Selected waveform with -n. Shifted up sine wave if necessary. Added new

waveforms.  Fixed cycloid. :-)

diff --git a/demo/ao_waveform.c b/demo/ao_waveform.c
index 10d07d15a8bca34e639c733165cb7917a9ac571f..6586241b3102e8b0f6c63b34f9884983b2645bc7 100644 (file)
--- a/demo/ao_waveform.c
+++ b/demo/ao_waveform.c
@@ -15,9 +15,10 @@
  *
  * This demo uses an analog output subdevice with an
  * asynchronous command to generate a waveform.  The
- * waveform in this example is a sine wave (surprise!),
- * but this can be easily changed to make a generic
- * function generator.
+ * demo hijacks for -n option to select a waveform from
+ * a predefined list.  The default waveform is a sine
+ * wave (surprise!).  Other waveforms include sawtooth,
+ * square, triangle and cycloid.
  *
  * The function generation algorithm is the same as
  * what is typically used in digital function generators.
@@ -66,14 +67,26 @@ int external_trigger_number = 0;
 sampl_t data[BUF_LEN];
 
 void dds_output(sampl_t *buf,int n);
-void dds_init(double waveform_frequency, double update_frequency);
-
-/* This define determines which waveform to use. */
-#define dds_init_function dds_init_sine
+void dds_init(double waveform_frequency, double update_frequency, int fn);
 
 void dds_init_sine(void);
 void dds_init_pseudocycloid(void);
-void dds_init_sawtooth(void);
+void dds_init_cycloid(void);
+void dds_init_ramp_up(void);
+void dds_init_ramp_down(void);
+void dds_init_triangle(void);
+void dds_init_square(void);
+
+static void (* const dds_init_function[])(void) = {
+       dds_init_sine,
+       dds_init_ramp_up,
+       dds_init_ramp_down,
+       dds_init_triangle,
+       dds_init_square,
+       dds_init_cycloid,
+};
+
+#define NUMFUNCS       (sizeof(dds_init_function)/sizeof(dds_init_function[0]))
 
 int main(int argc, char *argv[])
 {
@@ -87,11 +100,19 @@ int main(int argc, char *argv[])
        comedi_range *rng;
        int ret;
        struct parsed_options options;
+       int fn;
 
        init_parsed_options(&options);
        options.subdevice = -1;
+       options.n_chan = 0;     /* default waveform */
        parse_options(&options, argc, argv);
 
+       /* Use n_chan to select waveform (cheat!) */
+       fn = options.n_chan;
+       if(fn < 0 || fn >= NUMFUNCS){
+               fn = 0;
+       }
+
        /* Force n_chan to be 1 */
        options.n_chan = 1;
 
@@ -133,7 +154,7 @@ int main(int argc, char *argv[])
        chanlist[0] = CR_PACK(options.channel, options.range, options.aref);
        //chanlist[1] = CR_PACK(options.channel + 1, options.range, options.aref);
 
-       dds_init(waveform_frequency, options.freq);
+       dds_init(waveform_frequency, options.freq, fn);
 
        dump_cmd(stdout,&cmd);
 
@@ -205,11 +226,11 @@ sampl_t waveform[WAVEFORM_LEN];
 unsigned int acc;
 unsigned int adder;
 
-void dds_init(double waveform_frequency, double update_frequency)
+void dds_init(double waveform_frequency, double update_frequency, int fn)
 {
        adder = waveform_frequency / update_frequency * (1 << 16) * (1 << WAVEFORM_SHIFT);
 
-       dds_init_function();
+       (*dds_init_function[fn])();
 }
 
 void dds_output(sampl_t *buf,int n)
@@ -228,9 +249,15 @@ void dds_output(sampl_t *buf,int n)
 void dds_init_sine(void)
 {
        int i;
+       double ofs = offset;
+       double amp = 0.5 * amplitude;
 
+       if(ofs < amp){
+               /* Probably a unipolar range.  Bump up the offset. */
+               ofs = amp;
+       }
        for(i=0;i<WAVEFORM_LEN;i++){
-               waveform[i]=rint(offset+0.5*amplitude*cos(i*2*M_PI/WAVEFORM_LEN));
+               waveform[i]=rint(ofs+amp*cos(i*2*M_PI/WAVEFORM_LEN));
        }
 }
 
@@ -251,7 +278,26 @@ void dds_init_pseudocycloid(void)
        }
 }
 
-void dds_init_sawtooth(void)
+void dds_init_cycloid(void)
+{
+       enum { SUBSCALE = 2 };  /* Needs to be >= 2. */
+       int h, i, ni;
+       double t, x, y;
+
+       i = -1;
+       for (h = 0; h < WAVEFORM_LEN * SUBSCALE; h++){
+               t = (h * (2 * M_PI)) / (WAVEFORM_LEN * SUBSCALE);
+               x = t - sin(t);
+               ni = (int)floor((x * WAVEFORM_LEN) / (2 * M_PI));
+               if (ni > i) {
+                       i = ni;
+                       y = 1 - cos(t);
+                       waveform[i] = rint(offset + (amplitude * y / 2));
+               }
+       }
+}
+
+void dds_init_ramp_up(void)
 {
        int i;
 
@@ -260,3 +306,36 @@ void dds_init_sawtooth(void)
        }
 }
 
+void dds_init_ramp_down(void)
+{
+       int i;
+
+       for(i=0;i<WAVEFORM_LEN;i++){
+               waveform[i]=rint(offset+amplitude*((double)(WAVEFORM_LEN-1-i))/WAVEFORM_LEN);
+       }
+}
+
+void dds_init_triangle(void)
+{
+       int i;
+
+       for (i = 0; i <= WAVEFORM_LEN / 2; i++) {
+               waveform[i] = rint(offset + amplitude * (i * 2) / WAVEFORM_LEN);
+       }
+       for ( ; i < WAVEFORM_LEN; i++) {
+               waveform[i] = rint(offset + amplitude * ((WAVEFORM_LEN - i) * 2) / WAVEFORM_LEN);
+       }
+}
+
+void dds_init_square(void)
+{
+       int i;
+
+       for (i = 0; i < WAVEFORM_LEN / 2; i++) {
+               waveform[i] = rint(offset);
+       }
+       for ( ; i < WAVEFORM_LEN; i++) {
+               waveform[i] = rint(offset + amplitude);
+       }
+}
+