sysdeps/i386/memset.S

   1 /* memset with REP MOVSB/STOSB
   2    Copyright (C) 2015-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <sysdep.h>
  20
  21 #define CFI_PUSH(REG)                                           \
  22   cfi_adjust_cfa_offset (4);                                    \
  23   cfi_rel_offset (REG, 0)
  24
  25 #define CFI_POP(REG)                                            \
  26   cfi_adjust_cfa_offset (-4);                                   \
  27   cfi_restore (REG)
  28
  29 #define PUSH(REG)       pushl REG; CFI_PUSH (REG)
  30 #define POP(REG)        popl REG; CFI_POP (REG)
  31
  32 #define STR1  8
  33 #ifdef USE_AS_BZERO
  34 #define N     STR1+4
  35 #else
  36 #define STR2  STR1+4
  37 #define N     STR2+4
  38 #endif
  39
  40         .text
  41 #if defined SHARED && IS_IN (libc) && !defined USE_AS_BZERO
  42 ENTRY (__memset_chk)
  43         movl    12(%esp), %eax
  44         cmpl    %eax, 16(%esp)
  45         jb      HIDDEN_JUMPTARGET (__chk_fail)
  46 END (__memset_chk)
  47 #endif
  48 ENTRY (memset)
  49         PUSH    (%edi)
  50         movl    N(%esp), %ecx
  51         movl    STR1(%esp), %edi
  52 #ifdef USE_AS_BZERO
  53         xor     %eax, %eax
  54 #else
  55         movzbl  STR2(%esp), %eax
  56         mov     %edi, %edx
  57 #endif
  58         rep     stosb
  59 #ifndef USE_AS_BZERO
  60         mov     %edx, %eax
  61 #endif
  62         POP     (%edi)
  63         ret
  64 END (memset)
  65
  66 #ifndef USE_AS_BZERO
  67 libc_hidden_builtin_def (memset)
  68 #endif