Subversion Repositories lxp32

---------------------------------------------------------------------
-- DSP multiplier
--
-- Part of the LXP32 CPU
--
-- Copyright (c) 2016 by Alex I. Kuznetsov
--
-- This multiplier is designed for technologies that provide fast
-- 16x16 multipliers, including most modern FPGA families. One
-- multiplication takes 2 cycles.
---------------------------------------------------------------------
 
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
 
entity lxp32_mul_dsp is
	port(
		clk_i: in std_logic;
		rst_i: in std_logic;
		ce_i: in std_logic;
		op1_i: in std_logic_vector(31 downto 0);
		op2_i: in std_logic_vector(31 downto 0);
		ce_o: out std_logic;
		result_o: out std_logic_vector(31 downto 0)
	);
end entity;
 
architecture rtl of lxp32_mul_dsp is
 
signal pp00: unsigned(31 downto 0);
signal pp01: unsigned(31 downto 0);
signal pp10: unsigned(31 downto 0);
 
signal product: unsigned(31 downto 0);
 
signal ceo: std_logic:='0';
 
begin
 
mul00_inst: entity work.lxp32_mul16x16
	port map(
		clk_i=>clk_i,
		a_i=>op1_i(15 downto 0),
		b_i=>op2_i(15 downto 0),
		unsigned(p_o)=>pp00
	);
 
mul01_inst: entity work.lxp32_mul16x16
	port map(
		clk_i=>clk_i,
		a_i=>op1_i(15 downto 0),
		b_i=>op2_i(31 downto 16),
		unsigned(p_o)=>pp01
	);
 
mul10_inst: entity work.lxp32_mul16x16
	port map(
		clk_i=>clk_i,
		a_i=>op1_i(31 downto 16),
		b_i=>op2_i(15 downto 0),
		unsigned(p_o)=>pp10
	);
 
product(31 downto 16)<=pp00(31 downto 16)+pp01(15 downto 0)+pp10(15 downto 0);
product(15 downto 0)<=pp00(15 downto 0);
result_o<=std_logic_vector(product);
 
process (clk_i) is
begin
	if rising_edge(clk_i) then
		if rst_i='1' then
			ceo<='0';
		else
			ceo<=ce_i;
		end if;
	end if;
end process;
 
ce_o<=ceo;
 
end architecture;