NSDataAdditions.m

//
//  NSDataAdditions.m
//
// Adapted from Colloquy source code. Original copyright statements follow.
//
// Created by khammond on Mon Oct 29 2001.
// Formatted by Timothy Hatcher on Sun Jul 4 2004.
// Copyright (c) 2001 Kyle Hammond. All rights reserved.
// Original development by Dave Winer.

#import "NSDataAdditions.h"


static char encodingTable[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','+','/' };


@implementation NSData (NSDataAdditions)


- (NSString *) base64EncodingWithLineLength:(NSUInteger) lineLength {
  const unsigned char *bytes = [self bytes];
  NSMutableString *result = [NSMutableString stringWithCapacity:[self length]];
  unsigned long ixtext = 0;
  unsigned long lentext = [self length];
  long ctremaining = 0;
  unsigned char inbuf[3], outbuf[4];
  unsigned short i = 0;
  unsigned short charsonline = 0, ctcopy = 0;
  unsigned long ix = 0;
	
  while( YES ) {
    ctremaining = lentext - ixtext;
    if( ctremaining <= 0 ) break;
    
    for( i = 0; i < 3; i++ ) {
      ix = ixtext + i;
      if( ix < lentext ) inbuf[i] = bytes[ix];
      else inbuf [i] = 0;
    }
    
    outbuf [0] = (inbuf [0] & 0xFC) >> 2;
		outbuf [1] = ((inbuf [0] & 0x03) << 4) | ((inbuf [1] & 0xF0) >> 4);
    outbuf [2] = ((inbuf [1] & 0x0F) << 2) | ((inbuf [2] & 0xC0) >> 6);
    outbuf [3] = inbuf [2] & 0x3F;
    ctcopy = 4;
    
    switch( ctremaining ) {
      case 1:
        ctcopy = 2;
        break;
      case 2:
        ctcopy = 3;
        break;
    }
    
    for( i = 0; i < ctcopy; i++ )
      [result appendFormat:@"%c", encodingTable[outbuf[i]]];
    
    for( i = ctcopy; i < 4; i++ )
      [result appendString:@"="];
    
    ixtext += 3;
    charsonline += 4;
    
    if( lineLength > 0 ) {
      if( charsonline >= lineLength ) {
        charsonline = 0;
        [result appendString:@"\n"];
      }
    }
  }
	
  return [NSString stringWithString:result];
}


@end