Date: Wed, 16 Dec 2009 14:19:53 GMT From: Maxim Zakharov <maxime@maxime.net.ru> To: freebsd-gnats-submit@FreeBSD.org Subject: misc/141682: Fester version of stncpy function Message-ID: <200912161419.nBGEJr7T029073@www.freebsd.org> Resent-Message-ID: <200912161420.nBGEK1mG066838@freefall.freebsd.org>
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>Number: 141682
>Category: misc
>Synopsis: Fester version of stncpy function
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Wed Dec 16 14:20:01 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator: Maxim Zakharov
>Release: 7.1-BETA2
>Organization:
>Environment:
FreeBSD max.maxime.net.ru 7.1-BETA2 FreeBSD 7.1-BETA2 #0: Mon Oct 13 04:23:28 UTC 2008 root@logan.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC i386
>Description:
I would like to propose a faster version of strncpy function (/usr/src/lib/libc/string/strncpy.c). It's about 30% faster on aligned data, and about two times faster on unaligned data on modern pipelined processors (Intel Duo E8400 3MHz in particular).
>How-To-Repeat:
>Fix:
void * dps_strncpy(char *dst0, char *src0, size_t length) {
if (length) {
register size_t n = (length + 7) / 8;
register size_t r = (length % 8);
register char *dst = dst0, *src = src0;
if (r == 0) r = 8;
if (!(dst[0] = src[0])) return dst0;
if (r > 1) { if (!(dst[1] = src[1])) return dst0;
if (r > 2) { if (!(dst[2] = src[2])) return dst0;
if (r > 3) { if (!(dst[3] = src[3])) return dst0;
if (r > 4) { if (!(dst[4] = src[4])) return dst0;
if (r > 5) { if (!(dst[5] = src[5])) return dst0;
if (r > 6) { if (!(dst[6] = src[6])) return dst0;
if (r > 7) { if (!(dst[7] = src[7])) return dst0;
}}}}}}}
src += r; dst += r;
while (--n > 0) {
if (!(dst[0] = src[0])) break;
if (!(dst[1] = src[1])) break;
if (!(dst[2] = src[2])) break;
if (!(dst[3] = src[3])) break;
if (!(dst[4] = src[4])) break;
if (!(dst[5] = src[5])) break;
if (!(dst[6] = src[6])) break;
if (!(dst[7] = src[7])) break;
src += 8; dst += 8;
}
if (dst < dst0 + length) *dst = '\0';
}
return dst0;
}
>Release-Note:
>Audit-Trail:
>Unformatted:
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