#ifdef __aarch64__ #include #include #include int utf8_naive(const unsigned char *data, int len); #if 0 static void print128(const char *s, const uint8x16_t v128) { unsigned char v8[16]; vst1q_u8(v8, v128); if (s) printf("%s:\t", s); for (int i = 0; i < 16; ++i) printf("%02x ", v8[i]); printf("\n"); } #endif /* * Map high nibble of "First Byte" to legal character length minus 1 * 0x00 ~ 0xBF --> 0 * 0xC0 ~ 0xDF --> 1 * 0xE0 ~ 0xEF --> 2 * 0xF0 ~ 0xFF --> 3 */ static const uint8_t _first_len_tbl[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3, }; /* Map "First Byte" to 8-th item of range table (0xC2 ~ 0xF4) */ static const uint8_t _first_range_tbl[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, }; /* * Range table, map range index to min and max values * Index 0 : 00 ~ 7F (First Byte, ascii) * Index 1,2,3: 80 ~ BF (Second, Third, Fourth Byte) * Index 4 : A0 ~ BF (Second Byte after E0) * Index 5 : 80 ~ 9F (Second Byte after ED) * Index 6 : 90 ~ BF (Second Byte after F0) * Index 7 : 80 ~ 8F (Second Byte after F4) * Index 8 : C2 ~ F4 (First Byte, non ascii) * Index 9~15 : illegal: u >= 255 && u <= 0 */ static const uint8_t _range_min_tbl[] = { 0x00, 0x80, 0x80, 0x80, 0xA0, 0x80, 0x90, 0x80, 0xC2, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, }; static const uint8_t _range_max_tbl[] = { 0x7F, 0xBF, 0xBF, 0xBF, 0xBF, 0x9F, 0xBF, 0x8F, 0xF4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, }; /* * This table is for fast handling four special First Bytes(E0,ED,F0,F4), after * which the Second Byte are not 80~BF. It contains "range index adjustment". * - The idea is to minus byte with E0, use the result(0~31) as the index to * lookup the "range index adjustment". Then add the adjustment to original * range index to get the correct range. * - Range index adjustment * +------------+---------------+------------------+----------------+ * | First Byte | original range| range adjustment | adjusted range | * +------------+---------------+------------------+----------------+ * | E0 | 2 | 2 | 4 | * +------------+---------------+------------------+----------------+ * | ED | 2 | 3 | 5 | * +------------+---------------+------------------+----------------+ * | F0 | 3 | 3 | 6 | * +------------+---------------+------------------+----------------+ * | F4 | 4 | 4 | 8 | * +------------+---------------+------------------+----------------+ * - Below is a uint8x16x2 table, data is interleaved in NEON register. So I'm * putting it vertically. 1st column is for E0~EF, 2nd column for F0~FF. */ static const uint8_t _range_adjust_tbl[] = { /* index -> 0~15 16~31 <- index */ /* E0 -> */ 2, 3, /* <- F0 */ 0, 0, 0, 0, 0, 0, 0, 4, /* <- F4 */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* ED -> */ 3, 0, 0, 0, 0, 0, }; /* 2x ~ 4x faster than naive method */ /* Return 0 on success, -1 on error */ int utf8_range(const unsigned char *data, int len) { if (len >= 16) { uint8x16_t prev_input = vdupq_n_u8(0); uint8x16_t prev_first_len = vdupq_n_u8(0); /* Cached tables */ const uint8x16_t first_len_tbl = vld1q_u8(_first_len_tbl); const uint8x16_t first_range_tbl = vld1q_u8(_first_range_tbl); const uint8x16_t range_min_tbl = vld1q_u8(_range_min_tbl); const uint8x16_t range_max_tbl = vld1q_u8(_range_max_tbl); const uint8x16x2_t range_adjust_tbl = vld2q_u8(_range_adjust_tbl); /* Cached values */ const uint8x16_t const_1 = vdupq_n_u8(1); const uint8x16_t const_2 = vdupq_n_u8(2); const uint8x16_t const_e0 = vdupq_n_u8(0xE0); /* We use two error registers to remove a dependency. */ uint8x16_t error1 = vdupq_n_u8(0); uint8x16_t error2 = vdupq_n_u8(0); while (len >= 16) { const uint8x16_t input = vld1q_u8(data); /* high_nibbles = input >> 4 */ const uint8x16_t high_nibbles = vshrq_n_u8(input, 4); /* first_len = legal character length minus 1 */ /* 0 for 00~7F, 1 for C0~DF, 2 for E0~EF, 3 for F0~FF */ /* first_len = first_len_tbl[high_nibbles] */ const uint8x16_t first_len = vqtbl1q_u8(first_len_tbl, high_nibbles); /* First Byte: set range index to 8 for bytes within 0xC0 ~ 0xFF */ /* range = first_range_tbl[high_nibbles] */ uint8x16_t range = vqtbl1q_u8(first_range_tbl, high_nibbles); /* Second Byte: set range index to first_len */ /* 0 for 00~7F, 1 for C0~DF, 2 for E0~EF, 3 for F0~FF */ /* range |= (first_len, prev_first_len) << 1 byte */ range = vorrq_u8(range, vextq_u8(prev_first_len, first_len, 15)); /* Third Byte: set range index to saturate_sub(first_len, 1) */ /* 0 for 00~7F, 0 for C0~DF, 1 for E0~EF, 2 for F0~FF */ uint8x16_t tmp1, tmp2; /* tmp1 = (first_len, prev_first_len) << 2 bytes */ tmp1 = vextq_u8(prev_first_len, first_len, 14); /* tmp1 = saturate_sub(tmp1, 1) */ tmp1 = vqsubq_u8(tmp1, const_1); /* range |= tmp1 */ range = vorrq_u8(range, tmp1); /* Fourth Byte: set range index to saturate_sub(first_len, 2) */ /* 0 for 00~7F, 0 for C0~DF, 0 for E0~EF, 1 for F0~FF */ /* tmp2 = (first_len, prev_first_len) << 3 bytes */ tmp2 = vextq_u8(prev_first_len, first_len, 13); /* tmp2 = saturate_sub(tmp2, 2) */ tmp2 = vqsubq_u8(tmp2, const_2); /* range |= tmp2 */ range = vorrq_u8(range, tmp2); /* * Now we have below range indices calculated * Correct cases: * - 8 for C0~FF * - 3 for 1st byte after F0~FF * - 2 for 1st byte after E0~EF or 2nd byte after F0~FF * - 1 for 1st byte after C0~DF or 2nd byte after E0~EF or * 3rd byte after F0~FF * - 0 for others * Error cases: * 9,10,11 if non ascii First Byte overlaps * E.g., F1 80 C2 90 --> 8 3 10 2, where 10 indicates error */ /* Adjust Second Byte range for special First Bytes(E0,ED,F0,F4) */ /* See _range_adjust_tbl[] definition for details */ /* Overlaps lead to index 9~15, which are illegal in range table */ uint8x16_t shift1 = vextq_u8(prev_input, input, 15); uint8x16_t pos = vsubq_u8(shift1, const_e0); range = vaddq_u8(range, vqtbl2q_u8(range_adjust_tbl, pos)); /* Load min and max values per calculated range index */ uint8x16_t minv = vqtbl1q_u8(range_min_tbl, range); uint8x16_t maxv = vqtbl1q_u8(range_max_tbl, range); /* Check value range */ error1 = vorrq_u8(error1, vcltq_u8(input, minv)); error2 = vorrq_u8(error2, vcgtq_u8(input, maxv)); prev_input = input; prev_first_len = first_len; data += 16; len -= 16; } /* Merge our error counters together */ error1 = vorrq_u8(error1, error2); /* Delay error check till loop ends */ if (vmaxvq_u8(error1)) return -1; /* Find previous token (not 80~BF) */ uint32_t token4; vst1q_lane_u32(&token4, vreinterpretq_u32_u8(prev_input), 3); const int8_t *token = (const int8_t *)&token4; int lookahead = 0; if (token[3] > (int8_t)0xBF) lookahead = 1; else if (token[2] > (int8_t)0xBF) lookahead = 2; else if (token[1] > (int8_t)0xBF) lookahead = 3; data -= lookahead; len += lookahead; } /* Check remaining bytes with naive method */ return utf8_naive(data, len); } #endif