Module: IrcDH1080::Base64

Defined in:
lib/ircdh1080/base64.rb

Constant Summary collapse

B64 = 
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'.freeze

Class Method Summary collapse

Class Method Details

.decode(str) ⇒ Object 



31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
 
# File 'lib/ircdh1080/base64.rb', line 31

def self.decode(str)
  l = str.bytesize
  return str if l < 2

  buf = [0] * 256
  B64.each_byte.with_index { |x,i| buf[x] = i }

  str.reverse.each_byte do |x,i|
    break if buf[x] == 0
    l -= 1
  end

  return str if l < 2

  d = [0] * l

  i, k = 0, 0

  while true
    break unless k + 1 < l
    d[i] = (buf[str[k].ord] << 2) % 0x100
    d[i] |= buf[str[k+=1].ord] >> 4

    break unless k + 1 < l
    i += 1
    d[i] = (buf[str[k].ord] << 4) % 0x100
    d[i] |= buf[str[k+=1].ord] >> 2

    break unless k + 1 < l
    i += 1
    d[i] = (buf[str[k].ord] << 6) % 0x100
    d[i] |= buf[str[k+=1].ord] % 0x100

    i += 1
    k += 1
  end

  d[0,i].map { |x| x.chr }.join('')
end

.encode(bin) ⇒ Object 



5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
 
# File 'lib/ircdh1080/base64.rb', line 5

def self.encode(bin)
  str = ''

  i, j, t, m = 0, 0, 0, 0x80
  l = bin.bytesize * 8

  while i < l
    t |= 1 unless bin[i>>3].ord & m == 0
    j += 1
    m >>= 1
    m = 0x80 if m == 0

    if j % 6 == 0
      str += B64[t]
      t &= 0
    end

    t = (t << 1) % 0x100
    i += 1
  end

  m = 5 - (j % 6)
  str += B64[(t << m) % 0x100] unless m == 0
  str
end