string Encode(const char* Data,int DataByte)
{
//---------编码表
const char EncodeTable[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; //0-63
//---------
string str;
unsigned int Tmp[4]={0}; //初始化，无符号移位
for(int i=0;i<(int)(DataByte / 3);i++)
{
Tmp[1] = *Data++;
Tmp[2] = *Data++;
Tmp[3] = *Data++;
str+= EncodeTable[(Tmp[1] & 0xFC) >> 2]; //取前六位
str+= EncodeTable[(((Tmp[1] & 0x03) << 4) | ((Tmp[2] & 0xF0)>> 4)) & 0x3F]; //取后两位 | 取前四位
str+= EncodeTable[(((Tmp[2] & 0x0F) << 2) | ((Tmp[3] & 0xC0)>> 6)) & 0x3F]; //取前四位 | 取前两位
str+= EncodeTable[Tmp[3] & 0x3F]; //剩下六位
}
//对剩余数据进行编码
int Mod=DataByte % 3;
if(Mod==1)
{
Tmp[1] = *Data;
str+= EncodeTable[(Tmp[1] & 0xFC) >> 2]; //取前六位
str+= EncodeTable[((Tmp[1] & 0x03) << 4)]; //剩下两位
str+= "=="; //补==
}
else if(Mod==2)
{
Tmp[1] = *Data++;
Tmp[2] = *Data;
str+= EncodeTable[(Tmp[1] & 0xFC) >> 2]; //取前六位
str+= EncodeTable[((Tmp[1] & 0x03) << 4) | ((Tmp[2] & 0xF0) >> 4)]; //取后两位 | 取前四位
str+= EncodeTable[((Tmp[2] & 0x0F) << 2)]; //取剩下四位
str+= "="; //补=
}
return str;
}
string Decode(const char* Data,int DataByte)
{
//------解码表
const char DecodeTable[] =
{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //21
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 62, 0, 0, 0, 63, //47
52,53, 54, 55, 56, 57, 58, 59, 60, 61, //48-58 '0'-'9'
0, 0, 0, 0, 0, 0, 0, //64
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13,
14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // 'A'-'Z'
0,0,0,0,0,0,
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // 'a'-'z'
};
//---------
string str;
unsigned char tmp[3]={0}; //无符号移位
for(int i=0;i<(int)(DataByte / 4);i++)
{
tmp[0]=*Data++;
tmp[1]=*Data++;
tmp[2]=*Data++;
tmp[3]=*Data++;
str+=((DecodeTable[tmp[0]] & 0x3F) << 2) | ((DecodeTable[tmp[1]] & 0xF0) >> 4) ;
str+=((DecodeTable[tmp[1]] & 0x0F) << 4) | ((DecodeTable[tmp[2]] & 0x3C) >>2);
str+=((DecodeTable[tmp[2]] & 0x03) << 6) | (DecodeTable[tmp[3]] & 0x3F);
}
return str;
}
