CODEWITHSUNDEEP
vhdlhdl
Abhishek V. Pai
Abhishek V. Pai

Reputation: 351

Syntax error in if statement in vhdl

I am new to VHDL. I am trying out a code to find whether a bit vector is is even r not (using hamming weight of the bit vector). The code I wrote is:

entity hw_mod is
generic(
bits:integer  );
port (
inp : in std_logic_vector((bits-1) downto 0;
   cout : out std_logic );
end entity hw_mod

 architecture hw_arch of hw_mod is
begin

 process(inp)
 variable count : Integer:=0;

begin
    labelloop: for i in 0 to (bits-1) loop
                 if(inp(i)=='1') then
                   count:= count+1;
                         end if;
                      end loop;
                   if ((count mod 2)== '0') then
                       cout:=1;
                   else
           cout:=0;
           end if;
 end process;
   end hw_arch;

the error I keep getting is "near "=": syntax error in two places.

Upvotes: 0

Views: 2037

Answers (2)

Philippe
Philippe

Reputation: 3730

Several problems. Use an editor that checks your syntax while you type.

  • Parentheses are not matched.
  • You are missing some semicolons,
  • you use C-style comparisons (== instead of =)
  • variable assignments where you need signals (:= instead of <=)

enter image description here

Upvotes: 1

Stingray
Stingray

Reputation: 92

I checked your code: - the generic was not ok
- cout is a signal, so it needs <=
- := is only for variables

It gives no errors, but still there are latches. Variables need to be initalized before using. 

LIBRARY ieee;  
    USE ieee.std_logic_1164.all;  
    USE ieee.numeric_std.all;  
entity hw_mod is  
generic(  
    bits : integer range 0 to 3 := 3);   
port (  
    inp : in std_logic_vector((bits-1) downto 0);  
    cout : out std_logic );  
end entity hw_mod;  

architecture hw_arch of hw_mod is  
begin  
    process(inp)  
    variable count : Integer:=0;  
    begin  
        labelloop:   
            for i in 0 to (bits-1) loop  
                if(inp(i)='1') then
                    count:= count+1;
                end if;  
            end loop;  
            if ((count mod 2)= 0) then  
                cout <= '1';  
            else  
                cout <= '0';  
            end if;  
    end process;  
end hw_arch;

Upvotes: 0

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