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authorGábor Stefanik <netrolller.3d@gmail.com>2009-08-26 20:51:24 +0200
committerJohn W. Linville <linville@tuxdriver.com>2009-08-28 14:40:52 -0400
commitd8fa338ee01e7de029d2441a8c2b9c5fbfeac82f (patch)
treef744f9136f9f58136f03cd6e792d46a510474956 /drivers/net/wireless
parentca9152e37f57259ca92486ca5753af16fd9155c6 (diff)
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: Gábor Stefanik <netrolller.3d@gmail.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'drivers/net/wireless')
-rw-r--r--drivers/net/wireless/b43/phy_lp.c19
1 files changed, 8 insertions, 11 deletions
diff --git a/drivers/net/wireless/b43/phy_lp.c b/drivers/net/wireless/b43/phy_lp.c
index 7e70c078475..5306f2c66b3 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;