Implementation of CRC-16 algorithm and application in Perl language

#!/usr/bin/eperl-w

# filename:crc-16.pl

#

# Copyright Axxeo GmbH

# Licensed under the Apache License, Version 2.0 (the "License");

# You are not a use of this file except in compliance with the License.

# Obtain a copy of the License at

#

# http://www.apache.org/licenses/LICENSE-2.0

#

# unless required by applicable or agreed to writing, software

# Distributed under the License is distributed on a "as is" BASIS,

# without warranties or CONDITIONS of any KIND, either express or implied.

# See the License for the specific language governing permissions and

# Limitations under the License.

#

My @table;

Sub GenerateCRC16 ()

{

# globle @table;

# if (len (@table) = = & ($table [1] = = 49354))

# {

# return;

# }

my $i = 0;

My @lst;

My $data;

My $CRC;

while ($i < 256) {

# body ...

$data = ($i <<1);

$CRC = 0;

my $j = 8;

while ($j > 0)

{

$data >>=1;

if (($data ^ $crc) & 0x0001)

{

$CRC = ($CRC >> 1) ^ 0xa001;

}

Else

{

$CRC >>= 1;

}

$j-= 1;

}

$lst [$i] = $CRC;

$i +=1;

}

return @lst;

}

@table = generateCRC16 ();

print "-----------------------------------------------\ n";

Print "The following is the crc-16 table:\n";

my $c = 1;

For $a (@table)

{

printf ("0x%X", $a);

print "\ t";

if (($c% 8 = = 0) & ($c! = 0))

{

print "\ n";

}

$c + = 1;

}

print "-----------------------------------------------\ n";

Sub Calculatercrc ()

{

My $string = Shift (@_);

my $CRC = 0xFFFF;

#foreach $CHR (Unpack ("(a) *", $string))

foreach $chr (Unpack ("c*", $string))

{

$CRC = ($CRC >> 8) ^ $table [($crc ^ $chr) & 0xFF];

}

My $crcL = sprintf ("\\x%X", &_lo ($CRC));

My $crcH = sprintf ("\\x%X", &_hi ($CRC));

return $crcH. $crcL;

}

#printf ("%x\n", &CALCULATERCRC ("Hallo World");

Sub Convertchrtoacsii ()

{

My $string = Shift (@_);

foreach $chr (Unpack ("C0u4", $string))

{

Print $CHR. "The Acsii code is:". Ord ($CHR). In hex format: ";

printf "%x\n", (Ord ($CHR));

}

Return

}

Sub _lo ()

{

My $myhex = Shift (@_);

Return ($myhex & 0x00FF);

}

Sub _hi ()

{

My $myhex = Shift (@_);

Return (($myhex & 0xff00) >> 8);

}

Sub Checkcrc () # is used to check the CRC code when matching

{

My ($payload, $crcsum) = @_;

Print $payload. " ---\ n ";

Print $crcsum. " +++\n ";

if ($crcsum eq &CALCULATERCRC ($payload))

{

print "Check CRC summe>>: Not match!! \ n ";

return 1;

}

Else

{

print "Check CRC summe>>: match!! \ n ";

return 0;

}

}

Sub Embedpayload # This method primarily implements converting characters in a string to 16, and adding: as a delimiter

{

My $string = Shift (@_);

My @chrs = (Unpack ("(a) *", $string));

My @newchrs = map {sprintf ("%x", (Ord ($_))} @chrs;

My $iterms =join (":", @newchrs);

return $iterms;

}

Sub Extrapayload # Inverse operation of the above method

{

My $iterms = Shift (@_);

My @chrs = Split (":", $iterms);

My @newchrs = map {chr (hex ($_))} @chrs;

My $string =join ("", @newchrs);

return $string;

}

print "-----------------------------------------------\ n";

Print &embedpayload ("ABCD"). " \ n ";

print "---------\ n";

Print &extrapayload (&embedpayload ("ABCD"));

#print chr ("\x4f\x4b");

# Usage:

# for example

# Payload of message is ' Hallo world '

# PAYLOAD+CRC (Hi) +CRC (Lo)

This article is from the "EIT Tramp" blog, please be sure to keep this source http://zicowarn.blog.51cto.com/3815716/1614595

Implementation of CRC-16 algorithm and application in Perl language