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/* strspn with SSE4.2 intrinsics
Copyright (C) 2009-2022 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_sse2 (const char *, const char *) attribute_hidden;
size_t
__attribute__ ((section (".text.sse4.2")))
__strspn_sse42 (const char *s, const char *a)
{
if (*a == 0)
return 0;
const char *aligned;
__m128i mask;
int offset = (int) ((size_t) a & 15);
if (offset != 0)
{
/* Load masks. */
aligned = (const char *) ((size_t) a & -16L);
__m128i mask0 = _mm_load_si128 ((__m128i *) aligned);
mask = __m128i_shift_right (mask0, offset);
/* Find where the NULL terminator is. */
int length = _mm_cmpistri (mask, mask, 0x3a);
if (length == 16 - offset)
{
/* There is no NULL terminator. */
__m128i mask1 = _mm_load_si128 ((__m128i *) (aligned + 16));
int index = _mm_cmpistri (mask1, mask1, 0x3a);
length += index;
/* Don't use SSE4.2 if the length of A > 16. */
if (length > 16)
return __strspn_sse2 (s, a);
if (index != 0)
{
/* Combine mask0 and mask1. We could play games with
palignr, but frankly this data should be in L1 now
so do the merge via an unaligned load. */
mask = _mm_loadu_si128 ((__m128i *) a);
}
}
}
else
{
/* A is aligned. */
mask = _mm_load_si128 ((__m128i *) a);
/* Find where the NULL terminator is. */
int length = _mm_cmpistri (mask, mask, 0x3a);
if (length == 16)
{
/* There is no NULL terminator. Don't use SSE4.2 if the length
of A > 16. */
if (a[16] != 0)
return __strspn_sse2 (s, a);
}
}
offset = (int) ((size_t) s & 15);
if (offset != 0)
{
/* Check partial string. */
aligned = (const char *) ((size_t) s & -16L);
__m128i value = _mm_load_si128 ((__m128i *) aligned);
value = __m128i_shift_right (value, offset);
int length = _mm_cmpistri (mask, value, 0x12);
/* No need to check CFlag since it is always 1. */
if (length < 16 - offset)
return length;
/* Find where the NULL terminator is. */
int index = _mm_cmpistri (value, value, 0x3a);
if (index < 16 - offset)
return length;
aligned += 16;
}
else
aligned = s;
while (1)
{
__m128i value = _mm_load_si128 ((__m128i *) aligned);
int index = _mm_cmpistri (mask, value, 0x12);
int cflag = _mm_cmpistrc (mask, value, 0x12);
if (cflag)
return (size_t) (aligned + index - s);
aligned += 16;
}
}
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