Added audio playback

Playing music

code/os/audio.h

@@ -0,0 +1,39 @@
+#if !defined(LD_OS_AUDIO_H_)
+#define LD_OS_AUDIO_H_
+
+typedef struct Audio_Data Audio_Data;
+struct Audio_Data {
+	S16 *samples;
+	U32 n_frames;
+};
+
+typedef struct Audio_Track Audio_Track;
+struct Audio_Track {
+	B32 playing;
+
+	Audio_Data *data;
+
+	U32 n_played;
+	U32 next; // to play if playing, free otherwise
+};
+
+typedef struct Audio_Context Audio_Context;
+struct Audio_Context {
+	SDL_AudioStream *stream;
+
+	U32 n_tracks;
+	Audio_Track tracks[16];
+
+	U32 head;
+	U32 free;
+
+	F32 volume;
+
+	U32 n_sounds;
+	Audio_Data *sounds;
+};
+
+function void Audio_Init(M_Arena *arena, Audio_Context *audio, F32 volume);
+function void Audio_Play(Audio_Context *audio, U32 index);
+
+#endif  // LD_OS_AUDIO_H_

code/os/core.c

@@ -4,7 +4,6 @@
 	#include "impl/linux/core.c"
 #endif
 
-
 Str8 FS_ReadEntireFile(M_Arena *arena, Str8 path) {
 	Str8 result = { 0 };
 
@@ -19,3 +18,154 @@ Str8 FS_ReadEntireFile(M_Arena *arena, Str8 path) {
 
 	return result;
 }
+
+internal void SDL_SubmitAudio(void *user, SDL_AudioStream *stream, int needed, int total) {
+	Audio_Context *audio = cast(Audio_Context *) user;
+
+	(void) total;
+
+	M_TempScope(0, 0) {
+		U32 prev = 0;
+		U32 it   = audio->head;
+
+		U32 n_samples = needed    >> 1;
+		U32 n_frames  = n_samples >> 1;
+
+		F32 *left_f32  = M_ArenaPush(temp.arena, F32, .count = n_frames);
+		F32 *right_f32 = M_ArenaPush(temp.arena, F32, .count = n_frames);
+
+		while (it != 0) {
+			Audio_Track *track = &audio->tracks[it];
+			U32 next = track->next;
+
+			F32 *l0 = left_f32;
+			F32 *r0 = right_f32;
+
+			Assert(track->playing);
+
+			U32 remain = track->data->n_frames - track->n_played;
+			U32 play   = Min(n_frames, remain);
+			U32 off    = track->n_played << 1; // played n frames, thus double to n samples
+
+			for (U32 f = 0; f < play; ++f) {
+				*l0++ += cast(F32) (track->data->samples[off + (2 * f) + 0]) * audio->volume;
+				*r0++ += cast(F32) (track->data->samples[off + (2 * f) + 1]) * audio->volume;
+			}
+
+			track->n_played += play;
+
+			if (track->n_played == track->data->n_frames) {
+				if (prev == 0) {
+					// Head has finished playing
+					//
+					audio->head = track->next;
+					track->next = audio->free;
+					audio->free = it;
+				}
+				else {
+					// We're in the middle somewhere so prev->next == it->next
+					//
+					audio->tracks[prev].next = track->next;
+					track->next = audio->free;
+					audio->free = it;
+				}
+
+				track->playing = false;
+			}
+
+			it = next;
+		}
+
+		F32 *l0 = left_f32;
+		F32 *r0 = right_f32;
+
+		S16 *interleaved = M_ArenaPush(temp.arena, S16, .count = n_samples);
+		S16 *i0 = interleaved;
+
+		for (U32 n = 0; n < n_frames; ++n) {
+			*i0++ = cast(S16) (l0[n] + 0.5f);
+			*i0++ = cast(S16) (r0[n] + 0.5f);
+		}
+
+		SDL_PutAudioStreamData(stream, interleaved, needed);
+	}
+}
+
+void Audio_Init(M_Arena *arena, Audio_Context *audio, F32 volume) {
+	SDL_AudioSpec spec = { 0 };
+	spec.format   = SDL_AUDIO_S16LE;
+	spec.channels = 2;
+	spec.freq     = 44100;
+
+	audio->stream = SDL_OpenAudioDeviceStream(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, &spec, SDL_SubmitAudio, audio);
+
+	if (audio->stream) {
+		M_TempScope(0, 0) {
+			Str8 exec = FS_SystemPath(temp.arena, FS_SYSTEM_PATH_EXE);
+			Str8 path = Sf(temp.arena, "%.*s/assets", Sv(exec));
+
+			FS_List files = FS_PathList(temp.arena, path);
+
+			U32 n_audio = 0;
+			for (FS_Entry *it = files.first; it != 0; it = it->next) {
+				if (Str8_EndsWith(it->basename, S("wav"))) {
+					n_audio += 1;
+				}
+			}
+
+			audio->n_sounds = 0;
+			audio->sounds   = M_ArenaPush(arena, Audio_Data, .count = n_audio);
+
+			for (FS_Entry *it = files.first; it != 0; it = it->next) {
+				if (Str8_EndsWith(it->basename, S("wav"))) {
+					Audio_Data *sound = &audio->sounds[audio->n_sounds];
+
+					U8 *data;
+					U32 count;
+					SDL_AudioSpec wav;
+
+					SDL_LoadWAV((const char *) it->path.data, &wav, &data, &count);
+
+					Assert(wav.freq == 44100);
+
+					sound->samples  = (S16 *) data;
+					sound->n_frames = (count >> 2);
+
+					audio->n_sounds += 1;
+				}
+			}
+
+			audio->n_tracks = 16;
+			//audio->tracks   = M_ArenaPush(arena, Audio_Track, audio->n_tracks);
+
+			for (U32 it = 1; it < audio->n_tracks; ++it) {
+				audio->tracks[it].next = it + 1;
+			}
+
+			audio->tracks[audio->n_tracks - 1].next = 0;
+
+			audio->volume = volume;
+			audio->head   = 0;
+			audio->free   = 1;
+
+			printf("--- Loaded %d sounds ---\n", audio->n_sounds);
+		}
+	}
+}
+
+void Audio_Play(Audio_Context *audio, U32 index) {
+	if (audio->free != 0 && SDL_LockAudioStream(audio->stream)) {
+		U32 idx = audio->free;
+
+		Audio_Track *track = &audio->tracks[idx];
+		audio->free = track->next;
+
+		track->playing  = true;
+		track->data     = &audio->sounds[index];
+		track->n_played = 0;
+		track->next     = audio->head;
+		audio->head     = idx;
+
+		SDL_UnlockAudioStream(audio->stream);
+	}
+}

code/os/core.h

@@ -17,5 +17,6 @@ function void  VM_Decommit(void *base, U64 size);
 function void  VM_Release(void *base, U64 size);
 
 #include "filesystem.h"
+#include "audio.h"
 
 #endif  // LD_OS_CORE_H_