vgmstream/src/meta/ps2_jstm.c

#include "meta.h"
#include "../coding/coding.h"

static STREAMFILE* setup_jstm_streamfile(STREAMFILE *streamFile, off_t start_offset);

/* JSTM - from Tantei Jinguji Saburo - Kind of Blue (PS2) */
VGMSTREAM * init_vgmstream_ps2_jstm(STREAMFILE *streamFile) {
    VGMSTREAM * vgmstream = NULL;
    STREAMFILE *temp_streamFile = NULL;
    off_t start_offset;
    int loop_flag, channel_count;


    /* checks */
    /* .stm: original, .jstm: header id */
    if (!check_extensions(streamFile, "stm,jstm"))
        goto fail;
    if (read_32bitBE(0x00,streamFile) != 0x4A53544D) /* "JSTM" */
        goto fail;

    start_offset = 0x20;
    channel_count = read_16bitLE(0x04,streamFile);
    if (channel_count != read_16bitLE(0x06,streamFile)) /* 0x02, interleave? */
        goto fail;
    loop_flag = (read_32bitLE(0x14,streamFile) != -1);

    /* build the VGMSTREAM */
    vgmstream = allocate_vgmstream(channel_count,loop_flag);
    if (!vgmstream) goto fail;

    vgmstream->sample_rate = read_32bitLE(0x08,streamFile);
    vgmstream->num_samples = pcm_bytes_to_samples(read_32bitLE(0x0C,streamFile),channel_count,16);
    if (loop_flag) {
        vgmstream->loop_start_sample = pcm_bytes_to_samples(read_32bitLE(0x14,streamFile),channel_count,16);
        vgmstream->loop_end_sample = vgmstream->num_samples;
    }

    vgmstream->meta_type = meta_PS2_JSTM;
    vgmstream->coding_type = coding_PCM16LE;
    vgmstream->layout_type = layout_interleave;
    vgmstream->interleave_block_size = 0x02;

    temp_streamFile = setup_jstm_streamfile(streamFile, start_offset);
    if (!temp_streamFile) goto fail;

    if (!vgmstream_open_stream(vgmstream,temp_streamFile,start_offset))
        goto fail;
    
    close_streamfile(temp_streamFile);
    
    return vgmstream;

fail:
    close_streamfile(temp_streamFile);
    close_vgmstream(vgmstream);
    return NULL;
}


typedef struct {
    off_t start_offset;
} jstm_decryption_data;

static size_t jstm_decryption_read(STREAMFILE *streamfile, uint8_t *dest, off_t offset, size_t length, jstm_decryption_data* data) {
    size_t bytes_read;
    int i;

    bytes_read = streamfile->read(streamfile, dest, offset, length);

    /* decrypt data (xor) */
    for (i = 0; i < bytes_read; i++) {
        if (offset+i >= data->start_offset) {
            //VGM_LOG("xor %x to %x\n", dest[i], dest[i] ^ 0x5A);getchar();
            dest[i] = dest[i] ^ 0x5A;
        }
    }

    return bytes_read;
}

static STREAMFILE* setup_jstm_streamfile(STREAMFILE *streamFile, off_t start_offset) {
    STREAMFILE *temp_streamFile = NULL, *new_streamFile = NULL;
    jstm_decryption_data io_data = {0};
    size_t io_data_size = sizeof(jstm_decryption_data);

    /* setup decryption */
    io_data.start_offset = start_offset;


    /* setup custom streamfile */
    new_streamFile = open_wrap_streamfile(streamFile);
    if (!new_streamFile) goto fail;
    temp_streamFile = new_streamFile;

    new_streamFile = open_io_streamfile(temp_streamFile, &io_data,io_data_size, jstm_decryption_read);
    if (!new_streamFile) goto fail;
    temp_streamFile = new_streamFile;

    return temp_streamFile;

fail:
    close_streamfile(temp_streamFile);
    return NULL;
}