glibc/string/strncmp.c
2005-12-14 15:06:39 +00:00

74 lines
2.0 KiB
C

/* Copyright (C) 1991, 1996, 1997, 2003 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <string.h>
#include <memcopy.h>
#undef strncmp
/* Compare no more than N characters of S1 and S2,
returning less than, equal to or greater than zero
if S1 is lexicographically less than, equal to or
greater than S2. */
int
strncmp (s1, s2, n)
const char *s1;
const char *s2;
size_t n;
{
unsigned reg_char c1 = '\0';
unsigned reg_char c2 = '\0';
if (n >= 4)
{
size_t n4 = n >> 2;
do
{
c1 = (unsigned char) *s1++;
c2 = (unsigned char) *s2++;
if (c1 == '\0' || c1 != c2)
return c1 - c2;
c1 = (unsigned char) *s1++;
c2 = (unsigned char) *s2++;
if (c1 == '\0' || c1 != c2)
return c1 - c2;
c1 = (unsigned char) *s1++;
c2 = (unsigned char) *s2++;
if (c1 == '\0' || c1 != c2)
return c1 - c2;
c1 = (unsigned char) *s1++;
c2 = (unsigned char) *s2++;
if (c1 == '\0' || c1 != c2)
return c1 - c2;
} while (--n4 > 0);
n &= 3;
}
while (n > 0)
{
c1 = (unsigned char) *s1++;
c2 = (unsigned char) *s2++;
if (c1 == '\0' || c1 != c2)
return c1 - c2;
n--;
}
return c1 - c2;
}
libc_hidden_builtin_def (strncmp)