blob: 46a49d8a40548add009de8ab403f9f9bffab3013 (
plain) (
blame)
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
|
/* Zero byte detection; basics. ARM version.
Copyright (C) 2023 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
<http://www.gnu.org/licenses/>. */
#ifndef _STRING_FZA_H
#define _STRING_FZA_H 1
#include <limits.h>
#include <endian.h>
#include <string-optype.h>
#include <string-maskoff.h>
/* The functions return a byte mask. */
typedef op_t find_t;
/* Return the mask WORD shifted based on S_INT address value, to ignore
values not presented in the aligned word read. */
static __always_inline find_t
shift_find (find_t word, uintptr_t s)
{
if (__BYTE_ORDER == __LITTLE_ENDIAN)
return word >> (CHAR_BIT * (s % sizeof (op_t)));
else
return word << (CHAR_BIT * (s % sizeof (op_t)));
}
/* Mask off the bits defined the the S alignment value. */
static __always_inline find_t
shift_find_last (find_t word, uintptr_t s)
{
return word & create_mask (s);
}
/* This function returns at least one bit set within every byte
of X that is zero. */
static __always_inline find_t
find_zero_all (op_t x)
{
/* Use unsigned saturated subtraction from 1 in each byte.
That leaves 1 for every byte that was zero. */
op_t ones = repeat_bytes (0x01);
return __builtin_arm_uqsub8 (ones, x);
}
/* Identify bytes that are equal between X1 and X2. */
static __always_inline find_t
find_eq_all (op_t x1, op_t x2)
{
return find_zero_all (x1 ^ x2);
}
/* Identify zero bytes in X1 or equality between X1 and X2. */
static __always_inline find_t
find_zero_eq_all (op_t x1, op_t x2)
{
return find_zero_all (x1) | find_zero_all (x1 ^ x2);
}
/* Identify zero bytes in X1 or inequality between X1 and X2. */
static __always_inline find_t
find_zero_ne_all (op_t x1, op_t x2)
{
/* Make use of the fact that we'll already have ONES in a register. */
op_t ones = repeat_bytes (0x01);
return find_zero_all (x1) | (find_zero_all (x1 ^ x2) ^ ones);
}
/* Define the "inexact" versions in terms of the exact versions. */
#define find_zero_low find_zero_all
#define find_eq_low find_eq_all
#define find_zero_eq_low find_zero_eq_all
#define find_zero_ne_low find_zero_ne_all
#endif /* _STRING_FZA_H */
|
