1/* memset with REP MOVSB/STOSB
2 Copyright (C) 2015-2024 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#define STR2 STR1+4
34#define N STR2+4
35
36 .text
37#if defined SHARED && IS_IN (libc)
38ENTRY (__memset_chk)
39 movl 12(%esp), %eax
40 cmpl %eax, 16(%esp)
41 jb HIDDEN_JUMPTARGET (__chk_fail)
42END (__memset_chk)
43libc_hidden_builtin_def (__memset_chk)
44#endif
45ENTRY (memset)
46 PUSH (%edi)
47 movl N(%esp), %ecx
48 movl STR1(%esp), %edi
49 movzbl STR2(%esp), %eax
50 mov %edi, %edx
51 rep stosb
52 mov %edx, %eax
53 POP (%edi)
54 ret
55END (memset)
56
57libc_hidden_builtin_def (memset)
58

source code of glibc/sysdeps/i386/memset.S