-------------------------------------------------------------------------------
-- Title      : Package: GTU Signal Types
-- Project    : Prototype implementation of the GTU of the Alice TRD Experiment
-------------------------------------------------------------------------------
-- File       : gtu_types.vhd
-- Author     : Jan de Cuveland  <cuveland@kip.uni-heidelberg.de>
-- Company    : 
-- Last update: 2004/04/27
-- Platform   : 
-------------------------------------------------------------------------------
-- This is a prototype implementation of the Global Tracking Unit (GTU)
-- of the Alice TRD detector.
-------------------------------------------------------------------------------
-- Description: 
-------------------------------------------------------------------------------
-- Revisions  :
-- Date        Version  Author  Description
-- 2003/02/04  1.0      cuveland        Created
-------------------------------------------------------------------------------

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;

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

package gtu_types is

  -- *** BEGIN: Definition of link data word ***

  -- PID Signature
  constant pid_width  : integer := 8;
  constant pid_offset : integer := 24;

  -- Z Position (padrow number)
  constant zpos_width  : integer := 4;
  constant zpos_offset : integer := 20;

  -- Deflection length
  constant deflen_width      : integer := 7;
  constant deflen_offset     : integer := 13;
  constant deflen_resolution : real    := 140.0E-6;  -- [m]

  -- Y Position
  constant ypos_width      : integer := 13;
  constant ypos_offset     : integer := 0;
  constant ypos_resolution : real    := 160.0E-6;  -- [m]

  -- end markers
  constant link_end_word : std_logic_vector(15 downto 0) := "0001000000000000";
  constant link_end_mask : std_logic_vector(15 downto 0) := "0001111111000000";

  -- *** END: Definition of link data word ***


  -- *** BEGIN: May be changed ***

  constant proj_ypos_bit_decrease : integer := 3;
  constant approx_ypos_bit_decrease : integer := 3;

  -- Projected Y position window [m]
  constant proj_ypos_window_real : real := 0.011625;
  -- Deflection angle window [rad]
  constant deflang_window_real   : real := 0.05;

  -- *** END: May be changed ***


  -- detector geometry
  type real_t6 is array (0 to 5) of real;
  constant radius    : real_t6 :=
    (2.988, 3.114, 3.240, 3.366, 3.492, 3.618);  -- [m]
  constant rmid      : real    := 3.333;  -- [m]
  constant thickness : real    := 0.03;  -- [m]

  constant addr_width : integer := 6;
  constant idx_width  : integer := 3;

  constant proj_ypos_width      : integer :=
    ypos_width - proj_ypos_bit_decrease;
  constant proj_ypos_resolution : real    :=
    ypos_resolution * real(2 ** proj_ypos_bit_decrease);
  constant deflang_width        : integer := deflen_width;
  constant deflang_resolution   : real    := deflen_resolution / thickness;

  constant proj_ypos_window : signed(proj_ypos_width-1 downto 0) :=
    conv_signed(integer(proj_ypos_window_real / proj_ypos_resolution),
                proj_ypos_width);       -- e.g. 9

  constant deflang_window : signed(deflang_width-1 downto 0) :=
    conv_signed(integer(deflang_window_real / deflang_resolution),
                deflang_width);         -- e.g. 11

  constant approx_ypos_width : integer :=
    proj_ypos_width - approx_ypos_bit_decrease;

  constant pt_width : integer := 16;    -- fixed point "9.7" [GeV]

  -- internal end marker
  constant proj_ypos_end : signed(proj_ypos_width-1 downto 0) :=
    "0111111111";

  function is_end_word (signal word : std_logic_vector) return boolean;

end gtu_types;


package body gtu_types is

  function is_end_word (
    signal word : std_logic_vector)
    return boolean is
  begin
    return (word(15 downto 0) and link_end_mask)
       = (link_end_word and link_end_mask);
  end is_end_word;

end gtu_types;