string/bzero.c

   1 /* Copyright (C) 1991, 1997, 1999 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Torbjorn Granlund (tege@sics.se).
   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 <string.h>
  21 #include <memcopy.h>
  22
  23 #undef __bzero
  24
  25 /* Set N bytes of S to 0.  */
  26 void
  27 __bzero (s, len)
  28      void *s;
  29      size_t len;
  30 {
  31   long int dstp = (long int) s;
  32   const op_t zero = 0;
  33
  34   if (len >= 8)
  35     {
  36       size_t xlen;
  37
  38       /* There are at least some bytes to zero.  No need to test
  39          for LEN == 0 in this alignment loop.  */
  40       while (dstp % OPSIZ != 0)
  41         {
  42           ((byte *) dstp)[0] = 0;
  43           dstp += 1;
  44           len -= 1;
  45         }
  46
  47       /* Write 8 op_t per iteration until less than 8 op_t remain.  */
  48       xlen = len / (OPSIZ * 8);
  49       while (xlen != 0)
  50         {
  51           ((op_t *) dstp)[0] = zero;
  52           ((op_t *) dstp)[1] = zero;
  53           ((op_t *) dstp)[2] = zero;
  54           ((op_t *) dstp)[3] = zero;
  55           ((op_t *) dstp)[4] = zero;
  56           ((op_t *) dstp)[5] = zero;
  57           ((op_t *) dstp)[6] = zero;
  58           ((op_t *) dstp)[7] = zero;
  59           dstp += 8 * OPSIZ;
  60           xlen -= 1;
  61         }
  62       len %= OPSIZ * 8;
  63
  64       /* Write 1 op_t per iteration until less than op_t remain.  */
  65       xlen = len / OPSIZ;
  66       while (xlen != 0)
  67         {
  68           ((op_t *) dstp)[0] = zero;
  69           dstp += OPSIZ;
  70           xlen -= 1;
  71         }
  72       len %= OPSIZ;
  73     }
  74
  75   /* Write the last few bytes.  */
  76   while (len != 0)
  77     {
  78       ((byte *) dstp)[0] = 0;
  79       dstp += 1;
  80       len -= 1;
  81     }
  82 }
  83 weak_alias (__bzero, bzero)