2009/8/25 Gábor Stefanik <netrolller.3d@xxxxxxxxx>:
> The Qdiv roundup routine is essentially a fixed-point
> division algorithm, using only integer math.
> However, the version in the specs had a major error
> that has been recently fixed (a missing quotient++).
>
> Replace Qdiv roundup with a rewritten, simplified version.
Hi!
> @@ -1042,20 +1042,14 @@ static u32 lpphy_qdiv_roundup(u32 dividend, u32 divisor, u8 precision)
> quotient = dividend / divisor;
> remainder = dividend % divisor;
>
> - rbit = divisor & 0x1;
> - roundup = (divisor >> 1) + rbit;
> -
> while (precision != 0) {
> - tmp = remainder - roundup;
> quotient <<= 1;
> - if (remainder >= roundup)
> - remainder = (tmp << 1) + rbit;
> - else
> - remainder <<= 1;
> + quotient |= (remainder << 1) / divisor;
> + remainder = (remainder << 1) % divisor;
> precision--;
> }
Unless precision is 0, this just added a bunch of divides into
the inner loop, which might be a big surprise to anyone expecting
this to be fast...
--
Bob Copeland %% www.bobcopeland.com
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