starting work on apu

include/audio.h

@@ -12,3 +12,4 @@ typedef struct {
 } audio_context;
 
 void audio_init();
+void audio_tick();

lib/audio.c

@@ -77,13 +77,13 @@ void audio_init(){
     PaStream *stream;
     PaError err;
 
-    ctx.sq1_amp = 0;
-    ctx.sq1_duty = 0;
-    ctx.sq1_freq = 0;
+    ctx.sq1_amp = 0.2;
+    ctx.sq1_duty = 0.5;
+    ctx.sq1_freq = 200;
 
     ctx.sq2_amp = 0;
-    ctx.sq2_duty = 0;
-    ctx.sq2_freq = 0;
+    ctx.sq2_duty = 0.5;
+    ctx.sq2_freq = 400;
 
     for(int i = 0; i < TABLE_SIZE; i++) {
         sine[i] = (float) sin(((double)i/(double)TABLE_SIZE) * M_PI * 2.);
@@ -117,3 +117,12 @@ error:
     Pa_Terminate();
     fprintf(stderr, "portaudio stream error\n\tError Number: %d\n\tError Message: %s\n", err, Pa_GetErrorText(err));
 }
+
+static int change = 1;
+
+void audio_tick(){
+    ctx.sq1_freq += change;
+    if(ctx.sq1_freq >= 600 || ctx.sq1_freq <= 200) {
+        change = -change;
+    }
+}

lib/timer.c

@@ -1,6 +1,7 @@
 
 #include <timer.h>
 #include <interrupts.h>
+#include <audio.h>
 
 static timer_context ctx = {0};
 
@@ -37,6 +38,10 @@ void timer_tick() {
             cpu_request_interrupt(IT_TIMER);
         }
     }
+
+    if((prev_div & (1 << 12)) && (!(ctx.div & (1 << 12)))){
+        audio_tick();
+    }
 }
 
 void timer_write(u16 address, u8 value){