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Design Languages >> VHDL-AMS >> VHDL code for booth multiplier
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Message started by kalos on Jun 27^th, 2012, 7:44am

Title: VHDL code for booth multiplier
Post by kalos on Jun 27^th, 2012, 7:44am

Hello,
I should realize the VHDL description of a digital multiplier that
realize Booth's algorithm (encoded in 2 bits) for two terms
represented on N and M bits, respectively, and with a result of N + M
bits.

I have attached the 2 files:
1)booth that should implement the booth's algorithm
2)test that should simulate

Are they correct to implement and simulate a booth's multiplier?

I wrote and simulated with ALDEC ACTIVE-HDL Student Edition.
Compile the code and i have 0 Errors, but in the simulation the result
of multiplication is "UUUU" and the WAVEFORM panel is empty. so I
thought that the codes are wrong.

please help me.

1)
^{library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity booths is
GENERIC(k : POSITIVE := 7); --input number word length less one
Port ( a,b : in STD_LOGIC_VECTOR (k downto 0);
mul : out STD_LOGIC_VECTOR (2*k+1 downto 0));
end booths;

architecture Behavioral of booths is

begin

process(a,b)

variable m: std_logic_vector (2*k+1 downto 0);
variable s: std_logic;

begin
m:="00000000"&b;
s:='0';
for i in 0 to k loop
if(m(0)='0' and s='1') then
m(k downto k-3):= m(k downto k-3)+a;
s:=m(0);
m(k-1 downto 0):=m(k downto 1);
elsif(m(0)='1' and s='0') then
m(k downto k-3):= m(k downto k-3)-a;
s:=m(0);
m(k-1 downto 0):=m(k downto 1);
else
s:=m(0);
m(k-1 downto 0):=m(k downto 1);
end if;
end loop;
mul<=m;
end process;
end Behavioral;}

2)
^{library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity Testbench_di_Booth is
end Testbench_di_Booth;
architecture behavior of Testbench_di_Booth is

component booths
GENERIC(k : POSITIVE := 7); --input number word length less one
Port( a,b : in STD_LOGIC_VECTOR (k downto 0);
mul : out STD_LOGIC_VECTOR (2*k+1 downto 0));
end component;

--Inputs
signal A : STD_LOGIC_VECTOR (7 downto 0):= "00000011";
signal B : STD_LOGIC_VECTOR (7 downto 0):= "00000100";
--Outputs
signal MUL : STD_LOGIC_VECTOR(15 downto 0);

begin
--Instantiate the UnitUnder Test (UUT)
uut: booths PORT MAP
(a => A,
b => B,
mul => MUL);

--Stimulus process
stim_proc: process
begin

--insert stimulus here
A<="00000011"; B<="00000100"; wait for 500 fs;
A<="00000110"; B<="00000111"; wait for 500 fs;
A<="00001011"; B<="00000100"; wait for 500 fs;
wait;
end process;
end;}