volume options n64

// in src/audio/external.c (above play_music in my case)

void set_sequence_player_volume(s32 player, f32 volume) {
    gSequencePlayers[player].volumeScale = volume;
}

// in src/game/sound_init.c (above thread4_sound)

#define MAX_VOLUME 127
unsigned int configMasterVolume = MAX_VOLUME; // 0 - MAX_VOLUME
unsigned int configMusicVolume = MAX_VOLUME;
unsigned int configSfxVolume = MAX_VOLUME;
unsigned int configEnvVolume = MAX_VOLUME;

void change_audio_volumes(void) {
    const f32 master_mod = (f32)configMasterVolume / 127.0f;
    set_sequence_player_volume(SEQ_PLAYER_LEVEL, (f32)configMusicVolume / 127.0f * master_mod);
    set_sequence_player_volume(SEQ_PLAYER_SFX, (f32)configSfxVolume / 127.0f * master_mod);
    set_sequence_player_volume(SEQ_PLAYER_ENV, (f32)configEnvVolume / 127.0f * master_mod);
}

// in thread4_sound, change_audio_volumes() is called at the bottom of while (TRUE) like this

void thread4_sound(UNUSED void *arg) {
    audio_init();
    sound_init();

    // Zero-out unused vector
    vec3f_copy(unused80339DC0, gVec3fZero);

    osCreateMesgQueue(&sSoundMesgQueue, sSoundMesgBuf, ARRAY_COUNT(sSoundMesgBuf));
    set_vblank_handler(1, &sSoundVblankHandler, &sSoundMesgQueue, (OSMesg) 512);

    while (TRUE) {
        OSMesg msg;

        osRecvMesg(&sSoundMesgQueue, &msg, OS_MESG_BLOCK);
        if (gResetTimer < 25) {
            struct SPTask *spTask;
            profiler_log_thread4_time();
            spTask = create_next_audio_frame_task();
            if (spTask != NULL) {
                dispatch_audio_sptask(spTask);
            }
            profiler_log_thread4_time();
        }

#ifdef TARGET_N64 // TODO: save to EEPROM
        change_audio_volumes();
#endif
    }
}