// Adapted from https://github.com/lemire/fastvalidate-utf-8 #ifdef __AVX2__ #include #include #include #include #include /* * 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