>comedi_get_maxdata()</CODE> returns the maximum
-valid data value for channel <CODE>chan</CODE> of subdevice
-<CODE>subdevice</CODE> belonging to the comedi device <CODE>it</CODE>
-This function returns 0 on error.
-<P>Source: <CODE>/lib/get.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.16">4.16 comedi_get_n_channels()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_get_n_channels(comedi_t *it,unsigned int subdevice);</CODE>
-<P>The function <CODE>comedi_get_n_channels()</CODE> returns the number
-of channels of the subdevice belonging to the comedi device <CODE>it</CODE>
-and having index <CODE>subdevice</CODE>. This function returns -1 on error.
-<P>Source: <CODE>/lib/get.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.17">4.17 comedi_get_n_ranges()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_get_n_ranges(comedi_t *it,unsigned int subdevice, unsigned int
-chan);</CODE>
-<P>The function <CODE>comedi_get_n_ranges()</CODE> returns the number
-of ranges of the channel <CODE>chan</CODE> belonging to the <CODE>subdevice</CODE>
-of the comedi device <CODE>it</CODE>. This function returns -1 on error.
-<P>Source: <CODE>/lib/range.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.18">4.18 comedi_get_n_subdevices()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_get_n_subdevices(comedi_t *it);</CODE>
-<P>The function <CODE>comedi_get_n_subdevices</CODE> returns the
-number of subdevices associated with the comedi descriptor
-<CODE>it</CODE>, or -1 if there is an error.
-<P>Source: <CODE>/lib/get.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.19">4.19 comedi_get_range()</A>
-</H2>
-
-<P>
-<P><CODE>comedi_range * comedi_get_range(comedi_t *it,unsigned int subdevice,unsigned int chan,unsigned int
-range);</CODE>
-<P>The function <CODE>comedi_get_range</CODE> returns a pointer to a
-comedi_range structure that contains information that can be used to
-convert sample values to or from physical units. The pointer is valid
-until the comedi device <CODE>it</CODE> is closed. If there is an
-error, NULL is returned.
-<P>Source: <CODE>/lib/get.c</CODE>
-<P>
-<P>
-<H2><A NAME="ss4.20">4.20 comedi_get_rangetype()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_get_rangetype(comedi_t *it,unsigned int subdevice,unsigned int
-chan);</CODE>
-<P>The function <CODE>comedi_get_rangetype()</CODE> returns an integer
-that represents the number of range specifications available for a
-particular channel <CODE>chan</CODE> of the subdevice <CODE>subdevice</CODE>, as well as a conversion table to convert sample
-values to/from physical units.
-<P>The macro
-<CODE>RANGE_LENGTH(rangetype)</CODE>
-can be used to determine the number of range specifications for a given
-range type.
-<P>Source: <CODE>/lib/get.c</CODE>
-<P>
-<P>
-<H2><A NAME="comedi_get_subdevice_type"></A> <A NAME="ss4.21">4.21 comedi_get_subdevice_type()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_get_subdevice_type(comedi_t *it,unsigned int subdevice);</CODE>
-<P>The function <CODE>comedi_get_subdevice_type()</CODE> returns an
-integer describing the type of subdevice that belongs to the comedi
-device <CODE>it</CODE> and has the index <CODE>subdevice</CODE>. The
-function returns -1 is there is an error.
-<P>Valid subdevice types are:
-<P>
-<UL>
-<LI><CODE>COMEDI_SUBD_UNUSED</CODE>
-Subdevice has no functionality, i.e., a place-holder.</LI>
-<LI><CODE>COMEDI_SUBD_AI</CODE> Analog input</LI>
-<LI><CODE>COMEDI_SUBD_AO</CODE> Analog output</LI>
-<LI><CODE>COMEDI_SUBD_DI</CODE> Digital input</LI>
-<LI><CODE>COMEDI_SUBD_DO</CODE> Digital output</LI>
-<LI><CODE>COMEDI_SUBD_DIO</CODE>
-Digital input/output. Channels are configurable as to whether they
-are inputs or outputs.</LI>
-<LI><CODE>COMEDI_SUBD_COUNTER</CODE> Counter</LI>
-<LI><CODE>COMEDI_SUBD_TIMER</CODE> Timer</LI>
-<LI><CODE>COMEDI_SUBD_MEMORY</CODE>
-Memory, e.g., EEPROM or dual-ported RAM</LI>
-<LI><CODE>COMEDI_SUBD_CALIB</CODE>
-Calibration DACs</LI>
-<LI><CODE>COMEDI_SUBD_PROC</CODE>
-Processor or DSP</LI>
-</UL>
-<P>Source: <CODE>/lib/get.c</CODE>
-<P>
-<P>
-<H2><A NAME="ss4.22">4.22 comedi_get_timer()</A>
-</H2>
-
-<P>
-<P>
-<BLOCKQUOTE><CODE>
-<PRE>
-int comedi_get_timer(comedi_t *it,unsigned int subdev, double freq,unsigned int *trigvar,
- double *actual_freq);
-</PRE>
-</CODE></BLOCKQUOTE>
-<P><CODE>comedi_get_timer</CODE> returns the type of the timer of the subdevice
-<CODE>subdev</CODE> of the device <CODE>it</CODE> ,
-<P>Supported timers are:
-<P>
-<UL>
-<LI>NULL</LI>
-<LI>dt282x_timer</LI>
-<LI>dt2814_timer</LI>
-<LI>atmio_timer</LI>
-<LI>acl8112_timer</LI>
-<LI>nanosec_timer</LI>
-</UL>
-<P>Source: <CODE>/lib/timer.c</CODE>
-<P>
-<P>
-<H2><A NAME="ss4.23">4.23 comedi_get_version_code()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_get_version_code(comedi_t *it);</CODE>
-<P>The function <CODE>comedi_get_version_code()</CODE> returns the
-version code of the currently running comedi module. The version
-code is of the form 0x01072b, which is the version code for
-version 1.7.43.
-<P>Source: <CODE>/lib/get.c</CODE>
-<P>
-<P>
-<H2><A NAME="ss4.24">4.24 comedi_loglevel()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_loglevel(int loglevel);</CODE>
-<P>This function affects the output of debugging and error messages
-from comedlib. By increasing the loglevel, additional debugging
-information will be printed. This function returns the previous
-loglevel. Some debugging information will only be printed if
-comedilib was compiled with this debugging information included.
-The loglevel can also be affected by the environment
-variable COMEDI_LOGLEVEL. The meaning of the loglevels is as
-follows:
-<P>COMEDILIB_LOGLEVEL=0
-<P>Comedilib prints nothing.
-<P>COMEDILIB_LOGLEVEL=1 (default)
-<P>Comedilib only prints error messages when there is a
-self-consistency error.
-<P>COMEDILIB_LOGLEVEL=2
-<P>Comedilib prints an error message whenever an invalid
-parameter is passed to comedilib.
-<P>COMEDILIB_LOGLEVEL=3
-<P>Comedilib prints an error message whenever an error is generated
-in the comedilib library or is generated in the C library when
-called by comedilib.
-<P>COMEDILIB_LOGLEVEL=4
-<P>Comedilib prints a lot of debugging messages.
-<P>
-<P>Source: <CODE>/lib/error.c</CODE>
-<P>
-<P>
-<H2><A NAME="ss4.25">4.25 comedi_open()</A>
-</H2>
-
-<P>
-<P><CODE>comedi_t *comedi_open(char *fn);</CODE>
-<P>Opens a comedi device specified by the filename fn. Returns NULL
-on error. Returns a handle that is given as a parameter to other
-comedilib functions.
-<P>You are not supposed to have access to the structure comedi_t.
-<P>Source: <CODE>/lib/comedi.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="comedi_perror"></A> <A NAME="ss4.26">4.26 comedi_perror()</A>
-</H2>
-
-<P>
-<P><CODE>void comedi_perror(const char *s);</CODE>
-<P>When a comedilib function fails, it usually returns -1 or
-NULL, depending on the return type. An internal library
-variable stores an error number, which can be retrieved with
-<CODE>
-<A HREF="#comedi_errno">comedi_errno()</A></CODE>.
-This error number can be
-converted to a human-readable form by the functions
-<CODE>comedi_perror()</CODE>
-and <CODE>
-<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.
-<P>These functions are intended to mimic the behavior of the
-standard C library functions <CODE>perror()</CODE>,
-<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
-comedilib functions sometimes return an error that is generated
-inside the C library; the comedi error message in this case
-is the same as the C library.
-<P>The function <CODE>comedi_perror()</CODE> prints an error
-message to stderr. The error message consists of the
-argument string, a colon, a space, a description of the error
-condition, and a new line.
-<P>Source: <CODE>/lib/error.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="comedi_strerror"></A> <A NAME="ss4.27">4.27 comedi_strerror()</A>
-</H2>
-
-<P>
-<P><CODE>*comedi_strerror(int errnum);</CODE>
-<P>When a comedilib function fails, it usually returns -1 or
-NULL, depending on the return type. An internal library
-variable stores an error number, which can be retrieved with
-<CODE>
-<A HREF="#comedi_errno">comedi_errno()</A></CODE>. This error number can be
-converted to a human-readable form by the functions
-<CODE>
-<A HREF="#comedi_perror">comedi_perror()</A></CODE>
-and <CODE>comedi_strerror()</CODE>.
-<P>These functions are intended to mimic the behavior of the
-standard C library functions <CODE>perror()</CODE>,
-<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
-comedilib functions sometimes return an error that is generated
-inside the C library; the comedi error message in this case
-is the same as the C library.
-<P>The function <CODE>comedi_strerror()</CODE> returns a pointer to a
-character string
-describing the comedilib error <CODE>errnum</CODE>. The persistence
-of the returned pointer is undefined, and should not be trusted
-after the next comedilib call. An unrecognized error number will
-return a pointer to the string "undefined error", or similar.
-<P>Valid error strings are:
-<P>
-<UL>
-<LI><CODE>"No error"</CODE></LI>
-<LI><CODE>"Unknown error</CODE></LI>
-<LI><CODE>"Bad comedi_t structure"</CODE></LI>
-<LI><CODE>"Invalid subdevice"</CODE></LI>
-<LI><CODE>"Invalid channel"</CODE></LI>
-</UL>
-<P>Source: <CODE>/lib/error.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.28">4.28 comedi_sv_init()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_sv_init(comedi_sv_t *sv,comedi_t *dev,unsigned int subd,
-unsigned int chan);</CODE>
-<P>The special functions <CODE>comedi_sv_*()</CODE> are designed to
-make it easy to accurately measure slowly varying analog inputs.
-A slowly varying input is one that is effectively constant over the course
-of approximately 100 A/D conversions. However, since these
-conversions can sometimes be pre-empted by scheduling, for most
-purposes, a slowly varying signal should be effectively constant
-for greater than 20 ms (the default Linux timeslice).
-<P>By averaging many A/D conversions of a relatively constant
-signal, it is possible to get a better measurement of the signal
-than a single A/D conversion. In general, the uncertainty of the
-measurement decreases as the square root of the number of samples.
-This is limited by the rate that which the signal varies, and
-ultimately by the spurious free dynamic range of the A/D converter.
-<P><CODE>comedi_sv_init</CODE> initializes the slow varying comedi structure
-<CODE>sv</CODE> of the device <CODE>dev</CODE>, the subdevice <CODE>subd</CODE> (analog input) and
-the channel <CODE>chan</CODE>.
-The slow varying comedi structure <CODE>sv</CODE> of type <CODE>
-<A HREF="comedilib_reference-2.html#comedi_sv_t">comedi_sv_t</A></CODE>
-specifies the signal measurement. Default number of averaged samples is 100.
-Returns zero on success, -1 on error.
-<P>Source: <CODE>/lib/sv.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.29">4.29 comedi_sv_update()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_sv_update(comedi_sv_t *sv);</CODE>
-<P><CODE>comedi_sv_update</CODE> updates the slow varying comedi structure
-<CODE>sv</CODE>.
-Returns zero on success, -1 on error.
-<P>Source: <CODE>/lib/sv.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.30">4.30 int comedi_sv_measure()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_sv_measure(comedi_sv_t *it,double *data);</CODE>
-<P><CODE>comedi_sv_measure</CODE> measures the slow variing signal. The measurement
-is specified by the slow varying comedi structure <CODE>sv</CODE>, the result is
-stored in <CODE>data</CODE>.
-On success returns the number of samples, -1 on error.
-<P>Source: <CODE>/lib/sv.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="comedi_to_phys"></A> <A NAME="ss4.31">4.31 comedi_to_phys()</A>
-</H2>
-
-<P>
-<P><CODE>double comedi_to_phys(lsampl_t data, comedi_range *rng, lsampl_t maxdata);</CODE>
-<P>Converts data given in sample values (lsampl_t, between 0 and maxdata) into physical units (double).
-The parameter <CODE>rng</CODE> represents the conversion information to use, and the parameter <CODE>maxdata</CODE> represents
-the maximum possible data value for the channel that the data was read.
-<P>Source: <CODE>/lib/range.c</CODE>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.32">4.32 comedi_trigger()</A>
-</H2>
-
-<P>
-<P><CODE>int comedi_trigger(comedi_t *it,comedi_trig *trig);</CODE>
-<P>The function <CODE>comedi_trigger()</CODE> instructs comedi to
-perform the command specified by the
-<A HREF="comedilib_reference-3.html#comedi_trig_struct">trigger structure</A>
-<CODE>trig</CODE>. Results depend on the particular command
-being issued. If there is an error, -1 is returned.
-<P>Complete information about comedi commands is given in the
-manual page comedi(8).
-<P>Source: <CODE>/lib/comedi.c</CODE>
-<P>
-<P>
-<P>
-<P>
-<P>
-<P>
-<P>
-<P>
-<P>
-<P>
-<P>
-<P>
-<P>
-<P>
-<H2><A NAME="ss4.33">4.33 comedi_get_timer()</A>
-</H2>
-
-<P>
-<P>
-<BLOCKQUOTE><CODE>
-<PRE>
-int comedi_get_timer(comedi_t *it,unsigned int subdev,double freq,unsigned int *trigvar,
- double *actual_freq);
-</PRE>
-</CODE></BLOCKQUOTE>
-<P>
-<P>
-<P>
-<P>
-<HR>
-Next
-<A HREF="comedilib_reference-3.html">Previous</A>
-<A HREF="comedilib_reference.html#toc4">Contents</A>
-</BODY>
-</HTML>
+++ /dev/null
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
-<HTML>
-<HEAD>
- <META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.7.4">
- <TITLE>Comedi Documentation</TITLE>
- <LINK HREF="comedilib_reference-1.html" REL=next>
-
-
-</HEAD>
-<BODY>
-<A HREF="comedilib_reference-1.html">Next</A>
-Previous
-Contents
-<HR>
-<H1>Comedi Documentation</H1>
-
-<H2>David Schleef, <CODE>ds@stm.lbl.gov</CODE> </H2>
-<P>
-<H2><A NAME="toc1">1.</A> <A HREF="comedilib_reference-1.html">Libcomedi Reference</A></H2>
-
-<HR>
-<A HREF="comedilib_reference-1.html">Next</A>
-Previous
-Contents
-</BODY>
-</HTML>
+++ /dev/null
-<!doctype linuxdoc public "-//LinuxDoc//DTD LinuxDoc 96//EN">
-
-<article>
-<title>Comedi Documentation
-<author>David Schleef, <tt/ds@stm.lbl.gov/
-
-
-
-
-<sect>Libcomedi Reference
-<p>
-
-<sect1>Constants and Macros
-<p>
-
-
-<sect2>RANGE_LENGTH() <it/(deprecated)/
-<p>
-<label id="RANGE_LENGTH">
-
-<tt/RANGE_LENGTH(rangetype)/
-
-<p>
-Rangetype values are library-internal tokens that represent an
-array of range information structures. These numbers are primarily
-used for communication between the kernel and library.
-
-<p>
-The RANGE_LENGTH() macro returns the length of the array that is
-specified by the rangetype token.
-
-<p>
-The RANGE_LENGTH() macro is deprecated, and should not be used in
-new applications. It is scheduled to be removed from the header
-file at version 1.0. Binary compatibility may be broken for version
-1.1.
-
-
-<p>
-<sect1>Data Types and Structures
-
-<p>
-<sect2>comedi_t
-<label id="comedi_t">
-
-<p>
-The data type <tt/comedi_t/ is used to represent an open Comedi
-device. A valid <tt/comedi_t/ pointer is returned by a successful
-call to <tt/comedi_open()/, and should be used for subsequent
-access to the device.
-It is a transparent type, and pointers to type <tt/comedi_t/
-should not be dereferenced by the application.
-
-
-<p>
-<sect2>sampl_t
-<label id="sampl_t">
-
-<p>
-The data type <tt/sampl_t/ is one of the generic types used to represent
-data values in libcomedi. It is used in a few places where a shorter
-data type is useful, but is limited to 16 bits on the i386 architecture.
-
-
-<p>
-<sect2>lsampl_t
-<label id="lsampl_t">
-
-<p>
-The data type <tt/lsampl_t/ is one of the generic types used to represent
-data values in libcomedi. It is currently defined to be <tt/unsigned int/.
-
-
-
-
-<p>
-<sect2>comedi_trig_struct <it/(deprecated)/
-<label id="comedi_trig_struct">
-<p>
-
-The <tt/comedi_trig/ structure
-
-<tscreen><verb>
-struct comedi_trig_struct{
- unsigned int subdev; /* subdevice */
- unsigned int mode; /* mode */
- unsigned int flags;
- unsigned int n_chan; /* number of channels */
- unsigned int *chanlist; /* channel/range list */
- sampl_t *data; /* data list, size depends on subd flags */
- unsigned int n; /* number of scans */
- unsigned int trigsrc;
- unsigned int trigvar;
- unsigned int trigvar1;
- unsigned int data_len;
- unsigned int unused[3];
-}
-</verb></tscreen>
-
-The <tt/comedi_trig/ structure is a control structure used by the
-COMEDI_TRIG ioctl, an older method of communicating
-instructions to the driver and hardware. Use of comedi_trig is
-deprecated, and should not be used in new applications.
-
-<p>
-This structure is defined as part of the Comedi kernel interface.
-
-<p>
-<sect2>comedi_sv_t
-<label id="comedi_sv_t">
-<p>
-
-<tscreen><verb>
-struct comedi_sv_struct{
- comedi_t *dev;
- unsigned int subdevice;
- unsigned int chan;
-
- /* range policy */
- int range;
- int aref;
-
- /* number of measurements to average (for ai) */
- int n;
-
- lsampl_t maxdata;
-}
-</verb></tscreen>
-
-The <tt/comedi_sv_t/ structure is used by the <tt/comedi_sv_*()/
-functions to provide a simple method of accurately measuring
-slowly varying inputs. See the relevant section for more
-details.
-
-
-<p>
-<sect2>comedi_cmd
-<label id="comedi_cmd">
-<p>
-
-undocumented
-
-<p>
-Related functions are described in section XXX.
-
-<p>
-This structure is defined as part of the Comedi kernel interface.
-
-<p>
-<sect2>comedi_insn
-<label id="comedi_insn">
-<p>
-
-undocumented
-
-<p>
-Related functions are described in section XXX.
-
-<p>
-This structure is defined as part of the Comedi kernel interface.
-
-
-<p>
-<sect2>comedi_range
-<label id="comedi_range">
-<p>
-
-undocumented
-
-
-
-<sect1>Functions
-<p>
-
-<sect2>comedi_close()
-<label id="comedi_close">
-<p>
-
-<tt>void comedi_close(comedi_t *it);</tt>
-
-<p>
-Closes a device previously opened by comedi_open().
-
-<p>
-The return type of this function will change to <tt/int/, in
-order to match <tt/fclose/.
-
-<p>
-Source: <tt>/lib/comedi.c</tt>
-
-
-<sect2>comedi_data_read()
-<label id="comedi_data_read">
-<p>
-
-<tt>int comedi_data_read(comedi_t *it,unsigned int subd,unsigned int chan,
- unsigned int range,unsigned int aref,lsampl_t *data);</tt>
-
-<p>
-Reads a single sample on the channel that
-is specified by the comedi device <tt>it</tt>, the
-subdevice <tt>subd</tt>, and the channel <tt>chan</tt>.
-For the A/D conversion (if appropriate),
-the device is configured to use range specification
-<tt>range</tt> and (if appropriate) analog reference type
-<tt>aref</tt>. Analog reference types that are not supported
-by the device are silently ignored.
-
-<p>
-<tt>comedi_data_read()</tt> reads one data value from
-the specified channel and places the
-data value that is read in the location pointed to by
-<tt>data</tt>.
-
-<p>
-On sucess, <tt>comedi_data_read()</tt> returns 0. If there is an
-error, -1 is returned.
-
-<p>
-Valid analog reference numbers are:
-
-<itemize>
-<item>AREF_GROUND Reference to analog ground
-<item>AREF_COMMON Reference to analog common
-<item>AREF_DIFF Differential reference
-<item>AREF_OTHER Board-specific meaning
-</itemize>
-
-Valid data values returned by these function is an unsigned integer
-less than or equal to <tt>maxdata</tt>, which is channel-dependent.
-Conversion of these data value to physical units can be performed
-by <tt><ref id="comedi_to_phys" name =
-"comedi_to_phys()"></tt>.
-
-Source: <tt>/lib/data.c</tt>
-
-
-<sect2>comedi_data_write()
-<p>
-
-<tt>int comedi_data_write(comedi_t *it,unsigned int subd,unsigned int chan,
- unsigned int range,unsigned int aref,lsampl_t data);</tt>
-
-<p>
-Writes a single sample on the channel that
-is specified by the comedi device <tt/it/, the
-subdevice <tt/subd/, and the channel <tt/chan/.
-For the D/A conversion (if appropriate), the device is
-configured to use range specification
-<tt/range/ and (if appropriate) analog reference type
-<tt/aref/. Analog reference types that are not supported
-by the device are silently ignored.
-
-<tt/comedi_data_write()/ writes the data value
-specified by the argument <tt/data/ to
-the specified channel.
-
-On sucess, <tt>comedi_data_write()</tt> returns 0. If there is an error, -1 is
-returned.
-
-Valid analog reference numbers are:
-
-<itemize>
-<item>AREF_GROUND Reference to analog ground
-<item>AREF_COMMON Reference to analog common
-<item>AREF_DIFF Differential reference
-<item>AREF_OTHER Board-specific meaning
-</itemize>
-
-Valid data values used by these functions is an unsigned integer
-less than or equal to <tt>maxdata</tt>, which is channel-dependent.
-Conversion of physical units to these data value can be performed
-by <tt><ref id="comedi_from_phys" name =
-"comedi_from_phys()"></tt>.
-
-Source: <tt>/lib/data.c</tt>
-
-
-<p>
-<sect2>comedi_dio_bitfield();
-
-<p>
-<tt/int comedi_dio_bitfield(comedi_t *it,unsigned int subd,unsigned
-int write_mask,unsigned int *bits);/
-
-<p>
-The function <tt/comedi_dio_bitfield()/ allows multiple channels to
-be read simultaneously from a digital input or digital I/O device.
-The parameter <tt/write_mask/ and the value pointed to by <tt/bits/
-are interpreted as bit fields, with the least significant bit
-representing channel 0. For each bit in <tt/write_mask/ that is
-set, the cooresponding bit in <tt/*bits/ is written to the digital
-output channel. Each digital input channel is read, and the result
-placed in the approprate bits in <tt/*bits/.
-
-<p>
-The current implementation reads and writes bits using separate
-system calls, which is not ideal. When the kernel driver supports
-simultaneous reading/writing, this will be fixed in the library.
-
-<p>
-It should be noted that it is not possible to access channels
-greater than 31 using this function.
-
-<p>
-Source: <tt>/lib/dio.c</tt>
-
-
-<p>
-<sect2>comedi_dio_config()
-<p>
-<tt/int comedi_dio_config(comedi_t *it,unsigned int subd,unsigned
-int chan,unsigned int dir);/
-
-<p>
-The function <tt/comedi_dio_config/ configures individual channels
-in a digital I/O subdevice to be either input or output, depending
-on the value of parameter <tt/dir/. Depending on the capabilities
-of the hardware device, multiple channels may be affected by
-a single call to <tt/comedi_dio_config/.
-
-
-Valid directions are:
-<itemize>
-<item> COMEDI_INPUT
-<item> COMEDI_OUTPUT
-</itemize>
-
-Source: <tt>/lib/dio.c</tt>
-
-
-<p>
-<sect2>comedi_dio_read()
-<p>
-<tt/int comedi_dio_read(comedi_t *it,unsigned int subd,unsigned int
-chan,unsigned int *bit);/
-
-<p>
-The function reads the status of channel <tt/chan/ belonging to the digital
-input subdevice <tt/subd/ of device <tt/it/. The result, 0 or 1, is stored
-in bit. Returns -1 on failure.
-
-<p>
-This function is equivalent to <tt/comedi_data_read(it,subd,chan,0,0,bit)/.
-
-
-Source: <tt>/lib/dio.c</tt>
-
-<p>
-<sect2>comedi_dio_write()
-<p>
-<tt/int comedi_dio_write(comedi_t *it,unsigned int subd,unsigned
-int chan,unsigned int bit);/
-
-<p>
-The function writes the value of <tt/bit/, 0 or 1, to channel <tt/chan/,
-belonging to the digital output device <tt/subd/ of device <tt/it/. Returns
--1 on failure.
-
-<p>
-Source: <tt>/lib/dio.c</tt>
-
-<p>
-<sect2>comedi_fileno()
-<p>
-
-<tt/int comedi_fileno(comedi_t *it);/
-<p>
-
-The function <tt/comedi_fileno/
-returns the integer descriptor for the handle <tt/it/. It
-is equivalent to the standard function <tt/fileno/. If
-<tt>it</tt> is an invalid <tt>comedi_t</tt> pointer, the function
-returns -1 and sets the appropriate libcomedi error value.
-
-Source: <tt>/lib/comedi.c</tt>
-
-
-<p>
-<sect2>comedi_find_range()
-<p>
-
-<tt/int comedi_find_range(comedi_t *it, unsigned int subdevice, unsigned
-int chan, unsigned int unit, double min, double max);/
-
-<p>
-The function <tt/comedi_find_range/ tries to
-locate the optimal (smallest) range for the channel <tt>chan</tt>
-belonging to a <tt>subdevice</tt> of the comedi device <tt>it</tt>,
-that includes both <tt>min</tt> and <tt>max</tt> in <tt>units</tt>.
-If it finds a matching range, it returns its index. If no
-matching range is available, it returns -1.
-
-<p>
-Valid units are:
-
-<itemize>
-<item>UNIT_volt
-<item>UNIT_mA
-<item>UNIT_none
-</itemize>
-
-Source: <tt>/lib/range.c</tt>
-
-
-<p>
-<sect2>comedi_errno()
-<label id="comedi_errno">
-<p>
-<tt/int comedi_errno(void);/
-
-<p>
-The function <tt>comedi_errno()</tt>
-returns an integer describing the most recent comedilib error. This
-integer may be used as the <tt>errnum</tt> parameter for
-<tt><ref id="comedi_strerror" name ="comedi_strerror()"></tt>.
-
-When a libcomedi function fails, it usually returns -1 or
-NULL, depending on the return type. An internal library
-variable stores an error number, which can be retrieved with
-<tt>comedi_errno()</tt>. This error number can be
-converted to a human-readable form by the functions
-<tt><ref id="comedi_perror" name ="comedi_perror()"></tt>
- and <tt><ref id="comedi_strerror" name ="comedi_strerror()"></tt>.
-
-These functions are intended to mimic the behavior of the
-standard C library functions <tt>perror()</tt>,
-<tt>strerror</tt>, and <tt>errno()</tt>. In particular,
-libcomedi functions sometimes return an error that is generated
-by the C library; the Comedi error message in this case
-is the same as the C library.
-
-Source: <tt>/lib/error.c</tt>
-
-
-<p>
-<sect2>comedi_find_subdevice_by_type()
-<p>
-
-<tt>int comedi_find_subdevice_by_type(comedi_t *it,int type,unsigned int
-start_subdevice);</tt>
-
-<p>
-The function <tt>comedi_find_subdevice_by_type</tt> tries to
-locate a subdevice belonging to comedi device <tt>it</tt>,
-having type <tt>type</tt>, starting with the subdevice
-<tt>start_subdevice</tt>. If it finds the requested subdevice,
-it returns its index. If it does not locate the requested
-subdevice, it returns -1 and sets the comedi error number to
-"subdevice not found". If there is an error, the function
-returns -1 and sets the appropriate error.
-
-<p>
-For subdevice types, see the manual page for the function
-<tt><ref id="comedi_get_subdevice_type" name =
-"comedi_get_subdevice_type()"></tt>.
-
-Source: <tt>/lib/get.c</tt>
-
-
-<p>
-<sect2>comedi_from_phys()<label id="comedi_from_phys">
-<p>
-
-<tt/lsampl_t comedi_from_phys(double data, comedi_range *rng,
-lsampl_t maxdata);/
-
-Converts data given in physical units (<tt/data/) into sample values
-(lsampl_t, between 0 and maxdata). The parameter <tt>rng</tt>
-represents the conversion information to use, and the parameter
-<tt>maxdata</tt> represents the maximum possible data value for the
-channel that the data will be written to.
-
-
-Source: <tt>/lib/range.c</tt>
-
-
-<p>
-<sect2>comedi_get_board_name()
-<p>
-
-<tt/char *comedi_get_board_name(comedi_t *it);/
-
-The function <tt/comedi_get_board_name/ returns a pointer
-to a string containing the name of the device. This pointer is
-valid until the comedi descriptor <tt/it/ is closed. This
-function returns <tt/NULL/ if there is an error.
-
-Source: <tt>/lib/get.c</tt>
-
-
-<p>
-<sect2>comedi_get_driver_name()
-<p>
-
-<tt/char *comedi_get_driver_name(comedi_t *it);/
-
-The function <tt/comedi_get_driver_name/ returns a pointer
-to a string containing the name of the driver being used by comedi
-for the comedi device represented by <tt/it/. This pointer is
-valid until the comedi descriptor <tt/it/ is closed. This
-function returns <tt/NULL/ if there is an error.
-
-Source: <tt>/lib/get.c</tt>
-
-
-<p>
-<sect2>comedi_get_maxdata()
-<p>
-
-<tt/lsampl_t comedi_get_maxdata(comedi_t *it,unsigned int
-subdevice,unsigned int chan);/
-
-<p>
-The function <tt/comedi_get_maxdata()/ returns the maximum
-valid data value for channel <tt/chan/ of subdevice
-<tt/subdevice/ belonging to the comedi device <tt/it/
-This function returns 0 on error.
-
-Source: <tt>/lib/get.c</tt>
-
-
-<p>
-<sect2>comedi_get_n_channels()
-<p>
-
-<tt/int comedi_get_n_channels(comedi_t *it,unsigned int subdevice);/
-
-The function <tt>comedi_get_n_channels()</tt> returns the number
-of channels of the subdevice belonging to the comedi device <tt>it</tt>
-and having index <tt>subdevice</tt>. This function returns -1 on error.
-
-Source: <tt>/lib/get.c</tt>
-
-
-<p>
-<sect2>comedi_get_n_ranges()
-<p>
-
-<tt>int comedi_get_n_ranges(comedi_t *it,unsigned int subdevice, unsigned int
-chan);</tt>
-
-The function <tt>comedi_get_n_ranges()</tt> returns the number
-of ranges of the channel <tt>chan</tt> belonging to the <tt>subdevice</tt>
-of the comedi device <tt>it</tt>. This function returns -1 on error.
-
-Source: <tt>/lib/range.c</tt>
-
-
-<p>
-<sect2>comedi_get_n_subdevices()
-<p>
-
-<tt>int comedi_get_n_subdevices(comedi_t *it);</tt>
-
-The function <tt>comedi_get_n_subdevices</tt> returns the
-number of subdevices associated with the comedi descriptor
-<tt>it</tt>, or -1 if there is an error.
-
-Source: <tt>/lib/get.c</tt>
-
-
-<p>
-<sect2>comedi_get_range()
-<p>
-
-<tt>comedi_range * comedi_get_range(comedi_t *it,unsigned int subdevice,unsigned int chan,unsigned int
-range);</tt>
-
-The function <tt>comedi_get_range</tt> returns a pointer to a
-comedi_range structure that contains information that can be used to
-convert sample values to or from physical units. The pointer is valid
-until the comedi device <tt>it</tt> is closed. If there is an
-error, NULL is returned.
-
-Source: <tt>/lib/get.c</tt>
-
-<p>
-<sect2>comedi_get_rangetype() <it/deprecated/
-<p>
-
-<tt>int comedi_get_rangetype(comedi_t *it,unsigned int subdevice,unsigned int
-chan);</tt>
-
-The function <tt>comedi_get_rangetype()</tt> returns an integer
-that represents the number of range specifications available for a
-particular channel <tt/chan/ of the subdevice <tt/subdevice/, as well as a conversion table to convert sample
-values to/from physical units.
-
- The macro
-<tt>RANGE_LENGTH(rangetype)</tt>
-can be used to determine the number of range specifications for a given
-range type.
-
-<p>
-This function is deprecated and should not be used in new code.
-
-Source: <tt>/lib/get.c</tt>
-
-<p>
-<sect2>comedi_get_subdevice_type()<label id="comedi_get_subdevice_type">
-<p>
-
-<tt>int comedi_get_subdevice_type(comedi_t *it,unsigned int subdevice);</tt>
-
-The function <tt>comedi_get_subdevice_type()</tt> returns an
-integer describing the type of subdevice that belongs to the comedi
-device <tt>it</tt> and has the index <tt>subdevice</tt>. The
-function returns -1 is there is an error.
-
-Valid subdevice types are:
-
-<itemize>
-<item><tt>COMEDI_SUBD_UNUSED</tt>
-Subdevice has no functionality, i.e., a place-holder.
-<item><tt>COMEDI_SUBD_AI</tt> Analog input
-<item><tt>COMEDI_SUBD_AO</tt> Analog output
-<item><tt>COMEDI_SUBD_DI</tt> Digital input
-<item><tt>COMEDI_SUBD_DO</tt> Digital output
-<item><tt>COMEDI_SUBD_DIO</tt>
-Digital input/output. Channels are configurable as to whether they
-are inputs or outputs.
-<item><tt>COMEDI_SUBD_COUNTER</tt> Counter
-<item><tt>COMEDI_SUBD_TIMER</tt> Timer
-<item><tt>COMEDI_SUBD_MEMORY</tt>
-Memory, e.g., EEPROM or dual-ported RAM
-<item><tt>COMEDI_SUBD_CALIB</tt>
-Calibration DACs
-<item><tt>COMEDI_SUBD_PROC</tt>
-Processor or DSP
-</itemize>
-
-Source: <tt>/lib/get.c</tt>
-
-<p>
-<sect2>comedi_get_timer() <it/(deprecated)/
-<p>
-
-<tt/int comedi_get_timer(comedi_t *it,unsigned int subdev, double
-freq,unsigned int *trigvar, double *actual_freq);/
-
-<p>
-The function <tt>comedi_get_timer</tt> converts the frequency <tt/freq/
-to a number suitable to send to the driver in a <tt/comedi_trig/
-structure. This function remains for compatibility with very
-old versions of Comedi, that converted sampling rates to timer
-values in the libary. This conversion is now done in the kernel,
-and every device has the timer type <tt/nanosec_timer/, indicating
-that timer values are simply a time specified in nanoseconds.
-
-<p>
-This function is deprecated and should not be used in new applications.
-
-<p>
-Source: <tt>/lib/timer.c</tt>
-
-<p>
-<sect2>comedi_get_version_code()
-<p>
-
-<tt/int comedi_get_version_code(comedi_t *it);/
-
-<p>
-The function <tt/comedi_get_version_code()/ returns the
-version code of the currently running comedi module. The version
-code is of the form 0x01072b, which is the version code for
-version 1.7.43.
-
-<p>
-This function is of limited usefulness. A typical mis-application
-of this function is to use it to determine if a certain feature is
-supported. If the application needs
-to know of the existence of a particular feature, an existence
-test function should be written and put in the libcomedi source.
-
-Source: <tt>/lib/get.c</tt>
-
-<p>
-<sect2>comedi_loglevel()
-<P>
-
-<tt>int comedi_loglevel(int loglevel);</tt>
-
-<p>
-This function affects the output of debugging and error messages
-from libcomedi. By increasing the loglevel, additional debugging
-information will be printed. This function returns the previous
-loglevel. Error messages and debugging are printed to the
-stream <tt/stderr/. The loglevel can also be affected by the
-environment variable COMEDI_LOGLEVEL.
-
-<p>
-In order to conserve resources, some debugging information is
-disabled when libcomedi is compiled.
-
-<p>The meaning of the loglevels is as follows:
-
-<itemize>
-<item><tt/COMEDILIB_LOGLEVEL=0/
-
-Comedilib prints nothing.
-
-<item><tt/COMEDILIB_LOGLEVEL=1/ (default)
-
-Comedilib only prints error messages when there is a
-self-consistency error (i.e., internal bug).
-
-<item><tt/COMEDILIB_LOGLEVEL=2/
-
-Comedilib prints an error message when an invalid
-parameter is passed to comedilib.
-
-<item><tt/COMEDILIB_LOGLEVEL=3/
-
-Comedilib prints an error message whenever an error is generated
-in the comedilib library or is generated in the C library when
-called by comedilib.
-
-<item><tt/COMEDILIB_LOGLEVEL=4/
-
-Comedilib prints a lot of debugging messages.
-
-</itemize>
-
-Bugs: Libcomedi doesn't currently have much debugging information.
-
-Source: <tt>/lib/error.c</tt>
-
-<p>
-<sect2>comedi_open()
-<p>
-
-<tt/comedi_t *comedi_open(char *filename);/
-
-Opens a comedi device specified by the filename <tt/filename/.
-Returns NULL on error. On sucess, it returns a handle that is
-given as a parameter to other libcomedi functions.
-
-<p>
-You are not supposed to have access to the internals of the
-<tt/comedi_t/ structure.
-
-Bugs: Not strictly identical to <tt/fopen/
-
-Source: <tt>/lib/comedi.c</tt>
-
-
-<p>
-<sect2>comedi_perror()<label id="comedi_perror">
-<p>
-
-<tt>void comedi_perror(const char *s);</tt>
-
-When a comedilib function fails, it usually returns -1 or
-NULL, depending on the return type. An internal library
-variable stores an error number, which can be retrieved with
-<tt><ref id="comedi_errno" name ="comedi_errno()"></tt>.
- This error number can be
- converted to a human-readable form by the functions
-<tt>comedi_perror()</tt>
- and <tt><ref id="comedi_strerror" name ="comedi_strerror()"></tt>.
-
-These functions are intended to mimic the behavior of the
-standard C library functions <tt>perror()</tt>,
-<tt>strerror</tt>, and <tt>errno()</tt>. In particular,
-comedilib functions sometimes return an error that is generated
-inside the C library; the comedi error message in this case
-is the same as the C library.
-
-The function <tt>comedi_perror()</tt> prints an error
-message to stderr. The error message consists of the
-argument string, a colon, a space, a description of the error
-condition, and a new line.
-
-Bugs: Does not support internationalization.
-
-Source: <tt>/lib/error.c</tt>
-
-
-<p>
-<sect2>comedi_strerror()<label id="comedi_strerror">
-<p>
-
-<tt>*comedi_strerror(int errnum);</tt>
-
-When a comedilib function fails, it usually returns -1 or
-NULL, depending on the return type. An internal library
-variable stores an error number, which can be retrieved with
-<tt><ref id="comedi_errno" name ="comedi_errno()"></tt>. This error number can be
-converted to a human-readable form by the functions
-<tt><ref id="comedi_perror" name ="comedi_perror()"></tt>
- and <tt>comedi_strerror()</tt>.
-
-These functions are intended to mimic the behavior of the
-standard C library functions <tt>perror()</tt>,
-<tt>strerror</tt>, and <tt>errno()</tt>. In particular,
-comedilib functions sometimes return an error that is generated
-inside the C library; the comedi error message in this case
-is the same as the C library.
-
-The function <tt>comedi_strerror()</tt> returns a pointer to a
-character string
-describing the comedilib error <tt>errnum</tt>. The persistence
-of the returned pointer is undefined, and should not be trusted
-after the next libcomedi call. An unrecognized error number will
-return a pointer to the string "undefined error", or similar.
-
-Bugs: Does not support internationalization.
-
-Source: <tt>/lib/error.c</tt>
-
-
-<p>
-<sect2>comedi_sv_init()
-<p>
-
-<tt/int comedi_sv_init(comedi_sv_t *sv,comedi_t *dev,unsigned int subd,
-unsigned int chan);/
-
-
-<tt/comedi_sv_init/ initializes the slow varying comedi structure
-<tt/sv/ of the device <tt/dev/, the subdevice <tt/subd/ (analog input) and
-the channel <tt/chan/.
-The slow varying comedi structure <tt/sv/ of type <tt><ref id="comedi_sv_t"
-name="comedi_sv_t"</tt>
-specifies the signal measurement. The default number of averaged
-samples is 100. Returns zero on success, -1 on error.
-
-Bugs: comedi_sv_* was very poorly designed.
-
-Source: <tt>/lib/sv.c</tt>
-
-
-<p>
-<sect2>comedi_sv_update()
-<p>
-
-<tt/int comedi_sv_update(comedi_sv_t *sv);/
-
-The function <tt/comedi_sv_update/ updates the slow varying comedi structure
-<tt/sv/.
-Returns zero on success, -1 on error.
-
-Source: <tt>/lib/sv.c</tt>
-
-
-<p>
-<sect2>int comedi_sv_measure()
-<p>
-
-<tt>int comedi_sv_measure(comedi_sv_t *it,double *data);</tt>
-
-<tt/comedi_sv_measure/ measures the slow variing signal. The measurement
-is specified by the slow varying comedi structure <tt/sv/, the result is
-stored in <tt/data/.
-On success returns the number of samples, -1 on error.
-
-Source: <tt>/lib/sv.c</tt>
-
-
-<p>
-<sect2>comedi_to_phys()<label id="comedi_to_phys">
-<p>
-
-<tt/double comedi_to_phys(lsampl_t data, comedi_range *rng,
-lsampl_t maxdata);/
-
-Converts data given in sample values (lsampl_t, between 0 and
-maxdata) into physical units (double). The parameter <tt/rng/
-represents the conversion information to use, and the parameter
-<tt/maxdata/ represents the maximum possible data value for the
-channel that the data was read.
-
-Source: <tt>/lib/range.c</tt>
-
-
-<p>
-<sect2>comedi_trigger() <it/(deprecated)/
-<p>
-
-<tt/int comedi_trigger(comedi_t *it,comedi_trig *trig);/
-
-The function <tt/comedi_trigger/ instructs comedi to
-perform the command specified by the <ref id="comedi_trig_struct" name
-="trigger structure"> <tt/trig/. Results depend on
-the particular command being issued. If there is an
-error, -1 is returned.
-
-Lifetime: removal at 1.0.
-
-Source: <tt>/lib/comedi.c</tt>
-
-
-<p>
-<sect2>comedi_get_subdevice_flags()
-<label id="comedi_get_subdevice_flags">
-<p>
-
-<tt/int comedi_get_subdevice_flags(comedi_t *dev, unsigned int subdevice);/
-
-<p>
-This function returns a bitfield describing the capabilities of the
-specified subdevice. If there is an error, -1 is returned.
-
-<p>The bits are:
-
-<itemize>
-<item>SDF_BUSY subdevice is running a command
-<item>SDF_BUSY_OWNER subdevice is running a command started by
-the file descriptor used by <tt/dev/.
-<item>SDF_LOCKED subdevice is locked
-<item>SDF_LOCKED_OWNER subdevice is locked by the file descriptor used
-by <tt/dev/.
-<item>SDF_MAXDATA maximum data values are channel dependent
-<item>SDF_FLAGS channel flags are channel dependent
-<item>SDF_RANGETYPE range types are channel dependent
-<item>SDF_MODE0 deprecated
-<item>SDF_MODE1 deprecated
-<item>SDF_MODE2 deprecated
-<item>SDF_MODE3 deprecated
-<item>SDF_MODE4 deprecated
-<item>SDF_CMD subdevice supports commands
-<item>SDF_READABLE subdevice can be read from
-<item>SDF_WRITEABLE subdevice can be written to
-<item>SDF_RT deprecated
-<item>SDF_GROUND subdevice is capable of ground analog reference
-<item>SDF_COMMON subdevice is capable of common analog reference
-<item>SDF_DIFF subdevice is capable of differential analog reference
-<item>SDF_OTHER subdevice is capable of other analog reference
-<item>SDF_DITHER subdevice recognizes dither flag
-<item>SDF_DEGLITCH subdevice recognizes deglitch flag
-<item>SDF_MMAP deprecated
-<item>SDF_RUNNING subdevice is acquiring data (i.e., command has not
-completed)
-<item>SDF_LSAMPL subdevice uses samples of type lsampl_t (otherwise
-sampl_t)
-<item>SDF_PACKED subdevice uses bitfield samples (otherwise it uses
-one sample per channel)
-</itemize>
-
-
-
-<p>
-The bit definitions are part of the Comedi kernel interface.
-
-
-<p>
-<sect2>comedi_range_is_chan_specific()
-<label id="comedi_range_is_chan_specific">
-<p>
-
-<tt/int comedi_range_is_chan_specific(comedi_t *dev,unsigned int subdevice);/
-
-<p>
-If each channel of the specified subdevice has a different range
-specification, this function returns 1. Otherwise, this function
-returns 0. On error, this function returns -1.
-
-
-<p>
-<sect2>Undocumented functions
-<label id="undocumented">
-<p>
-
-
-<itemize>
-<item>comedi_maxdata_is_chan_specific()
-<item>comedi_get_buffer_size()
-<item>comedi_get_max_buffer_size()
-<item>comedi_set_buffer_size()
-<item>comedi_set_max_buffer_size()
-<item>comedi_do_insnlist()
-<item>comedi_do_insn()
-<item>comedi_lock()
-<item>comedi_unlock()
-<item>comedi_get_cmd_src_mask()
-<item>comedi_get_cmd_generic_timed()
-<item>comedi_cancel()
-<item>comedi_command()
-<item>comedi_command_test()
-<item>comedi_poll()
-<item>comedi_get_buffer_contents()
-<item>comedi_mark_buffer_read()
-<item>comedi_get_buffer_offset()
-<item>comedi_set_global_oor_behavior()
-</itemize>
-
-
-
-
-
-
-
-
-
-
-</article>
-
projects / comedilib.git / commitdiff