| #ifdef __aarch64__ |
| |
| #include <stdio.h> |
| #include <stdint.h> |
| #include <arm_neon.h> |
| |
| 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 caluclated |
| * 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 |
