On Fri, Aug 03 2012, George Spelvin wrote: > If you're going to have a conditional branch after > each 32x32->64-bit multiply, might as well shrink the code > and make it a loop. > > This also avoids using the long multiply for small integers. > > (This leaves the comments in a confusing state, but that's a separate > patch to make review easier.) > > Signed-off-by: George Spelvin <[email protected]>
NAK.
> ---
> lib/vsprintf.c | 20 ++++++--------------
> 1 file changed, 6 insertions(+), 14 deletions(-)
>
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index a8e7392..3ca77b8 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -174,20 +174,12 @@ char *put_dec_trunc8(char *buf, unsigned r)
> unsigned q;
>
> /* Copy of previous function's body with added early returns */
> - q = (r * (uint64_t)0x1999999a) >> 32;
> - *buf++ = (r - 10 * q) + '0'; /* 2 */
> - if (q == 0)
> - return buf;
> - r = (q * (uint64_t)0x1999999a) >> 32;
> - *buf++ = (q - 10 * r) + '0'; /* 3 */
> - if (r == 0)
> - return buf;
> - q = (r * (uint64_t)0x1999999a) >> 32;
> - *buf++ = (r - 10 * q) + '0'; /* 4 */
> - if (q == 0)
> - return buf;
> - r = (q * (uint64_t)0x1999999a) >> 32;
> - *buf++ = (q - 10 * r) + '0'; /* 5 */
> + while (r >= 10000) {
> + q = r + '0';
> + r = (r * (uint64_t)0x1999999a) >> 32;
> + *buf++ = q - 10*r;
> + }
This loop looks nothing like the original code. Why are you adding '0'
at the beginning? Also, the original code switches the role of q and r,
the loop does not.
> if (r == 0)
> return buf;
> q = (r * 0x199a) >> 16;
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michał “mina86” Nazarewicz (o o)
ooo +----<email/xmpp: [email protected]>--------------ooO--(_)--Ooo--
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