Subversion Repositories versatile_fft

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

-- Title      : icpx

-- Project    : DP RAM based FFT processor

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

-- File       : icpx_pkg.vhd

-- Author     : Wojciech Zabolotny  wzab01<at>gmail.com

-- Company    : 

-- License    : BSD

-- Created    : 2014-01-18

-- Platform   : 

-- Standard   : VHDL'93

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

-- Description: This package defines the format used to store complex numbers

--              In this implementation we store numbers from range <-2.0, 2.0)

--              scaled to signed integers with width of ICPX_WIDTH (including

--              the sign bit)

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

-- Copyright (c) 2014 

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

-- Revisions  :

-- Date        Version  Author  Description

-- 2014-01-18  1.0      wzab    Created

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

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

use ieee.math_real.all;

use ieee.math_complex.all;

library work;

use work.fft_len.all;

package icpx is

  -- Definition below is generated in the fft_len package

  --constant ICPX_WIDTH : integer := 16;

  -- constant defining the size of std_logic_vector

  -- needed to store the number

  constant ICPX_BV_LEN : integer := ICPX_WIDTH * 2;

  type icpx_number is record

    Re : signed(ICPX_WIDTH-1 downto 0);

    Im : signed(ICPX_WIDTH-1 downto 0);

  end record;

  -- conversion functions

  function icpx2stlv (

    constant din : icpx_number)

    return std_logic_vector;

  function stlv2icpx (

    constant din : std_logic_vector)

    return icpx_number;

  function cplx2icpx (

    constant din : complex)

    return icpx_number;

  function icpx_zero

    return icpx_number;

end icpx;

package body icpx is

  function icpx2stlv (

    constant din : icpx_number)

    return std_logic_vector is

    variable vres : std_logic_vector(2*ICPX_WIDTH-1 downto 0) :=

      (others => '0');

  begin  -- icpx2stlv

    vres := std_logic_vector(din.re) & std_logic_vector(din.im);

    return vres;

  end icpx2stlv;

  function stlv2icpx (

    constant din : std_logic_vector)

    return icpx_number is

    variable vres : ICPX_NUMBER := icpx_zero;

  begin  -- stlv2icpx

    vres.Re := signed(din(2*ICPX_WIDTH-1 downto ICPX_WIDTH));

    vres.Im := signed(din(ICPX_WIDTH-1 downto 0));

    return vres;

  end stlv2icpx;

  function cplx2icpx (

    constant din : complex)

    return icpx_number is

    variable vres : ICPX_NUMBER := icpx_zero;

  begin  -- cplx2icpx

    vres.Re := to_signed(integer(din.Re*(2.0**(ICPX_WIDTH-2))), ICPX_WIDTH);

    vres.Im := to_signed(integer(din.Im*(2.0**(ICPX_WIDTH-2))), ICPX_WIDTH);

    return vres;

  end cplx2icpx;

  function icpx_zero

    return icpx_number is

    variable vres : ICPX_NUMBER;

  begin  -- icpx_zero

    vres.Re := (others => '0');

    vres.Im := (others => '0');

    return vres;

  end icpx_zero;

end icpx;