#!/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 ("%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() ＃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("\x4F\x4B");
# usage:
# for example
# payload of message is "Hallo World"
# payload+crc(Hi)+crc(Lo)