/root/doris/be/src/util/simdutf8check.h

Source
// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#pragma once

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <x86intrin.h>

/*
 * These functions are used for validating utf8 string.
 * Details can be seen here: https://github.com/lemire/fastvalidate-utf-8
 */

/*
 * 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
 *
 */

// all byte values must be no larger than 0xF4
static inline void checkSmallerThan0xF4(__m128i current_bytes, __m128i* has_error) {
    // unsigned, saturates to 0 below max
    *has_error = _mm_or_si128(*has_error, _mm_subs_epu8(current_bytes, _mm_set1_epi8(0xF4)));
}

static inline __m128i continuationLengths(__m128i high_nibbles) {
    return _mm_shuffle_epi8(_mm_setr_epi8(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)
                            high_nibbles);
}

static inline __m128i carryContinuations(__m128i initial_lengths, __m128i previous_carries) {
    __m128i right1 = _mm_subs_epu8(_mm_alignr_epi8(initial_lengths, previous_carries, 16 - 1),
                                   _mm_set1_epi8(1));
    __m128i sum = _mm_add_epi8(initial_lengths, right1);

    __m128i right2 =
            _mm_subs_epu8(_mm_alignr_epi8(sum, previous_carries, 16 - 2), _mm_set1_epi8(2));
    return _mm_add_epi8(sum, right2);
}

static inline void checkContinuations(__m128i initial_lengths, __m128i carries,
                                      __m128i* has_error) {
    // overlap || underlap
    // carry > length && length > 0 || !(carry > length) && !(length > 0)
    // (carries > length) == (lengths > 0)
    __m128i overunder = _mm_cmpeq_epi8(_mm_cmpgt_epi8(carries, initial_lengths),
                                       _mm_cmpgt_epi8(initial_lengths, _mm_setzero_si128()));

    *has_error = _mm_or_si128(*has_error, 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(__m128i current_bytes, __m128i off1_current_bytes,
                                             __m128i* has_error) {
    __m128i maskED = _mm_cmpeq_epi8(off1_current_bytes, _mm_set1_epi8(0xED));
    __m128i maskF4 = _mm_cmpeq_epi8(off1_current_bytes, _mm_set1_epi8(0xF4));

    __m128i badfollowED = _mm_and_si128(_mm_cmpgt_epi8(current_bytes, _mm_set1_epi8(0x9F)), maskED);
    __m128i badfollowF4 = _mm_and_si128(_mm_cmpgt_epi8(current_bytes, _mm_set1_epi8(0x8F)), maskF4);

    *has_error = _mm_or_si128(*has_error, _mm_or_si128(badfollowED, badfollowF4));
}

// map off1_hibits => error condition
// hibits     off1    cur
// C       => < C2 && true
// E       => < E1 && < A0
// F       => < F1 && < 90
// else      false && false
static inline void checkOverlong(__m128i current_bytes, __m128i off1_current_bytes, __m128i hibits,
                                 __m128i previous_hibits, __m128i* has_error) {
    __m128i off1_hibits = _mm_alignr_epi8(hibits, previous_hibits, 16 - 1);
    __m128i initial_mins =
            _mm_shuffle_epi8(_mm_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128, -128,
                                           -128, -128, -128, // 10xx => false
                                           0xC2, -128,       // 110x
                                           0xE1,             // 1110
                                           0xF1),
                             off1_hibits);

    __m128i initial_under = _mm_cmpgt_epi8(initial_mins, off1_current_bytes);

    __m128i second_mins =
            _mm_shuffle_epi8(_mm_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128, -128,
                                           -128, -128, -128, // 10xx => false
                                           127, 127,         // 110x => true
                                           0xA0,             // 1110
                                           0x90),
                             off1_hibits);
    __m128i second_under = _mm_cmpgt_epi8(second_mins, current_bytes);
    *has_error = _mm_or_si128(*has_error, _mm_and_si128(initial_under, second_under));
}

struct processed_utf_bytes {
    __m128i rawbytes;
    __m128i high_nibbles;
    __m128i carried_continuations;
};

static inline void count_nibbles(__m128i bytes, struct processed_utf_bytes* answer) {
    answer->rawbytes = bytes;
    answer->high_nibbles = _mm_and_si128(_mm_srli_epi16(bytes, 4), _mm_set1_epi8(0x0F));
}

// check whether the current bytes are valid UTF-8
// at the end of the function, previous gets updated
static struct processed_utf_bytes checkUTF8Bytes(__m128i current_bytes,
                                                 struct processed_utf_bytes* previous,
                                                 __m128i* has_error) {
    struct processed_utf_bytes pb;
    count_nibbles(current_bytes, &pb);

    checkSmallerThan0xF4(current_bytes, has_error);

    __m128i initial_lengths = continuationLengths(pb.high_nibbles);

    pb.carried_continuations = carryContinuations(initial_lengths, previous->carried_continuations);

    checkContinuations(initial_lengths, pb.carried_continuations, has_error);

    __m128i off1_current_bytes = _mm_alignr_epi8(pb.rawbytes, previous->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 bool validate_utf8_fast(const char* src, size_t len) {
    size_t i = 0;
    __m128i has_error = _mm_setzero_si128();
    struct processed_utf_bytes previous = {.rawbytes = _mm_setzero_si128(),
                                           .high_nibbles = _mm_setzero_si128(),
                                           .carried_continuations = _mm_setzero_si128()};
    if (len >= 16) {
        for (; i <= len - 16; i += 16) {
            __m128i current_bytes = _mm_loadu_si128((const __m128i*)(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);
        __m128i current_bytes = _mm_loadu_si128((const __m128i*)(buffer));
        previous = checkUTF8Bytes(current_bytes, &previous, &has_error);
    } else {
        has_error = _mm_or_si128(
                _mm_cmpgt_epi8(previous.carried_continuations,
                               _mm_setr_epi8(9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 1)),
                has_error);
    }

    return _mm_testz_si128(has_error, has_error);
}

#ifdef __AVX2__

/*****************************/
static inline __m256i push_last_byte_of_a_to_b(__m256i a, __m256i b) {
    return _mm256_alignr_epi8(b, _mm256_permute2x128_si256(a, b, 0x21), 15);
}

static inline __m256i push_last_2bytes_of_a_to_b(__m256i a, __m256i b) {
    return _mm256_alignr_epi8(b, _mm256_permute2x128_si256(a, b, 0x21), 14);
}

// all byte values must be no larger than 0xF4
static inline void avxcheckSmallerThan0xF4(__m256i current_bytes, __m256i* has_error) {
    // unsigned, saturates to 0 below max
    *has_error =
            _mm256_or_si256(*has_error, _mm256_subs_epu8(current_bytes, _mm256_set1_epi8(0xF4)));
}

static inline __m256i avxcontinuationLengths(__m256i high_nibbles) {
    return _mm256_shuffle_epi8(_mm256_setr_epi8(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)
                                                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)
                                                ),
                               high_nibbles);
}

static inline __m256i avxcarryContinuations(__m256i initial_lengths, __m256i previous_carries) {
    __m256i right1 = _mm256_subs_epu8(push_last_byte_of_a_to_b(previous_carries, initial_lengths),
                                      _mm256_set1_epi8(1));
    __m256i sum = _mm256_add_epi8(initial_lengths, right1);

    __m256i right2 = _mm256_subs_epu8(push_last_2bytes_of_a_to_b(previous_carries, sum),
                                      _mm256_set1_epi8(2));
    return _mm256_add_epi8(sum, right2);
}

static inline void avxcheckContinuations(__m256i initial_lengths, __m256i carries,
                                         __m256i* has_error) {
    // overlap || underlap
    // carry > length && length > 0 || !(carry > length) && !(length > 0)
    // (carries > length) == (lengths > 0)
    __m256i overunder =
            _mm256_cmpeq_epi8(_mm256_cmpgt_epi8(carries, initial_lengths),
                              _mm256_cmpgt_epi8(initial_lengths, _mm256_setzero_si256()));

    *has_error = _mm256_or_si256(*has_error, 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 avxcheckFirstContinuationMax(__m256i current_bytes, __m256i off1_current_bytes,
                                                __m256i* has_error) {
    __m256i maskED = _mm256_cmpeq_epi8(off1_current_bytes, _mm256_set1_epi8(0xED));
    __m256i maskF4 = _mm256_cmpeq_epi8(off1_current_bytes, _mm256_set1_epi8(0xF4));

    __m256i badfollowED =
            _mm256_and_si256(_mm256_cmpgt_epi8(current_bytes, _mm256_set1_epi8(0x9F)), maskED);
    __m256i badfollowF4 =
            _mm256_and_si256(_mm256_cmpgt_epi8(current_bytes, _mm256_set1_epi8(0x8F)), maskF4);

    *has_error = _mm256_or_si256(*has_error, _mm256_or_si256(badfollowED, badfollowF4));
}

// map off1_hibits => error condition
// hibits     off1    cur
// C       => < C2 && true
// E       => < E1 && < A0
// F       => < F1 && < 90
// else      false && false
static inline void avxcheckOverlong(__m256i current_bytes, __m256i off1_current_bytes,
                                    __m256i hibits, __m256i previous_hibits, __m256i* has_error) {
    __m256i off1_hibits = push_last_byte_of_a_to_b(previous_hibits, hibits);
    __m256i initial_mins =
            _mm256_shuffle_epi8(_mm256_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128,
                                                 -128, -128, -128, -128, // 10xx => false
                                                 0xC2, -128,             // 110x
                                                 0xE1,                   // 1110
                                                 0xF1, -128, -128, -128, -128, -128, -128, -128,
                                                 -128, -128, -128, -128, -128, // 10xx => false
                                                 0xC2, -128,                   // 110x
                                                 0xE1,                         // 1110
                                                 0xF1),
                                off1_hibits);

    __m256i initial_under = _mm256_cmpgt_epi8(initial_mins, off1_current_bytes);

    __m256i second_mins =
            _mm256_shuffle_epi8(_mm256_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128,
                                                 -128, -128, -128, -128, // 10xx => false
                                                 127, 127,               // 110x => true
                                                 0xA0,                   // 1110
                                                 0x90, -128, -128, -128, -128, -128, -128, -128,
                                                 -128, -128, -128, -128, -128, // 10xx => false
                                                 127, 127,                     // 110x => true
                                                 0xA0,                         // 1110
                                                 0x90),
                                off1_hibits);
    __m256i second_under = _mm256_cmpgt_epi8(second_mins, current_bytes);
    *has_error = _mm256_or_si256(*has_error, _mm256_and_si256(initial_under, second_under));
}

struct avx_processed_utf_bytes {
    __m256i rawbytes;
    __m256i high_nibbles;
    __m256i carried_continuations;
};

static inline void avx_count_nibbles(__m256i bytes, struct avx_processed_utf_bytes* answer) {
    answer->rawbytes = bytes;
    answer->high_nibbles = _mm256_and_si256(_mm256_srli_epi16(bytes, 4), _mm256_set1_epi8(0x0F));
}

#endif // __AVX2__

Coverage Report

Created: 2025-10-28 05:36

Line	Count	Source
1		// Licensed to the Apache Software Foundation (ASF) under one
2		// or more contributor license agreements. See the NOTICE file
3		// distributed with this work for additional information
4		// regarding copyright ownership. The ASF licenses this file
5		// to you under the Apache License, Version 2.0 (the
6		// "License"); you may not use this file except in compliance
7		// with the License. You may obtain a copy of the License at
8		//
9		// http://www.apache.org/licenses/LICENSE-2.0
10		//
11		// Unless required by applicable law or agreed to in writing,
12		// software distributed under the License is distributed on an
13		// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14		// KIND, either express or implied. See the License for the
15		// specific language governing permissions and limitations
16		// under the License.
17
18		#pragma once
19
20		#include <stdbool.h>
21		#include <stddef.h>
22		#include <stdint.h>
23		#include <string.h>
24		#include <x86intrin.h>
25
26		/*
27		* These functions are used for validating utf8 string.
28		* Details can be seen here: https://github.com/lemire/fastvalidate-utf-8
29		*/
30
31		/*
32		* legal utf-8 byte sequence
33		* http://www.unicode.org/versions/Unicode6.0.0/ch03.pdf - page 94
34		*
35		* Code Points 1st 2s 3s 4s
36		* U+0000..U+007F 00..7F
37		* U+0080..U+07FF C2..DF 80..BF
38		* U+0800..U+0FFF E0 A0..BF 80..BF
39		* U+1000..U+CFFF E1..EC 80..BF 80..BF
40		* U+D000..U+D7FF ED 80..9F 80..BF
41		* U+E000..U+FFFF EE..EF 80..BF 80..BF
42		* U+10000..U+3FFFF F0 90..BF 80..BF 80..BF
43		* U+40000..U+FFFFF F1..F3 80..BF 80..BF 80..BF
44		* U+100000..U+10FFFF F4 80..8F 80..BF 80..BF
45		*
46		*/
47
48		// all byte values must be no larger than 0xF4
49	168M	static inline void checkSmallerThan0xF4(__m128i current_bytes, __m128i* has_error) {
50		// unsigned, saturates to 0 below max
51	168M	has_error = _mm_or_si128(has_error, _mm_subs_epu8(current_bytes, _mm_set1_epi8(0xF4)));
52	168M	}
53
54	168M	static inline __m128i continuationLengths(__m128i high_nibbles) {
55	168M	return _mm_shuffle_epi8(_mm_setr_epi8(1, 1, 1, 1, 1, 1, 1, 1, // 0xxx (ASCII)
56	168M	0, 0, 0, 0, // 10xx (continuation)
57	168M	2, 2, // 110x
58	168M	3, // 1110
59	168M	4), // 1111, next should be 0 (not checked here)
60	168M	high_nibbles);
61	168M	}
62
63	168M	static inline __m128i carryContinuations(__m128i initial_lengths, __m128i previous_carries) {
64	168M	__m128i right1 = _mm_subs_epu8(_mm_alignr_epi8(initial_lengths, previous_carries, 16 - 1),
65	168M	_mm_set1_epi8(1));
66	168M	__m128i sum = _mm_add_epi8(initial_lengths, right1);
67
68	168M	__m128i right2 =
69	168M	_mm_subs_epu8(_mm_alignr_epi8(sum, previous_carries, 16 - 2), _mm_set1_epi8(2));
70	168M	return _mm_add_epi8(sum, right2);
71	168M	}
72
73		static inline void checkContinuations(__m128i initial_lengths, __m128i carries,
74	168M	__m128i* has_error) {
75		// overlap \|\| underlap
76		// carry > length && length > 0 \|\| !(carry > length) && !(length > 0)
77		// (carries > length) == (lengths > 0)
78	168M	__m128i overunder = _mm_cmpeq_epi8(_mm_cmpgt_epi8(carries, initial_lengths),
79	168M	_mm_cmpgt_epi8(initial_lengths, _mm_setzero_si128()));
80
81	168M	has_error = _mm_or_si128(has_error, overunder);
82	168M	}
83
84		// when 0xED is found, next byte must be no larger than 0x9F
85		// when 0xF4 is found, next byte must be no larger than 0x8F
86		// next byte must be continuation, ie sign bit is set, so signed < is ok
87		static inline void checkFirstContinuationMax(__m128i current_bytes, __m128i off1_current_bytes,
88	168M	__m128i* has_error) {
89	168M	__m128i maskED = _mm_cmpeq_epi8(off1_current_bytes, _mm_set1_epi8(0xED));
90	168M	__m128i maskF4 = _mm_cmpeq_epi8(off1_current_bytes, _mm_set1_epi8(0xF4));
91
92	168M	__m128i badfollowED = _mm_and_si128(_mm_cmpgt_epi8(current_bytes, _mm_set1_epi8(0x9F)), maskED);
93	168M	__m128i badfollowF4 = _mm_and_si128(_mm_cmpgt_epi8(current_bytes, _mm_set1_epi8(0x8F)), maskF4);
94
95	168M	has_error = _mm_or_si128(has_error, _mm_or_si128(badfollowED, badfollowF4));
96	168M	}
97
98		// map off1_hibits => error condition
99		// hibits off1 cur
100		// C => < C2 && true
101		// E => < E1 && < A0
102		// F => < F1 && < 90
103		// else false && false
104		static inline void checkOverlong(__m128i current_bytes, __m128i off1_current_bytes, __m128i hibits,
105	168M	__m128i previous_hibits, __m128i* has_error) {
106	168M	__m128i off1_hibits = _mm_alignr_epi8(hibits, previous_hibits, 16 - 1);
107	168M	__m128i initial_mins =
108	168M	_mm_shuffle_epi8(_mm_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128, -128,
109	168M	-128, -128, -128, // 10xx => false
110	168M	0xC2, -128, // 110x
111	168M	0xE1, // 1110
112	168M	0xF1),
113	168M	off1_hibits);
114
115	168M	__m128i initial_under = _mm_cmpgt_epi8(initial_mins, off1_current_bytes);
116
117	168M	__m128i second_mins =
118	168M	_mm_shuffle_epi8(_mm_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128, -128,
119	168M	-128, -128, -128, // 10xx => false
120	168M	127, 127, // 110x => true
121	168M	0xA0, // 1110
122	168M	0x90),
123	168M	off1_hibits);
124	168M	__m128i second_under = _mm_cmpgt_epi8(second_mins, current_bytes);
125	168M	has_error = _mm_or_si128(has_error, _mm_and_si128(initial_under, second_under));
126	168M	}
127
128		struct processed_utf_bytes {
129		__m128i rawbytes;
130		__m128i high_nibbles;
131		__m128i carried_continuations;
132		};
133
134	168M	static inline void count_nibbles(__m128i bytes, struct processed_utf_bytes* answer) {
135	168M	answer->rawbytes = bytes;
136	168M	answer->high_nibbles = _mm_and_si128(_mm_srli_epi16(bytes, 4), _mm_set1_epi8(0x0F));
137	168M	}
138
139		// check whether the current bytes are valid UTF-8
140		// at the end of the function, previous gets updated
141		static struct processed_utf_bytes checkUTF8Bytes(__m128i current_bytes,
142		struct processed_utf_bytes* previous,
143	168M	__m128i* has_error) {
144	168M	struct processed_utf_bytes pb;
145	168M	count_nibbles(current_bytes, &pb);
146
147	168M	checkSmallerThan0xF4(current_bytes, has_error);
148
149	168M	__m128i initial_lengths = continuationLengths(pb.high_nibbles);
150
151	168M	pb.carried_continuations = carryContinuations(initial_lengths, previous->carried_continuations);
152
153	168M	checkContinuations(initial_lengths, pb.carried_continuations, has_error);
154
155	168M	__m128i off1_current_bytes = _mm_alignr_epi8(pb.rawbytes, previous->rawbytes, 16 - 1);
156	168M	checkFirstContinuationMax(current_bytes, off1_current_bytes, has_error);
157
158	168M	checkOverlong(current_bytes, off1_current_bytes, pb.high_nibbles, previous->high_nibbles,
159	168M	has_error);
160	168M	return pb;
161	168M	}
162
163	30.4M	static bool validate_utf8_fast(const char* src, size_t len) {
164	30.4M	size_t i = 0;
165	30.4M	__m128i has_error = _mm_setzero_si128();
166	30.4M	struct processed_utf_bytes previous = {.rawbytes = _mm_setzero_si128(),
167	30.4M	.high_nibbles = _mm_setzero_si128(),
168	30.4M	.carried_continuations = _mm_setzero_si128()};
169	30.4M	if (len >= 16) {
170	170M	for (; i <= len - 16; i += 16) {
171	140M	__m128i current_bytes = _mm_loadu_si128((const __m128i*)(src + i));
172	140M	previous = checkUTF8Bytes(current_bytes, &previous, &has_error);
173	140M	}
174	30.1M	}
175
176		// last part
177	30.4M	if (i < len) {
178	28.2M	char buffer[16];
179	28.2M	memset(buffer, 0, 16);
180	28.2M	memcpy(buffer, src + i, len - i);
181	28.2M	__m128i current_bytes = _mm_loadu_si128((const __m128i*)(buffer));
182	28.2M	previous = checkUTF8Bytes(current_bytes, &previous, &has_error);
183	28.2M	} else {
184	2.18M	has_error = _mm_or_si128(
185	2.18M	_mm_cmpgt_epi8(previous.carried_continuations,
186	2.18M	_mm_setr_epi8(9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 1)),
187	2.18M	has_error);
188	2.18M	}
189
190	30.4M	return _mm_testz_si128(has_error, has_error);
191	30.4M	}
192
193		#ifdef __AVX2__
194
195		/*****************************/
196	0	static inline __m256i push_last_byte_of_a_to_b(__m256i a, __m256i b) {
197	0	return _mm256_alignr_epi8(b, _mm256_permute2x128_si256(a, b, 0x21), 15);
198	0	}
199
200	0	static inline __m256i push_last_2bytes_of_a_to_b(__m256i a, __m256i b) {
201	0	return _mm256_alignr_epi8(b, _mm256_permute2x128_si256(a, b, 0x21), 14);
202	0	}
203
204		// all byte values must be no larger than 0xF4
205	0	static inline void avxcheckSmallerThan0xF4(__m256i current_bytes, __m256i* has_error) {
206	0	// unsigned, saturates to 0 below max
207	0	*has_error =
208	0	_mm256_or_si256(*has_error, _mm256_subs_epu8(current_bytes, _mm256_set1_epi8(0xF4)));
209	0	}
210
211	0	static inline __m256i avxcontinuationLengths(__m256i high_nibbles) {
212	0	return _mm256_shuffle_epi8(_mm256_setr_epi8(1, 1, 1, 1, 1, 1, 1, 1, // 0xxx (ASCII)
213	0	0, 0, 0, 0, // 10xx (continuation)
214	0	2, 2, // 110x
215	0	3, // 1110
216	0	4, // 1111, next should be 0 (not checked here)
217	0	1, 1, 1, 1, 1, 1, 1, 1, // 0xxx (ASCII)
218	0	0, 0, 0, 0, // 10xx (continuation)
219	0	2, 2, // 110x
220	0	3, // 1110
221	0	4 // 1111, next should be 0 (not checked here)
222	0	),
223	0	high_nibbles);
224	0	}
225
226	0	static inline __m256i avxcarryContinuations(__m256i initial_lengths, __m256i previous_carries) {
227	0	__m256i right1 = _mm256_subs_epu8(push_last_byte_of_a_to_b(previous_carries, initial_lengths),
228	0	_mm256_set1_epi8(1));
229	0	__m256i sum = _mm256_add_epi8(initial_lengths, right1);
230	0
231	0	__m256i right2 = _mm256_subs_epu8(push_last_2bytes_of_a_to_b(previous_carries, sum),
232	0	_mm256_set1_epi8(2));
233	0	return _mm256_add_epi8(sum, right2);
234	0	}
235
236		static inline void avxcheckContinuations(__m256i initial_lengths, __m256i carries,
237	0	__m256i* has_error) {
238	0	// overlap \|\| underlap
239	0	// carry > length && length > 0 \|\| !(carry > length) && !(length > 0)
240	0	// (carries > length) == (lengths > 0)
241	0	__m256i overunder =
242	0	_mm256_cmpeq_epi8(_mm256_cmpgt_epi8(carries, initial_lengths),
243	0	_mm256_cmpgt_epi8(initial_lengths, _mm256_setzero_si256()));
244	0
245	0	has_error = _mm256_or_si256(has_error, overunder);
246	0	}
247
248		// when 0xED is found, next byte must be no larger than 0x9F
249		// when 0xF4 is found, next byte must be no larger than 0x8F
250		// next byte must be continuation, ie sign bit is set, so signed < is ok
251		static inline void avxcheckFirstContinuationMax(__m256i current_bytes, __m256i off1_current_bytes,
252	0	__m256i* has_error) {
253	0	__m256i maskED = _mm256_cmpeq_epi8(off1_current_bytes, _mm256_set1_epi8(0xED));
254	0	__m256i maskF4 = _mm256_cmpeq_epi8(off1_current_bytes, _mm256_set1_epi8(0xF4));
255	0
256	0	__m256i badfollowED =
257	0	_mm256_and_si256(_mm256_cmpgt_epi8(current_bytes, _mm256_set1_epi8(0x9F)), maskED);
258	0	__m256i badfollowF4 =
259	0	_mm256_and_si256(_mm256_cmpgt_epi8(current_bytes, _mm256_set1_epi8(0x8F)), maskF4);
260	0
261	0	has_error = _mm256_or_si256(has_error, _mm256_or_si256(badfollowED, badfollowF4));
262	0	}
263
264		// map off1_hibits => error condition
265		// hibits off1 cur
266		// C => < C2 && true
267		// E => < E1 && < A0
268		// F => < F1 && < 90
269		// else false && false
270		static inline void avxcheckOverlong(__m256i current_bytes, __m256i off1_current_bytes,
271	0	__m256i hibits, __m256i previous_hibits, __m256i* has_error) {
272	0	__m256i off1_hibits = push_last_byte_of_a_to_b(previous_hibits, hibits);
273	0	__m256i initial_mins =
274	0	_mm256_shuffle_epi8(_mm256_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128,
275	0	-128, -128, -128, -128, // 10xx => false
276	0	0xC2, -128, // 110x
277	0	0xE1, // 1110
278	0	0xF1, -128, -128, -128, -128, -128, -128, -128,
279	0	-128, -128, -128, -128, -128, // 10xx => false
280	0	0xC2, -128, // 110x
281	0	0xE1, // 1110
282	0	0xF1),
283	0	off1_hibits);
284	0
285	0	__m256i initial_under = _mm256_cmpgt_epi8(initial_mins, off1_current_bytes);
286	0
287	0	__m256i second_mins =
288	0	_mm256_shuffle_epi8(_mm256_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128,
289	0	-128, -128, -128, -128, // 10xx => false
290	0	127, 127, // 110x => true
291	0	0xA0, // 1110
292	0	0x90, -128, -128, -128, -128, -128, -128, -128,
293	0	-128, -128, -128, -128, -128, // 10xx => false
294	0	127, 127, // 110x => true
295	0	0xA0, // 1110
296	0	0x90),
297	0	off1_hibits);
298	0	__m256i second_under = _mm256_cmpgt_epi8(second_mins, current_bytes);
299	0	has_error = _mm256_or_si256(has_error, _mm256_and_si256(initial_under, second_under));
300	0	}
301
302		struct avx_processed_utf_bytes {
303		__m256i rawbytes;
304		__m256i high_nibbles;
305		__m256i carried_continuations;
306		};
307
308	0	static inline void avx_count_nibbles(__m256i bytes, struct avx_processed_utf_bytes* answer) {
309	0	answer->rawbytes = bytes;
310	0	answer->high_nibbles = _mm256_and_si256(_mm256_srli_epi16(bytes, 4), _mm256_set1_epi8(0x0F));
311	0	}
312
313		#endif // __AVX2__