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[glibc/history.git] / string / strncmp.c
blob1adb2c0ebdfd9d5bd28f1c5d47c1b2ca40043a5b
1 /* Copyright (C) 1991, 1996, 1997, 2003 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, write to the Free
16 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
17 02111-1307 USA. */
19 #include <string.h>
20 #include <memcopy.h>
22 #undef strncmp
24 /* Compare no more than N characters of S1 and S2,
25 returning less than, equal to or greater than zero
26 if S1 is lexicographically less than, equal to or
27 greater than S2. */
28 int
29 strncmp (s1, s2, n)
30 const char *s1;
31 const char *s2;
32 size_t n;
34 unsigned reg_char c1 = '\0';
35 unsigned reg_char c2 = '\0';
37 if (n >= 4)
39 size_t n4 = n >> 2;
42 c1 = (unsigned char) *s1++;
43 c2 = (unsigned char) *s2++;
44 if (c1 == '\0' || c1 != c2)
45 return c1 - c2;
46 c1 = (unsigned char) *s1++;
47 c2 = (unsigned char) *s2++;
48 if (c1 == '\0' || c1 != c2)
49 return c1 - c2;
50 c1 = (unsigned char) *s1++;
51 c2 = (unsigned char) *s2++;
52 if (c1 == '\0' || c1 != c2)
53 return c1 - c2;
54 c1 = (unsigned char) *s1++;
55 c2 = (unsigned char) *s2++;
56 if (c1 == '\0' || c1 != c2)
57 return c1 - c2;
58 } while (--n4 > 0);
59 n &= 3;
62 while (n > 0)
64 c1 = (unsigned char) *s1++;
65 c2 = (unsigned char) *s2++;
66 if (c1 == '\0' || c1 != c2)
67 return c1 - c2;
68 n--;
71 return c1 - c2;
73 libc_hidden_builtin_def (strncmp)