public static bool TryParse(ReadOnlySpan<char> value, out bool result)
{
      if (IsTrueStringIgnoreCase(value))  //關(guān)注IsTrueStringIgnoreCase
      {
            result = true;
            return true;
      }
      if (IsFalseStringIgnoreCase(value)) //關(guān)注和IsFalseStringIgnoreCase
      {
            result = false;
            return true;
      }
      value = TrimWhiteSpaceAndNull(value);
      if (IsTrueStringIgnoreCase(value))
      {
            result = true;
            return true;
      }
      if (IsFalseStringIgnoreCase(value))
      {
            result = false;
            return true;
      }
      result = false;
      return false;
}

//只保留IsTrueStringIgnoreCase和IsFalseStringIgnoreCase
internal static bool IsTrueStringIgnoreCase(ReadOnlySpan<char> value)
{
    // "true" as a ulong, each char |'d with 0x0020 for case-insensitivity
    // 先判斷cpu支持大小端模式, 采用無符號long類型存儲4個字符的ASCII碼值 小端:: 65→e 75→u   72→r  74→t  
    // 將value轉(zhuǎn)為byte數(shù)組,讀取為ulong類型,然后或運(yùn)算, 0x20為十六進(jìn)制 是十進(jìn)制32  或運(yùn)算:: A | 32 = a  這樣就不用區(qū)分大小寫
    // 0x0020002000200020為4個0x20,因?yàn)橹狄粯?不區(qū)分大小端
    ulong true_val = BitConverter.IsLittleEndian ? 0x65007500720074ul : 0x74007200750065ul;
    return value.Length == 4 &&
            (MemoryMarshal.Read<ulong>(MemoryMarshal.AsBytes(value)) | 0x0020002000200020) == true_val;
}

internal static bool IsFalseStringIgnoreCase(ReadOnlySpan<char> value)
{
    // "fals" as a ulong, each char |'d with 0x0020 for case-insensitivity
    // ulong類型只能存4個字符,所以存儲 "fals"這4個字符  73→s  6c→l 61→a 66→f 
    // 最后1個字符進(jìn)行與0x20進(jìn)行或運(yùn)算,得到小寫字符和'e'進(jìn)行判斷
    ulong fals_val = BitConverter.IsLittleEndian ? 0x73006C00610066ul : 0x660061006C0073ul;
    return value.Length == 5 &&
            (((MemoryMarshal.Read<ulong>(MemoryMarshal.AsBytes(value)) | 0x0020002000200020) == fals_val) &
            ((value[4] | 0x20) == 'e'));
}

public bool TryFormat(Span<char> destination, out int charsWritten)
{
      if (m_value) //為真
      {
            if ((uint)destination.Length > 3u)
            {
                   //進(jìn)行4次賦值操作
                  destination[0] = 'T';
                  destination[1] = 'r';
                  destination[2] = 'u';
                  destination[3] = 'e';
                  charsWritten = 4;
                  return true;
            }
      }
      else if ((uint)destination.Length > 4u)  //不為真
      {
             //進(jìn)行5次賦值操作
            destination[0] = 'F';
            destination[1] = 'a';
            destination[2] = 'l';
            destination[3] = 's';
            destination[4] = 'e';
            charsWritten = 5;
            return true;
      }
      charsWritten = 0;
      return false;
}

public bool TryFormat(Span<char> destination, out int charsWritten)
{
    if (m_value)
    {
        if ((uint)destination.Length > 3) // uint cast, per https://github.com/dotnet/runtime/issues/10596
        {
            //先判斷cpu支持大小端模式, 采用無符號long類型存儲4個字符的ASCII碼值 小端:: 65→e 75→u   72→r  74→t  
            //將Span<char>轉(zhuǎn)為byte數(shù)組,將true_val寫入,減少賦值的次數(shù),與.Net 6中4次賦值操作,這里只有1次
            ulong true_val = BitConverter.IsLittleEndian ? 0x65007500720054ul : 0x54007200750065ul; // "True"
            MemoryMarshal.Write<ulong>(MemoryMarshal.AsBytes(destination), ref true_val);
            charsWritten = 4;
            return true;
        }
    }
    else
    {
        if ((uint)destination.Length > 4)
        {
            //不為真時,進(jìn)行2次賦值操作 第1次 ulong 只能存4個字符, 第2次通過下標(biāo)賦值為'e'
            ulong fals_val = BitConverter.IsLittleEndian ? 0x73006C00610046ul : 0x460061006C0073ul; // "Fals"
            MemoryMarshal.Write<ulong>(MemoryMarshal.AsBytes(destination), ref fals_val);
            destination[4] = 'e';
            charsWritten = 5;
            return true;
        }
    }

    charsWritten = 0;
    return false;
}

#define LOWER(c)     (unsigned char)(c | 0x20)