Class: Flt::C51BCDFormat

Inherits:

BCDFormat

• Object
• FormatBase
• DecimalFormatBase
• BCDFormat
• Flt::C51BCDFormat

Defined in:

lib/float-formats/formats.rb

Overview

C51 (C compiler for the Intel 8051) BCD Floating point formats

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

• .bcd_field?(i) ⇒ Boolean
• .exponent_digits ⇒ Object
• .exponent_radix ⇒ Object

  :nodoc:.

• .minus_sign_value ⇒ Object
• .pack(s, m, e) ⇒ Object
• .unpack(v) ⇒ Object

Methods inherited from BCDFormat

define, pack_fields, total_bits, total_bytes, total_nibbles, unpack_fields

Methods inherited from DecimalFormatBase

decimal_digits_necessary, decimal_digits_stored, decimal_max_exp, decimal_min_exp, define, radix, radix_log, radix_log10, radix_power

Methods inherited from FormatBase

#<=>, arithmetic, arithmetic_type, bias, canonicalized, context, #convert_to, decimal_digits_necessary, decimal_digits_stored, decimal_max_exp, decimal_min_exp, define, 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, 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, radix_power, 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, define, 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

.bcd_field?(i) ⇒ Boolean

Returns:

• (Boolean)

# File 'lib/float-formats/formats.rb', line 563

def self.bcd_field?(i)
  @field_meaning[i]==:significand
end

.exponent_digits ⇒ Object

# File 'lib/float-formats/formats.rb', line 534

def self.exponent_digits
  @fields[:exponent_sign]*4-1
end

.exponent_radix ⇒ Object

:nodoc:

# File 'lib/float-formats/formats.rb', line 531

def self.exponent_radix
  2
end

.minus_sign_value ⇒ Object

# File 'lib/float-formats/formats.rb', line 537

def self.minus_sign_value
  1
end

.pack(s, m, e) ⇒ Object

# File 'lib/float-formats/formats.rb', line 567

def self.pack(s,m,e)
  s = sign_from_unit(s)
  msb = radix_power(@significand_digits-1)
  es = 0    
  if e==:zero
    e = @zero_encoded_exp
    m = 0
  elsif e==:infinity
    e = @infinite_encoded_exp || radix_power(@fields[:exponent])-1
    m = 0
  elsif e==:nan
    e = @infinite_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
    # to do: try to adjust m to keep e in range if out of valid range
    # to do: 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 *= radix
      end      
    end
    if m<msb && @denormal_encoded_exp
      e = @denormal_encoded_exp
    elsif m==0 # => && @denormal_encoded_exp.nil?
      e = 0
    else
      e = encode_exponent(e, :integral_significand)
    end
  end    
  exp_bits = exponent_digits
  e_s = e + (s << exp_bits)
  pack_fields_hash :significand=>m, :exponent_sign=>e_s
end

.unpack(v) ⇒ Object

# File 'lib/float-formats/formats.rb', line 540

def self.unpack(v)
  f = to_fields_hash(v)
  m = f[:significand]
  e_s = f[:exponent_sign]
  exp_bits = exponent_digits
  e = e_s & (2**exp_bits-1)
  s = e_s >> exp_bits
  if m==0
    # +-zero
    e = :zero
  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)
  end
  s = sign_to_unit(s)
  [s,m,e]    
end