Subversion Repositories plasma_fpu

-- --------------------------------------------------------------------------

-- >>>>>>>>>>>>>>>>>>>>>>>>>>>> COPYRIGHT NOTICE <<<<<<<<<<<<<<<<<<<<<<<<<<<<

-- --------------------------------------------------------------------------

-- TITLE:       Plasma PROGRAM COUNTER

-- AUTHOR:      Alex Schoenberger (Alex.Schoenberger@ies.tu-darmstadt.de)

-- COMMENT:     This project is based on Plasma CPU core by Steve Rhoads

--

-- www.ies.tu-darmstadt.de

-- TU Darmstadt

-- Institute for Integrated Systems

-- Merckstr. 25

-- 

-- 64283 Darmstadt - GERMANY

-- --------------------------------------------------------------------------

-- PROJECT:       Plasma CPU core with FPU

-- FILENAME:      plasma_pc.vhd

-- --------------------------------------------------------------------------

-- COPYRIGHT: 

--  This project is distributed by GPLv2.0

--  Software placed into the public domain by the author.

--  Software 'as is' without warranty.  Author liable for nothing.

-- --------------------------------------------------------------------------

-- DESCRIPTION:

--    program counter logic, pc-register, imm<->inc mux, control input

--

--    NOT SYNTHESIZABLE

--

----------------------------------------------------------------------------

-- Revision History

-- --------------------------------------------------------------------------

-- Revision   Date    Author     CHANGES

-- 1.0      4/2014    AS         initial

-- --------------------------------------------------------------------------

library IEEE;

   use IEEE.std_logic_1164.ALL;

   use IEEE.numeric_std.ALL;

library PLASMA;

  use PLASMA.plasma_pack.ALL;

entity plasma_pc is

    port(

      control                 : in  t_main_control;

      stall                   : in  std_logic;

      pc_new_value            : in  t_plasma_word;

      pc_imm_in               : in  t_plasma_word;

      pc_out                  : out t_plasma_pc_out

    );

end entity plasma_pc;

architecture structure_plasma_pc of plasma_pc is

  -- pc register

  signal reg_pc               : t_plasma_word  := (others => '0');

  -- pc calculated values

  signal i_pc_inc             : t_plasma_word;

  signal i_pc_branch          : t_plasma_word;

begin

  -- INCREMENTATION

  i_pc_inc      <= std_logic_vector(unsigned(reg_pc) + unsigned(PLASMA_INC_WORD));

  -- BRANCH VALUE

  i_pc_branch   <= std_logic_vector(unsigned(reg_pc) + unsigned(pc_imm_in));

 -- PC REGISTER

pc_register:process( control.clk )

  begin

    if rising_edge( control.clk ) then

      if control.rst = '1' then

        reg_pc          <= PLASMA_ZERO_WORD;

      else

        if stall = '0' then

          reg_pc        <= pc_new_value;

        end if;

      end if;

    end if;

  end process;

  -- OUTPUT

  pc_out.pc_out           <= reg_pc;

  pc_out.pc_out_inc       <= i_pc_inc;

  pc_out.pc_out_branch    <= i_pc_branch;

end architecture structure_plasma_pc;