.
[glibc/history.git] / string / strncat.c
blob2e2de11508f86b25b8b1cd7bbcb57bbd6f274080
1 /* Copyright (C) 1991, 1997 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>
21 #ifdef _LIBC
22 # include <memcopy.h>
23 #else
24 typedef char reg_char;
25 #endif
27 #undef strncat
29 char *
30 strncat (s1, s2, n)
31 char *s1;
32 const char *s2;
33 size_t n;
35 reg_char c;
36 char *s = s1;
38 /* Find the end of S1. */
40 c = *s1++;
41 while (c != '\0');
43 /* Make S1 point before next character, so we can increment
44 it while memory is read (wins on pipelined cpus). */
45 s1 -= 2;
47 if (n >= 4)
49 size_t n4 = n >> 2;
52 c = *s2++;
53 *++s1 = c;
54 if (c == '\0')
55 return s;
56 c = *s2++;
57 *++s1 = c;
58 if (c == '\0')
59 return s;
60 c = *s2++;
61 *++s1 = c;
62 if (c == '\0')
63 return s;
64 c = *s2++;
65 *++s1 = c;
66 if (c == '\0')
67 return s;
68 } while (--n4 > 0);
69 n &= 3;
72 while (n > 0)
74 c = *s2++;
75 *++s1 = c;
76 if (c == '\0')
77 return s;
78 n--;
81 if (c != '\0')
82 *++s1 = '\0';
84 return s;