regen

diff --git a/doc/comedilib-4.html b/doc/comedilib-4.html
index 689e47b706ca0d89d3a36a0d1254411860c479d2..306f359c5bfed9d0f160053dade2dd27b37a764d 100644 (file)
--- a/doc/comedilib-4.html
+++ b/doc/comedilib-4.html
@@ -52,8 +52,7 @@ int main(int argc,char *argv[])
 <P>
 <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.  Including all
-the appropriate headers is sometimes a little tricky.
+without error checking or fancy options.
 Compile it using 
 <P>
 <BLOCKQUOTE><CODE>
@@ -61,7 +60,6 @@ Compile it using
 cc tut1.c -lcomedi -o tut1
 </PRE>
 </CODE></BLOCKQUOTE>
-<P>Hopefully it works.
 <P>A few notes:  The range variable tells comedi which gain
 to use when measuring an analog voltage.  Since we don't
 know (yet) which numbers are valid, or what each means,
@@ -85,18 +83,23 @@ you probably prefer to have this number translated to
 a voltage.  Naturally, as a good programmer, your first
 question is: "How do I do this in a device-independent
 manner?"
-<P>For each subdevice, the comedi kernel module keeps a
-'range_type' variable.  This variable contains the number
-of available ranges (i.e., gains) that you can select,
-along with an offset in a list of range information
-structures.  If you know the range_type variable, you
-can use these macros:
-<P>RANGE_OFFSET(range_type)
-RANGE_LENGTH(range_type)
-<P>to extract such information.  However, you want the
-actual voltage information, not some integer offset
-in a table.  Rather than messing with the library
-internals, use the function
+<P>Most devices give you a choice of gain and unipolar/bipolar
+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
+and the unipolar/bipolar aspects.
+<P>Comedi keeps the number of available ranges and the largest
+sample value for each subdevice/channel combination.  (Some
+devices allow different input/output ranges for different
+channels in a subdevice.)
+<P>The largest sample value can be found using the function:
+<P>comedi_get_maxdata()
+<P>The number of available ranges can be found using the function:
+<P>comedi_get_n_ranges()
+<P>For each value of the range parameter for a particular
+subdevice/channel, you can get range information using the
+function:
 <P>ptr=comedi_get_range(comedi_file,subdevice,channel,
 range)
 <P>which returns a pointer to a comedi_range structure.
@@ -112,8 +115,7 @@ typedef struct{
 }comedi_range;
 </PRE>
 </CODE></BLOCKQUOTE>
-<P>As you might expect, ptr[range] is for range 'range',
-which you provided to comedi_data_read() above.  'min' represents
+<P>The structure element 'min' represents
 the voltage corresponding to comedi_data_read() returning 0,
 and 'max' represents comedi_data_read() returning 'maxdata',
 (i.e., 4095 for 12 bit A/C converters, 65535 for 16 bit,
@@ -136,12 +138,6 @@ volts=comedi_to_phys(it,data,range,maxdata);
 data=comedi_from_phys(it,volts,range,maxdata);
 </PRE>
 </CODE></BLOCKQUOTE>
-<P>You probably noticed (and were worried) that we haven't
-discussed how to determine maxdata and range_type.  Well,
-you could ask the kernel this information each time you need
-it, but since there are other variables, special cases,
-and several subdevices to worry about, it would be nice
-if the library could take care of this...  (read on...)
 <P>
 <P>
 <P>
@@ -167,7 +163,7 @@ file=comedi_open("/dev/comedi0");
 calls <CODE>open()</CODE>, like we did explicitly in a previous
 section, but also fills the <CODE>comedi_t</CODE> structure with
 lots of goodies -- information that we will need to use
-soon.
+soon.  
 <P>Specifically, we needed to know maxdata for a specific
 subdevice/channel.  How about:
 <P>