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
|
/* strspn with SSE4.2 intrinsics
Copyright (C) 2009-2024 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/>. */
#include <nmmintrin.h>
#include <string.h>
#include "varshift.h"
/* We use 0x12:
_SIDD_SBYTE_OPS
| _SIDD_CMP_EQUAL_ANY
| _SIDD_NEGATIVE_POLARITY
| _SIDD_LEAST_SIGNIFICANT
on pcmpistri to compare xmm/mem128
0 1 2 3 4 5 6 7 8 9 A B C D E F
X X X X X X X X X X X X X X X X
against xmm
0 1 2 3 4 5 6 7 8 9 A B C D E F
A A A A A A A A A A A A A A A A
to find out if the first 16byte data element has any non-A byte and
the offset of the first byte. There are 2 cases:
1. The first 16byte data element has the non-A byte, including
EOS, at the offset X.
2. The first 16byte data element is valid and doesn't have the non-A
byte.
Here is the table of ECX, CFlag, ZFlag and SFlag for 2 cases:
case ECX CFlag ZFlag SFlag
1 X 1 0/1 0
2 16 0 0 0
We exit from the loop for case 1. */
extern size_t __strspn_generic (const char *, const char *) attribute_hidden;
#ifndef STRSPN
# define STRSPN __strspn_sse42
#endif
size_t
__attribute__ ((section (".text.sse4.2")))
STRSPN (const char *s, const char *a)
{
if (*a == 0)
return 0;
const char *aligned;
__m128i mask, maskz, zero;
unsigned int maskz_bits;
unsigned int offset = (int) ((size_t) a & 15);
zero = _mm_set1_epi8 (0);
if (offset != 0)
{
/* Load masks. */
aligned = (const char *) ((size_t) a & -16L);
__m128i mask0 = _mm_load_si128 ((__m128i *) aligned);
maskz = _mm_cmpeq_epi8 (mask0, zero);
/* Find where the NULL terminator is. */
maskz_bits = _mm_movemask_epi8 (maskz) >> offset;
if (maskz_bits != 0)
{
mask = __m128i_shift_right (mask0, offset);
offset = (unsigned int) ((size_t) s & 15);
if (offset)
goto start_unaligned;
aligned = s;
goto start_loop;
}
}
/* A is aligned. */
mask = _mm_loadu_si128 ((__m128i *) a);
/* Find where the NULL terminator is. */
maskz = _mm_cmpeq_epi8 (mask, zero);
maskz_bits = _mm_movemask_epi8 (maskz);
if (maskz_bits == 0)
{
/* There is no NULL terminator. Don't use SSE4.2 if the length
of A > 16. */
if (a[16] != 0)
return __strspn_generic (s, a);
}
aligned = s;
offset = (unsigned int) ((size_t) s & 15);
if (offset != 0)
{
start_unaligned:
/* Check partial string. */
aligned = (const char *) ((size_t) s & -16L);
__m128i value = _mm_load_si128 ((__m128i *) aligned);
__m128i adj_value = __m128i_shift_right (value, offset);
unsigned int length = _mm_cmpistri (mask, adj_value, 0x12);
/* No need to check CFlag since it is always 1. */
if (length < 16 - offset)
return length;
/* Find where the NULL terminator is. */
maskz = _mm_cmpeq_epi8 (value, zero);
maskz_bits = _mm_movemask_epi8 (maskz) >> offset;
if (maskz_bits != 0)
return length;
aligned += 16;
}
start_loop:
while (1)
{
__m128i value = _mm_load_si128 ((__m128i *) aligned);
unsigned int index = _mm_cmpistri (mask, value, 0x12);
unsigned int cflag = _mm_cmpistrc (mask, value, 0x12);
if (cflag)
return (size_t) (aligned + index - s);
aligned += 16;
}
}
|
