mirror of
https://github.com/simdjson/simdjson
synced 2026-06-08 17:27:07 +00:00
Daniel Lemire
200 lines
7.5 KiB
C
200 lines
7.5 KiB
C
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#ifndef SIMDUTF8CHECK_H
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#define SIMDUTF8CHECK_H
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#ifdef _MSC_VER
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/* Microsoft C/C++-compatible compiler */
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#include <intrin.h>
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#else
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#include <x86intrin.h>
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#endif
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#include <string.h>
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/*
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* legal utf-8 byte sequence
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* http://www.unicode.org/versions/Unicode6.0.0/ch03.pdf - page 94
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*
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* Code Points 1st 2s 3s 4s
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* U+0000..U+007F 00..7F
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* U+0080..U+07FF C2..DF 80..BF
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* U+0800..U+0FFF E0 A0..BF 80..BF
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* U+1000..U+CFFF E1..EC 80..BF 80..BF
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* U+D000..U+D7FF ED 80..9F 80..BF
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* U+E000..U+FFFF EE..EF 80..BF 80..BF
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* U+10000..U+3FFFF F0 90..BF 80..BF 80..BF
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* U+40000..U+FFFFF F1..F3 80..BF 80..BF 80..BF
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* U+100000..U+10FFFF F4 80..8F 80..BF 80..BF
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*
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*/
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// all byte values must be no larger than 0xF4
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#ifdef __AVX2__
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/*****************************/
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static inline __m256i push_last_byte_of_a_to_b(__m256i a, __m256i b) {
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return _mm256_alignr_epi8(b, _mm256_permute2x128_si256(a, b, 0x21), 15);
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}
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static inline __m256i push_last_2bytes_of_a_to_b(__m256i a, __m256i b) {
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return _mm256_alignr_epi8(b, _mm256_permute2x128_si256(a, b, 0x21), 14);
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}
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// all byte values must be no larger than 0xF4
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static inline void avxcheckSmallerThan0xF4(__m256i current_bytes,
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__m256i *has_error) {
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// unsigned, saturates to 0 below max
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*has_error = _mm256_or_si256(
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*has_error, _mm256_subs_epu8(current_bytes, _mm256_set1_epi8(0xF4)));
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}
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static inline __m256i avxcontinuationLengths(__m256i high_nibbles) {
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return _mm256_shuffle_epi8(
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_mm256_setr_epi8(1, 1, 1, 1, 1, 1, 1, 1, // 0xxx (ASCII)
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0, 0, 0, 0, // 10xx (continuation)
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2, 2, // 110x
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3, // 1110
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4, // 1111, next should be 0 (not checked here)
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1, 1, 1, 1, 1, 1, 1, 1, // 0xxx (ASCII)
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0, 0, 0, 0, // 10xx (continuation)
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2, 2, // 110x
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3, // 1110
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4 // 1111, next should be 0 (not checked here)
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),
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high_nibbles);
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}
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static inline __m256i avxcarryContinuations(__m256i initial_lengths,
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__m256i previous_carries) {
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__m256i right1 = _mm256_subs_epu8(
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push_last_byte_of_a_to_b(previous_carries, initial_lengths),
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_mm256_set1_epi8(1));
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__m256i sum = _mm256_add_epi8(initial_lengths, right1);
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__m256i right2 = _mm256_subs_epu8(
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push_last_2bytes_of_a_to_b(previous_carries, sum), _mm256_set1_epi8(2));
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return _mm256_add_epi8(sum, right2);
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}
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static inline void avxcheckContinuations(__m256i initial_lengths,
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__m256i carries, __m256i *has_error) {
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// overlap || underlap
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// carry > length && length > 0 || !(carry > length) && !(length > 0)
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// (carries > length) == (lengths > 0)
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__m256i overunder = _mm256_cmpeq_epi8(
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_mm256_cmpgt_epi8(carries, initial_lengths),
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_mm256_cmpgt_epi8(initial_lengths, _mm256_setzero_si256()));
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*has_error = _mm256_or_si256(*has_error, overunder);
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}
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// when 0xED is found, next byte must be no larger than 0x9F
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// when 0xF4 is found, next byte must be no larger than 0x8F
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// next byte must be continuation, ie sign bit is set, so signed < is ok
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static inline void avxcheckFirstContinuationMax(__m256i current_bytes,
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__m256i off1_current_bytes,
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__m256i *has_error) {
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__m256i maskED =
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_mm256_cmpeq_epi8(off1_current_bytes, _mm256_set1_epi8(0xED));
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__m256i maskF4 =
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_mm256_cmpeq_epi8(off1_current_bytes, _mm256_set1_epi8(0xF4));
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__m256i badfollowED = _mm256_and_si256(
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_mm256_cmpgt_epi8(current_bytes, _mm256_set1_epi8(0x9F)), maskED);
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__m256i badfollowF4 = _mm256_and_si256(
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_mm256_cmpgt_epi8(current_bytes, _mm256_set1_epi8(0x8F)), maskF4);
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*has_error =
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_mm256_or_si256(*has_error, _mm256_or_si256(badfollowED, badfollowF4));
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}
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// map off1_hibits => error condition
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// hibits off1 cur
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// C => < C2 && true
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// E => < E1 && < A0
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// F => < F1 && < 90
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// else false && false
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static inline void avxcheckOverlong(__m256i current_bytes,
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__m256i off1_current_bytes, __m256i hibits,
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__m256i previous_hibits,
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__m256i *has_error) {
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__m256i off1_hibits = push_last_byte_of_a_to_b(previous_hibits, hibits);
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__m256i initial_mins = _mm256_shuffle_epi8(
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_mm256_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128, -128,
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-128, -128, -128, // 10xx => false
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0xC2, -128, // 110x
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0xE1, // 1110
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0xF1, -128, -128, -128, -128, -128, -128, -128, -128,
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-128, -128, -128, -128, // 10xx => false
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0xC2, -128, // 110x
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0xE1, // 1110
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0xF1),
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off1_hibits);
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__m256i initial_under = _mm256_cmpgt_epi8(initial_mins, off1_current_bytes);
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__m256i second_mins = _mm256_shuffle_epi8(
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_mm256_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128, -128,
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-128, -128, -128, // 10xx => false
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127, 127, // 110x => true
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0xA0, // 1110
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0x90, -128, -128, -128, -128, -128, -128, -128, -128,
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-128, -128, -128, -128, // 10xx => false
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127, 127, // 110x => true
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0xA0, // 1110
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0x90),
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off1_hibits);
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__m256i second_under = _mm256_cmpgt_epi8(second_mins, current_bytes);
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*has_error = _mm256_or_si256(*has_error,
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_mm256_and_si256(initial_under, second_under));
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}
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struct avx_processed_utf_bytes {
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__m256i rawbytes;
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__m256i high_nibbles;
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__m256i carried_continuations;
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};
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static inline void avx_count_nibbles(__m256i bytes,
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struct avx_processed_utf_bytes *answer) {
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answer->rawbytes = bytes;
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answer->high_nibbles =
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_mm256_and_si256(_mm256_srli_epi16(bytes, 4), _mm256_set1_epi8(0x0F));
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}
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// check whether the current bytes are valid UTF-8
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// at the end of the function, previous gets updated
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static struct avx_processed_utf_bytes
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avxcheckUTF8Bytes(__m256i current_bytes,
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struct avx_processed_utf_bytes *previous,
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__m256i *has_error) {
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struct avx_processed_utf_bytes pb;
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avx_count_nibbles(current_bytes, &pb);
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avxcheckSmallerThan0xF4(current_bytes, has_error);
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__m256i initial_lengths = avxcontinuationLengths(pb.high_nibbles);
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pb.carried_continuations =
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avxcarryContinuations(initial_lengths, previous->carried_continuations);
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avxcheckContinuations(initial_lengths, pb.carried_continuations, has_error);
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__m256i off1_current_bytes =
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push_last_byte_of_a_to_b(previous->rawbytes, pb.rawbytes);
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avxcheckFirstContinuationMax(current_bytes, off1_current_bytes, has_error);
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avxcheckOverlong(current_bytes, off1_current_bytes, pb.high_nibbles,
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previous->high_nibbles, has_error);
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return pb;
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}
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#else // __AVX2__
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#warning "We require AVX2 support!"
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#endif // __AVX2__
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#endif
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