wcsmbs/wcpncpy.c

   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.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 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   --dest;
  35
  36   if (n >= 4)
  37     {
  38       size_t n4 = n >> 2;
  39
  40       for (;;)
  41         {
  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;
  60         }
  61       n = n - (dest - s) - 1;
  62       if (n == 0)
  63         return dest;
  64       goto zero_fill;
  65     }
  66
  67  last_chars:
  68   n &= 3;
  69   if (n == 0)
  70     return dest;
  71
  72   do
  73     {
  74       c = *src++;
  75       *++dest = c;
  76       if (--n == 0)
  77         return dest;
  78     }
  79   while (c != L'\0');
  80
  81  zero_fill:
  82   do
  83     *++dest = L'\0';
  84   while (--n > 0);
  85
  86   return dest;
  87 }
  88
  89 weak_alias (__wcpncpy, wcpncpy)