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git.ipfire.org Git - thirdparty/glibc.git/blob - sysdeps/x86_64/multiarch/strcspn-c.c
1 /* strcspn with SSE4.2 intrinsics
2 Copyright (C) 2009, 2010 Free Software Foundation, Inc.
3 Contributed by Intel Corporation.
4 This file is part of the GNU C Library.
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.
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.
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 <http://www.gnu.org/licenses/>. */
20 #include <nmmintrin.h>
27 | _SIDD_POSITIVE_POLARITY
28 | _SIDD_LEAST_SIGNIFICANT
29 on pcmpistri to compare xmm/mem128
31 0 1 2 3 4 5 6 7 8 9 A B C D E F
32 X X X X X X X X X X X X X X X X
36 0 1 2 3 4 5 6 7 8 9 A B C D E F
37 A A A A A A A A A A A A A A A A
39 to find out if the first 16byte data element has any byte A and
40 the offset of the first byte. There are 3 cases:
42 1. The first 16byte data element has the byte A at the offset X.
43 2. The first 16byte data element has EOS and doesn't have the byte A.
44 3. The first 16byte data element is valid and doesn't have the byte A.
46 Here is the table of ECX, CFlag, ZFlag and SFlag for 2 cases:
52 We exit from the loop for cases 1 and 2 with jbe which branches
53 when either CFlag or ZFlag is 1. If CFlag == 1, ECX has the offset
57 # define STRCSPN_SSE2 __strcspn_sse2
58 # define STRCSPN_SSE42 __strcspn_sse42
62 # define RETURN(val1, val2) return val1
64 # define RETURN(val1, val2) return val2
73 STRCSPN_SSE2 (const char *, const char *);
81 __attribute__ ((section (".text.sse4.2")))
82 STRCSPN_SSE42 (const char *s
, const char *a
)
85 RETURN (NULL
, strlen (s
));
89 int offset
= (int) ((size_t) a
& 15);
93 aligned
= (const char *) ((size_t) a
& -16L);
94 __m128i mask0
= _mm_load_si128 ((__m128i
*) aligned
);
96 mask
= __m128i_shift_right (mask0
, offset
);
98 /* Find where the NULL terminator is. */
99 int length
= _mm_cmpistri (mask
, mask
, 0x3a);
100 if (length
== 16 - offset
)
102 /* There is no NULL terminator. */
103 __m128i mask1
= _mm_load_si128 ((__m128i
*) (aligned
+ 16));
104 int index
= _mm_cmpistri (mask1
, mask1
, 0x3a);
107 /* Don't use SSE4.2 if the length of A > 16. */
109 return STRCSPN_SSE2 (s
, a
);
113 /* Combine mask0 and mask1. We could play games with
114 palignr, but frankly this data should be in L1 now
115 so do the merge via an unaligned load. */
116 mask
= _mm_loadu_si128 ((__m128i
*) a
);
123 mask
= _mm_load_si128 ((__m128i
*) a
);
125 /* Find where the NULL terminator is. */
126 int length
= _mm_cmpistri (mask
, mask
, 0x3a);
129 /* There is no NULL terminator. Don't use SSE4.2 if the length
132 return STRCSPN_SSE2 (s
, a
);
136 offset
= (int) ((size_t) s
& 15);
139 /* Check partial string. */
140 aligned
= (const char *) ((size_t) s
& -16L);
141 __m128i value
= _mm_load_si128 ((__m128i
*) aligned
);
143 value
= __m128i_shift_right (value
, offset
);
145 int length
= _mm_cmpistri (mask
, value
, 0x2);
146 /* No need to check ZFlag since ZFlag is always 1. */
147 int cflag
= _mm_cmpistrc (mask
, value
, 0x2);
149 RETURN ((char *) (s
+ length
), length
);
150 /* Find where the NULL terminator is. */
151 int index
= _mm_cmpistri (value
, value
, 0x3a);
152 if (index
< 16 - offset
)
153 RETURN (NULL
, index
);
161 __m128i value
= _mm_load_si128 ((__m128i
*) aligned
);
162 int index
= _mm_cmpistri (mask
, value
, 0x2);
163 int cflag
= _mm_cmpistrc (mask
, value
, 0x2);
164 int zflag
= _mm_cmpistrz (mask
, value
, 0x2);
166 RETURN ((char *) (aligned
+ index
), (size_t) (aligned
+ index
- s
));
169 /* Find where the NULL terminator is. */
170 (size_t) (aligned
+ _mm_cmpistri (value
, value
, 0x3a) - s
));