-
Notifications
You must be signed in to change notification settings - Fork 14
/
lemire-neon.c
215 lines (179 loc) · 7.33 KB
/
lemire-neon.c
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
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
// Adapted from https://github.com/lemire/fastvalidate-utf-8
#ifdef __aarch64__
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <inttypes.h>
#include <arm_neon.h>
/*
* legal utf-8 byte sequence
* http://www.unicode.org/versions/Unicode6.0.0/ch03.pdf - page 94
*
* Code Points 1st 2s 3s 4s
* U+0000..U+007F 00..7F
* U+0080..U+07FF C2..DF 80..BF
* U+0800..U+0FFF E0 A0..BF 80..BF
* U+1000..U+CFFF E1..EC 80..BF 80..BF
* U+D000..U+D7FF ED 80..9F 80..BF
* U+E000..U+FFFF EE..EF 80..BF 80..BF
* U+10000..U+3FFFF F0 90..BF 80..BF 80..BF
* U+40000..U+FFFFF F1..F3 80..BF 80..BF 80..BF
* U+100000..U+10FFFF F4 80..8F 80..BF 80..BF
*
*/
#if 0
static void print128(const char *s, const int8x16_t *v128)
{
int8_t v8[16];
vst1q_s8(v8, *v128);
if (s)
printf("%s:\t", s);
for (int i = 0; i < 16; ++i)
printf("%02x ", (unsigned char)v8[i]);
printf("\n");
}
#endif
// all byte values must be no larger than 0xF4
static inline void checkSmallerThan0xF4(int8x16_t current_bytes,
int8x16_t *has_error) {
// unsigned, saturates to 0 below max
*has_error = vorrq_s8(*has_error,
vreinterpretq_s8_u8(vqsubq_u8(vreinterpretq_u8_s8(current_bytes), vdupq_n_u8(0xF4))));
}
static const int8_t _nibbles[] = {
1, 1, 1, 1, 1, 1, 1, 1, // 0xxx (ASCII)
0, 0, 0, 0, // 10xx (continuation)
2, 2, // 110x
3, // 1110
4, // 1111, next should be 0 (not checked here)
};
static inline int8x16_t continuationLengths(int8x16_t high_nibbles) {
return vqtbl1q_s8(vld1q_s8(_nibbles), vreinterpretq_u8_s8(high_nibbles));
}
static inline int8x16_t carryContinuations(int8x16_t initial_lengths,
int8x16_t previous_carries) {
int8x16_t right1 =
vreinterpretq_s8_u8(vqsubq_u8(vreinterpretq_u8_s8(vextq_s8(previous_carries, initial_lengths, 16 - 1)),
vdupq_n_u8(1)));
int8x16_t sum = vaddq_s8(initial_lengths, right1);
int8x16_t right2 = vreinterpretq_s8_u8(vqsubq_u8(vreinterpretq_u8_s8(vextq_s8(previous_carries, sum, 16 - 2)),
vdupq_n_u8(2)));
return vaddq_s8(sum, right2);
}
static inline void checkContinuations(int8x16_t initial_lengths, int8x16_t carries,
int8x16_t *has_error) {
// overlap || underlap
// carry > length && length > 0 || !(carry > length) && !(length > 0)
// (carries > length) == (lengths > 0)
uint8x16_t overunder =
vceqq_u8(vcgtq_s8(carries, initial_lengths),
vcgtq_s8(initial_lengths, vdupq_n_s8(0)));
*has_error = vorrq_s8(*has_error, vreinterpretq_s8_u8(overunder));
}
// when 0xED is found, next byte must be no larger than 0x9F
// when 0xF4 is found, next byte must be no larger than 0x8F
// next byte must be continuation, ie sign bit is set, so signed < is ok
static inline void checkFirstContinuationMax(int8x16_t current_bytes,
int8x16_t off1_current_bytes,
int8x16_t *has_error) {
uint8x16_t maskED = vceqq_s8(off1_current_bytes, vdupq_n_s8(0xED));
uint8x16_t maskF4 = vceqq_s8(off1_current_bytes, vdupq_n_s8(0xF4));
uint8x16_t badfollowED =
vandq_u8(vcgtq_s8(current_bytes, vdupq_n_s8(0x9F)), maskED);
uint8x16_t badfollowF4 =
vandq_u8(vcgtq_s8(current_bytes, vdupq_n_s8(0x8F)), maskF4);
*has_error = vorrq_s8(*has_error, vreinterpretq_s8_u8(vorrq_u8(badfollowED, badfollowF4)));
}
static const int8_t _initial_mins[] = {
-128, -128, -128, -128, -128, -128, -128, -128, -128, -128,
-128, -128, // 10xx => false
0xC2, -128, // 110x
0xE1, // 1110
0xF1,
};
static const int8_t _second_mins[] = {
-128, -128, -128, -128, -128, -128, -128, -128, -128, -128,
-128, -128, // 10xx => false
127, 127, // 110x => true
0xA0, // 1110
0x90,
};
// map off1_hibits => error condition
// hibits off1 cur
// C => < C2 && true
// E => < E1 && < A0
// F => < F1 && < 90
// else false && false
static inline void checkOverlong(int8x16_t current_bytes,
int8x16_t off1_current_bytes, int8x16_t hibits,
int8x16_t previous_hibits, int8x16_t *has_error) {
int8x16_t off1_hibits = vextq_s8(previous_hibits, hibits, 16 - 1);
int8x16_t initial_mins = vqtbl1q_s8(vld1q_s8(_initial_mins), vreinterpretq_u8_s8(off1_hibits));
uint8x16_t initial_under = vcgtq_s8(initial_mins, off1_current_bytes);
int8x16_t second_mins = vqtbl1q_s8(vld1q_s8(_second_mins), vreinterpretq_u8_s8(off1_hibits));
uint8x16_t second_under = vcgtq_s8(second_mins, current_bytes);
*has_error =
vorrq_s8(*has_error, vreinterpretq_s8_u8(vandq_u8(initial_under, second_under)));
}
struct processed_utf_bytes {
int8x16_t rawbytes;
int8x16_t high_nibbles;
int8x16_t carried_continuations;
};
static inline void count_nibbles(int8x16_t bytes,
struct processed_utf_bytes *answer) {
answer->rawbytes = bytes;
answer->high_nibbles =
vreinterpretq_s8_u8(vshrq_n_u8(vreinterpretq_u8_s8(bytes), 4));
}
// check whether the current bytes are valid UTF-8
// at the end of the function, previous gets updated
static inline struct processed_utf_bytes
checkUTF8Bytes(int8x16_t current_bytes, struct processed_utf_bytes *previous,
int8x16_t *has_error) {
struct processed_utf_bytes pb;
count_nibbles(current_bytes, &pb);
checkSmallerThan0xF4(current_bytes, has_error);
int8x16_t initial_lengths = continuationLengths(pb.high_nibbles);
pb.carried_continuations =
carryContinuations(initial_lengths, previous->carried_continuations);
checkContinuations(initial_lengths, pb.carried_continuations, has_error);
int8x16_t off1_current_bytes =
vextq_s8(previous->rawbytes, pb.rawbytes, 16 - 1);
checkFirstContinuationMax(current_bytes, off1_current_bytes, has_error);
checkOverlong(current_bytes, off1_current_bytes, pb.high_nibbles,
previous->high_nibbles, has_error);
return pb;
}
static const int8_t _verror[] = {9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 1};
/* Return 0 on success, -1 on error */
int utf8_lemire(const unsigned char *src, int len) {
size_t i = 0;
int8x16_t has_error = vdupq_n_s8(0);
struct processed_utf_bytes previous = {.rawbytes = vdupq_n_s8(0),
.high_nibbles = vdupq_n_s8(0),
.carried_continuations =
vdupq_n_s8(0)};
if (len >= 16) {
for (; i <= len - 16; i += 16) {
int8x16_t current_bytes = vld1q_s8((int8_t*)(src + i));
previous = checkUTF8Bytes(current_bytes, &previous, &has_error);
}
}
// last part
if (i < len) {
char buffer[16];
memset(buffer, 0, 16);
memcpy(buffer, src + i, len - i);
int8x16_t current_bytes = vld1q_s8((int8_t *)buffer);
previous = checkUTF8Bytes(current_bytes, &previous, &has_error);
} else {
has_error =
vorrq_s8(vreinterpretq_s8_u8(vcgtq_s8(previous.carried_continuations,
vld1q_s8(_verror))),
has_error);
}
return vmaxvq_u8(vreinterpretq_u8_s8(has_error)) == 0 ? 0 : -1;
}
#endif