irc/ArchBlackmann/base64.cpp

   1 // base64.cpp
   2
   3 #include "base64.h"
   4
   5 using std::string;
   6
   7 static const char* alfabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
   8
   9 string base64_encode ( const string& sInput )
  10 {
  11         unsigned char x=0, topbit=0;
  12         int v=0;
  13         string sOutput;
  14         do
  15         {
  16                 if ( topbit < 6 )
  17                 {
  18                         x++;
  19                         v <<= 8;
  20                         if ( x <= sInput.length() ) v += sInput[x-1];
  21                         topbit += 8;
  22                 }
  23                 topbit -= 6;
  24                 if ( x > sInput.length() && !v )
  25                         break;
  26                 sOutput += alfabet[(v >> topbit) & 63];
  27                 v &= (1 << topbit) - 1;
  28         } while ( x < sInput.length() || v );
  29         int eq = (8 - (sOutput.length() % 4)) % 4;
  30         while ( eq-- )
  31                 sOutput += '=';
  32         return sOutput;
  33 }
  34
  35 string base64_decode ( const string& sInput )
  36 {
  37         unsigned char x=0, topbit=0;
  38         int v=0, inlen = sInput.length();
  39         string sOutput;
  40         while ( inlen && sInput[inlen-1] == '=' )
  41                 inlen--;
  42         do
  43         {
  44                 while ( topbit < 8 )
  45                 {
  46                         x++;
  47                         v <<= 6;
  48                         if ( x <= inlen ) v += (strchr(alfabet, sInput[x-1]) - alfabet);
  49                         topbit += 6;
  50                 }
  51                 topbit -= 8;
  52                 if ( x > inlen && !v )
  53                         break;
  54                 sOutput += (char)((v >> topbit) & 255);
  55                 v &= ((1 << topbit) - 1);
  56         } while ( x <= inlen || v );
  57         return sOutput;
  58 }