CSTMのループ情報を LOOPSTART/LOOPLENGTH に変換して出力

getloop.c

#include <stdio.h>
#include <stdint.h>

// reference: https://www.3dbrew.org/wiki/BCSTM

#define CSTM_SIGNATURE      'MTSC'

#define CSTM_LITTLE_ENDIAN  0xfeff

#define CSTM_REF_TYPE_INFO  0x4000
#define CSTM_REF_TYPE_SEEK  0x4001
#define CSTM_REF_TYPE_DATA  0x4002

struct CSTM_reference
{
    uint16_t type_id;
    uint16_t padding;
    uint32_t offset;
};

struct CSTM_sized_reference
{
    struct CSTM_reference reference;
    uint32_t size;
};

struct CSTM_header
{
    uint32_t cstm;
    uint16_t endianness;
    uint16_t header_size;
    uint32_t version;
    uint32_t file_size;
    uint16_t num_of_blocks;
    uint16_t reserved1;
    
    struct CSTM_sized_reference info_block;
    struct CSTM_sized_reference seek_block;
    struct CSTM_sized_reference data_block;
};

#define CSTM_BLOCK_INFO 'OFNI'
#define CSTM_BLOCK_SEEK 'KEES'
#define CSTM_BLOCK_DATA 'ATAD'

struct CSTM_block_header
{
    uint32_t magic;
    uint32_t size;
};

struct CSTM_stream_info
{
    uint8_t encoding;
    uint8_t looped;
    uint8_t channel_count;
    uint8_t padding;
    uint32_t sample_rate;
    uint32_t loop_start_frame;
    uint32_t loop_end_frame;
    uint32_t sample_block_count;
    uint32_t sample_block_size;
    uint32_t sample_block_sample_count;
    uint32_t last_sample_block_size;
    uint32_t last_sample_block_padded_size;
    uint32_t seek_data_size;
    uint32_t seek_interval_sample_count;
    struct CSTM_reference sample_data_reference;
};

struct CSTM_info_block
{
    struct CSTM_block_header header;
    struct CSTM_reference stream_info_reference;
    struct CSTM_reference track_info_reference;
    struct CSTM_reference channel_info_reference;
    struct CSTM_stream_info stream_info;
    // ...
};

int get_loop_info(char* filename)
{
    FILE* fp = fopen(filename, "rb");
    if(!fp) {
        fprintf(stderr, "Cannot open %s\n", filename);
        return -1;
    }

    struct CSTM_header file_header;
    fread(&file_header, sizeof file_header, 1, fp);
    if(file_header.cstm != CSTM_SIGNATURE) {
        fprintf(stderr, "%s: is not a CSTM\n", filename);
        fclose(fp);
        return -1;
    }
    if(file_header.endianness != CSTM_LITTLE_ENDIAN) {
        fprintf(stderr, "%s: unsupported endianness\n", filename);
        fclose(fp);
        return -1;
    }

    if(file_header.info_block.reference.type_id != CSTM_REF_TYPE_INFO) {
        fprintf(stderr, "%s: unexpected info block layout\n", filename);
        fclose(fp);
        return -1;
    }

    fseek(fp, file_header.info_block.reference.offset, SEEK_SET);

    struct CSTM_info_block info_block;
    fread(&info_block, sizeof info_block, 1, fp);
    if(info_block.header.magic != CSTM_BLOCK_INFO) {
        fprintf(stderr, "%s: referenced info block is not actuaully an info block\n", filename);
        fclose(fp);
        return -1;
    }

    printf("[%s]\n", filename);

    printf("LOOPSTART=%d\n", info_block.stream_info.loop_start_frame);
    printf("LOOPLENGTH=%d\n", info_block.stream_info.loop_end_frame 
        - info_block.stream_info.loop_start_frame);

    printf("\n");

    fclose(fp);

    return 0;
}

int main(int ac, char** av)
{
    if(ac == 1) {
        fprintf(stderr, "Usage: %s *.bcstm...\n", *av);
        return 1;
    }

    av++;
    while(*av)
    {
        get_loop_info(*av);
        av++;
    }

    return 0;
}