memset.c

   1 /* The standard memset function.
   2
   3    Copyright (C) 2011 Richard Henderson
   4
   5    This file is part of QEMU PALcode.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the text
  15    of the GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; see the file COPYING.  If not see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21
  22 #include <string.h>
  23
  24 void *memset(void *optr, int ival, unsigned long size)
  25 {
  26   unsigned long val = ival;
  27   void *ptr = optr;
  28
  29   if (__builtin_expect (size == 0, 0))
  30     return optr;
  31
  32   if (__builtin_expect (val != 0, 0))
  33     {
  34       val = val & 0xff;
  35       val |= val << 8;
  36       val |= val << 16;
  37       val |= val << 32;
  38     }
  39
  40   if (__builtin_expect ((unsigned long)ptr & 1, 0))
  41     {
  42       *(char *)ptr = val;
  43       ptr += 1;
  44       size -= 1;
  45     }
  46
  47   if (__builtin_expect ((unsigned long)ptr & 2, 0))
  48     {
  49       if (size < 2)
  50         goto tail_1;
  51       *(short *)ptr = val;
  52       ptr += 2;
  53       size -= 2;
  54     }
  55
  56   if (__builtin_expect ((unsigned long)ptr & 4, 0))
  57     {
  58       if (size < 4)
  59         goto tail_3;
  60       *(int *)ptr = val;
  61       ptr += 4;
  62       size -= 4;
  63     }
  64
  65   while (size >= 8)
  66     {
  67       *(long *)ptr = val;
  68       ptr += 8;
  69       size -= 8;
  70     }
  71
  72   if (size >= 4)
  73     {
  74       *(int *)ptr = val;
  75       ptr += 4;
  76       size -= 4;
  77     }
  78
  79  tail_3:
  80   if (size >= 2)
  81     {
  82       *(short *)ptr = val;
  83       ptr += 2;
  84       size -= 2;
  85     }
  86
  87  tail_1:
  88   if (size > 0)
  89     {
  90       *(char *)ptr = val;
  91       ptr += 1;
  92       size -= 1;
  93     }
  94
  95   return optr;
  96 }