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
|
/* Copyright (C) 2010-2024 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/>. */
/*
Assumes:
ARMv6T2, AArch32
*/
#include <arm-features.h>
#include <sysdep.h>
#ifdef __ARMEB__
#define S2LO lsl
#define S2HI lsr
#else
#define S2LO lsr
#define S2HI lsl
#endif
/* This code is best on Thumb. */
.thumb
/* Parameters and result. */
#define srcin r0
#define result r0
/* Internal variables. */
#define src r1
#define data1a r2
#define data1b r3
#define const_m1 r12
#define const_0 r4
#define tmp1 r4 /* Overlaps const_0 */
#define tmp2 r5
.text
.p2align 6
ENTRY(strlen)
pld [srcin, #0]
strd r4, r5, [sp, #-8]!
cfi_adjust_cfa_offset (8)
cfi_rel_offset (r4, 0)
cfi_rel_offset (r5, 4)
cfi_remember_state
bic src, srcin, #7
mvn const_m1, #0
ands tmp1, srcin, #7 /* (8 - bytes) to alignment. */
pld [src, #32]
bne.w .Lmisaligned8
mov const_0, #0
mov result, #-8
.Lloop_aligned:
/* Bytes 0-7. */
ldrd data1a, data1b, [src]
pld [src, #64]
add result, result, #8
.Lstart_realigned:
uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
uadd8 data1b, data1b, const_m1
sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
cbnz data1b, .Lnull_found
/* Bytes 8-15. */
ldrd data1a, data1b, [src, #8]
uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
add result, result, #8
sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
uadd8 data1b, data1b, const_m1
sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
cbnz data1b, .Lnull_found
/* Bytes 16-23. */
ldrd data1a, data1b, [src, #16]
uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
add result, result, #8
sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
uadd8 data1b, data1b, const_m1
sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
cbnz data1b, .Lnull_found
/* Bytes 24-31. */
ldrd data1a, data1b, [src, #24]
add src, src, #32
uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
add result, result, #8
sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
uadd8 data1b, data1b, const_m1
sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
cmp data1b, #0
beq .Lloop_aligned
.Lnull_found:
cmp data1a, #0
itt eq
addeq result, result, #4
moveq data1a, data1b
#ifndef __ARMEB__
rev data1a, data1a
#endif
clz data1a, data1a
ldrd r4, r5, [sp], #8
cfi_adjust_cfa_offset (-8)
cfi_restore (r4)
cfi_restore (r5)
add result, result, data1a, lsr #3 /* Bits -> Bytes. */
DO_RET(lr)
.Lmisaligned8:
cfi_restore_state
ldrd data1a, data1b, [src]
and tmp2, tmp1, #3
rsb result, tmp1, #0
lsl tmp2, tmp2, #3 /* Bytes -> bits. */
tst tmp1, #4
pld [src, #64]
S2HI tmp2, const_m1, tmp2
orn data1a, data1a, tmp2
itt ne
ornne data1b, data1b, tmp2
movne data1a, const_m1
mov const_0, #0
b .Lstart_realigned
END(strlen)
libc_hidden_builtin_def (strlen)
|
