Subversion Repositories plasma_fpu

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

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

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

-- TITLE:       Plasma FPU comparator

-- AUTHORS:     Maximilian Reuter (maximilian.reuter@fs-etit.de)

--              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_fpu_comparator.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

--    

--

--    NOT SYNTHESIZABLE

--

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

-- Revision History

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

-- Revision   Date    Author     CHANGES

-- 1.0       4/2015    MR         initial

-- 2.0       5/2015    AS         changed to plasma coding style 

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

library IEEE;

  use IEEE.std_logic_1164.ALL;

  use IEEE.numeric_std.ALL;

library FLOATFIXLIB;

  use FLOATFIXLIB.fixed_float_types.all;

  use FLOATFIXLIB.float_pkg.all;

library PLASMA;

  use PLASMA.mips_instruction_set.ALL;

  use PLASMA.plasma_pack.ALL;

entity plasma_fpu_comparator is

  port (

    comp_a_in                 : in  t_plasma_dword;

    comp_b_in                 : in  t_plasma_dword;

    fpu_ctrl                  : in  t_fpu_ctrl;

    comp_out                  : out std_logic

  );

end entity plasma_fpu_comparator;

architecture behav_plasma_fpu_comparator of plasma_fpu_comparator is

begin

  process( comp_a_in, comp_b_in, fpu_ctrl )

    variable a_in     : float64;

    variable b_in     : float64;

    variable bool_cc  : Boolean;

  begin

    --

    -- convert input

    --

    if fpu_ctrl.double = '1' then

      a_in := Float64( comp_a_in );

      b_in := Float64( comp_b_in );

    else

      a_in := to_Float64( Float32( comp_a_in(31 downto 0)));

      b_in := to_Float64( Float32( comp_b_in(31 downto 0)));

    end if;

    --

    -- default values

    --

    bool_cc   := False;

    comp_out  <= '0';

    --

    -- partially implemented comparator functions

    --

    if fpu_ctrl.operation(5 downto 4) = "11" then

    case fpu_ctrl.operation is

      when MIPS_FUNC_FMT_C_F    =>

      when MIPS_FUNC_FMT_C_UN   =>

      when MIPS_FUNC_FMT_C_EQ   => bool_cc := a_in = b_in;

      when MIPS_FUNC_FMT_C_UEQ  =>

      when MIPS_FUNC_FMT_C_OLT  => bool_cc := a_in < b_in;

      when MIPS_FUNC_FMT_C_ULT  =>

      when MIPS_FUNC_FMT_C_OLE  =>

      when MIPS_FUNC_FMT_C_ULE  => bool_cc := not (a_in > b_in);

      when MIPS_FUNC_FMT_C_SF   => bool_cc := (a_in < b_in) or (a_in = b_in);

      when MIPS_FUNC_FMT_C_NGLE =>

      when MIPS_FUNC_FMT_C_SEQ  => bool_cc := a_in = b_in;

      when MIPS_FUNC_FMT_C_NGL  =>

      when MIPS_FUNC_FMT_C_LT   => bool_cc := a_in < b_in;

      when MIPS_FUNC_FMT_C_NGE  => bool_cc := (a_in > b_in) or (a_in = b_in);

      when MIPS_FUNC_FMT_C_LE   => bool_cc := (a_in < b_in) or (a_in = b_in);

      when MIPS_FUNC_FMT_C_NGT  => bool_cc := not (a_in > b_in);

      when others               => report "WARNING: Unknown FPU comparator command" & sv2string( fpu_ctrl.operation);

    end case;

    end if;

    --

    -- comparator output

    --

    if bool_cc then comp_out <= '1'; end if;

  end process;

end architecture behav_plasma_fpu_comparator;