pck_crc16_d8.vhd

无线耳机通讯用CPLD的VHDL源码

-----------------------------------------------------------------------
-- File:  PCK_CRC16_D8.vhd                              
-- Date:  Sun Apr 22 10:18:13 2001                                                      
--                                                                     
-- Copyright (C) 1999 Easics NV.                 
-- This source file may be used and distributed without restriction    
-- provided that this copyright statement is not removed from the file 
-- and that any derivative work contains the original copyright notice
-- and the associated disclaimer.
--
-- THIS SOURCE FILE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS
-- OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
-- WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
--
-- Purpose: VHDL package containing a synthesizable CRC function
--   * polynomial: (0 2 15 16)
--   * data width: 8
--                                                                     
-- Info: [e-mail] (Jan Decaluwe)                           
--       http://www.easics.com                                  
-----------------------------------------------------------------------


library IEEE;
use IEEE.std_logic_1164.all;

package PCK_CRC16_D8 is

  -- polynomial: (0 2 15 16)
  -- data width: 8
  -- convention: the first serial data bit is D(7)
  function nextCRC16_D8
    ( Data:  std_logic_vector(7 downto 0);
      CRC:   std_logic_vector(15 downto 0) )
    return std_logic_vector;

end PCK_CRC16_D8;

library IEEE;
use IEEE.std_logic_1164.all;

package body PCK_CRC16_D8 is

  -- polynomial: (0 2 15 16)
  -- data width: 8
  -- convention: the first serial data bit is D(7)
  function nextCRC16_D8  
    ( Data:  std_logic_vector(7 downto 0);
      CRC:   std_logic_vector(15 downto 0) )
    return std_logic_vector is

    variable D: std_logic_vector(7 downto 0);
    variable C: std_logic_vector(15 downto 0);
    variable NewCRC: std_logic_vector(15 downto 0);

  begin

    D := Data;
    C := CRC;

    NewCRC(0) := D(7) xor D(6) xor D(5) xor D(4) xor D(3) xor D(2) xor 
                 D(1) xor D(0) xor C(8) xor C(9) xor C(10) xor C(11) xor 
                 C(12) xor C(13) xor C(14) xor C(15);
    NewCRC(1) := D(7) xor D(6) xor D(5) xor D(4) xor D(3) xor D(2) xor 
                 D(1) xor C(9) xor C(10) xor C(11) xor C(12) xor C(13) xor 
                 C(14) xor C(15);
    NewCRC(2) := D(1) xor D(0) xor C(8) xor C(9);
    NewCRC(3) := D(2) xor D(1) xor C(9) xor C(10);
    NewCRC(4) := D(3) xor D(2) xor C(10) xor C(11);
    NewCRC(5) := D(4) xor D(3) xor C(11) xor C(12);
    NewCRC(6) := D(5) xor D(4) xor C(12) xor C(13);
    NewCRC(7) := D(6) xor D(5) xor C(13) xor C(14);
    NewCRC(8) := D(7) xor D(6) xor C(0) xor C(14) xor C(15);
    NewCRC(9) := D(7) xor C(1) xor C(15);
    NewCRC(10) := C(2);
    NewCRC(11) := C(3);
    NewCRC(12) := C(4);
    NewCRC(13) := C(5);
    NewCRC(14) := C(6);
    NewCRC(15) := D(7) xor D(6) xor D(5) xor D(4) xor D(3) xor D(2) xor 
                  D(1) xor D(0) xor C(7) xor C(8) xor C(9) xor C(10) xor 
                  C(11) xor C(12) xor C(13) xor C(14) xor C(15);

    return NewCRC;

  end nextCRC16_D8;

end PCK_CRC16_D8;