// Adapted from https://github.com/lemire/fastvalidate-utf-8 #ifdef __aarch64__ #include #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 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