about summary refs log tree commit diff
path: root/sysdeps/i386/i686/multiarch/strchr-sse2-bsf.S
blob: 2d63876538a388261706cf267735ae0b4d4e3214 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
/* strchr with SSE2 with bsf
   Copyright (C) 2011-2021 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#if IS_IN (libc)

# include <sysdep.h>

# define CFI_PUSH(REG)	\
	cfi_adjust_cfa_offset (4);	\
	cfi_rel_offset (REG, 0)

# define CFI_POP(REG)	\
	cfi_adjust_cfa_offset (-4);	\
	cfi_restore (REG)

# define PUSH(REG) pushl REG; CFI_PUSH (REG)
# define POP(REG) popl REG; CFI_POP (REG)

# define PARMS  8
# define ENTRANCE PUSH(%edi)
# define RETURN  POP(%edi); ret; CFI_PUSH(%edi);

# define STR1  PARMS
# define STR2  STR1+4

	.text
ENTRY (__strchr_sse2_bsf)

	ENTRANCE
	mov	STR1(%esp), %ecx
	movd	STR2(%esp), %xmm1

	pxor	%xmm2, %xmm2
	mov	%ecx, %edi
	punpcklbw %xmm1, %xmm1
	punpcklbw %xmm1, %xmm1
	/* ECX has OFFSET. */
	and	$15, %ecx
	pshufd	$0, %xmm1, %xmm1
	je	L(loop)

/* Handle unaligned string.  */
	and	$-16, %edi
	movdqa	(%edi), %xmm0
	pcmpeqb	%xmm0, %xmm2
	pcmpeqb	%xmm1, %xmm0
	/* Find where NULL is.  */
	pmovmskb %xmm2, %edx
	/* Check if there is a match.  */
	pmovmskb %xmm0, %eax
	/* Remove the leading bytes.  */
	sarl	%cl, %edx
	sarl	%cl, %eax
	test	%eax, %eax
	je	L(unaligned_no_match)
	/* Check which byte is a match.  */
	bsf	%eax, %eax
	/* Is there a NULL? */
	test	%edx, %edx
	je	L(unaligned_match)
	bsf	%edx, %edx
	cmpl	%edx, %eax
	/* Return NULL if NULL comes first.  */
	ja	L(return_null)
L(unaligned_match):
	add	%edi, %eax
	add	%ecx, %eax
	RETURN

	.p2align 4
L(unaligned_no_match):
	test	%edx, %edx
	jne	L(return_null)
	pxor	%xmm2, %xmm2

	add	$16, %edi

	.p2align 4
/* Loop start on aligned string.  */
L(loop):
	movdqa	(%edi), %xmm0
	pcmpeqb	%xmm0, %xmm2
	add	$16, %edi
	pcmpeqb	%xmm1, %xmm0
	pmovmskb %xmm2, %edx
	pmovmskb %xmm0, %eax
	or	%eax, %edx
	jnz	L(matches)

	movdqa	(%edi), %xmm0
	pcmpeqb	%xmm0, %xmm2
	add	$16, %edi
	pcmpeqb	%xmm1, %xmm0
	pmovmskb %xmm2, %edx
	pmovmskb %xmm0, %eax
	or	%eax, %edx
	jnz	L(matches)

	movdqa	(%edi), %xmm0
	pcmpeqb	%xmm0, %xmm2
	add	$16, %edi
	pcmpeqb	%xmm1, %xmm0
	pmovmskb %xmm2, %edx
	pmovmskb %xmm0, %eax
	or	%eax, %edx
	jnz	L(matches)

	movdqa	(%edi), %xmm0
	pcmpeqb	%xmm0, %xmm2
	add	$16, %edi
	pcmpeqb	%xmm1, %xmm0
	pmovmskb %xmm2, %edx
	pmovmskb %xmm0, %eax
	or	%eax, %edx
	jnz	L(matches)
	jmp	L(loop)

L(matches):
	pmovmskb %xmm2, %edx
	test	%eax, %eax
	jz	L(return_null)
	bsf	%eax, %eax
	/* There is a match.  First find where NULL is.  */
	test	%edx, %edx
	je	L(match)
	bsf	%edx, %ecx
	/* Check if NULL comes first.  */
	cmpl	%ecx, %eax
	ja	L(return_null)
L(match):
	sub	$16, %edi
	add	%edi, %eax
	RETURN

/* Return NULL.  */
	.p2align 4
L(return_null):
	xor	%eax, %eax
	RETURN

END (__strchr_sse2_bsf)
#endif