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  1 /******************************************************************************
  2 *
  3 * Copyright (C) 2009, The Gentee Group. All rights reserved. 
  4 * This file is part of the Gentee open source project - http://www.gentee.com. 
  5 * 
  6 * THIS FILE IS PROVIDED UNDER THE TERMS OF THE GENTEE LICENSE ("AGREEMENT"). 
  7 * ANY USE, REPRODUCTION OR DISTRIBUTION OF THIS FILE CONSTITUTES RECIPIENTS 
  8 * ACCEPTANCE OF THE AGREEMENT.
  9 *
 10 * Author: Alexey Krivonogov ( gentee )
 11 *
 12 ******************************************************************************/
 13 
 14 func uint enbase64( uint u )
 15 {
 16   if u < 26 : return 'A' + u
 17   if u < 52 : return 'a' + ( u-26 )
 18   if u < 62 : return '0' + ( u-52 )
 19   if u == 62 : return '+'
 20   
 21   return '/'
 22 }
 23 
 24 func uint debase64( uint c ) 
 25 {
 26   if c >= 'A' && c <= 'Z' : return c - 'A'
 27   if c >= 'a' && c <= 'z' : return c - 'a' + 26
 28   if c >= '0' && c <= '9' : return c - '0' + 52
 29   if c == '+' : return 62
 30   
 31   return 63
 32 }
 33 
 34 func uint isbase64( uint c )
 35 {
 36    if (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') ||
 37      (c >= '0' && c <= '9') || (c == '+')             ||
 38      (c == '/')             || (c == '=')
 39    {
 40       return 1
 41    }
 42    return 0
 43 }
 44 
 45 method str str.tobase64( str input )
 46 {
 47    uint size i
 48    
 49    this.clear()
 50    
 51    size = *input
 52    
 53    this.reserve( size * 4 / 3 + 4 )
 54         
 55    for i=0, i<size, i+=3
 56    {
 57       uint  b1 b2 b3 b4 b5 b6 b7
 58       
 59       b1 = input[i]
 60       
 61       if i+1 < size : b2 = input[i+1]
 62       
 63       if i+2 < size : b3 = input[i+2]
 64       
 65       b4 = b1>>2
 66       b5 = ((b1&0x3)<<4)|(b2>>4)
 67       b6 = ((b2&0xf)<<2)|(b3>>6)
 68       b7 = b3&0x3f
 69       
 70       this.appendch( enbase64( b4 ))
 71       this.appendch( enbase64( b5 ))
 72       
 73       if i+1 < size : this.appendch( enbase64( b6 ))
 74       else : this.appendch( '=' )
 75       
 76       if i+2 < size : this.appendch( enbase64( b7 ))
 77       else : this.appendch( '=' )
 78    }
 79    return this
 80 }
 81 
 82 method str str.frombase64( str input ) 
 83 {
 84    str stemp
 85    uint k l
 86    
 87    this.clear()
 88    
 89    if !*input : return this
 90 
 91    this.reserve( *input + 4 )
 92    stemp.reserve( *input + 1 )     
 93    fornum k, *input
 94    {
 95       if isbase64( input[k] ) : stemp[l++] = input[k]
 96    } 
 97    stemp.setlen( l )
 98        
 99    for k=0, k<l, k+=4
100    {
101       uint c1='A', c2='A', c3='A', c4='A'
102       uint b1 b2 b3 b4
103       
104       c1 = stemp[ k ]
105       
106       if k+1 < l : c2 = stemp[ k+1 ]
107       if k+2 < l : c3 = stemp[ k+2 ]
108       if k+3 < l : c4 = stemp[ k+3 ]
109       b1= debase64(c1)
110       b2= debase64(c2)
111       b3= debase64(c3)
112       b4= debase64(c4)
113       
114       this.appendch( (b1<<2)|(b2>>4) )
115       
116       if c3 != '=' : this.appendch( ((b2&0xf)<<4)|(b3>>2) )
117       if c4 != '=' : this.appendch( ((b3&0x3)<<6)|b4 )
118    }
119    return this
120 }
121