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[glibc.git] / wcsmbs / wcpncpy.c
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1 /* Copyright (C) 1996, 1997, 2003 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 if (n >= 4)
36 size_t n4 = n >> 2;
38 for (;;)
40 c = *src++;
41 *dest++ = c;
42 if (c == L'\0')
43 break;
44 c = *src++;
45 *dest++ = c;
46 if (c == L'\0')
47 break;
48 c = *src++;
49 *dest++ = c;
50 if (c == L'\0')
51 break;
52 c = *src++;
53 *dest++ = c;
54 if (c == L'\0')
55 break;
56 if (--n4 == 0)
57 goto last_chars;
59 n -= dest - s;
60 goto zero_fill;
63 last_chars:
64 n &= 3;
65 if (n == 0)
66 return dest;
68 for (;;)
70 c = *src++;
71 --n;
72 *dest++ = c;
73 if (c == L'\0')
74 break;
75 if (n == 0)
76 return dest;
79 zero_fill:
80 while (n-- > 0)
81 dest[n] = L'\0';
83 return dest - 1;
86 weak_alias (__wcpncpy, wcpncpy)