Unit Crc16;
Interface
{ Note: Your crc Variable must be initialized to 0, before       }
{       using tis routine.                                       }
{ Translated to Turbo Pascal (tm) V4.0 March, 1988 by J.R.Louvau }
{                                                                }
Function UpdCrc(cp: Byte; crc: Word): Word;

Implementation

(* crctab calculated by Mark G. Mendel, Network Systems Corporation *)
Const crctab : Array[0..255] of Word = (
    $0000,  $1021,  $2042,  $3063,  $4084,  $50a5,  $60c6,  $70e7,
    $8108,  $9129,  $a14a,  $b16b,  $c18c,  $d1ad,  $e1ce,  $f1ef,
    $1231,  $0210,  $3273,  $2252,  $52b5,  $4294,  $72f7,  $62d6,
    $9339,  $8318,  $b37b,  $a35a,  $d3bd,  $c39c,  $f3ff,  $e3de,
    $2462,  $3443,  $0420,  $1401,  $64e6,  $74c7,  $44a4,  $5485,
    $a56a,  $b54b,  $8528,  $9509,  $e5ee,  $f5cf,  $c5ac,  $d58d,
    $3653,  $2672,  $1611,  $0630,  $76d7,  $66f6,  $5695,  $46b4,
    $b75b,  $a77a,  $9719,  $8738,  $f7df,  $e7fe,  $d79d,  $c7bc,
    $48c4,  $58e5,  $6886,  $78a7,  $0840,  $1861,  $2802,  $3823,
    $c9cc,  $d9ed,  $e98e,  $f9af,  $8948,  $9969,  $a90a,  $b92b,
    $5af5,  $4ad4,  $7ab7,  $6a96,  $1a71,  $0a50,  $3a33,  $2a12,
    $dbfd,  $cbdc,  $fbbf,  $eb9e,  $9b79,  $8b58,  $bb3b,  $ab1a,
    $6ca6,  $7c87,  $4ce4,  $5cc5,  $2c22,  $3c03,  $0c60,  $1c41,
    $edae,  $fd8f,  $cdec,  $ddcd,  $ad2a,  $bd0b,  $8d68,  $9d49,
    $7e97,  $6eb6,  $5ed5,  $4ef4,  $3e13,  $2e32,  $1e51,  $0e70,
    $ff9f,  $efbe,  $dfdd,  $cffc,  $bf1b,  $af3a,  $9f59,  $8f78,
    $9188,  $81a9,  $b1ca,  $a1eb,  $d10c,  $c12d,  $f14e,  $e16f,
    $1080,  $00a1,  $30c2,  $20e3,  $5004,  $4025,  $7046,  $6067,
    $83b9,  $9398,  $a3fb,  $b3da,  $c33d,  $d31c,  $e37f,  $f35e,
    $02b1,  $1290,  $22f3,  $32d2,  $4235,  $5214,  $6277,  $7256,
    $b5ea,  $a5cb,  $95a8,  $8589,  $f56e,  $e54f,  $d52c,  $c50d,
    $34e2,  $24c3,  $14a0,  $0481,  $7466,  $6447,  $5424,  $4405,
    $a7db,  $b7fa,  $8799,  $97b8,  $e75f,  $f77e,  $c71d,  $d73c,
    $26d3,  $36f2,  $0691,  $16b0,  $6657,  $7676,  $4615,  $5634,
    $d94c,  $c96d,  $f90e,  $e92f,  $99c8,  $89e9,  $b98a,  $a9ab,
    $5844,  $4865,  $7806,  $6827,  $18c0,  $08e1,  $3882,  $28a3,
    $cb7d,  $db5c,  $eb3f,  $fb1e,  $8bf9,  $9bd8,  $abbb,  $bb9a,
    $4a75,  $5a54,  $6a37,  $7a16,  $0af1,  $1ad0,  $2ab3,  $3a92,
    $fd2e,  $ed0f,  $dd6c,  $cd4d,  $bdaa,  $ad8b,  $9de8,  $8dc9,
    $7c26,  $6c07,  $5c64,  $4c45,  $3ca2,  $2c83,  $1ce0,  $0cc1,
    $ef1f,  $ff3e,  $cf5d,  $df7c,  $af9b,  $bfba,  $8fd9,  $9ff8,
    $6e17,  $7e36,  $4e55,  $5e74,  $2e93,  $3eb2,  $0ed1,  $1ef0
);

(*
 * updcrc derived from article Copyright (C) 1986 Stephen Satchell.
 *  NOTE: First argument must be in range 0 to 255.
 *        Second argument is referenced twice.
 *
 * Programmers may incorporate any or all code into their Programs,
 * giving proper credit within the source. Publication of the
 * source routines is permitted so long as proper credit is given
 * to Stephen Satchell, Satchell Evaluations and Chuck Forsberg,
 * Omen Technology.
 *)
Function UpdCrc(cp: Byte; crc: Word): Word;
begin { UpdCrc }
  UpdCrc := crctab[((crc SHR 8) and 255)] xor (crc SHL 8) xor cp
end;

end. {Unit}