Module: Flt::IEEE

Defined in:
lib/float-formats/formats.rb

Overview

Helper methods to define IEEE 754r formats

Class Method Summary collapse

Class Method Details

.binary(name, parameters) ⇒ Object

Define an IEEE binary format by passing parameters in a hash; :significand and :exponent are used to defined the fields, optional parameters may follow.



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# File 'lib/float-formats/formats.rb', line 22

def self.binary(name, parameters)
  significand_bits = parameters[:significand]
  exponent_bits = parameters[:exponent]
  Flt.define(name,{
    :base=>BinaryFormat,
    :fields=>[:significand,significand_bits,:exponent,exponent_bits,:sign,1], 
    :bias=>2**(exponent_bits-1)-1, :bias_mode=>:scientific_significand,
    :hidden_bit=>true,
    :endianness=>:little_endian, :round=>:half_even,
    :gradual_underflow=>true, :infinity=>true, :nan=>true
  }.merge(parameters))
end

.decimal(name, parameters) ⇒ Object

Define an IEEE decimal format by passing parameters in a hash; :significand and :exponent are used to defined the fields, optional parameters may follow.



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# File 'lib/float-formats/formats.rb', line 45

def self.decimal(name,parameters)
  significand_continuation_bits = parameters[:significand]
  exponent_continuation_bits = parameters[:exponent]
  Flt.define(name,{    
    :base=>DPDFormat,
    :fields=>[:significand_continuation,significand_continuation_bits,:exponent_continuation,exponent_continuation_bits,:combination,5,:sign,1],
    :normalized=>false,
    :endianness=>:big_endian,
    :gradual_underflow=>true, :infinity=>true, :nan=>true,
    :round=>:half_even
  }.merge(parameters))
end

.interchange_binary(name, width_in_bits, options = {}) ⇒ Object

Define an IEEE binary interchange format given its width in bits



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# File 'lib/float-formats/formats.rb', line 36

def self.interchange_binary(name,width_in_bits, options={})
  raise "Invalid IEEE binary interchange format definition: size (#{width_in_bits}) is not valid" unless (width_in_bits%32)==0 && (width_in_bits/32)>=4
  p = width_in_bits - (4*Math.log(width_in_bits)/Math.log(2)).round.to_i + 13
  binary(name,{:significand=>p-1, :exponent=>width_in_bits-p}.merge(options))
end

.interchange_decimal(name, width_in_bits, options = {}) ⇒ Object

Define an IEEE decimal interchange format given its width in bits



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# File 'lib/float-formats/formats.rb', line 59

def self.interchange_decimal(name,width_in_bits, options={})
  raise "Invalid IEEE decimal interchange format definition: size (#{width_in_bits}) is not valid" unless (width_in_bits%32)==0
  p = width_in_bits*9/32 - 2
  t = (p-1)*10/3
  w = width_in_bits - t - 6
  decimal(name,{:significand=>t, :exponent=>w}.merge(options))
end