wcsmbs/wcpncpy.c

   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.
   4
   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.
   9
  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.
  14
  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.  */
  19
  20 #include <wchar.h>
  21
  22
  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;
  30 {
  31   wint_t c;
  32   wchar_t *const s = dest;
  33
  34   if (n >= 4)
  35     {
  36       size_t n4 = n >> 2;
  37
  38       for (;;)
  39         {
  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;
  58         }
  59       n -= dest - s;
  60       goto zero_fill;
  61     }
  62
  63  last_chars:
  64   n &= 3;
  65   if (n == 0)
  66     return dest;
  67
  68   for (;;)
  69     {
  70       c = *src++;
  71       --n;
  72       *dest++ = c;
  73       if (c == L'\0')
  74         break;
  75       if (n == 0)
  76         return dest;
  77     }
  78
  79  zero_fill:
  80   while (n-- > 0)
  81     dest[n] = L'\0';
  82
  83   return dest - 1;
  84 }
  85
  86 weak_alias (__wcpncpy, wcpncpy)