static void decode_refpass(Jpeg2000T1Context *t1, int width, int height,
                           int bpno)
{
    int phalf, nhalf;
    int y0, x, y;

    phalf = 1 << (bpno - 1);
    nhalf = -phalf;

    for (y0 = 0; y0 < height; y0 += 4)
        for (x = 0; x < width; x++)
            for (y = y0; y < height && y < y0 + 4; y++)
                if ((t1->flags[y + 1][x + 1] & (JPEG2000_T1_SIG | JPEG2000_T1_VIS)) == JPEG2000_T1_SIG) {
                    int ctxno = ff_jpeg2000_getrefctxno(t1->flags[y + 1][x + 1]);
                    int r     = ff_mqc_decode(&t1->mqc,
                                              t1->mqc.cx_states + ctxno)
                                ? phalf : nhalf;
                    t1->data[y][x]          += t1->data[y][x] < 0 ? -r : r;
                    t1->flags[y + 1][x + 1] |= JPEG2000_T1_REF;
                }
}
Unknown