Utf8Array.Compare実装

[finphie]

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[finphie]

GetUtf8SequenceLength

https://sharplab.io/#v2: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

using System;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;

int A1(byte value)
{
    if (value < 0x80)
    {
        return 1;
    }

    if ((value & 0xE0) == 0xC0)
    {
        return 2;
    }

    if ((value & 0xF0) == 0xE0)
    {
        return 3;
    }

    if ((value & 0xF8) == 0xF0)
    {
        return 4;
    }

    return default;
}


int A2(byte value)
{
    ReadOnlySpan<byte>  TrailingBytesForUTF8 = new byte[]
    {
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
        2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
        3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
        4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
    };
     
    ref var table = ref MemoryMarshal.GetReference(TrailingBytesForUTF8);
    return Unsafe.Add(ref table, (nint)value) + 1;
}

<Program>$.<<Main>$>g__A1|0_0(Byte)
    L0000: movzx edx, cl
    L0003: cmp edx, 0x80
    L0009: jge short L0011
    L000b: mov eax, 1
    L0010: ret
    L0011: mov eax, edx
    L0013: and eax, 0xe0
    L0018: cmp eax, 0xc0
    L001d: jne short L0025
    L001f: mov eax, 2
    L0024: ret
    L0025: mov eax, edx
    L0027: and eax, 0xf0
    L002c: cmp eax, 0xe0
    L0031: jne short L0039
    L0033: mov eax, 3
    L0038: ret
    L0039: and edx, 0xf8
    L003f: cmp edx, 0xf0
    L0045: jne short L004e
    L0047: mov eax, 4
    L004c: jmp short L0050
    L004e: xor eax, eax
    L0050: ret

<Program>$.<<Main>$>g__A2|0_1(Byte)
    L0000: movzx eax, cl
    L0003: mov rdx, 0x19063c30954
    L000d: movzx eax, byte ptr [rax+rdx]
    L0011: ret