This is my code (to design Carry Look Ahead Adder)
library ieee;
use ieee.std_logic_1164.all;
entity CLAdder is
port(A,B: IN std_logic;
Cin: IN std_logic;
Sum: OUT std_logic_vector(3 DOWNTO 0);
Cout,G,P: OUT std_logic);
end CLAdder;
architecture behavior of CLAdder is
signal carryGen: std_logic_vector(3 DOWNTO 0);
signal carryProp: std_logic_vector(3 DOWNTO 0);
signal Sumation: std_logic_vector(3 DOWNTO 0);
signal carryIns: std_logic_vector(3 DOWNTO 0);
begin -- behavior
Sumation(0) <= A(0) xor B(0) xor Cin;
carryGen(0) <= A(0) and B(0);
carryProp(0) <= A(0) or B(0);
carryIns(0) <= carryGen(0) or (carryProp(0) and Cin);
Sumation(1) <= A(1) xor B(1) xor carryIns(0);
carryGen(1) <= A(1) and B(1);
carryProp(1) <= A(1) or B(1);
carryIns(1) <= carryGen(1) or (carryProp(1) and carryIns(0));
Sumation(2) <= A(2) xor B(2) xor CarryIns(1);
carryGen(2) <= A(2) and B(2);
carryProp(2) <= A(2) or B(2);
carryIns(2) <= carryGen(2) or (carryProp(2) and carryIns(1));
Sumation(3) <= A(3) xor B(3) xor CarryIns(2);
carryGen(3) <= A(3) and B(3);
carryProp(3) <= A(3) or B(3);
carryIns(3) <= carryGen(3) or (carryProp(3) and carryIns(2));
G <= carryGen(3) or (carryGen(2) and carryProp(3)) or (carryGen(1)
and carryProp(2) and carryProp(3)) or (carryGen(0) and carryProp(1) and
carryProp(2) and carryProp(3));
P <= carryProp(0) and carryProp(1) and carryProp(2) and
carryProp(3);
end behavior;
When using vhdlan to verify and check for errors I get 24 errors at each
of the signal assignments in the behavior body going like
Error-[OVBADAPPLIED] Illegal prefix
CLAdder.vhd, 36
BEHAVIOR
carryProp(3) <= A(3) or B(3);
^
Prefix of name cannot be interpreted as a subprogram or array.
This is just one of them. The rest are all the same but for different
assignments. I cannot figure out what is wrong here. Please help.
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I have written a VHDL code for a number of cascaded mux stages. During simulation it is observed that the syntax is succesfull and RTL schematic is generated. But I can't implement the test bench waveform. I'm attaching the code with this. Also attaching the generated RTL scheatic.
REKHA V P wrote: > I have written a VHDL code for a number of cascaded mux stages. Start a NEW thread for a NEW question! And post VHDL code as *.vhdl file. And don't use all the libraries you can find in the universe in one VHDL module:
1 | use IEEE.STD_LOGIC_ARITH.ALL; --- never |
2 | use IEEE.STD_LOGIC_UNSIGNED.ALL; --- ever |
3 | ...
|
4 | use IEEE.numeric_std.all; --- use those three together! |
> But I can't implement the test bench waveform.
What problems do you encounter?
:
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