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a7734672b9
- Introduced with the C++20 <bit> header - The problem with __builtin_c(l|t)z() is that 0 as input has an undefined result (*) and the code did not always check. The std:: versions do not have this issue. - In some cases, we continue to use buildin_c(l|t)z(), (e.g. in src/Common/BitHelpers.h) because the std:: versions only accept unsigned inputs (and they also check that) and the casting would be ugly. (*) https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
142 lines
4.3 KiB
C++
142 lines
4.3 KiB
C++
#pragma once
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#include <optional>
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#include <base/types.h>
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#include <Common/BitHelpers.h>
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#include <Poco/UTF8Encoding.h>
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#ifdef __SSE2__
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#include <emmintrin.h>
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#endif
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#if defined(__aarch64__) && defined(__ARM_NEON)
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# include <arm_neon.h>
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# ifdef HAS_RESERVED_IDENTIFIER
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# pragma clang diagnostic ignored "-Wreserved-identifier"
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# endif
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#endif
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namespace DB
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{
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namespace UTF8
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{
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static const UInt8 CONTINUATION_OCTET_MASK = 0b11000000u;
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static const UInt8 CONTINUATION_OCTET = 0b10000000u;
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/// return true if `octet` binary repr starts with 10 (octet is a UTF-8 sequence continuation)
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inline bool isContinuationOctet(const UInt8 octet)
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{
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return (octet & CONTINUATION_OCTET_MASK) == CONTINUATION_OCTET;
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}
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/// moves `s` backward until either first non-continuation octet or begin
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inline void syncBackward(const UInt8 * & s, const UInt8 * const begin)
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{
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while (isContinuationOctet(*s) && s > begin)
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--s;
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}
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/// moves `s` forward until either first non-continuation octet or string end is met
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inline void syncForward(const UInt8 * & s, const UInt8 * const end)
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{
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while (s < end && isContinuationOctet(*s))
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++s;
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}
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/// returns UTF-8 code point sequence length judging by it's first octet
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inline size_t seqLength(const UInt8 first_octet)
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{
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if (first_octet < 0x80 || first_octet >= 0xF8) /// The specs of UTF-8.
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return 1;
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const size_t bits = 8;
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const auto first_zero = bitScanReverse(static_cast<UInt8>(~first_octet));
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return bits - 1 - first_zero;
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}
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inline size_t countCodePoints(const UInt8 * data, size_t size)
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{
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size_t res = 0;
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const auto * end = data + size;
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#ifdef __SSE2__
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constexpr auto bytes_sse = sizeof(__m128i);
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const auto * src_end_sse = data + size / bytes_sse * bytes_sse;
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const auto threshold = _mm_set1_epi8(0xBF);
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for (; data < src_end_sse; data += bytes_sse)
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res += __builtin_popcount(_mm_movemask_epi8(
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_mm_cmpgt_epi8(_mm_loadu_si128(reinterpret_cast<const __m128i *>(data)), threshold)));
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#elif defined(__aarch64__) && defined(__ARM_NEON)
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/// Returns a 64 bit mask of nibbles (4 bits for each byte).
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auto get_nibble_mask
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= [](uint8x16_t input) -> uint64_t { return vget_lane_u64(vreinterpret_u64_u8(vshrn_n_u16(vreinterpretq_u16_u8(input), 4)), 0); };
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constexpr auto bytes_sse = 16;
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const auto * src_end_sse = data + size / bytes_sse * bytes_sse;
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const auto threshold = vdupq_n_s8(0xBF);
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for (; data < src_end_sse; data += bytes_sse)
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res += std::popcount(get_nibble_mask(vcgtq_s8(vld1q_s8(reinterpret_cast<const int8_t *>(data)), threshold)));
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res >>= 2;
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#endif
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for (; data < end; ++data) /// Skip UTF-8 continuation bytes.
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res += static_cast<Int8>(*data) > static_cast<Int8>(0xBF);
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return res;
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}
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template <typename CharT>
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requires (sizeof(CharT) == 1)
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size_t convertCodePointToUTF8(int code_point, CharT * out_bytes, size_t out_length)
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{
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static const Poco::UTF8Encoding utf8;
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int res = utf8.convert(code_point, reinterpret_cast<uint8_t *>(out_bytes), out_length);
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assert(res >= 0);
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return res;
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}
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template <typename CharT>
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requires (sizeof(CharT) == 1)
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std::optional<uint32_t> convertUTF8ToCodePoint(const CharT * in_bytes, size_t in_length)
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{
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static const Poco::UTF8Encoding utf8;
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int res = utf8.queryConvert(reinterpret_cast<const uint8_t *>(in_bytes), in_length);
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if (res >= 0)
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return res;
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return {};
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}
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/// returns UTF-8 wcswidth. Invalid sequence is treated as zero width character.
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/// `prefix` is used to compute the `\t` width which extends the string before
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/// and include `\t` to the nearest longer length with multiple of eight.
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size_t computeWidth(const UInt8 * data, size_t size, size_t prefix = 0) noexcept;
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/** Calculate the maximum number of bytes, so that substring of this size fits in 'limit' width.
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*
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* For example, we have string "x你好", it has 3 code points and visible width of 5 and byte size of 7.
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* Suppose we have limit = 3.
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* Then we have to return 4 as maximum number of bytes
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* and the truncated string will be "x你": two code points, visible width 3, byte size 4.
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*
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* The same result will be for limit 4, because the last character would not fit.
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*/
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size_t computeBytesBeforeWidth(const UInt8 * data, size_t size, size_t prefix, size_t limit) noexcept;
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}
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}
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