sysdeps/generic/bzero.c

   1 /* Copyright (C) 1991 Free Software Foundation, Inc.
   2    Contributed by Torbjorn Granlund (tege@sics.se).
   3
   4 This file is part of the GNU C Library.
   5
   6 The GNU C Library is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU Library General Public License as
   8 published by the Free Software Foundation; either version 2 of the
   9 License, or (at your option) any later version.
  10
  11 The GNU C Library is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Library General Public
  17 License along with the GNU C Library; see the file COPYING.LIB.  If
  18 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  19 Cambridge, MA 02139, USA.  */
  20
  21 #include <ansidecl.h>
  22 #include <string.h>
  23 #include <memcopy.h>
  24
  25 /* Set N bytes of S to 0.  */
  26 void
  27 DEFUN(bzero, (s, n), PTR s AND size_t len)
  28 {
  29   long int dstp = (long int) s;
  30   CONST op_t zero = 0;
  31
  32   if (len >= 8)
  33     {
  34       size_t xlen;
  35
  36       /* There are at least some bytes to zero.  No need to test
  37          for LEN == 0 in this alignment loop.  */
  38       while (dstp % OPSIZ != 0)
  39         {
  40           ((byte *) dstp)[0] = 0;
  41           dstp += 1;
  42           len -= 1;
  43         }
  44
  45       /* Write 8 op_t per iteration until less than 8 op_t remain.  */
  46       xlen = len / (OPSIZ * 8);
  47       while (xlen != 0)
  48         {
  49           ((op_t *) dstp)[0] = zero;
  50           ((op_t *) dstp)[1] = zero;
  51           ((op_t *) dstp)[2] = zero;
  52           ((op_t *) dstp)[3] = zero;
  53           ((op_t *) dstp)[4] = zero;
  54           ((op_t *) dstp)[5] = zero;
  55           ((op_t *) dstp)[6] = zero;
  56           ((op_t *) dstp)[7] = zero;
  57           dstp += 8 * OPSIZ;
  58           xlen -= 1;
  59         }
  60       len %= OPSIZ * 8;
  61
  62       /* Write 1 op_t per iteration until less than op_t remain.  */
  63       xlen = len / OPSIZ;
  64       while (xlen != 0)
  65         {
  66           ((op_t *) dstp)[0] = zero;
  67           dstp += OPSIZ;
  68           xlen -= 1;
  69         }
  70       len %= OPSIZ;
  71     }
  72
  73   /* Write the last few bytes.  */
  74   while (len != 0)
  75     {
  76       ((byte *) dstp)[0] = 0;
  77       dstp += 1;
  78       len -= 1;
  79     }
  80 }
  81