Class: FixedPoint::Number

Inherits:
Object
  • Object
show all
Defined in:
lib/fixed_point/number.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(number, input_format = Format.new(1,12,20), decimal_mark = ".") ⇒ Number

Returns a new instance of Number.



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# File 'lib/fixed_point/number.rb', line 16

def initialize(number, input_format=Format.new(1,12,20), decimal_mark=".")
  @source       = number
  @format       = input_format
  @decimal_mark = decimal_mark

  @warnings     = false

  #Now construct values based on config data
  @quantised    = quantise_value( source )
end

Instance Attribute Details

#format ⇒ Object (readonly)

Returns the value of attribute format.



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# File 'lib/fixed_point/number.rb', line 5

def format
  @format
end

#source ⇒ Object (readonly)

Input value



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# File 'lib/fixed_point/number.rb', line 4

def source
  @source
end

Instance Method Details

#bin ⇒ Object

Alias for binary.



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# File 'lib/fixed_point/number.rb', line 46

def bin
  binary
end

#binary ⇒ Object

Calculate Binary format



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# File 'lib/fixed_point/number.rb', line 87

def binary
  #Take signed quantised value and create binary string
  if (@quantised < 0) and frac.nonzero?
    # Fractional numbers not negative
    # So the integer part is 1 less than other wise would be and add 1+frac
    ret_bin_int = (@format.max_int_unsigned + to_i  )
    frac_value  = 1 + frac
  end

  if (@quantised < 0) and frac.zero?
    ret_bin_int = (@format.max_int_unsigned + to_i + 1 )
    frac_value  = frac
  end

  if @quantised >= 0
    ret_bin_int = self.to_i
    frac_value  = frac
  end

  ## Convert to binary String and extend to correct length
  ret_bin_int = ret_bin_int.to_s(2).rjust(@format.int_bits, '0')

  ## Normalise Fractional (fractional bits shifted to appear as integer)
  ret_bin_frac = Integer(frac_value * 2**@format.frac_bits)
  ret_bin_frac = ret_bin_frac.to_s(2).rjust(@format.frac_bits, '0' ) 

  #Decide if we need to add Decimal( Binary ) Point
  if @format.frac_bits > 0
    binary_string = ret_bin_int +  @decimal_mark + ret_bin_frac
  else 
    binary_string = ret_bin_int
  end

  return binary_string
end

#binary=(text) ⇒ Object

Methods to set value from fixed point format



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# File 'lib/fixed_point/number.rb', line 142

def binary=(text)
  if text.match(/([01]*)(.?)([01]*)/ )
    set_int       = $1
    int_bits      = $1.size 

    @decimal_mark = $2
    set_frac      = $3
    frac_bits     = $3.size

    #TODO Warn if the number of bits supplied does not match @format 

    ## This should now create a new format type
    #  Do not change the Signed format as can not detect that from bit pattern
    @format = Format.new(@format.signed, int_bits, frac_bits)

    @source  = binary_to_float( set_int, set_frac)
    
    ## Set the Quantised value
    @quantised = @source

    return binary
  else 
    $stderr.puts "ERROR invalid binary input \(#{text}\)"
    return nil
  end
end

#frac ⇒ Object

Fractional section of quantised value.



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# File 'lib/fixed_point/number.rb', line 76

def frac
  (@quantised - to_i)
end

#hex ⇒ Object

Alias for hexadecimal.



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# File 'lib/fixed_point/number.rb', line 51

def hex
  hexadecimal
end

#hex=(text) ⇒ Object

TODO this feature for version 0.2.1



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# File 'lib/fixed_point/number.rb', line 170

def hex=( text )
  ## Hex numbers do not get delimited
  ## TODO Strip leading \d+'h (Verilog denominator)
  
  if text.match(/(0x)?([0-9a-fA-F]*)/ )
    # Convert Hex to integer
    #   integer to binary string
    binary_bits = $2.to_i(16).to_s(2)
    
    #Ensure min length (for reliability manipulating string)
    binary_bits = binary_bits.rjust(text.size*4, '0')
   
    if @format.frac_bits > 0
      set_frac = binary_bits[-@format.frac_bits, @format.frac_bits]
    else
      set_frac = ""
    end
    
    set_int  = binary_bits[-(@format.width)..-(@format.frac_bits+1)]

    ## Was the input word length too Long
    oversized_bits = binary_bits.size - @format.width 
    if oversized_bits > 0
      # give a semantic name to the discarded bits
      discarded_bits = binary_bits[0,oversized_bits]

      #If data (mix of 1 and 0) contained in the discarded bits raise Error
      unless all_bits_the_same discarded_bits   
        $stderr.puts %{Error using hex=#{text}, format is #{@format.width}, truncated data is #{discarded_bits}
  The MSBs seem to contain data they are not just 0 or 1 padded}
      end
    end

    @source    = binary_to_float( set_int, set_frac )
    @quantised = @source

  else
    $stderr.puts "ERROR invalid hex input \(#{text}\)"
    return nil
  end
end

#hexadecimal ⇒ Object

Calculate Hexadecimal format



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# File 'lib/fixed_point/number.rb', line 126

def hexadecimal
  #Clean Binary code (remove _ - . etc)
  clean_binary = to_b.scan(/[01]/).join('')

  #Convert to unsigned int then to hex
  hex          = clean_binary.to_i(2).to_s(16)
  hex_chars    = (@format.width/4.0).ceil

  ## Extend to the correct length
  ## Negative numbers will already have MSBs this if for small +VE
  return hex.rjust(hex_chars, '0')
end

#overflow? ⇒ Boolean

Numerical overflow flag

Returns:

  • (Boolean) 


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# File 'lib/fixed_point/number.rb', line 30

def overflow?
  @overflow
end

#to_b ⇒ Object

Alias for binary.



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# File 'lib/fixed_point/number.rb', line 56

def to_b
  binary
end

#to_f ⇒ Object

Floating Point form of the quantised value.



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# File 'lib/fixed_point/number.rb', line 66

def to_f
  @quantised
end

#to_h ⇒ Object

Alias for hexadecimal.



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# File 'lib/fixed_point/number.rb', line 61

def to_h
  hexadecimal
end

#to_i ⇒ Object

Integer, integer part of quantised value.



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# File 'lib/fixed_point/number.rb', line 71

def to_i
  @quantised.to_i
end

#to_s ⇒ Object 



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# File 'lib/fixed_point/number.rb', line 80

def to_s
  to_f.to_s
end

#underflow? ⇒ Boolean

Numerical underflow flag

Returns:

  • (Boolean) 


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# File 'lib/fixed_point/number.rb', line 37

def underflow?
  @underflow
end

#warnings(val = true) ⇒ Object

TODO def log def log2



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# File 'lib/fixed_point/number.rb', line 217

def warnings( val=true )
  @warnings = val
end