[PATCH v2] b43: LP-PHY: Fix and simplify Qdiv roundup
flat view
STALE6255d
From: Gábor Stefanik <hidden>
Date: 2009-08-26 18:51:27
Subsystem:
networking drivers (wireless), the rest · Maintainers:
Johannes Berg, Linus Torvalds
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 <redacted> --- v2: Remove divide/modulo operations from the inner loop. drivers/net/wireless/b43/phy_lp.c | 19 ++++++++----------- 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 7e70c07..5306f2c 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;
--
1.5.6