static void decode_format80(const unsigned char *src, int src_size,
    unsigned char *dest, int dest_size, int check_size) {

    int src_index = 0;
    int dest_index = 0;
    int count;
    int src_pos;
    unsigned char color;
    int i;

    while (src_index < src_size) {

        av_dlog(NULL, "      opcode %02X: ", src[src_index]);

        /* 0x80 means that frame is finished */
        if (src[src_index] == 0x80)
            return;

        if (dest_index >= dest_size) {
            av_log(NULL, AV_LOG_ERROR, "  VQA video: decode_format80 problem: dest_index (%d) exceeded dest_size (%d)\n",
                dest_index, dest_size);
            return;
        }

        if (src[src_index] == 0xFF) {

            src_index++;
            count = AV_RL16(&src[src_index]);
            src_index += 2;
            src_pos = AV_RL16(&src[src_index]);
            src_index += 2;
            av_dlog(NULL, "(1) copy %X bytes from absolute pos %X\n", count, src_pos);
            CHECK_COUNT();
            for (i = 0; i < count; i++)
                dest[dest_index + i] = dest[src_pos + i];
            dest_index += count;

        } else if (src[src_index] == 0xFE) {

            src_index++;
            count = AV_RL16(&src[src_index]);
            src_index += 2;
            color = src[src_index++];
            av_dlog(NULL, "(2) set %X bytes to %02X\n", count, color);
            CHECK_COUNT();
            memset(&dest[dest_index], color, count);
            dest_index += count;

        } else if ((src[src_index] & 0xC0) == 0xC0) {

            count = (src[src_index++] & 0x3F) + 3;
            src_pos = AV_RL16(&src[src_index]);
            src_index += 2;
            av_dlog(NULL, "(3) copy %X bytes from absolute pos %X\n", count, src_pos);
            CHECK_COUNT();
            for (i = 0; i < count; i++)
                dest[dest_index + i] = dest[src_pos + i];
            dest_index += count;

        } else if (src[src_index] > 0x80) {

            count = src[src_index++] & 0x3F;
            av_dlog(NULL, "(4) copy %X bytes from source to dest\n", count);
            CHECK_COUNT();
            memcpy(&dest[dest_index], &src[src_index], count);
            src_index += count;
            dest_index += count;

        } else {

            count = ((src[src_index] & 0x70) >> 4) + 3;
            src_pos = AV_RB16(&src[src_index]) & 0x0FFF;
            src_index += 2;
            av_dlog(NULL, "(5) copy %X bytes from relpos %X\n", count, src_pos);
            CHECK_COUNT();
            for (i = 0; i < count; i++)
                dest[dest_index + i] = dest[dest_index - src_pos + i];
            dest_index += count;
        }
    }

    /* validate that the entire destination buffer was filled; this is
     * important for decoding frame maps since each vector needs to have a
     * codebook entry; it is not important for compressed codebooks because
     * not every entry needs to be filled */
    if (check_size)
        if (dest_index < dest_size)
            av_log(NULL, AV_LOG_ERROR, "  VQA video: decode_format80 problem: decode finished with dest_index (%d) < dest_size (%d)\n",
                dest_index, dest_size);
}