+ struct analog_gen *ag;
+ double t, frequency;
+ float value;
+ unsigned int num_samples, i;
+ int last_end;
+
+ ag = cg->priv;
+ num_samples = ANALOG_BUFSIZE / sizeof(float);
+
+ sr_dbg("Generating %s pattern for channel group %s",
+ analog_pattern_str[ag->pattern], cg->name);
+
+ switch (ag->pattern) {
+ case PATTERN_SQUARE:
+ value = ANALOG_AMPLITUDE;
+ last_end = 0;
+ for (i = 0; i < num_samples; i++) {
+ if (i % 5 == 0)
+ value = -value;
+ if (i % 10 == 0)
+ last_end = i - 1;
+ ag->pattern_data[i] = value;
+ }
+ ag->num_samples = last_end;
+ break;
+
+ case PATTERN_SINE:
+ frequency = (double) sample_rate / ANALOG_SAMPLES_PER_PERIOD;
+
+ /* Make sure the number of samples we put out is an integer
+ * multiple of our period size */
+ /* FIXME we actually need only one period. A ringbuffer would be
+ * usefull here.*/
+ while (num_samples % ANALOG_SAMPLES_PER_PERIOD != 0)
+ num_samples--;
+
+ for (i = 0; i < num_samples; i++) {
+ t = (double) i / (double) sample_rate;
+ ag->pattern_data[i] = ANALOG_AMPLITUDE *
+ sin(2 * M_PI * frequency * t);
+ }
+
+ ag->num_samples = num_samples;
+ break;
+
+ case PATTERN_TRIANGLE:
+ frequency = (double) sample_rate / ANALOG_SAMPLES_PER_PERIOD;
+
+ while (num_samples % ANALOG_SAMPLES_PER_PERIOD != 0)
+ num_samples--;
+
+ for (i = 0; i < num_samples; i++) {
+ t = (double) i / (double) sample_rate;
+ ag->pattern_data[i] = (2 * ANALOG_AMPLITUDE / M_PI) *
+ asin(sin(2 * M_PI * frequency * t));
+ }
+
+ ag->num_samples = num_samples;
+ break;
+
+ case PATTERN_SAWTOOTH:
+ frequency = (double) sample_rate / ANALOG_SAMPLES_PER_PERIOD;
+
+ while (num_samples % ANALOG_SAMPLES_PER_PERIOD != 0)
+ num_samples--;
+
+ for (i = 0; i < num_samples; i++) {
+ t = (double) i / (double) sample_rate;
+ ag->pattern_data[i] = 2 * ANALOG_AMPLITUDE *
+ ((t * frequency) - floor(0.5f + t * frequency));
+ }
+
+ ag->num_samples = num_samples;
+ break;
+ }