用Perl语言实现CRC-16算法和应用

#!/usr/bin/eperl -w

# ? Filename: crc-16.pl?

#

# ? Copyright 2012 Axxeo GmbH

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

# ? you may not use this file except in compliance with the License.

# ? You may obtain a copy of the License at

#

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

#

# ? Unless required by applicable law or agreed to in writing,software

# ? distributed under the License is distributed on an "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) == 256) & ($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 ("%Xn",&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 "%Xn",(ord($chr));

? ? }

? ? return;

}

sub _Lo()

{

? ? my $myhex = shift(@_);

? ? return ($myhex & 0x00FF);

}

sub _Hi()

{

? ? my $myhex = shift(@_);

? ? return (($myhex & 0xFF00) >> 8);

}

sub checkCrc()　＃用于检查ＣＲＣ码时候匹配

{

? ? 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　＃　此方法主要实现将字符串中的字符转换为十六进制，并加入：作为分隔符

{

? ? my $string = shift(@_);

? ? my @chrs = (unpack("(a)*",$string));

? ? my @newchrs = map { sprintf("%X",(ord($_)))} @chrs;

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

? ? return $iterms;

}

sub extraPayload　＃　上述方法的逆操作

{

? ? 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("x4Fx4B");

# usage:

# for example?

# payload of message is "Hallo World"

# payload+crc(Hi)+crc(Lo)