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?
>
> Signed-off-by: Gábor Stefanik <netrolller.3d@xxxxxxxxx>
> ---
> 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.
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