rdkit/Code/DataStructs/base64.cpp

// $Id$
//
// Copyright (c) 2002-2008 greg landrum and rational discovery llc
//
//  @@ All Rights Reserved @@
//  This file is part of the RDKit.
//  The contents are covered by the terms of the BSD license
//  which is included in the file license.txt, found at the root
//  of the RDKit source tree.
//
#include <iostream>
#include <cstring>
#include "base64.h"
// Encoding table from RFC 2045
//
//     Value Encoding  Value Encoding  Value Encoding  Value Encoding
//         0 A            17 R            34 i            51 z
//         1 B            18 S            35 j            52 0
//         2 C            19 T            36 k            53 1
//         3 D            20 U            37 l            54 2
//         4 E            21 V            38 m            55 3
//         5 F            22 W            39 n            56 4
//         6 G            23 X            40 o            57 5
//         7 H            24 Y            41 p            58 6
//         8 I            25 Z            42 q            59 7
//         9 J            26 a            43 r            60 8
//        10 K            27 b            44 s            61 9
//        11 L            28 c            45 t            62 +
//        12 M            29 d            46 u            63 /
//        13 N            30 e            47 v
//        14 O            31 f            48 w         (pad) =
//        15 P            32 g            49 x
//        16 Q            33 h            50 y

const int MaxLineLength=72;

char *Base64Encode(const char *inText,const unsigned int inLen){
  return Base64Encode((const unsigned char *)inText,inLen);
}
  

char *Base64Encode(const unsigned char *inText,const unsigned int inLen){
  // Notes:
  //   - whoever calls us is responsible for free'ing the result we return
  //   - we cheat and don't worry about breaking lines
  static unsigned char transTable[64]={'A','B','C','D','E','F','G','H',
                                       'I','J','K','L','M','N','O','P',
                                       'Q','R','S','T','U','V','W','X',
                                       'Y','Z','a','b','c','d','e','f',
                                       'g','h','i','j','k','l','m','n',
                                       'o','p','q','r','s','t','u','v',
                                       'w','x','y','z','0','1','2','3',
                                       '4','5','6','7','8','9','+','/'};
  
  char *res;
  int resSize;
  resSize = (4*inLen)/3;
  while(resSize % 4) resSize++;
  res = new char[resSize+1];
  unsigned int i = 0;
  int pos = 0;
  while(i < inLen){
    res[pos++]= transTable[inText[i]>>2];
    if( i+1 < inLen){
      res[pos++]= transTable[((inText[i]&3)<<4)|(inText[i+1]>>4)];
      if(i+2 < inLen){
        res[pos++] = transTable[((inText[i+1]&0xF)<<2)|(inText[i+2]>>6)];
        res[pos++] = transTable[inText[i+2]&0x3F];
      } else {
        // single padding
        res[pos++] = transTable[((inText[i+1]&0xF)<<2)];
        res[pos++] = '=';
      }
    } else {
      // double padding
      res[pos++] = transTable[((inText[i]&3)<<4)];
      res[pos++] = '=';
      res[pos++] = '=';
    }
    i += 3;
  }
  res[resSize] = 0;
  return res;
}

char *Base64Decode(const char *inText,unsigned int *size){
  // Notes:
  //   - whoever calls us is responsible for free'ing the result we return

  unsigned char transTable[256];
  int inLen = strlen(inText);

  int i;
  // FIX: we don't really need to build this table here
  for(i= 0;i<255;i++){
    transTable[i]= 0x80;
  }
  for(i='A';i<='Z';i++) transTable[i] = (unsigned char)i-'A';
  for(i='a';i<='z';i++) transTable[i] = (unsigned char)i-'a'+26;
  for(i='0';i<='9';i++) transTable[i] = (unsigned char)i-'0'+52;
  transTable[static_cast<int>('+')]=62;
  transTable[static_cast<int>('/')]=63;

  int outLen = 3*inLen/4;
  char *res = new char[outLen];
  res[outLen-1]=0;
  int pos = 0;
  i = 0;
  // decode 4 bytes at a time
  unsigned char block[4];
  int nInBlock=0;
  while(i < inLen){
    unsigned char c = inText[i];
    
    // above we set 0x80 as the junk marker in the translation table
    if ( !(transTable[c]&0x80) ){
      block[nInBlock++] = transTable[c];
      if( nInBlock == 4 ) {
        // finished a block
        res[pos++] = (block[0]<<2)|(block[1]>>4);
        res[pos++] = (block[1]<<4)|(block[2]>>2);
        res[pos++] = (block[2]<<6)|block[3];
        nInBlock = 0;
      }
    }
    i++;
  }

  // okay, now there can be 2 or 3 chars remaining to be processed
  //  (before the padding)
  if(nInBlock>1){
    res[pos++] = (block[0]<<2)|(block[1]>>4);
    if(nInBlock > 2){
      res[pos++] = (block[1]<<4)|(block[2]>>2);
      res[pos] = (block[2]<<6);
    }
  }
  *size = pos;
  return res;
}