1/* memset/bzero -- set memory area to CH/0
2   Highly optimized version for ix86, x>=6.
3   Copyright (C) 1999-2021 Free Software Foundation, Inc.
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 Lesser General Public
8   License as published by the Free Software Foundation; either
9   version 2.1 of the 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   Lesser General Public License for more details.
15
16   You should have received a copy of the GNU Lesser General Public
17   License along with the GNU C Library; if not, see
18   <https://www.gnu.org/licenses/>.  */
19
20#include <sysdep.h>
21#include "asm-syntax.h"
22
23#define PARMS	4+4	/* space for 1 saved reg */
24#ifdef USE_AS_BZERO
25# define DEST	PARMS
26# define LEN	DEST+4
27#else
28# define RTN	PARMS
29# define DEST	RTN
30# define CHR	DEST+4
31# define LEN	CHR+4
32#endif
33
34        .text
35#if defined SHARED && IS_IN (libc) && !defined USE_AS_BZERO
36ENTRY_CHK (__memset_chk)
37	movl	12(%esp), %eax
38	cmpl	%eax, 16(%esp)
39	jb	HIDDEN_JUMPTARGET (__chk_fail)
40END_CHK (__memset_chk)
41#endif
42ENTRY (memset)
43
44	cld
45	pushl	%edi
46	cfi_adjust_cfa_offset (4)
47	movl	DEST(%esp), %edx
48	movl	LEN(%esp), %ecx
49#ifdef USE_AS_BZERO
50	xorl	%eax, %eax	/* fill with 0 */
51#else
52	movzbl	CHR(%esp), %eax
53#endif
54	jecxz	1f
55	movl	%edx, %edi
56	cfi_rel_offset (edi, 0)
57	andl	$3, %edx
58	jz	2f	/* aligned */
59	jp	3f	/* misaligned at 3, store just one byte below */
60	stosb		/* misaligned at 1 or 2, store two bytes */
61	decl	%ecx
62	jz	1f
633:	stosb
64	decl	%ecx
65	jz	1f
66	xorl	$1, %edx
67	jnz	2f	/* was misaligned at 2 or 3, now aligned */
68	stosb		/* was misaligned at 1, store third byte */
69	decl	%ecx
702:	movl	%ecx, %edx
71	shrl	$2, %ecx
72	andl	$3, %edx
73#ifndef USE_AS_BZERO
74	imul	$0x01010101, %eax
75#endif
76	rep
77	stosl
78	movl	%edx, %ecx
79	rep
80	stosb
81
821:
83#ifndef USE_AS_BZERO
84	movl DEST(%esp), %eax	/* start address of destination is result */
85#endif
86	popl	%edi
87	cfi_adjust_cfa_offset (-4)
88	cfi_restore (edi)
89
90	ret
91END (memset)
92libc_hidden_builtin_def (memset)
93