Class: Flt::BinaryFormat

Inherits:

FieldsInBitsFormatBase

• Object
• FormatBase
• FieldsInBitsFormatBase
• Flt::BinaryFormat

Defined in:

lib/float-formats/classes.rb

Overview

Binary floating point formats

Direct Known Subclasses

CDCFormat

Constant Summary

Constants included from Flt

APPLE, IEEE_128, IEEE_128_BE, IEEE_DEC128, IEEE_DEC32, IEEE_DEC64, IEEE_DOUBLE, IEEE_D_BE, IEEE_EXTENDED, IEEE_HALF, IEEE_H_BE, IEEE_QUAD, IEEE_Q_BE, IEEE_SINGLE, IEEE_S_BE, IEEE_X_BE, IEEE_binaryx, RPL, RPL_X

Instance Attribute Summary

Attributes inherited from FormatBase

#exponent, #sign, #significand

Class Method Summary

• .define(params) ⇒ Object

  a hidden bit can be define with :hidden_bit.

• .pack(s, m, e) ⇒ Object
• .radix ⇒ Object

  :stopdoc:.

• .radix_power(n) ⇒ Object
• .total_bits ⇒ Object
• .total_bytes ⇒ Object
• .unpack(v) ⇒ Object

Methods inherited from FieldsInBitsFormatBase

fields_radix, pack_fields, unpack_fields

Methods inherited from FormatBase

#<=>, arithmetic, arithmetic_type, bias, canonicalized, context, #convert_to, decimal_digits_necessary, decimal_digits_stored, decimal_max_exp, decimal_min_exp, endianness, epsilon, #form_class, #fp_format, from, from_bits, from_bits_text, from_bytes, from_hex, from_number, from_text, gradual_underflow?, half_epsilon, #infinite?, infinity, #initialize, join, max_value, maximum_integral_significand, min_normalized_value, min_value, minimum_normalized_integral_significand, #minus, minus_sign_value, nan, #nan?, #next_minus, #next_plus, nio_read_neutral, #nio_write_neutral, #normal?, num, num_class, pack_fields_hash, radix_log, radix_log10, radix_max_exp, radix_min_exp, rounding_mode, sign_from_unit, sign_to_unit, #split, strict_epsilon, #subnormal?, switch_sign_value, #to, #to_a, #to_bits, #to_bits_text, #to_bytes, #to_hex, #to_num, #to_text, #ulp, unpack_fields_hash, zero, #zero?

Methods included from Flt

#*, #+, #-, #-@, #/, bcd2dpd, bitnot, convert_bytes, dbl_from_float, dbl_from_text, dbl_to_float, dpd2bcd, dpd_to_hexbcd, float_bin, float_dec, float_from_integral_sign_significand_exponent, float_from_integral_significand_exponent, float_shortest_dec, float_significant_dec, float_to_integral_sign_significand_exponent, float_to_integral_significand_exponent, hex_from_float, hex_to_float, hexbcd_to_dpd, sgl_from_float, sgl_from_text, sgl_to_float

Constructor Details

This class inherits a constructor from Flt::FormatBase

Class Method Details

.define(params) ⇒ Object

a hidden bit can be define with :hidden_bit

# File 'lib/float-formats/classes.rb', line 1458

def self.define(params)
  @hidden_bit = params[:hidden_bit]
  @hidden_bit = true if @hidden_bit.nil?

  @splitted_fields_supported = true
  define_fields params[:fields]

  @significand_digits = @fields[:significand] + (@hidden_bit ? 1 : 0)
  super  params

end

.pack(s, m, e) ⇒ Object

# File 'lib/float-formats/classes.rb', line 1519

def self.pack(s,m,e)
  msb = radix_power(@significand_digits-1)

  if e==:zero
    e = @zero_encoded_exp || @denormal_encoded_exp
    m = 0
  elsif e==:infinity
    e = @infinite_encoded_exp || radix_power(@fields[:exponent])-1
    m = 0
  elsif e==:nan
    e = @nan_encoded_exp || radix_power(@fields[:exponent])-1
    s = minus_sign_value # ?
    m = radix_power(@significand_digits-2) if m==0
  elsif e==:denormal
    e = @denormal_encoded_exp
  else
    # TODO: try to adjust m to keep e in range if out of valid range
    # TODO: reduce m and adjust e if m too big

    min_exp = radix_min_exp(:integral_significand)
    if m>0
      while m<msb && e>min_exp
        e -= 1
        m <<= 1 # m *= radix
      end
    end
    if m<msb && @denormal_encoded_exp
      e = @denormal_encoded_exp
    elsif m==0 # => && @denormal_encoded_exp.nil?
      e = 0
    else
      m &= (radix_power(@significand_digits-1)-1) if @hidden_bit
      e = encode_exponent(e, :integral_significand)
    end
  end
  s = sign_from_unit(s)
  m,e = neg_significand_exponent(0,m,e) if s%2==1
  pack_fields_hash :sign=>s, :significand=>m, :exponent=>e
end

.radix ⇒ Object

:stopdoc:

# File 'lib/float-formats/classes.rb', line 1472

def self.radix
  2
end

.radix_power(n) ⇒ Object

# File 'lib/float-formats/classes.rb', line 1475

def self.radix_power(n)
  if n>=0
    1 << n
  else
    2**n
  end
end

.total_bits ⇒ Object

# File 'lib/float-formats/classes.rb', line 1483

def self.total_bits
  @field_lengths.inject{|x,y| x+y}
end

.total_bytes ⇒ Object

# File 'lib/float-formats/classes.rb', line 1486

def self.total_bytes
  (total_bits+7)/8
end

.unpack(v) ⇒ Object

# File 'lib/float-formats/classes.rb', line 1490

def self.unpack(v)
  f = unpack_fields_hash(v)
  m = f[:significand]
  e = f[:exponent]
  s = f[:sign]
  m,e = neg_significand_exponent(s,m,e) if s%2==1
  if (m==0 && !@hidden_bit) ||
     (m==0 && (e==@zero_encoded_exp || e==@denormal_encoded_exp)) ||
     (e==@zero_encoded_exp && @min_encoded_exp>@zero_encoded_exp && !@denormal_encoded_exp)
     # +-zero
     e = :zero
  elsif (e==@denormal_encoded_exp)
    e = decode_exponent(e, :integral_significand)
    e += 1 if @denormal_encoded_exp==@zero_encoded_exp
  elsif @infinite_encoded_exp && e==@infinite_encoded_exp && m==0
    # +-inifinity
    e = :infinity
  elsif @nan_encoded_exp && e==@nan_encoded_exp && m!=0
    # NaN
    e = :nan
  else
    # normalized number
    e = decode_exponent(e, :integral_significand)
    m |= radix_power(@significand_digits-1) if @hidden_bit
  end
  s = sign_to_unit(s)
  [s,m,e]
end