static int decode_block_refinement(MJpegDecodeContext *s, DCTELEM *block, uint8_t *last_nnz,
                        int ac_index, int16_t *quant_matrix,
                        int ss, int se, int Al, int *EOBRUN)
{
    int code, i=ss, j, sign, val, run;
    int last = FFMIN(se, *last_nnz);

    OPEN_READER(re, &s->gb);
    if(*EOBRUN)
        (*EOBRUN)--;
    else {
        for(;;i++) {
            UPDATE_CACHE(re, &s->gb);
            GET_VLC(code, re, &s->gb, s->vlcs[1][ac_index].table, 9, 2)
            /* Progressive JPEG use AC coeffs from zero and this decoder sets offset 16 by default */
            code -= 16;
            if(code & 0xF) {
                run = ((unsigned) code) >> 4;
                UPDATE_CACHE(re, &s->gb);
                val = SHOW_UBITS(re, &s->gb, 1);
                LAST_SKIP_BITS(re, &s->gb, 1);
                ZERO_RUN;
                j = s->scantable.permutated[i];
                val--;
                block[j] = ((quant_matrix[j]^val)-val) << Al;
                if(i == se) {
                    if(i > *last_nnz)
                        *last_nnz = i;
                    CLOSE_READER(re, &s->gb)
                    return 0;
                }
            }else{
                run = ((unsigned) code) >> 4;
                if(run == 0xF){
                    ZERO_RUN;
                }else{
                    val = run;
                    run = (1 << run);
                    if(val) {
                        UPDATE_CACHE(re, &s->gb);
                        run += SHOW_UBITS(re, &s->gb, val);
                        LAST_SKIP_BITS(re, &s->gb, val);
                    }
                    *EOBRUN = run - 1;
                    break;
                }
            }
        }

        if(i > *last_nnz)
            *last_nnz = i;
    }

    for(;i<=last;i++) {
        j = s->scantable.permutated[i];
        if(block[j])
            REFINE_BIT(j)
    }
    CLOSE_READER(re, &s->gb);

    return 0;
}