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84 lines
2.2 KiB
C++
84 lines
2.2 KiB
C++
#pragma once
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#include <Core/Types.h>
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#include <Common/BitHelpers.h>
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#ifdef __SSE2__
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#include <emmintrin.h>
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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 < 0x80u)
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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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#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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/// 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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}
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}
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