Subversion Repositories simple_fm_receiver

-- $Id: adder_12bit.vhdl,v 1.4 2008-06-26 06:12:29 arif_endro Exp $

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

-- Title       : Adder 12 bit

-- Project     : FM Receiver 

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

-- File        : adder_12bit.vhdl

-- Author      : "Arif E. Nugroho" <arif_endro@yahoo.com>

-- Created     : 2004/12/01

-- Last update : 

-- Simulators  : 

-- Synthesizers: 

-- Target      : 

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

-- Description : Ripple carry adder 12 bit with output 13 bit

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

-- Copyright (C) 2004 Arif E. Nugroho

-- This VHDL design file is an open design; you can redistribute it and/or

-- modify it and/or implement it after contacting the author

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

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

-- 

--      THIS SOURCE FILE MAY BE USED AND DISTRIBUTED WITHOUT RESTRICTION

-- PROVIDED THAT THIS COPYRIGHT STATEMENT IS NOT REMOVED FROM THE FILE AND THAT

-- ANY DERIVATIVE WORK CONTAINS THE ORIGINAL COPYRIGHT NOTICE AND THE

-- ASSOCIATED DISCLAIMER.

-- 

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

-- 

--      THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

-- IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

-- MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO

-- EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

-- SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

-- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;

-- OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

-- WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

-- OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

-- ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-- 

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

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

entity adder_12bit is

   port (

      addend_12bit  : in  bit_vector (11 downto 0);

      augend_12bit  : in  bit_vector (11 downto 0);

      adder12_output: out bit_vector (12 downto 0)  -- 13bit output

      );

end adder_12bit;

architecture structural of adder_12bit is

   component fulladder

      port (

      addend        : in   bit;

      augend        : in   bit;

      carry_in      : in   bit;

      sum           : out  bit;

      carry         : out  bit

      );

   end component;

-- internal signal

signal over12 : bit;

signal adder12_output_int : bit_vector (11 downto 0);

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 c10 : bit;

signal c11 : bit;

signal c12 : bit;

signal ov  : bit;

begin

c00                     <= '0';

over12                  <= (addend_12bit (11) xor augend_12bit (11));

ov                      <= ((adder12_output_int (11) and over12) or

                           (c12 and (not (over12))));

adder12_output(11 downto 00) <= adder12_output_int;

adder12_output(12)           <= ov;

fa11 : fulladder

   port map (

      addend     => addend_12bit(11),

      augend     => augend_12bit(11),

      carry_in   => c11,

      sum        => adder12_output_int(11),

      carry      => c12

      );

fa10 : fulladder

   port map (

      addend     => addend_12bit(10),

      augend     => augend_12bit(10),

      carry_in   => c10,

      sum        => adder12_output_int(10),

      carry      => c11

      );

fa09 : fulladder

   port map (

      addend     => addend_12bit(09),

      augend     => augend_12bit(09),

      carry_in   => c09,

      sum        => adder12_output_int(09),

      carry      => c10

      );

fa08 : fulladder

   port map (

      addend     => addend_12bit(08),

      augend     => augend_12bit(08),

      carry_in   => c08,

      sum        => adder12_output_int(08),

      carry      => c09

      );

fa07 : fulladder

   port map (

      addend     => addend_12bit(07),

      augend     => augend_12bit(07),

      carry_in   => c07,

      sum        => adder12_output_int(07),

      carry      => c08

      );

fa06 : fulladder

   port map (

      addend     => addend_12bit(06),

      augend     => augend_12bit(06),

      carry_in   => c06,

      sum        => adder12_output_int(06),

      carry      => c07

      );

fa05 : fulladder

   port map (

      addend     => addend_12bit(05),

      augend     => augend_12bit(05),

      carry_in   => c05,

      sum        => adder12_output_int(05),

      carry      => c06

      );

fa04 : fulladder

   port map (

      addend     => addend_12bit(04),

      augend     => augend_12bit(04),

      carry_in   => c04,

      sum        => adder12_output_int(04),

      carry      => c05

      );

fa03 : fulladder

   port map (

      addend     => addend_12bit(03),

      augend     => augend_12bit(03),

      carry_in   => c03,

      sum        => adder12_output_int(03),

      carry      => c04

      );

fa02 : fulladder

   port map (

      addend     => addend_12bit(02),

      augend     => augend_12bit(02),

      carry_in   => c02,

      sum        => adder12_output_int(02),

      carry      => c03

      );

fa01 : fulladder

   port map (

      addend     => addend_12bit(01),

      augend     => augend_12bit(01),

      carry_in   => c01,

      sum        => adder12_output_int(01),

      carry      => c02

      );

fa00 : fulladder

   port map (

      addend     => addend_12bit(00),

      augend     => augend_12bit(00),

      carry_in   => c00,

      sum        => adder12_output_int(00),

      carry      => c01

      );

end structural;