fixed audio buffer.

include/audio.h

@@ -133,6 +133,7 @@ typedef struct {
 void audio_init();
 void audio_tick();
 void audio_period_tick();
+void lfsr_tick();
 
 u8 audio_read(u16 address);
 void audio_write(u16 address, u8 value);

lib/audio.c

@@ -15,7 +15,7 @@
 #define AUDIO_TICKS_PER_SAMPLE 2157281.28 / SAMPLE_RATE
 #define TIME_PER_WAVE_TICK 1.0f / (2104718.0f/1000.0f/1000.0f)
 #define LFSR_BASE_CLOCK 262144.0f
-#define AUDIO_BUFFER_SIZE 102400
+#define AUDIO_BUFFER_SIZE 10240
 
 static audio_context ctx;
 
@@ -25,7 +25,7 @@ audio_context *audio_get_context() {
 
 static float audio_time = 0;
 static float wave_time = 0;
-static float lfsr_timer = 0;
+static u32 lfsr_timer = 0;
 static float lfsr_clock = LFSR_BASE_CLOCK;
 static float lfsr_clock_buffer = LFSR_BASE_CLOCK;
 
@@ -94,17 +94,25 @@ static int audio_callback(const void* input_uffer, void *output_buffer,
                             PaStreamCallbackFlags status_flags,
                             void *userData ) {
     float *out = (float *)output_buffer;
+    //while(ctx.buffer_cnt < framesPerBuffer*AUDIO_TICKS_PER_SAMPLE) {
+    //    delay(1);
+    //}
     for(int i = 0; i < framesPerBuffer; i++) {
-        samples_occured = samples_occured + AUDIO_TICKS_PER_SAMPLE;
+        //samples_occured = samples_occured + AUDIO_TICKS_PER_SAMPLE-1;
-        if(ctx.buffer_cnt < (u8)samples_occured) {
+        while(ctx.buffer_cnt == 0) {
+            //delay(1);
+        }
+        if(ctx.buffer_cnt == 0) {
             //samples_occured = samples_occured - ((int)samples_occured - ctx.buffer_cnt);
             //ctx.sq1_read_index = ctx.sq1_write_index-1;
             //printf("buffer underflow\n");
+            return paContinue;
         } else {
-            ctx.buffer_cnt -= (u8)samples_occured;
+            //ctx.buffer_cnt -= (u8)samples_occured;
-            ctx.sq1_read_index += (u8)samples_occured;
+            //ctx.sq1_read_index += (u8)samples_occured;
-            ctx.sq1_read_index %= AUDIO_BUFFER_SIZE;
+            //ctx.sq1_read_index %= AUDIO_BUFFER_SIZE;
-            samples_occured -= (u8)samples_occured;
+            //samples_occured -= (u8)samples_occured;
+            ctx.buffer_cnt--;
         }
         if(ppu_get_context()->paused) {
             *out++ = 0;
@@ -211,6 +219,8 @@ static int audio_callback(const void* input_uffer, void *output_buffer,
 
         left = ctx.sq1_audio_buffer[ctx.sq1_read_index];
         right = ctx.sq2_audio_buffer[ctx.sq1_read_index];
+        ctx.sq1_read_index++;
+        ctx.sq1_read_index %= AUDIO_BUFFER_SIZE;
 
 
         bool dacs = ctx.ch1_dac || ctx.ch2_dac || ctx.ch3_dac || ctx.ch4_dac;
@@ -240,27 +250,8 @@ static int audio_callback(const void* input_uffer, void *output_buffer,
             right_out = 1;
         }
         history_timer++;
-        if(history_timer >= history_interval){
+        if(history_timer >= 5){
             history_timer = 0;
-            ctx.sq1_history[ctx.sq1_index++] = sq1_val;
-            if (ctx.sq1_index == 384) {
-                ctx.sq1_index = 0;
-            }
-
-            ctx.sq2_history[ctx.sq2_index++] = sq2_val;
-            if (ctx.sq2_index == 384) {
-                ctx.sq2_index = 0;
-            }
-
-            ctx.ch3_history[ctx.ch3_index++] = ch3_val;
-            if (ctx.ch3_index == 384) {
-                ctx.ch3_index = 0; 
-            }
-
-            ctx.ch4_history[ctx.ch4_index++] = ch4_val;
-            if (ctx.ch4_index == 384) {
-                ctx.ch4_index = 0;
-            }
             ctx.left_history[ctx.left_index++] = left_out;
             if (ctx.left_index == 384) {
                 ctx.left_index = 0;
@@ -338,9 +329,9 @@ void audio_init(){
     ctx.sq2_env_direction = false;
     ctx.sq2_env_pace = 0x0;
     ctx.sq2_env_timer = 0x0;
-    ctx.sq1_write_index = AUDIO_BUFFER_SIZE / 2;
+    ctx.sq1_write_index = 0;
     ctx.sq1_read_index = 0;
-    ctx.buffer_cnt = AUDIO_BUFFER_SIZE / 2;
+    ctx.buffer_cnt = 0;
     
     err = Pa_Initialize();
     if (err != paNoError) goto error;
@@ -388,6 +379,21 @@ static u32 start = 0;
 static u32 period_tick;
 static u32 samples_per_sec = 0;
 
+void lfsr_tick() {
+    lfsr_timer--;
+    if(lfsr_timer == 0) {
+        lfsr_timer = (ctx.ch4_clock_divider > 0 ? (ctx.ch4_clock_divider << 4) : 8) << ctx.ch4_clock_shift;
+        unsigned bit_mask = ctx.ch4_lfsr_width ? 0x4040 : 0x4000;
+        bool new_bit = (ctx.ch4_lfsr ^ (ctx.ch4_lfsr >> 1) ^ 1) & 1;
+        ctx.ch4_lfsr >>= 1;
+        if(new_bit) {
+            ctx.ch4_lfsr |= bit_mask;
+        } else {
+            ctx.ch4_lfsr &= ~bit_mask;
+        }
+    }
+}
+
 
 void audio_period_tick() {
     period_tick++;
@@ -432,18 +438,6 @@ void audio_period_tick() {
             ctx.ch3_last_sample = ctx.wave_ram[ctx.ch3_sample >> 1] >> 4;
         }
     }
-    lfsr_timer--;
-    if(lfsr_timer == 0) {
-        lfsr_timer = (ctx.ch4_clock_divider > 0 ? (ctx.ch4_clock_divider << 4) : 8) << ctx.ch4_clock_shift;
-        unsigned bit_mask = ctx.ch4_lfsr_width ? 0x4040 : 0x4000;
-        bool new_bit = (ctx.ch4_lfsr ^ (ctx.ch4_lfsr >> 1) ^ 1) & 1;
-        ctx.ch4_lfsr >>= 1;
-        if(new_bit) {
-            ctx.ch4_lfsr |= bit_mask;
-        } else {
-            ctx.ch4_lfsr &= ~bit_mask;
-        }
-    }
 
     float left = 0;
     float right = 0;
@@ -537,15 +531,40 @@ void audio_period_tick() {
     left *= (float)left_vol/7.0f;
     right *= (float)right_vol/7.0f;
 
-    if(ctx.buffer_cnt < AUDIO_BUFFER_SIZE){
+    if(period_tick % 100 == 0){
+        ctx.sq1_history[ctx.sq1_index++] = sq1_val;
+        if (ctx.sq1_index == 384) {
+            ctx.sq1_index = 0;
+        }
+
+        ctx.sq2_history[ctx.sq2_index++] = sq2_val;
+        if (ctx.sq2_index == 384) {
+            ctx.sq2_index = 0;
+        }
+
+        ctx.ch3_history[ctx.ch3_index++] = ch3_val;
+        if (ctx.ch3_index == 384) {
+            ctx.ch3_index = 0; 
+        }
+
+        ctx.ch4_history[ctx.ch4_index++] = ch4_val;
+        if (ctx.ch4_index == 384) {
+            ctx.ch4_index = 0;
+        }
+    }
+    
+    if((period_tick % (int)(AUDIO_TICKS_PER_SAMPLE)) == 0){
+        //printf("tick\n");
+        while(ctx.buffer_cnt == AUDIO_BUFFER_SIZE){
+            //delay(1);
+            //printf("overflow\n");
+        }
         ctx.sq1_audio_buffer[(ctx.sq1_write_index)] = left;
         ctx.sq2_audio_buffer[(ctx.sq1_write_index)] = right;
         //ctx.ch3_audio_buffer[(ctx.sq1_write_index)] = (((float)(ctx.ch3_last_sample >> shift)-7.5f)/7.5f);
         //ctx.ch4_audio_buffer[(ctx.sq1_write_index)] = (ctx.ch4_lfsr & 0b1) ? (float)(ctx.ch4_volume-7.5f)/7.5f : -1.0f;
         ctx.sq1_write_index = (ctx.sq1_write_index + 1) % AUDIO_BUFFER_SIZE;
         ctx.buffer_cnt++;
-    } else {
-        //printf("buffer overflow\n");
     }
 }
 
@@ -692,9 +711,6 @@ void enable_wave() {
 }
 
 void enable_noise() {
-    if(!ctx.ch4_dac){
-        return;
-    }
     ctx.ch4_enable = true;
     ctx.ch4_env_timer = ctx.ch4_env_pace_buffer != 0 ? ctx.ch4_env_pace_buffer : 8;
     ctx.ch4_env_direction = ctx.ch4_env_direction_buffer;
@@ -702,7 +718,10 @@ void enable_noise() {
     ctx.ch4_volume = ctx.ch4_initial_volume;
     ctx.ch4_lfsr = 0;
     lfsr_clock = lfsr_clock_buffer;
-    lfsr_timer = (ctx.ch4_clock_divider > 0 ? (ctx.ch4_clock_divider << 8) : 8) << ctx.ch4_clock_shift;
+    lfsr_timer = (ctx.ch4_clock_divider > 0 ? (ctx.ch4_clock_divider << 4) : 8) << ctx.ch4_clock_shift;
+    if(!ctx.ch4_dac){
+        ctx.ch4_enable = false;
+    }
 }
 
 u8 audio_read(u16 address) {
@@ -1117,9 +1136,9 @@ void audio_write(u16 address, u8 value){
         ctx.ch4_clock_shift = (value >> 4) & 0xF;
         ctx.ch4_lfsr_width = (value & 0x08);
         ctx.ch4_clock_divider = value & 0b111;
-        float div = (ctx.ch4_clock_divider == 0 ? 0.5f : (float)ctx.ch4_clock_divider);
+        //float div = (ctx.ch4_clock_divider == 0 ? 0.5f : (float)ctx.ch4_clock_divider);
-        float lfsr_rate = (LFSR_BASE_CLOCK) / (div * (float)(1 << ctx.ch4_clock_shift));
+        //float lfsr_rate = (LFSR_BASE_CLOCK) / (div * (float)(1 << ctx.ch4_clock_shift));
-        lfsr_clock_buffer = 1.0f / (lfsr_rate/1000.0f/1000.0f);
+        //lfsr_clock_buffer = 1.0f / (lfsr_rate/1000.0f/1000.0f);
         //printf("Ch4 clock: Shift: %01X, Width: %d, Div: %f (%01X), Rate: %f, Clock %f\n", ctx.ch4_clock_shift, ctx.ch4_lfsr_width, div, ctx.ch4_clock_divider, lfsr_rate, lfsr_clock);
         //printf("Write Ch4 Clock: %02X\n", value);
     }

lib/timer.c

@@ -39,6 +39,8 @@ void timer_tick() {
         }
     }
 
+    lfsr_tick();
+
     if((prev_div & (1 << 12)) && (!(ctx.div & (1 << 12)))){
         audio_tick();
     }