wcsmbs/wcsncpy.c

   1 /* Copyright (C) 1995 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   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 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <wcstr.h>
  20
  21
  22 /* Copy no more than N wide-characters of SRC to DEST.  */
  23 wchar_t *
  24 wcsncpy (dest, src, n)
  25       wchar_t *dest;
  26       const wchar_t *src;
  27       size_t n;
  28 {
  29   wchar_t c;
  30   wchar_t * const s = dest;
  31
  32   --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 = n - (dest - s) - 1;
  60       if (n == 0)
  61         return s;
  62       goto zero_fill;
  63     }
  64
  65  last_chars:
  66   n &= 3;
  67   if (n == 0)
  68     return s;
  69
  70   do
  71     {
  72       c = *src++;
  73       *++dest = c;
  74       if (--n == 0)
  75         return s;
  76     }
  77   while (c != L'\0');
  78
  79  zero_fill:
  80   do
  81     *++dest = L'\0';
  82   while (--n > 0);
  83
  84   return s;
  85 }