string/memset.c

   1 /* Copyright (C) 1991-2014 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <string.h>
  19 #include <memcopy.h>
  20
  21 #undef memset
  22
  23 void *
  24 inhibit_loop_to_libcall
  25 memset (dstpp, c, len)
  26      void *dstpp;
  27      int c;
  28      size_t len;
  29 {
  30   long int dstp = (long int) dstpp;
  31
  32   if (len >= 8)
  33     {
  34       size_t xlen;
  35       op_t cccc;
  36
  37       cccc = (unsigned char) c;
  38       cccc |= cccc << 8;
  39       cccc |= cccc << 16;
  40       if (OPSIZ > 4)
  41         /* Do the shift in two steps to avoid warning if long has 32 bits.  */
  42         cccc |= (cccc << 16) << 16;
  43
  44       /* There are at least some bytes to set.
  45          No need to test for LEN == 0 in this alignment loop.  */
  46       while (dstp % OPSIZ != 0)
  47         {
  48           ((byte *) dstp)[0] = c;
  49           dstp += 1;
  50           len -= 1;
  51         }
  52
  53       /* Write 8 `op_t' per iteration until less than 8 `op_t' remain.  */
  54       xlen = len / (OPSIZ * 8);
  55       while (xlen > 0)
  56         {
  57           ((op_t *) dstp)[0] = cccc;
  58           ((op_t *) dstp)[1] = cccc;
  59           ((op_t *) dstp)[2] = cccc;
  60           ((op_t *) dstp)[3] = cccc;
  61           ((op_t *) dstp)[4] = cccc;
  62           ((op_t *) dstp)[5] = cccc;
  63           ((op_t *) dstp)[6] = cccc;
  64           ((op_t *) dstp)[7] = cccc;
  65           dstp += 8 * OPSIZ;
  66           xlen -= 1;
  67         }
  68       len %= OPSIZ * 8;
  69
  70       /* Write 1 `op_t' per iteration until less than OPSIZ bytes remain.  */
  71       xlen = len / OPSIZ;
  72       while (xlen > 0)
  73         {
  74           ((op_t *) dstp)[0] = cccc;
  75           dstp += OPSIZ;
  76           xlen -= 1;
  77         }
  78       len %= OPSIZ;
  79     }
  80
  81   /* Write the last few bytes.  */
  82   while (len > 0)
  83     {
  84       ((byte *) dstp)[0] = c;
  85       dstp += 1;
  86       len -= 1;
  87     }
  88
  89   return dstpp;
  90 }
  91 libc_hidden_builtin_def (memset)