CRC32.coffee DeCaf Source Code

crc32 = (strData) ->
  arrFastTable = [
    0, 1996959894, 3993919788, 2567524794, 124634137, 1886057615, 3915621685,
    2657392035, 249268274, 2044508324, 3772115230, 2547177864, 162941995, 2125561021,
    3887607047, 2428444049, 498536548, 1789927666, 4089016648, 2227061214, 450548861,
    1843258603, 4107580753, 2211677639, 325883990, 1684777152, 4251122042, 2321926636,
    335633487, 1661365465, 4195302755, 2366115317, 997073096, 1281953886, 3579855332,
    2724688242, 1006888145, 1258607687, 3524101629, 2768942443, 901097722, 1119000684,
    3686517206, 2898065728, 853044451, 1172266101, 3705015759, 2882616665, 651767980,
    1373503546, 3369554304, 3218104598, 565507253, 1454621731, 3485111705, 3099436303,
    671266974, 1594198024, 3322730930, 2970347812, 795835527, 1483230225, 3244367275,
    3060149565, 1994146192, 31158534, 2563907772, 4023717930, 1907459465, 112637215,
    2680153253, 3904427059, 2013776290, 251722036, 2517215374, 3775830040, 2137656763,
    141376813, 2439277719, 3865271297, 1802195444, 476864866, 2238001368, 4066508878,
    1812370925, 453092731, 2181625025, 4111451223, 1706088902, 314042704, 2344532202,
    4240017532, 1658658271, 366619977, 2362670323, 4224994405, 1303535960, 984961486,
    2747007092, 3569037538, 1256170817, 1037604311, 2765210733, 3554079995, 1131014506,
    879679996, 2909243462, 3663771856, 1141124467, 855842277, 2852801631, 3708648649,
    1342533948, 654459306, 3188396048, 3373015174, 1466479909, 544179635, 3110523913,
    3462522015, 1591671054, 702138776, 2966460450, 3352799412, 1504918807, 783551873,
    3082640443, 3233442989, 3988292384, 2596254646, 62317068, 1957810842, 3939845945,
    2647816111, 81470997, 1943803523, 3814918930, 2489596804, 225274430, 2053790376,
    3826175755, 2466906013, 167816743, 2097651377, 4027552580, 2265490386, 503444072,
    1762050814, 4150417245, 2154129355, 426522225, 1852507879, 4275313526, 2312317920,
    282753626, 1742555852, 4189708143, 2394877945, 397917763, 1622183637, 3604390888,
    2714866558, 953729732, 1340076626, 3518719985, 2797360999, 1068828381, 1219638859,
    3624741850, 2936675148, 906185462, 1090812512, 3747672003, 2825379669, 829329135,
    1181335161, 3412177804, 3160834842, 628085408, 1382605366, 3423369109, 3138078467,
    570562233, 1426400815, 3317316542, 2998733608, 733239954, 1555261956, 3268935591,
    3050360625, 752459403, 1541320221, 2607071920, 3965973030, 1969922972, 40735498,
    2617837225, 3943577151, 1913087877, 83908371, 2512341634, 3803740692, 2075208622,
    213261112, 2463272603, 3855990285, 2094854071, 198958881, 2262029012, 4057260610,
    1759359992, 534414190, 2176718541, 4139329115, 1873836001, 414664567, 2282248934,
    4279200368, 1711684554, 285281116, 2405801727, 4167216745, 1634467795, 376229701,
    2685067896, 3608007406, 1308918612, 956543938, 2808555105, 3495958263, 1231636301,
    1047427035, 2932959818, 3654703836, 1088359270, 936918000, 2847714899, 3736837829,
    1202900863, 817233897, 3183342108, 3401237130, 1404277552, 615818150, 3134207493,
    3453421203, 1423857449, 601450431, 3009837614, 3294710456, 1567103746, 711928724,
    3020668471, 3272380065, 1510334235, 755167117
  ]

  arrBitZero = intToBinary({intA: 0})
  arrBit24Zeros = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1]

  arrCRCBit = logicalNot({arrBitA: arrBitZero})
  arrOrd = []
  intLength = length({var: strData})
  intIndex = 0
  while intIndex < intLength
    strChar = string({function: "substr", input: strData, arg1: intIndex, arg2: 1})
    strOrd = string({function: "ord", input: strChar})
    arrOrd[intIndex] = strOrd
    intIndex = intIndex + 1

  for intOrd in arrOrd
    arrOrdBit = intToBinary({intA: intOrd})
    arrCRCBitTruncated = logicalAnd({arrBitA: arrCRCBit, arrBitB: arrBit24Zeros})
    arrCRCXOROrd = logicalXOR({arrBitA: arrOrdBit, arrBitB: arrCRCBitTruncated})
    intCRCXOROrd = binaryToInt({arrBit: arrCRCXOROrd})
    intFastTableValue = arrFastTable[intCRCXOROrd]
    arrFastTableValue = intToBinary({intA: intFastTableValue})
    arrCRCRightShift8 = logicalRightShift({arrBit: arrCRCBit, intShift: 8})
    arrCRCBit = logicalXOR({arrBitA: arrFastTableValue, arrBitB: arrCRCRightShift8})

  arrCRCBit = logicalNot({arrBitA: arrCRCBit})

  return binaryToHex({arrBit: arrCRCBit})

makeFastTable = () ->
  # Only need to run this once, and copy the output back into the program.
  # This is for performance -- this takes ages because of the string-array conversions.
  arrFastTable = []
  arr0001 = intToBinary({intA: 1})
  int0xEDB88320 = 3988292384
  arr0xEDB88320 = intToBinary({intA: int0xEDB88320})
  arr255 = []
  intCount = 0
  while intCount <= 255
    arr255[intCount] = intCount
    intCount = intCount + 1

  arr7 = []
  intCount = 0
  while intCount <= 7
    arr7[intCount] = intCount
    intCount = intCount + 1

  for intI in arr255
    arrI = intToBinary({intA: intI})
    intIndex = index
    for intJ in arr7
      arrAnd = logicalAnd({arrBitA: arrI, arrBitB: arr0001})
      intAnd = binaryToInt({arrBit: arrAnd})

      if intAnd == 1
        arrI = logicalRightShift({arrBit: arrI, intShift: 1})
        arrI = logicalXOR({arrBitA: arrI, arrBitB: arr0xEDB88320})
      else
        arrI = logicalRightShift({arrBit: arrI, intShift: 1})
    arrFastTable[intIndex] = binaryToInt({arrBit: arrI})

  return arrFastTable


intToBinary = (intA) ->
  arrBit = []
  intLength = 32
  intIndex = 0

  while intIndex < intLength
    arrBit[intIndex] = 0

    if intA > 0
      intMod = intA % 2
      arrBit[intIndex] = intMod
      intA = (intA - intMod) / 2

    intIndex = intIndex + 1

  arrOut = []
  for intBit in sort({var: arrBit, with: "reverse"})
    arrOut[length({var: arrOut})] = intBit

  return arrOut

binaryToInt = (arrBit) ->
  intInt = 0
  intPower = length({var: arrBit}) - 1
  for intBit in arrBit
    intInt = intInt + math({op: "pow", arg1: 2, arg2: intPower}) * intBit
    intPower = intPower - 1

  return intInt

logicalRightShift = (arrBit, intShift) ->
  arrOut = arrBit
  for _ in arrOut
    if index - intShift >= 0
      arrOut[index] = arrBit[index - intShift]
    else
      arrOut[index] = 0

  return arrOut

logicalAnd = (arrBitA, arrBitB) ->
  arrAnd = arrBitA

  for intBitA in arrBitA
    if intBitA * arrBitB[index] == 1
      arrAnd[index] = 1
    else
      arrAnd[index] = 0

  return arrAnd

logicalXOR = (arrBitA, arrBitB) ->
  arrAnd = arrBitA

  for intBitA in arrBitA
    if intBitA != arrBitB[index]
      arrAnd[index] = 1
    else
      arrAnd[index] = 0

  return arrAnd

logicalNot = (arrBitA) ->
  for intBitA in arrBitA
    if intBitA == 1
      arrBitA[index] = 0
    else
      arrBitA[index] = 1
  return arrBitA

binaryToHex = (arrBit) ->
  strHex = ""

  mapColumn = [
    [0, 1, 2, 3],
    [4, 5, 6, 7],
    [8, 9, 10, 11],
    [12, 13, 14, 15],
    [16, 17, 18, 19],
    [20, 21, 22, 23],
    [24, 25, 26, 27],
    [28, 29, 30, 31],
  ]

  mapHexByDec = {
    10: "a",
    11: "b",
    12: "c",
    13: "d",
    14: "e",
    15: "f",
  }

  for arrPower in mapColumn
    intDec = 0
    intPower = 3
    for intIndex in arrPower
      intBit = arrBit[intIndex]
      intDec = intDec + math({op: "pow", arg1: 2, arg2: intPower}) * intBit
      intPower = intPower - 1
    if intDec < 10
      strHex = "#{strHex}#{intDec}"
    else
      strHex = "#{strHex}#{mapHexByDec[intDec]}"

  return strHex