string/bzero.c

   1 /* Copyright (C) 1991-2015 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <string.h>
  20 #include <memcopy.h>
  21
  22 #undef __bzero
  23
  24 /* Set N bytes of S to 0.  */
  25 void
  26 __bzero (s, len)
  27      void *s;
  28      size_t len;
  29 {
  30   long int dstp = (long int) s;
  31   const op_t zero = 0;
  32
  33   if (len >= 8)
  34     {
  35       size_t xlen;
  36
  37       /* There are at least some bytes to zero.  No need to test
  38          for LEN == 0 in this alignment loop.  */
  39       while (dstp % OPSIZ != 0)
  40         {
  41           ((byte *) dstp)[0] = 0;
  42           dstp += 1;
  43           len -= 1;
  44         }
  45
  46       /* Write 8 op_t per iteration until less than 8 op_t remain.  */
  47       xlen = len / (OPSIZ * 8);
  48       while (xlen != 0)
  49         {
  50           ((op_t *) dstp)[0] = zero;
  51           ((op_t *) dstp)[1] = zero;
  52           ((op_t *) dstp)[2] = zero;
  53           ((op_t *) dstp)[3] = zero;
  54           ((op_t *) dstp)[4] = zero;
  55           ((op_t *) dstp)[5] = zero;
  56           ((op_t *) dstp)[6] = zero;
  57           ((op_t *) dstp)[7] = zero;
  58           dstp += 8 * OPSIZ;
  59           xlen -= 1;
  60         }
  61       len %= OPSIZ * 8;
  62
  63       /* Write 1 op_t per iteration until less than op_t remain.  */
  64       xlen = len / OPSIZ;
  65       while (xlen != 0)
  66         {
  67           ((op_t *) dstp)[0] = zero;
  68           dstp += OPSIZ;
  69           xlen -= 1;
  70         }
  71       len %= OPSIZ;
  72     }
  73
  74   /* Write the last few bytes.  */
  75   while (len != 0)
  76     {
  77       ((byte *) dstp)[0] = 0;
  78       dstp += 1;
  79       len -= 1;
  80     }
  81 }
  82 weak_alias (__bzero, bzero)