原创 【转】4位除法器vhdl程序

4位除法器,vhdl

--
--
--------------------------------------------------------------------------------/
-- DESCRIPTION : Signed divider
-- A (A) input width : 4
-- B (B) input width : 4
-- Q (data_out) output width : 4
-- DIV_BY_0 (DIVz) output active : high
-- Download from : http://www.pld.com.cn
--------------------------------------------------------------------------------/

library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_unsigned.all;

entity fpdiv is
port (
DIVz: out STD_LOGIC;
A: in STD_LOGIC_VECTOR (3 downto 0);
B: in STD_LOGIC_VECTOR (3 downto 0);
data_out: out STD_LOGIC_VECTOR (3 downto 0)
);
end fpdiv;

architecture fpdiv_arch of fpdiv is
signal REMAINDERS0 : STD_LOGIC_VECTOR (5 downto 0);
signal REMAINDERS1 : STD_LOGIC_VECTOR (5 downto 0);
signal REMAINDERS2 : STD_LOGIC_VECTOR (5 downto 0);
signal REMAINDERS3 : STD_LOGIC_VECTOR (5 downto 0);

signal DIVISORS0 : STD_LOGIC_VECTOR (5 downto 0);
signal DIVISORS1 : STD_LOGIC_VECTOR (5 downto 0);
signal DIVISORS2 : STD_LOGIC_VECTOR (5 downto 0);
signal DIVISORS3 : STD_LOGIC_VECTOR (5 downto 0);

signal Q_TEMP : STD_LOGIC_VECTOR (3 downto 0);
signal Z0 : STD_LOGIC_VECTOR (2 downto 0);
signal Z1 : STD_LOGIC_VECTOR (2 downto 0);
signal ZERO : STD_LOGIC;

begin

Z0 <= (others => '0');
Z1 <= (others => '0');
DIVISORS0 <= Z0 & B(2 downto 0);
REMAINDERS3 <= Z1 & A(2 downto 0);

DIVISORS1 <= DIVISORS0(4 downto 0) & '0';
DIVISORS2 <= DIVISORS1(4 downto 0) & '0';
DIVISORS3 <= DIVISORS2(4 downto 0) & '0';

Q_TEMP(0) <= '1' when (REMAINDERS1 >= DIVISORS0) else '0';
Q_TEMP(1) <= '1' when (REMAINDERS2 >= DIVISORS1) else '0';
Q_TEMP(2) <= '1' when (REMAINDERS3 >= DIVISORS2) else '0';
Q_TEMP(3) <= A(3) xor B(3);

REMAINDERS2 <= REMAINDERS3 - DIVISORS2 when Q_TEMP(2) = '1' else REMAINDERS3;
REMAINDERS1 <= REMAINDERS2 - DIVISORS1 when Q_TEMP(1) = '1' else REMAINDERS2;
REMAINDERS0 <= REMAINDERS1 - DIVISORS0 when Q_TEMP(0) = '1' else REMAINDERS1;

ZERO <= '1' when B(2 downto 0) = Z1 else '0';
DIVz <= '1' when ZERO = '1' else '0';
data_out <= (others => '0') when ZERO = '1' else Q_TEMP;
end fpdiv_arch;