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@xxxxxxxxx>
---
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
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