Class: Pangrid::Checksum

Inherits:
Object
  • Object
show all
Defined in:
lib/pangrid/plugins/acrosslite.rb

Overview

CRC checksum for binary format

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(seed) ⇒ Checksum

Returns a new instance of Checksum.



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# File 'lib/pangrid/plugins/acrosslite.rb', line 27

def initialize(seed)
  @sum = seed
end

Instance Attribute Details

#sum ⇒ Object

Returns the value of attribute sum.



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# File 'lib/pangrid/plugins/acrosslite.rb', line 19

def sum
  @sum
end

Class Method Details

.of_string(s) ⇒ Object 



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# File 'lib/pangrid/plugins/acrosslite.rb', line 21

def self.of_string s
  c = self.new(0)
  c.add_string s
  c.sum
end

Instance Method Details

#add_char(b) ⇒ Object 



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# File 'lib/pangrid/plugins/acrosslite.rb', line 31

def add_char(b)
  low = sum & 0x0001
  @sum = sum >> 1
  @sum = sum | 0x8000 if low == 1
  @sum = (sum + b) & 0xffff
end

#add_string(s) ⇒ Object 



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# File 'lib/pangrid/plugins/acrosslite.rb', line 38

def add_string(s)
  s.bytes.map {|b| add_char b}
end

#add_string_0(s) ⇒ Object 



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# File 'lib/pangrid/plugins/acrosslite.rb', line 42

def add_string_0(s)
  add_string (s + "\0") unless s.empty?
end