Class: BitStruct::FloatField

Inherits:
Field
  • Object
show all
Defined in:
lib/bit-struct/float-field.rb

Overview

Class for floats (single and double precision) in network order. Declared with BitStruct.float.

Instance Attribute Summary

Attributes inherited from Field

#default, #display_name, #format, #length, #name, #offset, #options

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Field

#class_name, default, #describe, #initialize, #inspect_in_object, #inspectable?

Constructor Details

This class inherits a constructor from BitStruct::Field

Class Method Details

.class_name ⇒ Object

Used in describe.



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# File 'lib/bit-struct/float-field.rb', line 6

def self.class_name
  @class_name ||= "float"
end

Instance Method Details

#add_accessors_to(cl, attr = name) ⇒ Object

:nodoc:



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# File 'lib/bit-struct/float-field.rb', line 10

def add_accessors_to(cl, attr = name) # :nodoc:
  unless offset % 8 == 0
    raise ArgumentError,
      "Bad offset, #{offset}, for #{self.class} #{name}." +
      " Must be multiple of 8."
  end
  
  unless length == 32 or length == 64
    raise ArgumentError,
      "Bad length, #{length}, for #{self.class} #{name}." +
      " Must be 32 or 64."
  end
  
  offset_byte = offset / 8
  length_byte = length / 8
  last_byte = offset_byte + length_byte - 1
  byte_range = offset_byte..last_byte

  endian = (options[:endian] || options["endian"]).to_s
  case endian
  when "native"
    ctl = case length
      when 32; "f"
      when 64; "d"
    end
  when "little"
    ctl = case length
      when 32; "e"
      when 64; "E"
    end
  when "network", "big", ""
    ctl = case length
      when 32; "g"
      when 64; "G"
    end
  else
    raise ArgumentError,
      "Unrecognized endian option: #{endian.inspect}"
  end
  
  cl.class_eval do
    define_method attr do ||
      self[byte_range].unpack(ctl).first
    end

    define_method "#{attr}=" do |val|
      self[byte_range] = [val].pack(ctl)
    end
  end
end