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[glibc.git] / wcsmbs / wcpncpy.c
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1 /* Copyright (C) 1996, 1997 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
18 02111-1307 USA. */
20 #include <wchar.h>
23 /* Copy no more than N wide-characters of SRC to DEST, returning the
24 address of the last character written into DEST. */
25 wchar_t *
26 __wcpncpy (dest, src, n)
27 wchar_t *dest;
28 const wchar_t *src;
29 size_t n;
31 wint_t c;
32 wchar_t *const s = dest;
34 --dest;
36 if (n >= 4)
38 size_t n4 = n >> 2;
40 for (;;)
42 c = *src++;
43 *++dest = c;
44 if (c == L'\0')
45 break;
46 c = *src++;
47 *++dest = c;
48 if (c == L'\0')
49 break;
50 c = *src++;
51 *++dest = c;
52 if (c == L'\0')
53 break;
54 c = *src++;
55 *++dest = c;
56 if (c == L'\0')
57 break;
58 if (--n4 == 0)
59 goto last_chars;
61 n = n - (dest - s) - 1;
62 if (n == 0)
63 return dest;
64 goto zero_fill;
67 last_chars:
68 n &= 3;
69 if (n == 0)
70 return dest;
74 c = *src++;
75 *++dest = c;
76 if (--n == 0)
77 return dest;
79 while (c != L'\0');
81 zero_fill:
83 *++dest = L'\0';
84 while (--n > 0);
86 return dest;
89 weak_alias (__wcpncpy, wcpncpy)