void ff_lag_rac_init(lag_rac *l, GetBitContext *gb, int length)
{
    int i, j, left;

    /* According to reference decoder "1st byte is garbage",
     * however, it gets skipped by the call to align_get_bits()
     */
    align_get_bits(gb);
    left                = get_bits_left(gb) >> 3;
    l->bytestream_start =
    l->bytestream       = gb->buffer + get_bits_count(gb) / 8;
    l->bytestream_end   = l->bytestream_start + left;

    l->range        = 0x80;
    l->low          = *l->bytestream >> 1;
    l->hash_shift   = FFMAX(l->scale - 8, 0);

    for (i = j = 0; i < 256; i++) {
        unsigned r = i << l->hash_shift;
        while (l->prob[j + 1] <= r)
            j++;
        l->range_hash[i] = j;
    }

    /* Add conversion factor to hash_shift so we don't have to in lag_get_rac. */
    l->hash_shift += 23;
}