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-- ------------------------------------------------------------------------

-- Copyright (C) 2004 Arif Endro Nugroho

-- All rights reserved.

-- 

-- Redistribution and use in source and binary forms, with or without

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-- 1. Redistributions of source code must retain the above copyright

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-- 2. Redistributions in binary form must reproduce the above copyright

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-- 

-- THIS SOFTWARE IS PROVIDED BY ARIF ENDRO NUGROHO "AS IS" AND ANY EXPRESS

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-- ------------------------------------------------------------------------

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

entity adder_09bit is

   port (

      addend_09bit  : in  bit_vector (08 downto 0);

      augend_09bit  : in  bit_vector (08 downto 0);

      adder09_output: out bit_vector (09 downto 0)

      );

end adder_09bit;

architecture structural of adder_09bit is

   component fulladder

      port (

      addend        : in   bit;

      augend        : in   bit;

      carry_in      : in   bit;

      sum           : out  bit;

      carry         : out  bit

      );

   end component;

signal c00 : bit;

signal c01 : bit;

signal c02 : bit;

signal c03 : bit;

signal c04 : bit;

signal c05 : bit;

signal c06 : bit;

signal c07 : bit;

signal c08 : bit;

signal c09 : bit;

signal over09 : bit;

signal adder09_output_int : bit_vector (08 downto 0);

signal ov  : bit ;

begin

c00                     <= '0';

over09                  <= (addend_09bit (08) xor augend_09bit (08));

ov                      <= ((adder09_output_int (08) and over09) or

                           (c09 and (not (over09))));

adder09_output(08 downto 00) <= adder09_output_int;

adder09_output(09)           <= ov;

fa08 : fulladder

   port map (

      addend     => addend_09bit(08),

      augend     => augend_09bit(08),

      carry_in   => c08,

      sum        => adder09_output_int(08),

      carry      => c09

      );

fa07 : fulladder

   port map (

      addend     => addend_09bit(07),

      augend     => augend_09bit(07),

      carry_in   => c07,

      sum        => adder09_output_int(07),

      carry      => c08

      );

fa06 : fulladder

   port map (

      addend     => addend_09bit(06),

      augend     => augend_09bit(06),

      carry_in   => c06,

      sum        => adder09_output_int(06),

      carry      => c07

      );

fa05 : fulladder

   port map (

      addend     => addend_09bit(05),

      augend     => augend_09bit(05),

      carry_in   => c05,

      sum        => adder09_output_int(05),

      carry      => c06

      );

fa04 : fulladder

   port map (

      addend     => addend_09bit(04),

      augend     => augend_09bit(04),

      carry_in   => c04,

      sum        => adder09_output_int(04),

      carry      => c05

      );

fa03 : fulladder

   port map (

      addend     => addend_09bit(03),

      augend     => augend_09bit(03),

      carry_in   => c03,

      sum        => adder09_output_int(03),

      carry      => c04

      );

fa02 : fulladder

   port map (

      addend     => addend_09bit(02),

      augend     => augend_09bit(02),

      carry_in   => c02,

      sum        => adder09_output_int(02),

      carry      => c03

      );

fa01 : fulladder

   port map (

      addend     => addend_09bit(01),

      augend     => augend_09bit(01),

      carry_in   => c01,

      sum        => adder09_output_int(01),

      carry      => c02

      );

fa00 : fulladder

   port map (

      addend     => addend_09bit(00),

      augend     => augend_09bit(00),

      carry_in   => c00,

      sum        => adder09_output_int(00),

      carry      => c01

      );

end structural;