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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
/**
* @author Peter Boros
* @date 2004/08/20
* @version $Id$
* @file base64.cpp
* @brief Implementation of Base64 class methods
*
*/
#include <iostream>
#include <string>
#include "base64.h"
namespace fsa {
// {{{ Base64::_table, Base64::_padding
const unsigned char Base64::_table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
const unsigned char Base64::_padding = '=';
// }}}
// {{{ Base64::b2n()
inline int Base64::b2n(int b)
{
if (b>='A' && b<='Z')
return b-'A';
else if (b>='a' && b<='z')
return b-'a'+26;
else if (b>='0' && b<='9')
return b-'0'+52;
else if (b=='+')
return 62;
else if (b=='/')
return 63;
else
return -1;
}
// }}}
// {{{ Base64::n2b()
inline int Base64::n2b(int n)
{
if(n<0||n>63)
return -1;
return _table[n];
}
// }}}
// {{{ Base64::decode()
int Base64::decode(const std::string &src, std::string &dest)
{
if(src.length()&0x03){ // source length should be 4*n
dest.resize(0);
return -1;
}
dest.resize(3*(src.length()>>2),'\0');
std::string::size_type i, index = 0;
int s1,s2,s3,s4;
for (i =0; i<src.length(); i+=4) {
s1 = b2n(src[i]);
s2 = b2n(src[i+1]);
s3 = b2n(src[i+2]);
s4 = b2n(src[i+3]);
if(s1<0||s2<0){ // the first two symbols should not be '='
dest.resize(index);
return -1;
}
if(s3<0){ // only one output symbol
dest[index++] = s1<<2 | s2>>4;
if(s4>=0){ // if s3 is '=', s4 should be '=' too
dest.resize(index);
return -1;
}
}
else if(s4<0){ // two symbols
dest[index++] = s1<<2 | s2>>4;
dest[index++] = (s2&0x0f)<<4 | s3>>2;
}
else { // all three present
dest[index++] = s1<<2 | s2>>4;
dest[index++] = (s2&0x0f)<<4 | s3>>2;
dest[index++] = (s3&0x03)<<6 | s4;
}
}
dest.resize(index);
return index;
}
// }}}
// {{{ Base64::encode()
int Base64::encode(const std::string &src, std::string &dest)
{
dest.resize(4*((src.length()+2)/3),'\0');
std::string::size_type i, index = 0;
for(i=0;i+2<src.length();i+=3) {
dest[index++] = n2b(src[i]>>2);
dest[index++] = n2b((src[i]&0x03)<<4 | src[i+1]>>4);
dest[index++] = n2b((src[i+1]&0x0f)<<2 | src[i+2]>>6);
dest[index++] = n2b(src[i+2]&0x3f);
}
if (i<src.length()) { // handle padding
dest[index++] = n2b(src[i]>>2);
if (i<src.length()-1) { // 2 bytes left
dest[index++] = n2b((src[i]&0x03)<<4 | src[i+1]>>4);
dest[index++] = n2b((src[i+1]&0x0f)<<2);
dest[index++] = _padding;
} else { // 1 byte left
dest[index++] = n2b((src[i+1]&0x03)<<4);
dest[index++] = _padding;
dest[index++] = _padding;
}
}
return index;
}
// }}}
} // namespace fsa
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