Refactor audio to enable bgm looping

SDL_mixer reads loop information from WAV files if you use the Mix_Music
interface, but NOT the Mix_Chunk interface. So bgm now uses the
Mix_Music interface to get proper looping.

There's also some code here for reading bgi files (taken from xsystem35)
but it's not actually used. There doesn't seem to be a simple way to set
up custom loops with SDL_mixer.

include/audio.h

@@ -19,40 +19,43 @@
 
 #include <stdbool.h>
 
-enum audio_type {
-	AUDIO_MUSIC,
-	AUDIO_SOUND
-};
-
 void audio_init(void);
 void audio_fini(void);
 
-bool audio_exists(enum audio_type type, int no);
-int audio_prepare(enum audio_type type, int channel, int no);
-int audio_unprepare(enum audio_type type, int channel);
-int audio_play(enum audio_type type, int channel);
-int audio_stop(enum audio_type type, int channel);
-bool audio_is_playing(enum audio_type type, int channel);
-int audio_set_loop_count(enum audio_type type, int channel, int count);
-int audio_get_loop_count(enum audio_type type, int channel);
-int audio_set_loop_start_pos(enum audio_type type, int channel, int pos);
-int audio_set_loop_end_pos(enum audio_type type, int channel, int pos);
-int audio_fade(enum audio_type type, int channel, int time, int volume, bool stop);
-int audio_stop_fade(enum audio_type type, int channel);
-bool audio_is_fading(enum audio_type type, int channel);
-int audio_pause(enum audio_type type, int channel);
-int audio_restart(enum audio_type type, int channel);
-bool audio_is_paused(enum audio_type type, int channel);
-int audio_get_pos(enum audio_type type, int channel);
-int audio_get_length(enum audio_type type, int channel);
-int audio_get_sample_pos(enum audio_type type, int channel);
-int audio_get_sample_length(enum audio_type type, int channel);
-int audio_seek(enum audio_type type, int channel, int pos);
-int audio_get_unused_channel(enum audio_type type);
-int audio_reverse_LR(enum audio_type type, int channel);
-int audio_get_volume(enum audio_type type, int channel);
-int audio_get_time_length(enum audio_type type, int channel);
-int audio_get_group_num(enum audio_type type, int channel);
-int audio_prepare_from_file(enum audio_type type, int channel, char *filename);
+bool wav_exists(int no);
+bool bgm_exists(int no);
+int wav_prepare(int ch, int no);
+int bgm_prepare(int ch, int no);
+int wav_unprepare(int ch);
+int bgm_unprepare(int ch);
+int wav_play(int ch);
+int bgm_play(int ch);
+int wav_stop(int ch);
+int bgm_stop(int ch);
+bool wav_is_playing(int ch);
+bool bgm_is_playing(int ch);
+//int audio_set_loop_count(enum audio_type type, int channel, int count);
+//int audio_get_loop_count(enum audio_type type, int channel);
+//int audio_set_loop_start_pos(enum audio_type type, int channel, int pos);
+//int audio_set_loop_end_pos(enum audio_type type, int channel, int pos);
+int wav_fade(int ch, int time, int volume, bool stop);
+int bgm_fade(int ch, int time, int volume, bool stop);
+//int audio_stop_fade(enum audio_type type, int channel);
+//bool audio_is_fading(enum audio_type type, int channel);
+//int audio_pause(enum audio_type type, int channel);
+//int audio_restart(enum audio_type type, int channel);
+//bool audio_is_paused(enum audio_type type, int channel);
+//int audio_get_pos(enum audio_type type, int channel);
+//int audio_get_length(enum audio_type type, int channel);
+//int audio_get_sample_pos(enum audio_type type, int channel);
+//int audio_get_sample_length(enum audio_type type, int channel);
+//int audio_seek(enum audio_type type, int channel, int pos);
+int wav_get_unused_channel(void);
+int bgm_get_unused_channel(void);
+//int audio_reverse_LR(enum audio_type type, int channel);
+//int audio_get_volume(enum audio_type type, int channel);
+int wav_get_time_length(int ch);
+//int audio_get_group_num(enum audio_type type, int channel);
+//int audio_prepare_from_file(enum audio_type type, int channel, char *filename);
 
 #endif /* SYSTEM4_AUDIO_H */

include/xsystem4.h

@@ -29,6 +29,9 @@ struct config {
 	char *home_dir;
 	int view_width;
 	int view_height;
+
+	char *bgi_path;
+	char *wai_path;
 };
 
 struct config config;