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-- Copyright 2015, Jürgen Defurne

--

-- This file is part of the Experimental Unstable CPU System.

--

-- The Experimental Unstable CPU System Is free software: you can redistribute

-- it and/or modify it under the terms of the GNU Lesser General Public License

-- as published by the Free Software Foundation, either version 3 of the

-- License, or (at your option) any later version.

--

-- The Experimental Unstable CPU System is distributed in the hope that it will

-- be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of

-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser

-- General Public License for more details.

--

-- You should have received a copy of the GNU Lesser General Public License

-- along with Experimental Unstable CPU System. If not, see

-- http://www.gnu.org/licenses/lgpl.txt.

LIBRARY std;

USE std.textio.ALL;

USE work.exp_io.ALL;

ENTITY file_reader IS

END ENTITY file_reader;

ARCHITECTURE Imperative OF file_reader IS

  -- This provides a hard coded input file.

  -- This is opened when the program starts

  FILE input_file_1 : TEXT OPEN READ_MODE IS "test_input.txt";

  FILE std_out      : TEXT OPEN WRITE_MODE IS "STD_OUTPUT";

  -- These files could also be declared in the process that reads them. Then

  -- they need to be opened by using file_open()

BEGIN  -- ARCHITECTURE Imperative

  read_file : PROCESS IS

    VARIABLE input_line : LINE;

  BEGIN  -- PROCESS read_file

    -- The endfile() function tests if the end of the passed file has been

    -- reached.

    IF NOT endfile(input_file_1) THEN

      -- readline() reads a line from a file

      readline(input_file_1, input_line);

      writeline(std_out, input_line);

    ELSE

      write(input_line,test_f("Z"));

      writeline(std_out, input_line);

      WAIT;

    END IF;

  END PROCESS read_file;

  -- Files are declared by using FILE, in addition to SIGNALs and VARIABLEs.

  -- Since Xilinx XST only knows the type TEXT for file, it is of no use to try

  -- other types.

  -- When a file is declared in the ARCHITECTURE, then it is automatically opened.

  -- When a file is declared in a PROCESS, then the file can be opened by using

  -- the file_open() procedure.

  -- The contents of files are read into a VARIABLE of type LINE.

  -- Standard input and output must be declared as normal files, but with the

  -- file names "STD_INPUT" and "STD_OUTPUT".

END ARCHITECTURE Imperative;