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Commit d8fa338e authored by Gábor Stefanik's avatar Gábor Stefanik Committed by John W. Linville
Browse files

b43: LP-PHY: Fix and simplify Qdiv roundup 



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.

Signed-off-by: default avatarGábor Stefanik <netrolller.3d@gmail.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent ca9152e3

drivers/net/wireless/b43/phy_lp.c

+8 −11
Original line number Diff line number Diff line
@@ -1032,9 +1032,10 @@ static int lpphy_loopback(struct b43_wldev *dev) 
	return index;

}



/* Fixed-point division algorithm using only integer math. */

static u32 lpphy_qdiv_roundup(u32 dividend, u32 divisor, u8 precision)

{

	u32 quotient, remainder, rbit, roundup, tmp;

	u32 quotient, remainder;



	if (divisor == 0)

		return 0;
@@ -1042,20 +1043,16 @@ 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;

	while (precision > 0) {

		quotient <<= 1;

		if (remainder >= roundup)

			remainder = (tmp << 1) + rbit;

		else

			remainder <<= 1;

		if (remainder << 1 >= divisor) {

			quotient++;

			remainder = (remainder << 1) - divisor;

		}

		precision--;

	}



	if (remainder >= roundup)

	if (remainder << 1 >= divisor)

		quotient++;



	return quotient;