div_r32
u8 div_r32(u8 *buf, u8 rd, u8 rs, bool sign_ext);
len = div_r32(buf, dst, src, off == 1);
clip_prob(div_r32(((int64_t)tree_left * 256 +
clip_prob(div_r32(((int64_t)num * 256 +
clip_prob(div_r32(((int64_t)