Allow setting synth gain

2 files changed, 24 insertions, 8 deletions

diff --git a/include/xas/synth.h b/include/xas/synth.h
index 61f50bc..c13c53e 100644
--- a/include/xas/synth.h
+++ b/include/xas/synth.h
@@ -7,6 +7,7 @@
 #include <xas/object.h>
 #include <xas/audio.h>
 
+#define XAS_SYNTH_DEFAULT_GAIN      1.0f
 #define XAS_SYNTH_DEFAULT_FREQUENCY 2600 /* Hz */
 
 enum xas_synth_type {
@@ -36,7 +37,9 @@ struct _xas_synth {
 
     xas_synth_sample_callback sample;
 
-    float phase;
+    float phase,
+          gain;
+
     size_t frequency;
 };
 
@@ -46,6 +49,8 @@ xas_synth *xas_synth_new(xas_audio_format format,
 
 void xas_synth_destroy(xas_synth *synth);
 
+void xas_synth_set_gain(xas_synth *synth, float gain);
+
 void xas_synth_set_frequency(xas_synth *synth, size_t frequency);
 
 void xas_synth_start(xas_synth *synth);
diff --git a/src/synth.c b/src/synth.c
index fddd2a0..76d718b 100644
--- a/src/synth.c
+++ b/src/synth.c
@@ -9,7 +9,7 @@ static int16_t sample_sine(xas_synth *synth) {
     static float tau = 2.0f * M_PI;
 
     if (synth->state == XAS_SYNTH_ACTIVE) {
-        ret = (int16_t)roundf((INT16_MAX >> 2) * sinf(synth->phase));
+        ret = (int16_t)roundf(synth->gain * (INT16_MAX >> 2) * sinf(synth->phase));
 
         synth->phase += tau / (synth->format.sample_rate / synth->frequency);
 
@@ -29,8 +29,8 @@ static int16_t sample_square(xas_synth *synth) {
 
     if (synth->state == XAS_SYNTH_ACTIVE) {
         ret = (synth->phase - M_PI) > 0.0?
-            INT16_MAX / 4:
-            INT16_MIN / 4;
+            (int16_t)roundf(synth->gain * (INT16_MAX / 4)):
+            (int16_t)roundf(synth->gain * (INT16_MIN / 4));
 
         synth->phase += tau / (synth->format.sample_rate / synth->frequency);
 
@@ -51,7 +51,7 @@ static int16_t sample_triangle(xas_synth *synth) {
     if (synth->state == XAS_SYNTH_ACTIVE) {
         float v = 2.0f * fabs(2.0f * fabs(synth->phase - floorf(synth->phase + 0.5))) - 1.0f;
 
-        ret = (int16_t)roundf((INT16_MAX >> 2) * v);
+        ret = (int16_t)roundf(synth->gain * (INT16_MAX >> 2) * v);
 
         synth->phase += tau / (synth->format.sample_rate / synth->frequency);
 
@@ -72,7 +72,7 @@ static int16_t sample_sawtooth(xas_synth *synth) {
     if (synth->state == XAS_SYNTH_ACTIVE) {
         float v = 2.0f * (synth->phase / tau - 0.5f);
 
-        ret = (int16_t)roundf((INT16_MAX >> 2) * v);
+        ret = (int16_t)roundf(synth->gain * (INT16_MAX >> 2) * v);
 
         synth->phase += tau / (synth->format.sample_rate / synth->frequency);
 
@@ -111,6 +111,12 @@ static int synth_stop(xas_synth *synth) {
     return 0;
 }
 
+static int set_gain(xas_synth *synth, float gain) {
+    xas_synth_set_gain(synth, gain);
+
+    return 0;
+}
+
 xas_synth *xas_synth_new(xas_audio_format format,
                              size_t buffer_size,
                              enum xas_synth_type type) {
@@ -120,8 +126,9 @@ xas_synth *xas_synth_new(xas_audio_format format,
         goto error_malloc_synth;
     }
 
-    synth->obj.start = (xas_object_start_callback)synth_start;
-    synth->obj.stop  = (xas_object_stop_callback)synth_stop;
+    synth->obj.start    = (xas_object_start_callback)synth_start;
+    synth->obj.stop     = (xas_object_stop_callback)synth_stop;
+    synth->obj.set_gain = (xas_object_set_gain_callback)set_gain;
 
     synth->type      = type;
     synth->state     = XAS_SYNTH_IDLE;
@@ -158,6 +165,10 @@ void xas_synth_destroy(xas_synth *synth) {
     free(synth);
 }
 
+void xas_synth_set_gain(xas_synth *synth, float gain) {
+    synth->gain = gain;
+}
+
 void xas_synth_set_frequency(xas_synth *synth, size_t frequency) {
     synth->frequency = frequency;
 }