Base64.cpp

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/**********************************************************************
 
 Audacity: A Digital Audio Editor
 
 @file Base64.cpp
 
 @brief Base64 encode/decode (extracted from Audacity sources)
 
 **********************************************************************/
 
#include "Base64.h"
#include <wx/string.h>
 
// Base64 en/decoding
//
// Original routines marked as public domain and found at:
//
// http://en.wikibooks.org/wiki/Algorithm_implementation/Miscellaneous/Base64
//
 
// Lookup table for encoding
const static wxChar cset[] = wxT("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/");
const static char padc = wxT('=');
 
wxString Base64::Encode(const void *in, int len)
{
   auto p = static_cast<const unsigned char*>(in);
   wxString out;
 
   unsigned long temp;
   for (int i = 0; i < len / 3; i++)
   {
      temp  = (*p++) << 16; //Convert to big endian
      temp += (*p++) << 8;
      temp += (*p++);
      out += cset[(temp & 0x00FC0000) >> 18];
      out += cset[(temp & 0x0003F000) >> 12];
      out += cset[(temp & 0x00000FC0) >> 6];
      out += cset[(temp & 0x0000003F)];
   }
 
   switch (len % 3)
   {
      case 1:
         temp  = (*p++) << 16; //Convert to big endian
         out += cset[(temp & 0x00FC0000) >> 18];
         out += cset[(temp & 0x0003F000) >> 12];
         out += padc;
         out += padc;
      break;
 
      case 2:
         temp  = (*p++) << 16; //Convert to big endian
         temp += (*p++) << 8;
         out += cset[(temp & 0x00FC0000) >> 18];
         out += cset[(temp & 0x0003F000) >> 12];
         out += cset[(temp & 0x00000FC0) >> 6];
         out += padc;
      break;
   }
 
   return out;
}
 
int Base64::Decode(const wxString &in, void *out)
{
   const auto len = in.length();
   auto p = static_cast<unsigned char*>(out);
 
   if (len % 4)  //Sanity check
   {
      return 0;
   }
 
   //const char *a = in.mb_str();
   //Setup a vector to hold the result
   unsigned long temp = 0; //Holds decoded quanta
   size_t i = 0;
   while (i < len)
   {
      for (int quantumPosition = 0; quantumPosition < 4; quantumPosition++)
      {
         unsigned char c = in[i];
         temp <<= 6;
 
         if (c >= 0x41 && c <= 0x5A)
         {
            temp |= c - 0x41;
         }
         else if (c >= 0x61 && c <= 0x7A)
         {
            temp |= c - 0x47;
         }
         else if (c >= 0x30 && c <= 0x39)
         {
            temp |= c + 0x04;
         }
         else if (c == 0x2B)
         {
            temp |= 0x3E;
         }
         else if (c == 0x2F)
         {
            temp |= 0x3F;
         }
         else if (c == padc)
         {
            switch (len - i)
            {
               case 1: //One pad character
                  *p++ = (temp >> 16) & 0x000000FF;
                  *p++ = (temp >> 8) & 0x000000FF;
                  return p - static_cast<unsigned char*>(out);
               case 2: //Two pad characters
                  *p++ = (temp >> 10) & 0x000000FF;
                  return p - static_cast<unsigned char*>(out);
            }
         }
         i++;
      }
      *p++ = (temp >> 16) & 0x000000FF;
      *p++ = (temp >> 8) & 0x000000FF;
      *p++ = temp & 0x000000FF;
   }
 
   return p - static_cast<unsigned char*>(out);
}