从2进制文件读取一个UTF8字符串 ReadUTF8 ,跨平台

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string HSReadData::ReadUTF8()
{
    
    int utflen = ReadShort() & 0xffff;
    wstring str;
    str.resize(utflen);
    vector<char> bytes;
    bytes.resize(utflen);
    for (int i=0;i<utflen;++i)
    {
        bytes[i] = this->ReadByte();
    }

    int ch1, ch2, ch3;
    int length = 0;
    int index = 0;

    while(length < utflen)
    {
        ch1 = (int) bytes[length] & 0xff;
        switch(ch1 >> 4)
        {
        case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
            /* 0xxxxxxx*/
            length++;
            str[index++] = (wchar_t)ch1;
            break;
        case 12: case 13:
            /* 110x xxxx   10xx xxxx*/
            length += 2;
            if(length > utflen)
            {
                return "Error code -1";
            }

            ch2 = (int)bytes[length - 1];
            if((ch2 & 0xC0) != 0x80)
            {
                return "Error code -1";
            }

            str[index++] = (wchar_t)(((ch1 & 0x1F) << 6) | (ch2 & 0x3F));
            break;
        case 14:
            /* 1110 xxxx  10xx xxxx  10xx xxxx */
            length += 3;
            if(length > utflen)
            {
                return "Error code -1";
            }

            ch2 = (int)bytes[length - 2];
            ch3 = (int)bytes[length - 1];

            if(((ch2 & 0xC0) != 0x80) || ((ch3 & 0xC0) != 0x80))
            {
                return "Error code -1";
            }
            str[index++] = (wchar_t)(((ch1 & 0x0F) << 12) | ((ch2 & 0x3F) << 6) | ((ch3 & 0x3F) << 0));
            break;
        default:
            /* 10xx xxxx,  1111 xxxx */
            return "Error code -1";
        }
    }
    string text = HSTool::GetStringWithWstring(str);
    
    return text;
}

short  HSReadData::ReadShort()
{
    int b1 = Fgetc();
    int b2 = Fgetc();
    b1 &= 0xff;
    b2 &= 0xff;
    if (b1 == -1 || b2 == -1)
    {
        HSMessageBox("HSReadData @ ReadShort  throw -1 ");
    }
    int value = (b1 << 8) | (b2 << 0);
    return (short) value;
}

char  HSReadData::ReadByte()
{
    int b1 = Fgetc();
    b1 &= 0xff;
    if (b1 == -1)
    {
        HSMessageBox("SPX3 @ ReadByte  throw -1 ");
    }
    int value = b1 & 0xff;
    //CCLog("ReadByte : %d",b1);
    return (char) value;
}

std::string HSTool::GetStringWithWstring( const wstring& ws )
{
//     string curLocale = setlocale(LC_ALL, NULL); // curLocale = "C";
//     setlocale(LC_ALL, "chs"); 
//     const wchar_t* _Source = ws.c_str();
//     size_t _Dsize = 2 * ws.size() + 1;
//     char *_Dest = new char[_Dsize];
//     memset(_Dest,0,_Dsize);
//     wcstombs(_Dest,_Source,_Dsize);
//     string result = _Dest;
//     delete []_Dest;
//     setlocale(LC_ALL, curLocale.c_str());
    string ret;

    ret.resize(ws.size());

    for(size_t i = 0; i < ws.size(); ++i)
    {
        ret[i] = (string::value_type)ws[i];
    }

    return ret;
    return ret;
}

wstring HSTool::GetWstringWithString( const std::string& s )
{
//     std::string curLocale = setlocale(LC_ALL, NULL); // curLocale = "C";
//     setlocale(LC_ALL, "chs"); 
//     const char* _Source = s.c_str();
//     size_t _Dsize = s.size() + 1;
//     wchar_t *_Dest = new wchar_t[_Dsize];
//     wmemset(_Dest, 0, _Dsize);
//     mbstowcs(_Dest,_Source,_Dsize);
//     std::wstring result = _Dest;
//     delete []_Dest;
//     setlocale(LC_ALL, curLocale.c_str());
    wstring ret;

    ret.resize(s.size());

    for(size_t i = 0; i < s.size(); ++i)
    {
        ret[i] = (wstring::value_type)s[i];
    }

    return ret;
}