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
|
/* strlen(str) -- determine the length of the string STR.
Copyright (C) 2009, 2010 Free Software Foundation, Inc.
Contributed by Ulrich Drepper <drepper@redhat.com>.
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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <sysdep.h>
.text
ENTRY(strlen)
xor %rax, %rax
mov %edi, %ecx
and $0x3f, %ecx
pxor %xmm0, %xmm0
cmp $0x30, %ecx
ja L(next)
movdqu (%rdi), %xmm1
pcmpeqb %xmm1, %xmm0
pmovmskb %xmm0, %edx
test %edx, %edx
jnz L(exit_less16)
mov %rdi, %rax
and $-16, %rax
jmp L(align16_start)
L(next):
mov %rdi, %rax
and $-16, %rax
pcmpeqb (%rax), %xmm0
mov $-1, %esi
sub %rax, %rcx
shl %cl, %esi
pmovmskb %xmm0, %edx
and %esi, %edx
jnz L(exit)
L(align16_start):
pxor %xmm0, %xmm0
pxor %xmm1, %xmm1
pxor %xmm2, %xmm2
pxor %xmm3, %xmm3
.p2align 4
L(align16_loop):
pcmpeqb 16(%rax), %xmm0
pmovmskb %xmm0, %edx
test %edx, %edx
jnz L(exit16)
pcmpeqb 32(%rax), %xmm1
pmovmskb %xmm1, %edx
test %edx, %edx
jnz L(exit32)
pcmpeqb 48(%rax), %xmm2
pmovmskb %xmm2, %edx
test %edx, %edx
jnz L(exit48)
pcmpeqb 64(%rax), %xmm3
pmovmskb %xmm3, %edx
lea 64(%rax), %rax
test %edx, %edx
jz L(align16_loop)
L(exit):
sub %rdi, %rax
L(exit_less16):
bsf %rdx, %rdx
add %rdx, %rax
ret
.p2align 4
L(exit16):
sub %rdi, %rax
bsf %rdx, %rdx
lea 16(%rdx,%rax), %rax
ret
.p2align 4
L(exit32):
sub %rdi, %rax
bsf %rdx, %rdx
lea 32(%rdx,%rax), %rax
ret
.p2align 4
L(exit48):
sub %rdi, %rax
bsf %rdx, %rdx
lea 48(%rdx,%rax), %rax
ret
END(strlen)
libc_hidden_builtin_def (strlen)
|
