From d8fa338ee01e7de029d2441a8c2b9c5fbfeac82f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?G=C3=A1bor=20Stefanik?= <netrolller.3d@gmail.com>
Date: Wed, 26 Aug 2009 20:51:24 +0200
Subject: [PATCH] b43: LP-PHY: Fix and simplify Qdiv roundup
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
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: Gábor Stefanik <netrolller.3d@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
---
drivers/net/wireless/b43/phy_lp.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)
diff --git a/drivers/net/wireless/b43/phy_lp.c b/drivers/net/wireless/b43/phy_lp.c
index 7e70c078475b..5306f2c66b34 100644
--- a/drivers/net/wireless/b43/phy_lp.c
+++ b/drivers/net/wireless/b43/phy_lp.c
@@ -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;
--
GitLab