[SOLVED] VHDL: reading text file stops at endfile()

[igaco]

Hello Everyone,

I am implementing a test bench which will load the input stimuli vectors from a text file and save the resulting vector in another text file. While it was rather simple to write in a file, it is not so obvious for me how to read the file.

Below is a shorted part of test bench only to check if it can read the file:

library IEEE;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use std.textio.all;
use ieee.std_logic_textio.all;

entity CARRY_LOOKAHEAD_ADDER_TB is
    generic(
            VECTOR_LENGTH : natural := 98;
            MEMORY_DEPTH  : natural := 32;
            ADDRESS_WIDTH : natural := 6
            );
end entity CARRY_LOOKAHEAD_ADDER_TB;

architecture BEHAVIOURAL of CARRY_LOOKAHEAD_ADDER_TB is
    
    type MEMORY is array (0 to MEMORY_DEPTH - 1) of std_logic_vector(VECTOR_LENGTH - 1 downto 0);
    
    signal CLK : std_logic;
       
    signal TEST_DATA_MEMORY  : MEMORY;

    signal ADDRESS : natural range 0 to (2**ADDRESS_WIDTH - 1);
    signal ADDRESS_NEXT : natural range 0 to (2**ADDRESS_WIDTH - 1);
    signal NUMBER_OF_ERRORS : natural range MEMORY_DEPTH - 1 downto 0;
    
    file   TEST_DATA: text;
               
begin
    
    process
    begin
        CLK <= '1';
        wait for 5 ns;
        CLK <= '0';
        wait for 5 ns;
    end process;
    
    
    CI <= '0';
    
    file_open(TEST_DATA,   "cla_tb_v.txt", read_mode);
            
    process
        variable TEST_VECTOR : line;
        variable MEMORY_WORD : std_logic_vector(VECTOR_LENGTH - 1 downto 0);
    begin
        
        while not endfile(TEST_DATA)loop
            readline(TEST_DATA, TEST_VECTOR);
            read(TEST_VECTOR, MEMORY_WORD);
            TEST_DATA_MEMORY(ADDRESS) <= MEMORY_WORD;
        end loop;
     
        wait;
end process;

end BEHAVIOURAL;

Simulation stops at the line:

while not endfile(TEST_DATA)loop

And thus no data are read from the file.

I checked the status upon the file opening and the status is OPEN_OK. The text file to read is not empty, please see below for a snapshot of the file:

00000000000000000000000000000001011111111111111111111111111110000111111111111111111111111111100100
00000000000000000000000000000001011111111111111111111111111110010111111111111111111111111111101000
00000000000000000000000000000001011111111111111111111111111110100111111111111111111111111111101100
00000000000000000000000000000001011111111111111111111111111110110111111111111111111111111111110000

I definitely do a mistake, but I do not see it. Please advise.

 

[TrickyDicky]

You have the file open procedure outside of a process. It is hitting the while loop before the file is open.

Either open the file at the declaration or move the open procedure inside the process before the while loop.

 

[FvM]

Wrongly placed file_open() statement. Has to go in the process before the loop.

 

[igaco]

Thank you! That closes the question.