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
|
/*-----------------------------------------------------------------------
* ascii.h
*
* Portions Copyright (c) 1999-2023, PostgreSQL Global Development Group
*
* src/include/utils/ascii.h
*
*-----------------------------------------------------------------------
*/
#ifndef _ASCII_H_
#define _ASCII_H_
#include "port/simd.h"
extern void ascii_safe_strlcpy(char *dest, const char *src, size_t destsiz);
/*
* Verify a chunk of bytes for valid ASCII.
*
* Returns false if the input contains any zero bytes or bytes with the
* high-bit set. Input len must be a multiple of the chunk size (8 or 16).
*/
static inline bool
is_valid_ascii(const unsigned char *s, int len)
{
const unsigned char *const s_end = s + len;
Vector8 chunk;
Vector8 highbit_cum = vector8_broadcast(0);
#ifdef USE_NO_SIMD
Vector8 zero_cum = vector8_broadcast(0x80);
#endif
Assert(len % sizeof(chunk) == 0);
while (s < s_end)
{
vector8_load(&chunk, s);
/* Capture any zero bytes in this chunk. */
#ifdef USE_NO_SIMD
/*
* First, add 0x7f to each byte. This sets the high bit in each byte,
* unless it was a zero. If any resulting high bits are zero, the
* corresponding high bits in the zero accumulator will be cleared.
*
* If none of the bytes in the chunk had the high bit set, the max
* value each byte can have after the addition is 0x7f + 0x7f = 0xfe,
* and we don't need to worry about carrying over to the next byte. If
* any input bytes did have the high bit set, it doesn't matter
* because we check for those separately.
*/
zero_cum &= (chunk + vector8_broadcast(0x7F));
#else
/*
* Set all bits in each lane of the highbit accumulator where input
* bytes are zero.
*/
highbit_cum = vector8_or(highbit_cum,
vector8_eq(chunk, vector8_broadcast(0)));
#endif
/* Capture all set bits in this chunk. */
highbit_cum = vector8_or(highbit_cum, chunk);
s += sizeof(chunk);
}
/* Check if any high bits in the high bit accumulator got set. */
if (vector8_is_highbit_set(highbit_cum))
return false;
#ifdef USE_NO_SIMD
/* Check if any high bits in the zero accumulator got cleared. */
if (zero_cum != vector8_broadcast(0x80))
return false;
#endif
return true;
}
#endif /* _ASCII_H_ */
|
