base64helper.cpp

股票分析系统源码

////////////////////////////////////////////////////////////////////////////////
// General utilities : Base64 encode/decode helper class
//
// Copyright (c) 2003 by Morning
// http://morningspace.51.net
// mailto:[e-mail]
//
// Permission to use, copy, modify, distribute and sell this program for any 
// purpose is hereby granted without fee, provided that the above copyright 
// notice appear in all copies and that both that copyright notice and this 
// permission notice appear in supporting documentation.
//
// It is provided "as is" without express or implied warranty.
////////////////////////////////////////////////////////////////////////////////

#include "StdAfx.h"
#include "Base64Helper.h"
//
namespace MUtils {

const std::string Base64Helper::_base64_encode_chars = 
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

const char Base64Helper::_base64_decode_chars[] = 
{
    -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, 62, -1, -1, -1, 63,
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
    -1,  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, -1, -1, -1, -1, -1,
    -1, 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, -1, -1, -1, -1, -1
};

std::string Base64Helper::encode(const std::string in_str)
{
    std::string out_str;
    unsigned char c1, c2, c3;
    int i = 0;
    int len = in_str.length();

    while ( i<len )
    {
        // read the first byte
        c1 = in_str[i++];
        if ( i==len )       // pad with "="
        {
            out_str += _base64_encode_chars[ c1>>2 ];
            out_str += _base64_encode_chars[ (c1&0x3)<<4 ];
            out_str += "==";
            break;
        }

        // read the second byte
        c2 = in_str[i++];
        if ( i==len )       // pad with "="
        {
            out_str += _base64_encode_chars[ c1>>2 ];
            out_str += _base64_encode_chars[ ((c1&0x3)<<4) | ((c2&0xF0)>>4) ];
            out_str += _base64_encode_chars[ (c2&0xF)<<2 ];
            out_str += "=";
            break;
        }

        // read the third byte
        c3 = in_str[i++];
        // convert into four bytes string
        out_str += _base64_encode_chars[ c1>>2 ];
        out_str += _base64_encode_chars[ ((c1&0x3)<<4) | ((c2&0xF0)>>4) ];
        out_str += _base64_encode_chars[ ((c2&0xF)<<2) | ((c3&0xC0)>>6) ];
        out_str += _base64_encode_chars[ c3&0x3F ];
    }

    return out_str;
}

std::string Base64Helper::decode(const std::string in_str)
{
    std::string out_str;
    char c1, c2, c3, c4;
    int i = 0;
    int len = in_str.length();

    while ( i<len)
    {
        // read the first byte
        do {
            c1 = _base64_decode_chars[ in_str[i++] ];
        } while ( i<len && c1==-1);

        if ( c1==-1)
            break;

        // read the second byte
        do {
            c2 = _base64_decode_chars[ in_str[i++] ];
        } while ( i<len && c2==-1);

        if ( c2==-1 )
            break;

        // assamble the first byte
        out_str += char( (c1<<2) | ((c2&0x30)>>4) );

        // read the third byte
        do {
            c3 = in_str[i++];
            if ( c3==61 )       // meet with "=", break
                return out_str;
            c3 = _base64_decode_chars[ c3 ];
        } while ( i<len && c3==-1);

        if ( c3==-1 )
            break;

        // assamble the second byte
        out_str += char( ((c2&0XF)<<4) | ((c3&0x3C)>>2) );

        // read the fourth byte
        do {
            c4 = in_str[i++];
            if ( c4==61 )       // meet with "=", break
                return out_str;
            c4 = _base64_decode_chars[ c4 ];
        } while ( i<len && c4==-1 );

        if ( c4==-1 )
            break;

        // assamble the third byte
        out_str += char( ((c3&0x03)<<6) | c4 );
    }

    return out_str;
}

} // namespace MUtils