| // Adapted from https://github.com/lemire/fastvalidate-utf-8 |
| |
| #ifdef __AVX2__ |
| |
| #include <stdio.h> |
| #include <stddef.h> |
| #include <stdint.h> |
| #include <string.h> |
| #include <x86intrin.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 print256(const char *s, const __m256i v256) |
| { |
| const unsigned char *v8 = (const unsigned char *)&v256; |
| if (s) |
| printf("%s:\t", s); |
| for (int i = 0; i < 32; i++) |
| printf("%02x ", v8[i]); |
| printf("\n"); |
| } |
| #endif |
| |
| 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)); |
| } |
| |
| // check whether the current bytes are valid UTF-8 |
| // at the end of the function, previous gets updated |
| static struct avx_processed_utf_bytes |
| avxcheckUTF8Bytes(__m256i current_bytes, |
| struct avx_processed_utf_bytes *previous, |
| __m256i *has_error) { |
| struct avx_processed_utf_bytes pb; |
| avx_count_nibbles(current_bytes, &pb); |
| |
| avxcheckSmallerThan0xF4(current_bytes, has_error); |
| |
| __m256i initial_lengths = avxcontinuationLengths(pb.high_nibbles); |
| |
| pb.carried_continuations = |
| avxcarryContinuations(initial_lengths, previous->carried_continuations); |
| |
| avxcheckContinuations(initial_lengths, pb.carried_continuations, has_error); |
| |
| __m256i off1_current_bytes = |
| push_last_byte_of_a_to_b(previous->rawbytes, pb.rawbytes); |
| avxcheckFirstContinuationMax(current_bytes, off1_current_bytes, has_error); |
| |
| avxcheckOverlong(current_bytes, off1_current_bytes, pb.high_nibbles, |
| previous->high_nibbles, has_error); |
| return pb; |
| } |
| |
| /* Return 0 on success, -1 on error */ |
| int utf8_lemire_avx2(const unsigned char *src, int len) { |
| size_t i = 0; |
| __m256i has_error = _mm256_setzero_si256(); |
| struct avx_processed_utf_bytes previous = { |
| .rawbytes = _mm256_setzero_si256(), |
| .high_nibbles = _mm256_setzero_si256(), |
| .carried_continuations = _mm256_setzero_si256()}; |
| if (len >= 32) { |
| for (; i <= len - 32; i += 32) { |
| __m256i current_bytes = _mm256_loadu_si256((const __m256i *)(src + i)); |
| previous = avxcheckUTF8Bytes(current_bytes, &previous, &has_error); |
| } |
| } |
| |
| // last part |
| if (i < len) { |
| char buffer[32]; |
| memset(buffer, 0, 32); |
| memcpy(buffer, src + i, len - i); |
| __m256i current_bytes = _mm256_loadu_si256((const __m256i *)(buffer)); |
| previous = avxcheckUTF8Bytes(current_bytes, &previous, &has_error); |
| } else { |
| has_error = _mm256_or_si256( |
| _mm256_cmpgt_epi8(previous.carried_continuations, |
| _mm256_setr_epi8(9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, |
| 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, |
| 9, 9, 9, 9, 9, 9, 9, 1)), |
| has_error); |
| } |
| |
| return _mm256_testz_si256(has_error, has_error) ? 0 : -1; |
| } |
| |
| #endif |
