Mood:  rushed

http://www.mediafire.com/?hngth40zzy5 

###################################################################
#                                                                 #
# Parameterized CRC algorithm implementation for (G)AWK           #
# 20090202 themabus[at]inbox[dot]lv                               #
#                                                                 #
# please verify thoroughly before actual use                      #
#                                                                 #
###################################################################

function _ord_init(    low, high, i, t)
#this and following two functions are taken from GAWK manual
{
    low = sprintf("%c", 7) # BEL is ascii 7
    if (low == "\a") {    # regular ascii
        low = 0
        high = 127
    } else if (sprintf("%c", 128 + 7) == "\a") {
        # ascii, mark parity
        low = 128
        high = 255
    } else {        # ebcdic(!)
        low = 0
        high = 255
    }

    for (i = low; i <= high; i++) {
        t = sprintf("%c", i)
        _ord_[t] = i
    }
}

function ord(str,    c)
{
    # only first character is of interest
    c = substr(str, 1, 1)
    return _ord_[c]
}
     
function chr(c)
{
    # force c to be numeric by adding 0
    return sprintf("%c", c + 0)
}

###################################################################

function filltable(poly, width, refin, bitmask, table,    cnt1, cnt2, tmp1, mask)
{
  bitmask = 0
  for (cnt1 = 0; cnt1 < width; cnt1++) {
    bitmask = xor(bitmask, lshift(1, cnt1))
  }
  if (refin == 0) {
    mask = lshift(1, width-1)

    for (cnt1 = 0; cnt1 < 256; cnt1++) {
      tmp1 = lshift(cnt1, width-8)
      for (cnt2 = 0; cnt2 < 8; cnt2++) {
        and(tmp1, mask)==mask ? tmp1 = xor(lshift(tmp1, 1), poly) : tmp1 = lshift(tmp1, 1)
      }
      table[cnt1] = and(tmp1, bitmask)
#      printf( "%08x\n", table[cnt1])
    }
  } else {
    mask = 1
    poly = reflect(poly, width, bitmask)

    for (cnt1 = 0; cnt1 < 256; cnt1++) {
      tmp1 = cnt1
      for (cnt2 = 0; cnt2 < 8; cnt2++) {
        and(tmp1, mask)==mask ? tmp1 = xor(rshift(tmp1, 1), poly) : tmp1 = rshift(tmp1, 1)
      }
      table[cnt1] = and(tmp1, bitmask)
#      printf( "%08x\n", table[cnt1])
    }
  }
  return bitmask
}

###################################################################

function reflect(input, width, bitmask,    cnt1, tmp1, mask)
{
  mask = lshift(1, width-1)
  tmp1 = 0
  for (cnt1 = 0; cnt1 < width; cnt1++) {
    tmp1 = rshift(tmp1, 1)
    if (and(input, mask)==mask) tmp1 = xor(tmp1, mask)
    input = lshift(input, 1)
  }
  return and(tmp1, bitmask)
}

###################################################################

function calccrc(crc, width, refin, bitmask, table, message, type, len,    cnt1, tmp1, ind)
#type - 0: text string e.g. "123456789"
#       1: string of hex values e.g. "313233343536373839"
{
  cnt1 = 1

  if (refin == 0) {
    while (cnt1 <= len) {
      type == 0 ? tmp1 = ord(substr(message, cnt1, 1)) : tmp1 = strtonum("0x" substr(message, cnt1, 2))
      ind  = xor(and(rshift(crc, width-8), 255), tmp1)
      crc  = xor(lshift(crc, 8), table[ind])
      crc  = and(crc, bitmask)
      cnt1++
      if (type == 1) cnt1++
    }
  } else {
    while (cnt1 <= len) {
      type == 0 ? tmp1 = ord(substr(message, cnt1, 1)) : tmp1 = strtonum("0x" substr(message, cnt1, 2))
      ind  = xor(and(crc, 255), tmp1)
      crc  = xor(rshift(crc, 8), table[ind])
      crc  = and(crc, bitmask)
      cnt1++
      if (type == 1) cnt1++
    }
  }

  return crc
}

###################################################################

function selftest(    poly, init, xorout, width, refin, refout, bitmask, table, message, crc)
{
  bitmask = 0
  split("", table)

  print "CRC-32-IEEE 802.3"
  print "cbf43926" # expected value

  poly   = strtonum("0x04c11db7")
  init   = strtonum("0xffffffff")
  xorout = strtonum("0xffffffff")
  width  = 32
  refin  = 1 # 0 - false; 1 - true
  refout = 1 # 0 - false; 1 - true

  bitmask = filltable(poly, width, refin, bitmask, table)

  message="123456789"
  print ""
  print message

  crc = calccrc(init, width, refin, bitmask, table, message, 0, length(message))
  if (refin!=refout) crc = reflect(crc, width, bitmask)
  crc = xor(crc, xorout)
  printf("%0" (int(width / 4) + ((width % 4)!=0)) "x\n", crc)

  message="313233343536373839"
  print ""
  print message

  crc = calccrc(init, width, refin, bitmask, table, message, 1, length(message))
  if (refin!=refout) crc = reflect(crc, widht, bitmask)
  crc = xor(crc, xorout)
  printf("%0" (int(width / 4) + ((width % 4)!=0)) "x\n", crc)

  print ""
  print ""

  print "CRC-16-CCITT"
  print "29b1" # expected value

  poly   = strtonum("0x1021")
  init   = strtonum("0xffff")
  xorout = strtonum("0x0000")
  width  = 16
  refin  = 0 # 0 - false; 1 - true
  refout = 0 # 0 - false; 1 - true

  bitmask = filltable(poly, width, refin, bitmask, table)

  message="123456789"
  print ""
  print message

  crc = calccrc(init, width, refin, bitmask, table, message, 0, length(message))
  if (refin!=refout) crc = reflect(crc, width, bitmask)
  crc = xor(crc, xorout)
  printf("%0" (int(width / 4) + ((width % 4)!=0)) "x\n", crc)

  message="313233343536373839"
  print ""
  print message

  crc = calccrc(init, width, refin, bitmask, table, message, 1, length(message))
  if (refin!=refout) crc = reflect(crc, width, bitmask)
  crc = xor(crc, xorout)
  printf("%0" (int(width / 4) + ((width % 4)!=0)) "x\n", crc)
}

###################################################################

BEGIN{
  _ord_init()

#  selftest()

  bitmask = 0
  split("", table)

# set up your model here or with command-line parameters '-v var=val'
  poly   = strtonum("0x04c11db7")
  init   = strtonum("0xffffffff")
  xorout = strtonum("0xffffffff")
  width  = 32
  refin  = 1 # 0 - false; 1 - true
  refout = 1 # 0 - false; 1 - true

  bitmask = filltable(poly, width, refin, bitmask, table)

  crc_file= init
}

###################################################################

{
#  selftest()
  crc_line = calccrc(init, width, refin, bitmask, table, $0, 0, length($0))
  if (refin!=refout) crc_line = reflect(crc_line, width, bitmask)
  crc_line = xor(crc_line, xorout)
  printf("%0" (int(width / 4) + ((width % 4)!=0)) "x\n", crc_line)

  crc_file = calccrc(crc_file, width, refin, bitmask, table, $0, 0, length($0))
  # end console input with Ctrl + Z
}

###################################################################

END{
  if (refin!=refout) crc_file = reflect(crc_file, width, bitmask)
  crc_file = xor(crc_file, xorout)
  printf("%0" (int(width / 4) + ((width % 4)!=0)) "x\n", crc_file)
}