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#include <util/charset/wide.h>
#include <util/system/types.h>

#ifdef SSE41_STUB

namespace NDetail {
    void UTF8ToWideImplSSE41(const unsigned char*&, const unsigned char*, wchar16*&) noexcept {
    }
    void UTF8ToWideImplSSE41(const unsigned char*&, const unsigned char*, wchar32*&) noexcept {
    }
}

#else

    #include <util/system/compiler.h>

    #include <cstring>
    #include <emmintrin.h>
    #include <smmintrin.h>

//processes to the first error, or until less then 16 bytes left
//most code taken from https://woboq.com/blog/utf-8-processing-using-simd.html

//return dstAdvance 0 in case of problems 
static Y_FORCE_INLINE ui32 Unpack16BytesIntoUtf16IfNoSurrogats(const unsigned char*& cur, __m128i& utf16Low, __m128i& utf16High) { 
    unsigned char curAligned[16]; 

    memcpy(curAligned, cur, sizeof(__m128i)); 
    __m128i chunk = _mm_load_si128(reinterpret_cast<const __m128i*>(curAligned)); 

    //only ascii characters - simple copy 
    if (!_mm_movemask_epi8(chunk)) { 
        utf16Low = _mm_unpacklo_epi8(chunk, _mm_setzero_si128()); 
        utf16High = _mm_unpackhi_epi8(chunk, _mm_setzero_si128()); 
        cur += 16; 
        return 16; 
    } 

    __m128i chunkSigned = _mm_add_epi8(chunk, _mm_set1_epi8(0x80)); 
    __m128i isAsciiMask = _mm_cmpgt_epi8(chunk, _mm_set1_epi8(0)); 

    __m128i cond2 = _mm_cmplt_epi8(_mm_set1_epi8(0xc2 - 1 - 0x80), chunkSigned); 
    __m128i state = _mm_set1_epi8(0x0 | (char)0x80);

    __m128i cond3 = _mm_cmplt_epi8(_mm_set1_epi8(0xe0 - 1 - 0x80), chunkSigned); 
    state = _mm_blendv_epi8(state, _mm_set1_epi8(0x2 | (char)0xc0), cond2);

    int sourceAdvance; 
    __m128i shifts; 
    __m128i chunkLow, chunkHigh; 

    if (Y_LIKELY(!_mm_movemask_epi8(cond3))) { 
        //main case: no bloks of size 3 or 4 

        //rune len for start of multi-byte sequences (0 for b0... and b10..., 2 for b110..., etc.) 
        __m128i count = _mm_and_si128(state, _mm_set1_epi8(0x7)); 

        __m128i countSub1 = _mm_subs_epu8(count, _mm_set1_epi8(0x1)); 

        shifts = countSub1; 
        __m128i continuation1 = _mm_slli_si128(countSub1, 1); 

        shifts = _mm_add_epi8(shifts, _mm_slli_si128(shifts, 1)); 
        shifts = _mm_add_epi8(shifts, _mm_slli_si128(shifts, 2)); 

        __m128i counts = _mm_or_si128(count, continuation1); 

        __m128i isBeginMultibyteMask = _mm_cmpgt_epi8(count, _mm_set1_epi8(0)); 
        __m128i needNoContinuationMask = _mm_cmpeq_epi8(continuation1, _mm_set1_epi8(0)); 
        __m128i isBeginMask = _mm_add_epi8(isBeginMultibyteMask, isAsciiMask); 
        //each symbol should be exactly one of ascii, continuation or begin 
        __m128i okMask = _mm_cmpeq_epi8(isBeginMask, needNoContinuationMask); 

        if (_mm_movemask_epi8(okMask) != 0xFFFF) { 
            return 0; 
        } 

        shifts = _mm_add_epi8(shifts, _mm_slli_si128(shifts, 4)); 

        __m128i mask = _mm_and_si128(state, _mm_set1_epi8(0xf8)); 
        shifts = _mm_add_epi8(shifts, _mm_slli_si128(shifts, 8)); 

        chunk = _mm_andnot_si128(mask, chunk);                                    // from now on, we only have usefull bits 
        shifts = _mm_and_si128(shifts, _mm_cmplt_epi8(counts, _mm_set1_epi8(2))); // <=1 

        __m128i chunk_right = _mm_slli_si128(chunk, 1); 
        shifts = _mm_blendv_epi8(shifts, _mm_srli_si128(shifts, 1), 
                                 _mm_srli_si128(_mm_slli_epi16(shifts, 7), 1));

        chunkLow = _mm_blendv_epi8(chunk, 
                                   _mm_or_si128(chunk, _mm_and_si128(_mm_slli_epi16(chunk_right, 6), _mm_set1_epi8(0xc0))),
                                   _mm_cmpeq_epi8(counts, _mm_set1_epi8(1)));

        chunkHigh = _mm_and_si128(chunk, _mm_cmpeq_epi8(counts, _mm_set1_epi8(2))); 

        shifts = _mm_blendv_epi8(shifts, _mm_srli_si128(shifts, 2), 
                                 _mm_srli_si128(_mm_slli_epi16(shifts, 6), 2));
        chunkHigh = _mm_srli_epi32(chunkHigh, 2); 

        shifts = _mm_blendv_epi8(shifts, _mm_srli_si128(shifts, 4), 
                                 _mm_srli_si128(_mm_slli_epi16(shifts, 5), 4));
 
        int c = _mm_extract_epi16(counts, 7); 
        sourceAdvance = !(c & 0x0200) ? 16 : 15; 
 
    } else { 
        __m128i mask3 = _mm_slli_si128(cond3, 1); 
 
        __m128i cond4 = _mm_cmplt_epi8(_mm_set1_epi8(0xf0 - 1 - 0x80), chunkSigned); 
        state = _mm_blendv_epi8(state, _mm_set1_epi8(0x3 | (char)0xe0), cond3);
 
        // 4 bytes sequences are not vectorize. Fall back to the scalar processing 
        if (Y_UNLIKELY(_mm_movemask_epi8(cond4))) { 
            return 0; 
        } 
 
        //rune len for start of multi-byte sequences (0 for b0... and b10..., 2 for b110..., etc.) 
        __m128i count = _mm_and_si128(state, _mm_set1_epi8(0x7)); 
 
        __m128i countSub1 = _mm_subs_epu8(count, _mm_set1_epi8(0x1)); 
        __m128i continuation2 = _mm_slli_si128(_mm_subs_epu8(count, _mm_set1_epi8(0x2)), 2); 
 
        shifts = countSub1; 
        __m128i continuation1 = _mm_slli_si128(countSub1, 1); 
 
        shifts = _mm_add_epi8(shifts, _mm_slli_si128(shifts, 1)); 
        __m128i continuationsRunelen = _mm_or_si128(continuation1, continuation2); 
 
        shifts = _mm_add_epi8(shifts, _mm_slli_si128(shifts, 2)); 
        __m128i counts = _mm_or_si128(count, continuationsRunelen); 
 
        __m128i isBeginMultibyteMask = _mm_cmpgt_epi8(count, _mm_set1_epi8(0)); 
        __m128i needNoContinuationMask = _mm_cmpeq_epi8(continuationsRunelen, _mm_set1_epi8(0)); 
        __m128i isBeginMask = _mm_add_epi8(isBeginMultibyteMask, isAsciiMask); 
        //each symbol should be exactly one of ascii, continuation or begin 
        __m128i okMask = _mm_cmpeq_epi8(isBeginMask, needNoContinuationMask); 
 
        if (_mm_movemask_epi8(okMask) != 0xFFFF) { 
            return 0; 
        } 
 
        shifts = _mm_add_epi8(shifts, _mm_slli_si128(shifts, 4)); 
 
        __m128i mask = _mm_and_si128(state, _mm_set1_epi8(0xf8)); 
        shifts = _mm_add_epi8(shifts, _mm_slli_si128(shifts, 8)); 
 
        chunk = _mm_andnot_si128(mask, chunk);                                    // from now on, we only have usefull bits 
        shifts = _mm_and_si128(shifts, _mm_cmplt_epi8(counts, _mm_set1_epi8(2))); // <=1 
 
        __m128i chunk_right = _mm_slli_si128(chunk, 1); 
        shifts = _mm_blendv_epi8(shifts, _mm_srli_si128(shifts, 1), 
                                 _mm_srli_si128(_mm_slli_epi16(shifts, 7), 1));
 
        chunkLow = _mm_blendv_epi8(chunk, 
                                   _mm_or_si128(chunk, _mm_and_si128(_mm_slli_epi16(chunk_right, 6), _mm_set1_epi8(0xc0))),
                                   _mm_cmpeq_epi8(counts, _mm_set1_epi8(1)));
 
        chunkHigh = _mm_and_si128(chunk, _mm_cmpeq_epi8(counts, _mm_set1_epi8(2))); 
 
        shifts = _mm_blendv_epi8(shifts, _mm_srli_si128(shifts, 2), 
                                 _mm_srli_si128(_mm_slli_epi16(shifts, 6), 2));
        chunkHigh = _mm_srli_epi32(chunkHigh, 2); 
 
        shifts = _mm_blendv_epi8(shifts, _mm_srli_si128(shifts, 4), 
                                 _mm_srli_si128(_mm_slli_epi16(shifts, 5), 4));
        chunkHigh = _mm_or_si128(chunkHigh, 
                                 _mm_and_si128(_mm_and_si128(_mm_slli_epi32(chunk_right, 4), _mm_set1_epi8(0xf0)),
                                               mask3));

        int c = _mm_extract_epi16(counts, 7); 
        sourceAdvance = !(c & 0x0200) ? 16 : !(c & 0x02) ? 15
                                                         : 14;
    } 

    shifts = _mm_blendv_epi8(shifts, _mm_srli_si128(shifts, 8), 
                             _mm_srli_si128(_mm_slli_epi16(shifts, 4), 8));

    chunkHigh = _mm_slli_si128(chunkHigh, 1); 
 
    __m128i shuf = _mm_add_epi8(shifts, _mm_set_epi8(15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)); 
 
    chunkLow = _mm_shuffle_epi8(chunkLow, shuf); 
    chunkHigh = _mm_shuffle_epi8(chunkHigh, shuf); 
 
    utf16Low = _mm_unpacklo_epi8(chunkLow, chunkHigh); 
    utf16High = _mm_unpackhi_epi8(chunkLow, chunkHigh); 
 
    ui32 s = _mm_extract_epi32(shifts, 3); 
    ui32 destAdvance = sourceAdvance - (0xff & (s >> (8 * (3 - 16 + sourceAdvance)))); 
    cur += sourceAdvance; 
    return destAdvance; 
} 
 
namespace NDetail { 
    void UTF8ToWideImplSSE41(const unsigned char*& cur, const unsigned char* last, wchar16*& dest) noexcept { 
        alignas(16) wchar16 destAligned[16]; 
 
        while (cur + 16 <= last) { 
            __m128i utf16Low; 
            __m128i utf16High; 
            ui32 dstAdvance = Unpack16BytesIntoUtf16IfNoSurrogats(cur, utf16Low, utf16High); 
 
            if (dstAdvance == 0) { 
                break; 
            } 
 
            _mm_store_si128(reinterpret_cast<__m128i*>(destAligned), utf16Low); 
            _mm_store_si128(reinterpret_cast<__m128i*>(destAligned) + 1, utf16High); 
            memcpy(dest, destAligned, sizeof(__m128i) * 2);
            dest += dstAdvance; 
        } 
        //The rest will be handled sequencially. 
        // Possible improvement: go back to the vectorized processing after the error or the 4 byte sequence 
    } 

    void UTF8ToWideImplSSE41(const unsigned char*& cur, const unsigned char* last, wchar32*& dest) noexcept { 
        alignas(16) wchar32 destAligned[16]; 

        while (cur + 16 <= last) { 
            __m128i utf16Low; 
            __m128i utf16High; 
            ui32 dstAdvance = Unpack16BytesIntoUtf16IfNoSurrogats(cur, utf16Low, utf16High); 
 
            if (dstAdvance == 0) { 
                break; 
            } 
 
            //NOTE: we only work in case without surrogat pairs, so we can make simple copying with zeroes in 2 high bytes 
            __m128i utf32_lowlow = _mm_unpacklo_epi16(utf16Low, _mm_set1_epi8(0)); 
            __m128i utf32_lowhigh = _mm_unpackhi_epi16(utf16Low, _mm_set1_epi8(0)); 
            __m128i utf32_highlow = _mm_unpacklo_epi16(utf16High, _mm_set1_epi8(0)); 
            __m128i utf32_highhigh = _mm_unpackhi_epi16(utf16High, _mm_set1_epi8(0)); 
 
            _mm_store_si128(reinterpret_cast<__m128i*>(destAligned), utf32_lowlow); 
            _mm_store_si128(reinterpret_cast<__m128i*>(destAligned) + 1, utf32_lowhigh); 
            _mm_store_si128(reinterpret_cast<__m128i*>(destAligned) + 2, utf32_highlow); 
            _mm_store_si128(reinterpret_cast<__m128i*>(destAligned) + 3, utf32_highhigh); 
 
            memcpy(dest, destAligned, sizeof(__m128i) * 4); 
            dest += dstAdvance; 
        }
        //The rest will be handled sequencially.
        // Possible improvement: go back to the vectorized processing after the error or the 4 byte sequence 
    }
}

#endif