--------------------------------------------------------------------------------- Title       : Signed carry-save multiplier-- Project     : VHDL Library of Arithmetic Units--------------------------------------------------------------------------------- File        : MulCsvSgn.vhd-- Author      : Reto Zimmermann  <zimmi@iis.ee.ethz.ch>-- Company     : Integrated Systems Laboratory, ETH Zurich-- Date        : 1998/01/19--------------------------------------------------------------------------------- Copyright (c) 1998 Integrated Systems Laboratory, ETH Zurich--------------------------------------------------------------------------------- Description :-- Multiplier for signed numbers with one input operand and the-- result in carry-save number representation (Brown). First adds two-- numbers, then multiplies the result with the multiplicand without-- performing final addition. Result is only valid if sum of-- carry-save input operands does not overflow.-------------------------------------------------------------------------------library ieee;use ieee.std_logic_1164.all;use ieee.numeric_std.all;library arith_lib;use arith_lib.arith_lib.all;-------------------------------------------------------------------------------entity MulCsvSgn is  generic (widthX : positive := 8;     -- word width of XS, XC (<= widthY)	   widthY : positive := 8;     -- word width of Y	   speed : speedType := fast);  -- performance parameter  port (XS, XC : in std_logic_vector(widthX-1 downto 0);  -- multipliers	Y : in std_logic_vector(widthY-1 downto 0);  -- multiplicand        PS, PC : out std_logic_vector(widthX+widthY-1 downto 0));  -- productend MulCsvSgn;-------------------------------------------------------------------------------architecture Behavioral of MulCsvSgn is  signal XSuns, XCuns : signed(widthX-1 downto 0);  -- signed  signal Yuns : signed(widthY-1 downto 0);  -- signed  signal PSuns : signed(widthX+widthY-1 downto 0);  -- signedbegin  -- type conversion: std_logic_vector -> signed  XSuns <= signed(XS);  XCuns <= signed(XC);  Yuns <= signed(Y);  -- addition and multiplication  PSuns <= (XSuns + XCuns) * Yuns;  -- type conversion: signed -> std_logic_vector  PS <= std_logic_vector(PSuns);  PC <= (others => '0');end Behavioral;-------------------------------------------------------------------------------architecture Structural of MulCsvSgn is 						-- partial products  signal PP : std_logic_vector((widthX+1)*(widthX+widthY)-1 downto 0);						-- intermediate sum/carry bits  signal ST, CT : std_logic_vector(widthX+widthY-1 downto 0); begin  -- generation of partial products  ppGen : AddMulPPGenSgn    generic map (widthX, widthY)    port map (XS, XC, Y, PP);  -- carry-save addition of partial products  csvAdd : AddMopCsv    generic map (widthX+widthY, widthX+1, speed)    port map (PP, PS, PC);end Structural;-------------------------------------------------------------------------------