Module: Base32H

Extended by:
Base32H
Included in:
Base32H
Defined in:
lib/base32h.rb

Overview

This module provides Base32H encoding and decoding functions.

Constant Summary collapse

VERSION = 
"0.1.1"

Encoders collapse

Decoders collapse

Instance Method Summary collapse

Instance Method Details

#decode(str) ⇒ Integer

Decodes a Base32H number to its integer representation.



130
131
132
133
134
135
136
137
138
139
140
141
 
# File 'lib/base32h.rb', line 130

def decode(str)
  res = str.to_s.chars.reverse.reduce({acc: 0, exp: 0}) do |state, char|
    digit = decode_digit(char)
    if digit.nil?
      state
    else
      {acc: state[:acc] + (digit * 32**state[:exp]),
       exp: state[:exp] + 1}
    end
  end
  res[:acc]
end

#decode_bin(str) ⇒ String

Decodes a Base32H binary into a string of packed unsigned bytes.



149
150
151
152
153
154
155
156
157
158
159
 
# File 'lib/base32h.rb', line 149

def decode_bin(str)
  data = str.chars.reject {|c| decode_digit(c).nil?}
  extra = data.length % 8
  data = (['0'] * (8 - extra)) + data if extra > 0
  out = []
  data.each_slice(8) do |s|
    chunk = u40_to_bytes decode(s.join '')
    out += chunk
  end
  out.pack('C*')
end

#decode_digit(d) ⇒ Integer

Decodes a single Base32H digit to its integer representation. Returns nil if the input is not a Base32H digit.



119
120
121
122
 
# File 'lib/base32h.rb', line 119

def decode_digit(d)
  d = d.to_s
  digits.find_index {|i| i.include? d}
end

#digits ⇒ Array<String>

The complete list of Base32H digits, as an array of strings. The index of the array is the numeric value of the digit(s) in the string at that index. The first character in each string is the “canonical” digit (i.e. the one that Base32H-conformant encoders must emit for that value); all other characters (if present) are “aliases” (i.e. alternate forms of that digit that Base32H-conformant decoders must accept and correctly decode to that value).

Examples:

Base32H.digits[27] #=> 'VvUu'



22
23
24
25
26
27
28
29
30
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
 
# File 'lib/base32h.rb', line 22

def digits
  ['0Oo',
   '1Ii',
   '2',
   '3',
   '4',
   '5Ss',
   '6',
   '7',
   '8',
   '9',
   'Aa',
   'Bb',
   'Cc',
   'Dd',
   'Ee',
   'Ff',
   'Gg',
   'Hh',
   'Jj',
   'Kk',
   'Ll',
   'Mm',
   'Nn',
   'Pp',
   'Qq',
   'Rr',
   'Tt',
   'VvUu',
   'Ww',
   'Xx',
   'Yy',
   'Zz']
end

#encode(int) ⇒ String

Encodes an integer to its Base32H representation.



79
80
81
82
83
84
85
86
87
88
 
# File 'lib/base32h.rb', line 79

def encode(int)
  rem = int.to_i.abs
  out = []
  return '0' if rem == 0
  while rem > 0 do
    out.unshift(encode_digit(rem % 32))
    rem /= 32
  end
  out.join ''
end

#encode_bin(bin) ⇒ String

Encodes a (binary) string to its Base32H representation.



96
97
98
99
100
101
102
103
104
105
106
 
# File 'lib/base32h.rb', line 96

def encode_bin(bin)
  data = bin.unpack('C*')
  extra = data.length % 5
  data = ([0] * (5 - extra)) + data if extra > 0
  out = []
  data.each_slice(5) do |s|
    chunk = bytes_to_u40 s
    out.push encode(chunk).rjust(8, '0')
  end
  out.join ''
end

#encode_digit(d) ⇒ String, NilClass

Encodes an integer between 0 and 31 (inclusive) to its Base32H representation. Returns nil for input values outside that range.



67
68
69
70
71
 
# File 'lib/base32h.rb', line 67

def encode_digit(d)
  d = d.to_i
  return nil unless (0..31).include? d
  digits[d][0]
end