static int decode_tsw1(GetByteContext *gb, uint8_t *frame, int width, int height)

{

    const uint8_t *frame_start = frame;

    const uint8_t *frame_end   = frame + width * height;

    int mask = 0x10000, bitbuf = 0;

    int v, count, segments;

    unsigned offset;



    segments = bytestream2_get_le32(gb);

    offset   = bytestream2_get_le32(gb);

    if (segments == 0 && offset == frame_end - frame)

        return 0; // skip frame

    if (frame_end - frame <= offset)

        return AVERROR_INVALIDDATA;

    frame += offset;

    while (segments--) {

        if (bytestream2_get_bytes_left(gb) < 2)

            return AVERROR_INVALIDDATA;

        if (mask == 0x10000) {

            bitbuf = bytestream2_get_le16u(gb);

            mask = 1;

        }

        if (frame_end - frame < 2)

            return AVERROR_INVALIDDATA;

        if (bitbuf & mask) {

            v = bytestream2_get_le16(gb);

            offset = (v & 0x1FFF) << 1;

            count = ((v >> 13) + 2) << 1;

            if (frame - frame_start < offset || frame_end - frame < count)

                return AVERROR_INVALIDDATA;

            av_memcpy_backptr(frame, offset, count);

            frame += count;

        } else {

            *frame++ = bytestream2_get_byte(gb);

            *frame++ = bytestream2_get_byte(gb);

        }

        mask <<= 1;

    }



    return 0;

}
