Re: [PATCH] b43: LP-PHY: Fix and simplify Qdiv roundup
From: Michael Buesch <hidden>
Date: 2009-08-25 20:48:54
On Tuesday 25 August 2009 16:40:17 Gábor Stefanik wrote:
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.
Don't we have some sort of standard library function somewhere in the kernel for this? If not, what about creating one?
quoted hunk ↗ jump to hunk
Signed-off-by: Gábor Stefanik <redacted> --- drivers/net/wireless/b43/phy_lp.c | 14 ++++---------- 1 files changed, 4 insertions(+), 10 deletions(-)diff --git a/drivers/net/wireless/b43/phy_lp.c b/drivers/net/wireless/b43/phy_lp.c index 7e70c07..d0280d5 100644 --- a/drivers/net/wireless/b43/phy_lp.c +++ b/drivers/net/wireless/b43/phy_lp.c@@ -1034,7 +1034,7 @@ static int lpphy_loopback(struct b43_wldev *dev) 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 +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--; } - if (remainder >= roundup) + if (remainder << 1 >= divisor) quotient++; return quotient;
-- Greetings, Michael.