rockbox/lib/rbcodec/codecs/gbs.c

/* Ripped off from Game_Music_Emu 0.5.2. http://www.slack.net/~ant/ */

#include <codecs/lib/codeclib.h>
#include "libgme/gbs_emu.h" 

CODEC_HEADER

/* Maximum number of bytes to process in one iteration */
#define CHUNK_SIZE (1024*2)

static int16_t samples[CHUNK_SIZE] IBSS_ATTR;
static struct Gbs_Emu gbs_emu;

/****************** rockbox interface ******************/

static void set_codec_track(int t) {
    Gbs_start_track(&gbs_emu, t); 

    /* for loop mode we disable track limits */
    if (!ci->loop_track()) {
        Track_set_fade(&gbs_emu, Track_get_length( &gbs_emu, t ), 4000);
    }
    ci->set_elapsed(t*1000); /* t is track no to display */
}

/* this is the codec entry point */
enum codec_status codec_main(enum codec_entry_call_reason reason)
{
    if (reason == CODEC_LOAD) {
        /* we only render 16 bits */
        ci->configure(DSP_SET_SAMPLE_DEPTH, 16);

        /* 44 Khz, Interleaved stereo */
        ci->configure(DSP_SET_FREQUENCY, 44100);
        ci->configure(DSP_SET_STEREO_MODE, STEREO_INTERLEAVED);

        Gbs_init(&gbs_emu);
        Gbs_set_sample_rate(&gbs_emu, 44100);
    }

    return CODEC_OK;
}

/* this is called for each file to process */
enum codec_status codec_run(void)
{
    blargg_err_t err;
    uint8_t *buf;
    size_t n;
    intptr_t param;
    int track = 0;

    DEBUGF("GBS: next_track\n");
    if (codec_init()) {
        return CODEC_ERROR;
    }

    codec_set_replaygain(ci->id3);

    /* Read the entire file */
    DEBUGF("GBS: request file\n");
    ci->seek_buffer(0);
    buf = ci->request_buffer(&n, ci->filesize);
    if (!buf || n < (size_t)ci->filesize) {
        DEBUGF("GBS: file load failed\n");
        return CODEC_ERROR;
    }
   
    if ((err = Gbs_load_mem(&gbs_emu, buf, ci->filesize))) {
        DEBUGF("GBS: Gbs_load_mem failed (%s)\n", err);
        return CODEC_ERROR;
    }

    /* Update internal track count */
    if (gbs_emu.m3u.size > 0)
        gbs_emu.track_count = gbs_emu.m3u.size;

    if (ci->id3->elapsed) {
        track = ci->id3->elapsed/1000;
        if (track >= gbs_emu.track_count) return CODEC_OK;
    }

next_track:
    set_codec_track(track);

    /* The main decoder loop */
    while (1) {
        enum codec_command_action action = ci->get_command(&param);

        if (action == CODEC_ACTION_HALT)
            break;

        if (action == CODEC_ACTION_SEEK_TIME) {
            track = param/1000;
            ci->seek_complete();
            if (track >= gbs_emu.track_count) break;
            goto next_track;
        }

        /* Generate audio buffer */
        err = Gbs_play(&gbs_emu, CHUNK_SIZE, samples);
        if (err || Track_ended(&gbs_emu)) {
            track++;
            if (track >= gbs_emu.track_count) break;
            goto next_track;
        }

        ci->pcmbuf_insert(samples, NULL, CHUNK_SIZE >> 1);
    }

    return CODEC_OK;
}