// IMPORTANT:
//  This CANNOT be embedded in server-side script in the usual way:
//    <script runat="server" src="/common/crc16.js" type="text/javascript" language="javascript"></script>
//
//  Because the global variable declaration won't work.
//  Instead, use the versions of these functions in jsServer.js.

/*
  CRC-16 (as it is in ZMODEM) in table form

  Copyright (c) 1989 AnDan Software. You may use this program, or
  code or tables extracted from it, as long as this notice is not
  removed or changed.

  From http://www.digsys.se/js_crc.html. See the link for other CRCs,
  including 8 bit, 32 bit etc.
*/

function Crc16Add(aCrc16, crc,c)
/*
  'crc' should be initialized to 0x0000.
*/
{
  return aCrc16[((crc>>8)^c)&0xFF]^((crc<<8)&0xFFFF);
}

function Crc16Str(aCrc16, str)
{
  var n;
  var len=str.length;
  var crc;

  crc=0;
  for (n=0; n<len; n++)
  {
    crc=Crc16Add(aCrc16, crc,str.charCodeAt(n));
  }
  return crc;
}

/*
  Hex convert functions
*/

function Hex16(val)
/*
  Convert value as 16-bit unsigned integer to 4 digit hexadecimal number.
*/
{
  var n;
  var str;

  n=val&0xFFFF;
  str=n.toString(16).toUpperCase();
  while (str.length<4)
  {
    str="0"+str;
  }
  return str;
}

// Function to hash three values together in two ways to give an 8-hex-digit (32-bit) hash:
function Hash32(str1, str2, str3)
{
  var aCrc16 = new Array(
  0x0000,0x1021,0x2042,0x3063,0x4084,0x50A5,0x60C6,0x70E7,0x8108,0x9129,0xA14A,0xB16B,0xC18C,
  0xD1AD,0xE1CE,0xF1EF,0x1231,0x0210,0x3273,0x2252,0x52B5,0x4294,0x72F7,0x62D6,0x9339,0x8318,
  0xB37B,0xA35A,0xD3BD,0xC39C,0xF3FF,0xE3DE,0x2462,0x3443,0x0420,0x1401,0x64E6,0x74C7,0x44A4,
  0x5485,0xA56A,0xB54B,0x8528,0x9509,0xE5EE,0xF5CF,0xC5AC,0xD58D,0x3653,0x2672,0x1611,0x0630,
  0x76D7,0x66F6,0x5695,0x46B4,0xB75B,0xA77A,0x9719,0x8738,0xF7DF,0xE7FE,0xD79D,0xC7BC,0x48C4,
  0x58E5,0x6886,0x78A7,0x0840,0x1861,0x2802,0x3823,0xC9CC,0xD9ED,0xE98E,0xF9AF,0x8948,0x9969,
  0xA90A,0xB92B,0x5AF5,0x4AD4,0x7AB7,0x6A96,0x1A71,0x0A50,0x3A33,0x2A12,0xDBFD,0xCBDC,0xFBBF,
  0xEB9E,0x9B79,0x8B58,0xBB3B,0xAB1A,0x6CA6,0x7C87,0x4CE4,0x5CC5,0x2C22,0x3C03,0x0C60,0x1C41,
  0xEDAE,0xFD8F,0xCDEC,0xDDCD,0xAD2A,0xBD0B,0x8D68,0x9D49,0x7E97,0x6EB6,0x5ED5,0x4EF4,0x3E13,
  0x2E32,0x1E51,0x0E70,0xFF9F,0xEFBE,0xDFDD,0xCFFC,0xBF1B,0xAF3A,0x9F59,0x8F78,0x9188,0x81A9,
  0xB1CA,0xA1EB,0xD10C,0xC12D,0xF14E,0xE16F,0x1080,0x00A1,0x30C2,0x20E3,0x5004,0x4025,0x7046,
  0x6067,0x83B9,0x9398,0xA3FB,0xB3DA,0xC33D,0xD31C,0xE37F,0xF35E,0x02B1,0x1290,0x22F3,0x32D2,
  0x4235,0x5214,0x6277,0x7256,0xB5EA,0xA5CB,0x95A8,0x8589,0xF56E,0xE54F,0xD52C,0xC50D,0x34E2,
  0x24C3,0x14A0,0x0481,0x7466,0x6447,0x5424,0x4405,0xA7DB,0xB7FA,0x8799,0x97B8,0xE75F,0xF77E,
  0xC71D,0xD73C,0x26D3,0x36F2,0x0691,0x16B0,0x6657,0x7676,0x4615,0x5634,0xD94C,0xC96D,0xF90E,
  0xE92F,0x99C8,0x89E9,0xB98A,0xA9AB,0x5844,0x4865,0x7806,0x6827,0x18C0,0x08E1,0x3882,0x28A3,
  0xCB7D,0xDB5C,0xEB3F,0xFB1E,0x8BF9,0x9BD8,0xABBB,0xBB9A,0x4A75,0x5A54,0x6A37,0x7A16,0x0AF1,
  0x1AD0,0x2AB3,0x3A92,0xFD2E,0xED0F,0xDD6C,0xCD4D,0xBDAA,0xAD8B,0x9DE8,0x8DC9,0x7C26,0x6C07,
  0x5C64,0x4C45,0x3CA2,0x2C83,0x1CE0,0x0CC1,0xEF1F,0xFF3E,0xCF5D,0xDF7C,0xAF9B,0xBFBA,0x8FD9,
  0x9FF8,0x6E17,0x7E36,0x4E55,0x5E74,0x2E93,0x3EB2,0x0ED1,0x1EF0);
  return Hex16(Crc16Str(aCrc16, str1 + "/" + str2 + "-" + str3)) + Hex16(Crc16Str(aCrc16, str2 + "-" + str1 + "#" + str3));
}