doubt regarding port mapping

[tulip]

My code is

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity mod_exp is
Port ( T : in std_logic_vector(7 downto 0);
E : in std_logic_vector(7 downto 0);
M0 : in std_logic_vector(7 downto 0);
P,G1,G2 : buffer std_logic_vector(7 downto 0);
Gout : buffer std_logic_vector(7 downto 0)
);
end mod_exp;

architecture structural of mod_exp is

component str
port(A : in std_logic_vector(7 downto 0);
B : in std_logic_vector(7 downto 0);
M : in std_logic_vector(7 downto 0);
R : buffer std_logic_vector(7 downto 0)
);
end component;
signal C,one:std_logic_vector(7 downto 0);
begin
C<='00000100'; one<='00000001';
r0:str port map(C,T,M0,P); --line 1
r1:str port map(C,one,M0,G1); --line 2
r2:str port map(G1,G1,M0,Gout); --line 3

end structural;

IN THE ABOVE CODE, I GOT THE OUTPUTS P AND G1 IN LINE 1 AND LINE 2. BUT I
AM NOT GETTING THE OUTPUT Gout IN LINE 3. I AM GETTING 0XXXXXXX AS OUTPUT
FOR Gout. CAN ANYONE SUGGEST THE SOLUTION.

 

[rickman]

My code is

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity mod_exp is
Port ( T : in std_logic_vector(7 downto 0);
E : in std_logic_vector(7 downto 0);
M0 : in std_logic_vector(7 downto 0);
P,G1,G2 : buffer std_logic_vector(7 downto 0);
Gout : buffer std_logic_vector(7 downto 0)
);
end mod_exp;

architecture structural of mod_exp is

component str
port(A : in std_logic_vector(7 downto 0);
B : in std_logic_vector(7 downto 0);
M : in std_logic_vector(7 downto 0);
R : buffer std_logic_vector(7 downto 0)
);
end component;
signal C,one:std_logic_vector(7 downto 0);
begin
C<='00000100'; one<='00000001';
r0:str port map(C,T,M0,P); --line 1
r1:str port map(C,one,M0,G1); --line 2
r2:str port map(G1,G1,M0,Gout); --line 3

end structural;

IN THE ABOVE CODE, I GOT THE OUTPUTS P AND G1 IN LINE 1 AND LINE 2. BUT I
AM NOT GETTING THE OUTPUT Gout IN LINE 3. I AM GETTING 0XXXXXXX AS OUTPUT
FOR Gout. CAN ANYONE SUGGEST THE SOLUTION.

You don't say what the values of G1 or T are. You also did not provide
the code for the str module. What does str do?

While we are at it, I don't see where E is used and I don't see where G2
is assigned a value.

--

Rick "rickman" Collins

(e-mail address removed)
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