| // Adapted from https://github.com/lemire/fastvalidate-utf-8 |
| |
| #ifdef __aarch64__ |
| |
| #include <stdio.h> |
| #include <stddef.h> |
| #include <stdint.h> |
| #include <string.h> |
| #include <inttypes.h> |
| #include <arm_neon.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 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 |
