fixed fast forward

include/audio.h

@@ -117,11 +117,29 @@ typedef struct {
     float right_history[384];
     u32 right_index; 
 
+    u64 buffer_write_index; 
+    float *left_audio_buffer;
+    float *right_audio_buffer;
+
+    u32 lfsr_timer;
+
+    float left_cap;
+    float right_cap;
+
+    int history_timer;
+
+    double cycles_needed;
+
+    u32 period_tick; 
+    u32 ticks;
+
 } audio_context;
 
 void audio_init();
 void audio_tick();
 void audio_period_tick();
+void lfsr_tick();
+void audio_sample_tick();
 
 u8 audio_read(u16 address);
 void audio_write(u16 address, u8 value);

include/common.h

@@ -10,6 +10,7 @@ typedef uint16_t u16;
 typedef uint32_t u32;
 typedef uint64_t u64;
 
+#define FAST_FORWARD_SPEED 2
 #define BIT(a, n) ((a & (1 << n)) ? 1 : 0)
 #define BIT_SET(a, n, on) {if(on) a |= (1 << n); else a &= ~(1 << n);}
 #define BETWEEN(a, b, c) ((a >= b) && (a <= c))

include/emu.h

@@ -8,6 +8,7 @@ typedef struct {
     bool die;
     u64 ticks;
     const char *app_path;
+    bool fast_forward;
 } emu_context;
 
 int emu_run(int, char**);

lib/audio.c

@@ -5,32 +5,13 @@
 
 #include <portaudio.h>
 #include <pa_ringbuffer.h>
+#include <math.h>
+#include <string.h>
 
-#define SAMPLE_RATE 44100
+#define SAMPLE_RATE 192000.0
 #define FRAMES_PER_BUFFER 64
-#define TIME_PER_SAMPLE 1.0f / (SAMPLE_RATE/1000.0f/1000.0f)
-#define TIME_PER_AUDIO_TICK 1.0f / (1048576.0f/1000.0f/1000.0f)
-#define TIME_PER_WAVE_TICK 1.0f / (2097152.0f/1000.0f/1000.0f)
-#define LFSR_BASE_CLOCK 262144.0f
-
-static audio_context ctx;
-
-audio_context *audio_get_context() {
-    return &ctx;
-}
-
-static float audio_time = 0;
-static float wave_time = 0;
-static float lfsr_timer = 0;
-static float lfsr_clock = LFSR_BASE_CLOCK;
-static float lfsr_clock_buffer = LFSR_BASE_CLOCK;
-
-static float left_cap = 0.0f;
-static float right_cap = 0.0f;
-
-static int history_timer = 0;
-const int history_interval = 5;
-static int lfsr_clocks = 0;
+#define SAMPLES_PER_AUDIO_TICK SAMPLE_RATE / 4194304.0
+#define HISTORY_INTERVAL 5
 
 const u8 square_sample_00[8] = {
     0x0,
@@ -83,248 +64,23 @@ const u8 *square_sample[4] = {
     square_sample_11
 };
 
-static int audio_callback(const void* input_uffer, void *output_buffer,
-                            unsigned long framesPerBuffer,
-                            const PaStreamCallbackTimeInfo *time_info,
-                            PaStreamCallbackFlags status_flags,
-                            void *userData ) {
-    float *out = (float *)output_buffer;
-    for(int i = 0; i < framesPerBuffer; i++) {
-        if(ppu_get_context()->paused) {
-            *out++ = 0;
-            *out++ = 0;
-            continue;
-        }
-        float left = 0;
-        float right = 0;
-        audio_time += TIME_PER_SAMPLE;
-        wave_time += TIME_PER_SAMPLE;
-        for(;audio_time >= TIME_PER_AUDIO_TICK;audio_time -= TIME_PER_AUDIO_TICK) {
-            ctx.sq1_period_timer++;
-            ctx.sq2_period_timer++;
-
-            if(ctx.sq1_period_timer >= 0x800) {
-                ctx.sq1_period_timer = ctx.sq1_period_reset;
-                ctx.sq1_sample = (ctx.sq1_sample + 1) % 8;
-            }
-            if(ctx.sq2_period_timer >= 0x800) {
-                ctx.sq2_period_timer = ctx.sq2_period_reset;
-                ctx.sq2_sample = (ctx.sq2_sample + 1) % 8;
-            }
-        }
-        for(;wave_time >= TIME_PER_WAVE_TICK;wave_time -= TIME_PER_WAVE_TICK) {
-            ctx.ch3_period_timer++;
-            if(ctx.ch3_period_timer >= 0x800) {
-                ctx.ch3_period_timer = ctx.ch3_period_reset;
-                ctx.ch3_sample = (ctx.ch3_sample + 1) % 32;
-                if((ctx.ch3_sample & 0b1) == 0b1) {
-                    ctx.ch3_last_sample = ctx.wave_ram[ctx.ch3_sample >> 1] & 0xF;
-                } else {
-                    ctx.ch3_last_sample = ctx.wave_ram[ctx.ch3_sample >> 1] >> 4;
-                }
-            }
-        }
-        lfsr_timer += TIME_PER_SAMPLE;
-        for(;lfsr_timer >= lfsr_clock;lfsr_timer -= lfsr_clock) {
-            //if(ctx.ch4_enable) {
-                lfsr_clocks++;
-                lfsr_clock = lfsr_clock_buffer;
-                //lfsr_timer = 0;
-                //u16 new = ~((ctx.ch4_lfsr & 0b1) ^ ((ctx.ch4_lfsr & 0b10) >> 1)) & 0b1;
-                //ctx.ch4_lfsr &= ~(1 << 15);
-                //ctx.ch4_lfsr |= ((new << 15) & 0x8000);
-                //printf("new bit: %02X\n", (new << 15));
-                //if(ctx.ch4_lfsr_width) {
-                //    ctx.ch4_lfsr &= ~(1 << 7);
-                //    ctx.ch4_lfsr |= (new << 7);
-                //}
-                //ctx.ch4_lfsr = ctx.ch4_lfsr >> 1;
-                //printf("lfsr: %02X, bit: %d\n", ctx.ch4_lfsr, new);
-                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 sq1_val = 0;
-        float sq2_val = 0;
-        float ch3_val = 0;
-        float ch4_val = 0;
-        if(ctx.audio_enabled){
-            if(ctx.ch1_dac){
-                sq1_val = -1;
-                if(ctx.sq1_enable) {
-                    sq1_val = ((float)ctx.sq1_volume/15.0f) * (((float)(square_sample[ctx.sq1_duty][ctx.sq1_sample]) - 7.5f)/7.5f);
-                    if(ctx.ch1_left) {
-                        left += sq1_val;
-                    }else {
-                        left -= 1;
-                    }
-                    if(ctx.ch1_right) {
-                        right += sq1_val;
-                    }else {
-                        right -= 1;
-                    }
-                } else {
-                    left -= 1;
-                    right -= 1;
-                }
-            }
-            if(ctx.ch2_dac){
-                sq2_val = -1;
-                if(ctx.sq2_enable) {
-                    sq2_val = ((float)ctx.sq2_volume/15.0f) * (((float)(square_sample[ctx.sq2_duty][ctx.sq2_sample]) - 7.5f)/7.5f);
-                    if(ctx.ch2_left) {
-                        left += sq2_val;
-                    }else {
-                        left -= 1;
-                    }
-                    if(ctx.ch2_right) {
-                        right += sq2_val;
-                    }else {
-                        right -= 1;
-                    }
-                } else {
-                    left -= 1;
-                    right -= 1;
-                }
-            }
-            if(ctx.ch3_dac){
-                ch3_val = -1;
-                if(ctx.ch3_enable) {
-                    u8 shift = 0;
-                    if(ctx.ch3_volume == 0b10) {
-                        shift = 1;
-                    }
-                    if(ctx.ch3_volume == 0b00) {
-                        shift = 4;
-                    }
-                    if(ctx.ch3_volume == 0b11) {
-                        shift = 2;
-                    }
-                    ch3_val = (((float)(ctx.ch3_last_sample >> shift) - 7.5f)/7.5f);
-                    if(ctx.ch3_left) {
-                        left += ch3_val;
-                        //printf("left: %d\n", ctx.ch3_volume);
-                    }else {
-                        left -= 1;
-                    }
-                    if(ctx.ch3_right) {
-                        right += ch3_val;
-                    }else {
-                        right -= 1;
-                    }
-                } else {
-                    left -= 1;
-                    right -= 1;
-                }
-            }
-            if(ctx.ch4_dac){
-                ch4_val = -1;
-                if(ctx.ch4_enable) {
-                    ch4_val = ((ctx.ch4_lfsr & 0b1) == 0b1) ? (((float)ctx.ch4_volume - 7.5f)/7.5f) : -1.0f;
-                    if(ctx.ch4_left) {
-                        left += ch4_val;
-                        //printf("left: %d\n", ctx.ch3_volume);
-                    }else {
-                        left -= 1;
-                    }
-                    if(ctx.ch4_right) {
-                        right += ch4_val;
-                    } else {
-                        right -= 1;
-                    }
-                } else {
-                    left -= 1;
-                    right -= 1;
-                }
-            }
-        }
-        u8 left_vol = ctx.volume_left == 0 ? 1 : ctx.volume_left;
-        u8 right_vol = ctx.volume_right == 0 ? 1 : ctx.volume_right;
-        left *= (float)left_vol/7.0f;
-        right *= (float)right_vol/7.0f;
-
-        //left /= 4;
-        //right /= 4;
-
-
-        bool dacs = ctx.ch1_dac || ctx.ch2_dac || ctx.ch3_dac || ctx.ch4_dac;
-        float left_out = 0;
-        float right_out = 0;
-        if(dacs) {
-            left_out = left - left_cap;
-            right_out = right - right_cap;
-            left_cap = left - left_out * 0.996f;
-            right_cap = right - right_out * 0.996f;
-        }
-
-        
-        left_out /= 4;
-        right_out /= 4;
-
-        if(left_out < -1.0f) {
-            left_out = -1;
-        }
-        if(left_out > 1.0f) {
-            left_out = 1;
-        }
-        if(right_out < -1.0f) {
-            right_out = -1;
-        }
-        if(right_out > 1.0f) {
-            right_out = 1;
-        }
-        history_timer++;
-        if(history_timer >= history_interval){
-            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;
-            }
-
-            ctx.right_history[ctx.right_index++] = right_out;
-            if (ctx.right_index == 384) {
-                ctx.right_index = 0;
-            }
-        }
-
-        *out++ = left_out;
-        *out++ = right_out;
-    }
-    return paContinue;
-}
+static audio_context ctx;
 static PaStream *stream;
 
-void audio_sample();
+audio_context *audio_get_context() {
+    return &ctx;
+}
 
 void audio_init(){
     PaStreamParameters output_parameters;
     PaError err;
 
+    ctx.left_audio_buffer = malloc(sizeof(float) * FRAMES_PER_BUFFER);
+    ctx.right_audio_buffer = malloc(sizeof(float) * FRAMES_PER_BUFFER);
+
+    memset(ctx.left_audio_buffer, 0, sizeof(float) * FRAMES_PER_BUFFER);
+    memset(ctx.right_audio_buffer, 0, sizeof(float) * FRAMES_PER_BUFFER);
+
     ctx.audio_enabled = false;
     ctx.ch1_left = false;
     ctx.ch1_right = false;
@@ -377,7 +133,7 @@ void audio_init(){
         goto error;
     }
     output_parameters.channelCount = 2;
-    output_parameters.sampleFormat = paFloat32;
+    output_parameters.sampleFormat = paFloat32 | paNonInterleaved;
     output_parameters.suggestedLatency = Pa_GetDeviceInfo(output_parameters.device)->defaultLowOutputLatency;
     output_parameters.hostApiSpecificStreamInfo = NULL;
 
@@ -385,9 +141,9 @@ void audio_init(){
                         NULL,
                         &output_parameters,
                         SAMPLE_RATE,
-                        paFramesPerBufferUnspecified,
+                        FRAMES_PER_BUFFER,
                         paNoFlag,
-                        audio_callback,
+                        NULL,
                         &ctx);
     if(err != paNoError) goto error;
     err = Pa_StartStream(stream);
@@ -409,14 +165,239 @@ void sq1_sweep() {
 		}
 }
 
-static int change = 1;
-static u32 ticks = 0;
-static u32 start, end = 0;
+void lfsr_tick() {
+    ctx.lfsr_timer--;
+    if(ctx.lfsr_timer == 0) {
+        ctx.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_sample_tick() {
+    lfsr_tick();
+    float left = 0;
+    float right = 0;
+    float sq1_val = 0;
+    float sq2_val = 0;
+    float ch3_val = 0;
+    float ch4_val = 0;
+    if(ctx.audio_enabled){
+        if(ctx.ch1_dac){
+            sq1_val = -1;
+            if(ctx.sq1_enable && (ctx.ch1_left || ctx.ch1_right)) {
+                sq1_val = ((float)ctx.sq1_volume/15.0f) * (((float)(square_sample[ctx.sq1_duty][ctx.sq1_sample]) - 7.5f)/7.5f);
+                if(ctx.ch1_left) {
+                    left += sq1_val;
+                }else {
+                    left -= 1;
+                }
+                if(ctx.ch1_right) {
+                    right += sq1_val;
+                }else {
+                    right -= 1;
+                }
+            } else {
+                left -= 1;
+                right -= 1;
+            }
+        }
+        if(ctx.ch2_dac){
+            sq2_val = -1;
+            if(ctx.sq2_enable && (ctx.ch2_left || ctx.ch2_right)) {
+                sq2_val = ((float)ctx.sq2_volume/15.0f) * (((float)(square_sample[ctx.sq2_duty][ctx.sq2_sample]) - 7.5f)/7.5f);
+                if(ctx.ch2_left) {
+                    left += sq2_val;
+                }else {
+                    left -= 1;
+                }
+                if(ctx.ch2_right) {
+                    right += sq2_val;
+                }else {
+                    right -= 1;
+                }
+            } else {
+                left -= 1;
+                right -= 1;
+            }
+        }
+        if(ctx.ch3_dac){
+            u8 shift = 0;
+            if(ctx.ch3_volume == 0b10) {
+                shift = 1;
+            }
+            if(ctx.ch3_volume == 0b00) {
+                shift = 4;
+            }
+            if(ctx.ch3_volume == 0b11) {
+                shift = 2;
+            }
+            ch3_val = -1;
+            if(ctx.ch3_enable && (ctx.ch3_left || ctx.ch3_right)) {
+                ch3_val = (((float)(ctx.ch3_last_sample >> shift) - 7.5f)/7.5f);
+                if(ctx.ch3_left) {
+                    left += ch3_val;
+                }else {
+                    left -= 1;
+                }
+                if(ctx.ch3_right) {
+                    right += ch3_val;
+                }else {
+                    right -= 1;
+                }
+            } else {
+                left -= 1;
+                right -= 1;
+            }
+        }
+        if(ctx.ch4_dac){
+            ch4_val = -1;
+            if(ctx.ch4_enable && (ctx.ch4_left || ctx.ch4_right)) {
+                ch4_val = ((ctx.ch4_lfsr & 0b1) == 0b1) ? (((float)ctx.ch4_volume - 7.5f)/7.5f) : -1.0f;
+                if(ctx.ch4_left) {
+                    left += ch4_val;
+                }else {
+                    left -= 1;
+                }
+                if(ctx.ch4_right) {
+                    right += ch4_val;
+                } else {
+                    right -= 1;
+                }
+            } else {
+                left -= 1;
+                right -= 1;
+            }
+        }
+    }
+
+    u8 left_vol = ctx.volume_left == 0 ? 1 : ctx.volume_left;
+    u8 right_vol = ctx.volume_right == 0 ? 1 : ctx.volume_right;
+    left *= (float)left_vol/7.0f;
+    right *= (float)right_vol/7.0f;
+    ctx.cycles_needed += emu_get_context()->fast_forward ? SAMPLES_PER_AUDIO_TICK/FAST_FORWARD_SPEED : SAMPLES_PER_AUDIO_TICK;
+    if(ctx.cycles_needed > 1){
+        ctx.cycles_needed -= 1;
+        
+
+        bool dacs = ctx.ch1_dac || ctx.ch2_dac || ctx.ch3_dac || ctx.ch4_dac;
+        float left_out = 0;
+        float right_out = 0;
+        if(dacs) {
+            left_out = left - ctx.left_cap;
+            right_out = right - ctx.right_cap;
+            ctx.left_cap = left - left_out * 0.999958;
+            ctx.right_cap = right - right_out * 0.999958;
+        }
+
+        
+        left_out /= 4;
+        right_out /= 4;
+
+        if(left_out < -1.0f) {
+            left_out = -1;
+        }
+        if(left_out > 1.0f) {
+            left_out = 1;
+        }
+        if(right_out < -1.0f) {
+            right_out = -1;
+        }
+        if(right_out > 1.0f) {
+            right_out = 1;
+        }
+
+        if(ctx.buffer_write_index < FRAMES_PER_BUFFER){
+            ctx.left_audio_buffer[(ctx.buffer_write_index)] = left_out;
+            ctx.right_audio_buffer[(ctx.buffer_write_index)] = right_out;
+            ctx.buffer_write_index++;
+        }
+
+        ctx.history_timer++;
+        if(ctx.history_timer >= HISTORY_INTERVAL){
+            ctx.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;
+            }
+    
+            ctx.right_history[ctx.right_index++] = right_out;
+            if (ctx.right_index == 384) {
+                ctx.right_index = 0;
+            }
+        }
+
+        if(ctx.buffer_write_index == FRAMES_PER_BUFFER) {
+            ctx.buffer_write_index = 0;
+            float *data[2];
+            data[0] = ctx.left_audio_buffer;
+            data[1] = ctx.right_audio_buffer;
+            int err = Pa_WriteStream(stream, data, FRAMES_PER_BUFFER);
+            if(err != paNoError && err != paOutputUnderflowed) {
+                fprintf(stderr, "portaudio stream error\n\tError Number: %d\n\tError Message: %s\n", err, Pa_GetErrorText(err));
+            }
+        }
+    }
+}
+
+bool skipped = false;
+void audio_period_tick() {
+    ctx.period_tick++;
+    if(ctx.period_tick % 2 == 0){
+        ctx.sq1_period_timer++;
+        ctx.sq2_period_timer++;
+
+        if(ctx.sq1_period_timer >= 0x800) {
+            ctx.sq1_period_timer = ctx.sq1_period_reset;
+            ctx.sq1_sample = (ctx.sq1_sample + 1) % 8;
+        }
+
+        if(ctx.sq2_period_timer >= 0x800) {
+            ctx.sq2_period_timer = ctx.sq2_period_reset;
+            ctx.sq2_sample = (ctx.sq2_sample + 1) % 8;
+        }
+    }
+    ctx.ch3_period_timer++;
+    if(ctx.ch3_period_timer >= 0x800) {
+        ctx.ch3_period_timer = ctx.ch3_period_reset;
+        ctx.ch3_sample = (ctx.ch3_sample + 1) % 32;
+        if((ctx.ch3_sample & 0b1) == 0b1) {
+            ctx.ch3_last_sample = ctx.wave_ram[ctx.ch3_sample >> 1] & 0xF;
+        } else {
+            ctx.ch3_last_sample = ctx.wave_ram[ctx.ch3_sample >> 1] >> 4;
+        }
+    }
+}
 
 void audio_tick(){ 
-    u32 prev_ticks = ticks;
-    ticks++;
-    if((ticks % 2) == 0) {
+    u32 prev_ticks = ctx.ticks;
+    ctx.ticks++;
+    if((ctx.ticks % 2) == 0) {
         if(ctx.sq1_len_enable) {
             ctx.sq1_len++;
             if(ctx.sq1_len >= 64) {
@@ -445,7 +426,6 @@ void audio_tick(){
 
         if(ctx.ch4_len_enable && ctx.ch4_enable) {
             ctx.ch4_len++;
-            //printf("Ch4 len: %02X\n", ctx.ch4_len);
             if(ctx.ch4_len >= 64) {
                 ctx.ch4_len = 0;
                 ctx.ch4_enable = false;
@@ -454,7 +434,7 @@ void audio_tick(){
         }
     }
 
-    if((prev_ticks & (1 << 2)) && !(ticks & (1 << 2))) {
+    if((prev_ticks & (1 << 2)) && !(ctx.ticks & (1 << 2))) {
         if(ctx.sq1_env_pace != 0){
             ctx.sq1_env_timer++;
             if(ctx.sq1_env_timer >= ctx.sq1_env_pace) {
@@ -480,30 +460,26 @@ void audio_tick(){
                     if(ctx.sq2_volume > 15)
                         ctx.sq2_volume = 15;
                 }
-                //printf("sq2 vol: %01X\n", ctx.sq2_volume);
             }
         }
 
-        //if(ctx.ch4_env_pace != 0){
         ctx.ch4_env_timer--;
         if(ctx.ch4_env_timer <= 0) {
             ctx.ch4_env_timer = ctx.ch4_env_pace_buffer != 0 ? ctx.ch4_env_pace_buffer : 8;
             if(ctx.ch4_env_pace != 0 && ((ctx.ch4_env_direction && ctx.ch4_volume != 15) || (!ctx.ch4_env_direction && ctx.ch4_volume != 0))){
                 ctx.ch4_volume += ctx.ch4_env_direction ? 1 : -1;
-                //printf("Noise Vol: %02X\n", ctx.ch4_volume);
                 if(ctx.ch4_volume < 0)
                     ctx.ch4_volume = 0;
                 if(ctx.ch4_volume > 15)
                     ctx.ch4_volume = 15;
             }
         }
-        //}
 
     }
 
-    if((prev_ticks & (1 << 1)) && !(ticks & (1 << 1)) && ctx.sq1_sweep_enabled) {
+    if((prev_ticks & (1 << 1)) && !(ctx.ticks & (1 << 1)) && ctx.sq1_sweep_enabled) {
         ctx.sq1_sweep_timer--;
-        if(ctx.sq1_sweep_timer <= 0){//(ctx.sq1_sweep_timer >= ctx.sq1_sweep_pace && ctx.sq1_sweep_pace > 0) || (ctx.sq1_sweep_timer >= 8 && ctx.sq1_sweep_pace == 0)) {
+        if(ctx.sq1_sweep_timer <= 0){
             ctx.sq1_sweep_timer = ctx.sq1_sweep_pace != 0 ? ctx.sq1_sweep_pace : 8;
             if(ctx.sq1_enable && ctx.sq1_sweep_pace > 0 && ctx.sq1_sweep_enabled){
                 sq1_sweep();
@@ -551,23 +527,20 @@ void enable_wave() {
     }
     ctx.ch3_enable = true;
     ctx.ch3_sample = 0;
-    //ctx.ch3_volume = ctx.ch3_initial_volume;
     ctx.ch3_period_timer = ctx.ch3_period_reset;
 }
 
 void enable_noise() {
-    if(!ctx.ch4_dac){
-        return;
-    }
-    start = get_ticks();
     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;
     ctx.ch4_env_pace = ctx.ch4_env_pace_buffer;
     ctx.ch4_volume = ctx.ch4_initial_volume;
     ctx.ch4_lfsr = 0;
-    lfsr_clock = lfsr_clock_buffer;
-    lfsr_timer = 0;
+    ctx.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) {
@@ -777,7 +750,6 @@ void audio_write(u16 address, u8 value){
     if(address == 0xFF26) {
         ctx.audio_enabled = (value & 0x80) == 0x80;
         if(!ctx.audio_enabled) {
-            //printf("audio disabled\n");
             reset_buffers();
         }
     }
@@ -796,14 +768,11 @@ void audio_write(u16 address, u8 value){
         ctx.ch3_right = value & 0b00000100;
         ctx.ch2_right = value & 0b00000010;
         ctx.ch1_right = value & 0b00000001;
-        //printf("write at %02X; Value: %02X\n", address, value);
     }
 
     if(address == 0xFF24) {
         ctx.volume_left = (value >> 4) & 0b111;
-        //if(ctx.volume_left == 0) ctx.volume_left = 1;
         ctx.volume_right = value & 0b111;
-        //if(ctx.volume_right == 0) ctx.volume_right = 1;
         ctx.vin_left = value & 0x80;
         ctx.vin_right = value & 0x8;
     }
@@ -819,7 +788,6 @@ void audio_write(u16 address, u8 value){
         ctx.sq1_initial_len = value & 0x3F;
         ctx.sq1_len = ctx.sq1_initial_len;
         ctx.ch1_len_fz = false;
-        //printf("initial len: %02X\n", ctx.sq1_initial_len);
     }
     if(address == 0xFF12) {
         ctx.sq1_initial_volume = (value >> 4) & 0x0F;
@@ -841,7 +809,7 @@ void audio_write(u16 address, u8 value){
         }
         ctx.sq1_period_reset = (ctx.sq1_period_reset & 0x0FF) | ((value & 0b111) << 8);
         bool len_en = (value & 0x40) == 0x40;
-        if((ticks % 2) == 0 && !ctx.ch1_len_fz && !ctx.sq1_len_enable && len_en){
+        if((ctx.ticks % 2) == 0 && !ctx.ch1_len_fz && !ctx.sq1_len_enable && len_en){
             ctx.sq1_len++;
             if(ctx.sq1_len >= 64) {
                 ctx.sq1_len = 0;
@@ -849,7 +817,7 @@ void audio_write(u16 address, u8 value){
                 ctx.ch1_len_fz = true;
             }
         } 
-        if((ticks % 2) == 0 && ctx.ch1_len_fz && (value & 0x80) == 0x80){
+        if((ctx.ticks % 2) == 0 && ctx.ch1_len_fz && (value & 0x80) == 0x80){
             ctx.ch1_len_fz = false;
             if(len_en){
                 ctx.sq1_len++;
@@ -882,7 +850,6 @@ void audio_write(u16 address, u8 value){
     if(address == 0xFF18) {
         u16 prev_period = ctx.sq2_period_reset;
         ctx.sq2_period_reset = (ctx.sq2_period_reset & 0xF00) | value;
-        //printf("period: %03X, old_period: %03X\n", ctx.sq2_period_reset, prev_period);
     }
     if(address == 0xFF19) {
         if(ctx.sq2_len == 64) {
@@ -890,7 +857,7 @@ void audio_write(u16 address, u8 value){
         }
         ctx.sq2_period_reset = (ctx.sq2_period_reset & 0x0FF) | ((value & 0b111) << 8);
         bool len_en = (value & 0x40) == 0x40;
-        if((ticks % 2) == 0 && !ctx.ch2_len_fz && !ctx.sq2_len_enable && len_en){
+        if((ctx.ticks % 2) == 0 && !ctx.ch2_len_fz && !ctx.sq2_len_enable && len_en){
             ctx.sq2_len++;
             if(ctx.sq2_len >= 64) {
                 ctx.sq2_len = 0;
@@ -898,7 +865,7 @@ void audio_write(u16 address, u8 value){
                 ctx.ch2_len_fz = true;
             }
         } 
-        if((ticks % 2) == 0 && ctx.ch2_len_fz && (value & 0x80) == 0x80){
+        if((ctx.ticks % 2) == 0 && ctx.ch2_len_fz && (value & 0x80) == 0x80){
             ctx.ch2_len_fz = false;
             if(len_en){
                 ctx.sq2_len++;
@@ -914,7 +881,6 @@ void audio_write(u16 address, u8 value){
         ctx.ch3_dac = value >> 7;
         if(!ctx.ch3_dac){
             ctx.ch3_enable = false;
-            //printf("ch3 off\n");
         }
     }
     
@@ -926,7 +892,6 @@ void audio_write(u16 address, u8 value){
 
     if(address == 0xFF1C) {
         ctx.ch3_volume = (value >> 5) & 0b11;
-        //printf("Ch3 vol: %d\n", ctx.ch3_volume);
     }
 
     if(address == 0xFF1D) {
@@ -936,7 +901,7 @@ void audio_write(u16 address, u8 value){
     if(address == 0xFF1E) {
         ctx.ch3_period_reset = (ctx.ch3_period_reset & 0x0FF) | ((value & 0b111) << 8);
         bool len_en = (value & 0x40) == 0x40;
-        if((ticks % 2) == 0 && !ctx.ch3_len_fz && !ctx.ch3_len_enable && len_en){
+        if((ctx.ticks % 2) == 0 && !ctx.ch3_len_fz && !ctx.ch3_len_enable && len_en){
             if(ctx.ch3_len >= 255) {
                 ctx.ch3_len = 0;
                 ctx.ch3_enable = false;
@@ -945,7 +910,7 @@ void audio_write(u16 address, u8 value){
                 ctx.ch3_len++;
             }
         } 
-        if((ticks % 2) == 0 && ctx.ch3_len_fz && (value & 0x80) == 0x80){
+        if((ctx.ticks % 2) == 0 && ctx.ch3_len_fz && (value & 0x80) == 0x80){
             ctx.ch3_len_fz = false;
             if(len_en){
                 ctx.ch3_len++;
@@ -961,8 +926,6 @@ void audio_write(u16 address, u8 value){
         ctx.ch4_initial_len = value & 0b111111;
         ctx.ch4_len = ctx.ch4_initial_len;
         ctx.ch4_len_fz = false;
-        //printf("ch4 len: %02X\n", ctx.ch4_len);
-        printf("Write Ch4 Len: %02X\n", value);
     }
 
     if(address == 0xFF21) {
@@ -975,18 +938,12 @@ void audio_write(u16 address, u8 value){
         } else {
             ctx.ch4_dac = true;
         }
-        printf("Write Ch4 env: %02X\n", value);
     }
 
     if(address == 0xFF22) {
         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 lfsr_rate = (LFSR_BASE_CLOCK) / (div * (float)(1 << ctx.ch4_clock_shift));
-        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);
     }
 
     if(address == 0xFF23) {
@@ -994,7 +951,7 @@ void audio_write(u16 address, u8 value){
             ctx.ch4_len = 0;
         }
         bool len_en = (value & 0x40) == 0x40;
-        if((ticks % 2) == 0 && !ctx.ch4_len_fz && !ctx.ch4_len_enable && len_en){
+        if((ctx.ticks % 2) == 0 && !ctx.ch4_len_fz && !ctx.ch4_len_enable && len_en){
             ctx.ch4_len++;
             if(ctx.ch4_len >= 64) {
                 ctx.ch4_len = 0;
@@ -1002,17 +959,15 @@ void audio_write(u16 address, u8 value){
                 ctx.ch4_len_fz = true;
             }
         } 
-        if((ticks % 2) == 0 && ctx.ch4_len_fz && (value & 0x80) == 0x80){
+        if((ctx.ticks % 2) == 0 && ctx.ch4_len_fz && (value & 0x80) == 0x80){
             ctx.ch4_len_fz = false;
             if(len_en){
                 ctx.ch4_len++;
             }
         }
         ctx.ch4_len_enable = len_en;
-        //printf("ch4 trigger: LenEn %d\n", len_en);
         if(value & 0x80) {
             enable_noise();
         }
-        printf("Write Ch4 Trigger: %02X\n", value);
     }
 }

lib/timer.c

@@ -39,12 +39,14 @@ void timer_tick() {
         }
     }
 
+    audio_sample_tick();
+
     if((prev_div & (1 << 12)) && (!(ctx.div & (1 << 12)))){
         audio_tick();
     }
 
-    if((prev_div & (1 << 1)) && (!(ctx.div & (1 << 1)))){
-        //audio_period_tick();
+    if((prev_div & (1 << 0)) && (!(ctx.div & (1 << 0)))){
+        audio_period_tick();
     }
 }
 

lib/ui.c

@@ -282,13 +282,11 @@ void ui_update() {
     update_debug_window();
 }
 
-static bool ff = false;
-
 void ui_on_key(bool down, u32 key_code) {
     if(key_code == SDLK_SPACE && down == true) {
-        ff = !ff;
-        if(ff){
-            ppu_get_context()->target_frame_time = 1000/300;
+        emu_get_context()->fast_forward = !emu_get_context()->fast_forward;
+        if(emu_get_context()->fast_forward){
+            ppu_get_context()->target_frame_time = 1000/(60 * FAST_FORWARD_SPEED);
         } else {
             ppu_get_context()->target_frame_time = 1000/60;
         }