Actually add SDL audio source and blip_buf link

Makefile

@@ -23,7 +23,7 @@ LDLIBS_1 = -lSDL2
 SRC_SRCS_1 = nese.c ines.c
 SRC_SRCS_1 += nes.c ppu.c input.c
 SRC_SRCS_1 += cart.c mapper.c
-SRC_SRCS_1 += apu.c
+SRC_SRCS_1 += apu.c audio.c
 SRC_SRCS_1 += sdl_render.c sdl_input.c sdl_audio.c
 
 MAPDIR = src/map

blip-buf

@@ -0,0 +1 @@
+../blip-buf

src/audio.c

@@ -0,0 +1,17 @@
+#include "audio.h"
+#include "blip-buf/blip_buf.h"
+
+
+int nes_audio_fill(nes_Audio_Stream* stream, nes_apu* apu) {
+    int status = 0;
+    blip_end_frame(apu->blip, apu->time);
+    apu->time = 0;
+    while (status == 0 && blip_samples_avail(apu->blip) > 0) {
+        short samples[1024];
+        int n_samples = blip_read_samples(
+                apu->blip, samples, 1024, 0
+            );
+        status = nes_audio_push(stream, samples, n_samples);
+    }
+    return status;
+}

src/audio.h

@@ -0,0 +1,37 @@
+#ifndef NES_AUDIO_H_
+#define NES_AUDIO_H_
+
+#include "apu.h"
+
+
+// System Glue
+
+typedef struct nes_Audio_Stream_t {
+    int (*init)(struct nes_Audio_Stream_t*, int frequency);
+    void (*done)(struct nes_Audio_Stream_t*);
+    int (*push)(struct nes_Audio_Stream_t*, short*, int);
+    void* data;
+} nes_Audio_Stream;
+
+
+static inline int nes_audio_init(nes_Audio_Stream* stream,
+                                 int frequency) {
+    return stream->init(stream, frequency);
+}
+
+static inline void nes_audio_done(nes_Audio_Stream* stream) {
+    stream->done(stream);
+}
+
+static inline int nes_audio_push(nes_Audio_Stream* stream,
+                                 short* samples, int n_samples) {
+    return stream->push(stream, samples, n_samples);
+}
+
+
+// Convenience
+
+int nes_audio_fill(nes_Audio_Stream* stream, nes_apu* apu);
+
+
+#endif // NES_AUDIO_H_

src/sdl_audio.c

@@ -0,0 +1,60 @@
+#include <SDL2/SDL.h>
+
+#include "audio.h"
+
+
+typedef struct {
+    SDL_AudioDeviceID id;
+} sdl_audio_device;
+
+static sdl_audio_device the_audio_device = {0};
+
+
+int sdl_audio_init(nes_Audio_Stream* stream, int frequency) {
+    int status = SDL_Init(SDL_INIT_AUDIO);
+
+    if (0 == status) {
+        sdl_audio_device* device = &the_audio_device;
+
+        SDL_AudioSpec as = {
+            .freq = frequency,
+            .format = AUDIO_S16SYS,
+            .channels = 1,
+        };
+
+        device->id = SDL_OpenAudioDevice(NULL, 0, &as, NULL, 0);
+        if (0 == device->id) {
+            printf("SDL: %s\n", SDL_GetError());
+            status = -1;
+        } else {
+            stream->data = device;
+            SDL_PauseAudioDevice(device->id, 0);
+        }
+    }
+
+    return status;
+}
+
+void sdl_audio_done(nes_Audio_Stream* stream) {
+    if (stream->data) {
+        SDL_CloseAudioDevice(
+                ((sdl_audio_device*)stream->data)->id
+            );
+        stream->data = NULL;
+    }
+}
+
+int sdl_audio_push(nes_Audio_Stream* stream,
+                   short* samples, int n_samples) {
+    return SDL_QueueAudio(
+            ((sdl_audio_device*)stream->data)->id,
+            samples, n_samples * sizeof(short)
+        );
+}
+
+
+nes_Audio_Stream sdl_audio = {
+    .init = sdl_audio_init,
+    .done = sdl_audio_done,
+    .push = sdl_audio_push,
+};