mixer: support looping bgms with a separate intro

src/audio_mixer.c

@@ -19,7 +19,7 @@
 
 static bool mixer_loaded = false;
 
-const char *mixer_audio_exts[] = { ".wav", ".ogg", ".mp3", ".mod", ".xm", ".s3m",
+const char *mixer_audio_exts[] = { ".bgm", ".wav", ".ogg", ".mp3", ".mod", ".xm", ".s3m",
 		".669", ".it", ".med", ".mid", ".flac", ".aiff", ".voc",
 		NULL };
 
@@ -109,8 +109,8 @@ void audio_backend_set_bgm_volume(float gain) {
 		Mix_VolumeMusic(gain * MIX_MAX_VOLUME);
 }
 
-char* audio_mixer_sound_path(const char *prefix, const char *name) {
-	for(const char **ext = mixer_audio_exts; *ext; ++ext) {
+char* audio_mixer_sound_path(const char *prefix, const char *name, bool isbgm) {
+	for(const char **ext = mixer_audio_exts + !isbgm; *ext; ++ext) {
 		char *p = strjoin(prefix, name, *ext, NULL);
 
 		if(vfs_query(p).exists) {
@@ -124,16 +124,31 @@ char* audio_mixer_sound_path(const char *prefix, const char *name) {
 }
 
 bool audio_mixer_check_sound_path(const char *path, bool isbgm) {
-	if(strstartswith(resource_util_filename(path), "bgm_") == isbgm) {
-		return strendswith_any(path, mixer_audio_exts);
-	}
+	return strendswith_any(path, mixer_audio_exts + !isbgm);
+}
 
-	return false;
+static Mix_Music *next_loop;
+
+static void mixer_music_finished(void) {
+	// XXX: there may be a race condition in here
+	// probably should protect next_loop with a mutex
+
+	log_debug("Intro stopped playing");
+
+	if(next_loop) {
+		if(Mix_PlayMusic(next_loop, -1) == -1) {
+			log_warn("Mix_PlayMusic() failed: %s", Mix_GetError());
+		} else {
+			next_loop = NULL;
+		}
+	}
 }
 
 void audio_backend_music_stop(void) {
-	if(mixer_loaded)
+	if(mixer_loaded) {
+		Mix_HookMusicFinished(NULL);
 		Mix_HaltMusic();
+	}
 }
 
 bool audio_backend_music_is_paused(void) {
@@ -145,20 +160,40 @@ bool audio_backend_music_is_playing(void) {
 }
 
 void audio_backend_music_resume(void) {
-	if(mixer_loaded)
+	if(mixer_loaded) {
+		Mix_HookMusicFinished(mixer_music_finished);
 		Mix_ResumeMusic();
+	}
 }
 
 void audio_backend_music_pause(void) {
-	if(mixer_loaded)
+	if(mixer_loaded) {
+		Mix_HookMusicFinished(NULL);
 		Mix_PauseMusic();
+	}
 }
 
 bool audio_backend_music_play(void *impl) {
 	if(!mixer_loaded)
 		return false;
 
-	bool result = (Mix_PlayMusic((Mix_Music*)impl, -1) != -1);
+	MixerInternalMusic *imus = impl;
+	Mix_Music *mmus;
+	int loops;
+
+	if(imus->intro) {
+		next_loop = imus->loop;
+		mmus = imus->intro;
+		loops = 0;
+		assert(next_loop != NULL);
+		Mix_HookMusicFinished(mixer_music_finished);
+	} else {
+		mmus = imus->loop;
+		loops = -1;
+		Mix_HookMusicFinished(NULL);
+	}
+
+	bool result = (Mix_PlayMusic(mmus, loops) != -1);
 
 	if(!result) {
 		log_warn("Mix_PlayMusic() failed: %s", Mix_GetError());
@@ -193,7 +228,6 @@ bool audio_backend_sound_loop(void *impl) {
 	}
 
 	return true;
-
 }
 
 bool audio_backend_sound_stop_loop(void *impl) {

src/audio_mixer.h

@@ -8,6 +8,9 @@
 
 #pragma once
 
+#include <SDL_mixer.h>
+#include <stdbool.h>
+
 // I needed to add this for supporting loop sounds since Mixer doesn’t remember
 // what channel a sound is playing on.
 
@@ -16,3 +19,10 @@ typedef struct {
 	int loopchan; // channel the sound may be looping on. -1 if not looping
 } MixerInternalSound;
 
+typedef struct MixerInternalMusic {
+    Mix_Music *intro;
+    Mix_Music *loop;
+} MixerInternalMusic;
+
+char* audio_mixer_sound_path(const char *prefix, const char *name, bool isbgm);
+bool audio_mixer_check_sound_path(const char *path, bool isbgm);

src/resource/bgm_mixer.c

@@ -10,20 +10,22 @@
 #include <SDL_mixer.h>
 
 #include "resource.h"
-#include "sfx.h"
-
-char* audio_mixer_sound_path(const char *prefix, const char *name);
-bool audio_mixer_check_sound_path(const char *path, bool isbgm);
+#include "bgm.h"
+#include "audio_mixer.h"
 
 char* music_path(const char *name) {
-	return audio_mixer_sound_path(BGM_PATH_PREFIX, name);
+	return audio_mixer_sound_path(BGM_PATH_PREFIX, name, true);
 }
 
 bool check_music_path(const char *path) {
 	return strstartswith(path, BGM_PATH_PREFIX) && audio_mixer_check_sound_path(path, true);
 }
 
-void* load_music_begin(const char *path, unsigned int flags) {
+static Mix_Music* load_mix_music(const char *path) {
+	if(!path) {
+		return NULL;
+	}
+
 	SDL_RWops *rwops = vfs_open(path, VFS_MODE_READ | VFS_MODE_SEEKABLE);
 
 	if(!rwops) {
@@ -38,8 +40,35 @@ void* load_music_begin(const char *path, unsigned int flags) {
 		return NULL;
 	}
 
+	return music;
+}
+
+void* load_music_begin(const char *path, unsigned int flags) {
 	Music *mus = calloc(1, sizeof(Music));
-	mus->impl = music;
+	MixerInternalMusic *imus = calloc(1, sizeof(MixerInternalMusic));
+	mus->impl = imus;
+
+	if(strendswith(path, ".bgm")) {
+		Hashtable *bgm = parse_keyvalue_file(path, 8);
+
+		if(!bgm) {
+			log_warn("Failed to parse bgm config '%s'", path);
+		} else {
+			imus->intro = load_mix_music(hashtable_get_string(bgm, "intro"));
+			imus->loop = load_mix_music(hashtable_get_string(bgm, "loop"));
+			hashtable_foreach(bgm, hashtable_iter_free_data, NULL);
+			hashtable_free(bgm);
+		}
+	} else {
+		imus->loop = load_mix_music(path);
+	}
+
+	if(!imus->loop) {
+		assert(imus->intro == NULL);
+		free(imus);
+		mus = NULL;
+		log_warn("Failed to load bgm '%s'", path);
+	}
 
 	return mus;
 }
@@ -50,6 +79,9 @@ void* load_music_end(void *opaque, const char *path, unsigned int flags) {
 
 void unload_music(void *vmus) {
 	Music *mus = vmus;
-	Mix_FreeMusic((Mix_Music*)mus->impl);
+	MixerInternalMusic *imus = mus->impl;
+	Mix_FreeMusic(imus->intro);
+	Mix_FreeMusic(imus->loop);
+	free(mus->impl);
 	free(mus);
 }

src/resource/sfx_mixer.c

@@ -13,11 +13,8 @@
 #include "sfx.h"
 #include "audio_mixer.h"
 
-char* audio_mixer_sound_path(const char *prefix, const char *name);
-bool audio_mixer_check_sound_path(const char *path, bool isbgm);
-
 char* sound_path(const char *name) {
-	return audio_mixer_sound_path(SFX_PATH_PREFIX, name);
+	return audio_mixer_sound_path(SFX_PATH_PREFIX, name, true);
 }
 
 bool check_sound_path(const char *path) {
@@ -35,7 +32,7 @@ void* load_sound_begin(const char *path, unsigned int flags) {
 	Mix_Chunk *sound = Mix_LoadWAV_RW(rwops, true);
 
 	if(!sound) {
-		log_warn("Mix_LoadWAV() failed: %s", Mix_GetError());
+		log_warn("Mix_LoadWAV_RW() failed: %s", Mix_GetError());
 		return NULL;
 	}