VC UTF-8转换到Unicode的函数

short Utf8TextBytes (const unsigned char *mstr)
{
    short textbytes = 0;
    if (mstr == 0)
    {                           //Returns 0 if mstr contains a null string or if there is
        return 0;               //no valid character in mstr.
    }
    /* code checking.
because all unicode used now is lower than 0xffff, only 1~3 bytes UTF-8 has means, 
the other length will not be dealed with in other functions */
    if (((*mstr) & 0x80) == 0)
    {
        textbytes = 1;          //0xxxxxxx, normal ASCII code
    }
    else if ((((*mstr) & 0xe0) == 0xc0) && (((*(mstr + 1)) & 0xc0) == 0x80))
    {
        if (((*mstr) & 0xfe) == 0xc0) //1100,000x is illegal data,
        {
            textbytes = 0;
        }
        else
        {
            textbytes = 2;      //110xxxxx 10xxxxxx
        }
    }
    else if ((((*mstr) & 0xf0) == 0xe0) && (((*(mstr + 1)) & 0xc0) == 0x80) && (((*(mstr + 2)) & 0xc0) == 0x80))
    {
        if ((*mstr == (char) 0xe0) && (((*(mstr + 1)) & 0xe0) == 0x80)) //1110,0000,100x,xxxx is illegal data
        {
            textbytes = 0;
        }
        else
        {
            textbytes = 3;      //1110xxxx 10xxxxxx 10xxxxxx
        }
    }
    else if ((((*mstr) & 0xf8) == 0xf0) && (((*(mstr + 1)) & 0xc0) == 0x80) && (((*(mstr + 2)) & 0xc0) == 0x80)
             && (((*(mstr + 3)) & 0xc0) == 0x80))
    {
        if (((*mstr) == (char) 0xf0) && (((*(mstr + 1)) & 0xf0) == 0x80)) // 1111,0000,1000,xxxx is illegal data
        {
            textbytes = 0;
        }
        else
        {
            textbytes = 4;      // 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
        }
    }
    else if ((((*mstr) & 0xfc) == 0xf8) && (((*(mstr + 1)) & 0xc0) == 0x80) &&
             (((*(mstr + 2)) & 0xc0) == 0x80) && (((*(mstr + 3)) & 0xc0) == 0x80) && (((*(mstr + 4)) & 0xc0) == 0x80))
    {
        if ((*mstr == (char) 0xf8) && (((*(mstr + 1)) & 0xf8) == 0x80)) //1111,1000,1000,0xxx is illegal data
        {
            textbytes = 0;
        }
        else
        {
            textbytes = 5;      //111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
        }
    }
    else if ((((*mstr) & 0xfe) == 0xfc) && (((*(mstr + 1)) & 0xc0) == 0x80) &&
             (((*(mstr + 2)) & 0xc0) == 0x80) && (((*(mstr + 3)) & 0xc0) == 0x80) && (((*(mstr + 4)) & 0xc0) == 0x80) &&
             (((*(mstr + 5)) & 0xc0) == 0x80))
    {
        if ((*mstr == (char) 0xfc) && (((*(mstr + 1)) & 0xfc) == 0x80)) //1111,1100,1000,00xx is illegal data
        {
            textbytes = 0;
        }
        else
        {
            textbytes = 6;      //1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
        }
    }
    else
    {
        textbytes = 0;          //illegal formal, return 0
    }

    return textbytes;
}

    utf8Str     --UTF8 source string
    utf8strlen    --max utf8 length
    unStr     -- Unicode Str dest
    unMaxlen  --Unicode 最大个数 
    return :  --实际转化的长度
short FromUTF8ToUnicode (unsigned char *utf8Str, short utf8StrLen, WORD * unStr, unsigned short unMaxLen)

{
short zen_han, len_dest;
unsigned char *p_src;
unsigned char utf8_len = 0;
len_dest = 0;
p_src = (unsigned char *) (utf8Str);

/* limit the total bytes of the *mstr */
if (utf8StrLen <= 0)
{
return (0);
}

/* converting at here utf8_len <= utf8StrLen 改为 utf8_len < utf8StrLen*/
for (; (*p_src != 0x00) && (len_dest <= unMaxLen - 1) && (utf8_len < utf8StrLen);)
{
zen_han = Utf8TextBytes ((const unsigned char *) p_src);
if (zen_han == 1)       //ASCII, just add 0x00 at beginning
{
(*unStr) = *(p_src);
unStr++;
p_src++;
utf8_len++;
len_dest += 1;
}
else if (zen_han == 2)
{
*unStr = (((((*p_src) >> 2) & (unsigned char) 0x07)) & 0x00ff) << 8;
*unStr |= ((((*p_src) << 6) | ((*(p_src + 1)) & (unsigned char) 0x3f))) & 0x00ff;
unStr++;
p_src += 2;
utf8_len += 2;
len_dest += 1;

}
else if (zen_han == 3)
{
*(unStr) = ((((*(p_src)) << 4) | (((*(p_src + 1)) >> 2) & 0x0f)) & 0x00ff) << 8;

*unStr |= ((((*(p_src + 1)) << 6) | ((*(p_src + 2)) & (unsigned char) 0x3f))) & 0x00ff;
unStr++;
p_src += 3;
utf8_len += 3;
len_dest += 1;
}
else if (zen_han == 4)  //
{
*unStr = (*(p_src)) & 0x7;
for (int i=1; i<4;i++)
{
*unStr <<= 6; // 左移6位后与后续字节的有效位值"位或"赋值
*unStr = *unStr | ((*(p_src + i)) & 0x3f);//先与后或
}
unStr++;
p_src += 4;
utf8_len += 4;
len_dest += 1;
}
else if (zen_han == 5)  //
{
*unStr = (*(p_src)) & 0x3;
for (int i=1; i<5;i++)
{
*unStr <<= 6; // 左移6位后与后续字节的有效位值"位或"赋值
*unStr = *unStr | ((*(p_src + i)) & 0x3f);//先与后或
}
unStr++;
p_src += 5;
utf8_len += 5;
len_dest += 1;
}
else if (zen_han == 6)  //
{
*unStr = (*(p_src)) & 0x1;
for (int i=1; i<6;i++)
{
*unStr <<= 6; // 左移6位后与后续字节的有效位值"位或"赋值
*unStr = *unStr | ((*(p_src + i)) & 0x3f);//先与后或
}
unStr++;
p_src += 6;
utf8_len += 6;
len_dest += 1;
}
else                    //treated as illegal character, search the next character
{
p_src++;
utf8_len++;
}
}
*(unStr) = 0x0000;
return (len_dest);

}