eleksir/rle
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eleksir
2018-09-23 14:39:28 +03:00
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LICENSE Normal file
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Copyright 2010 Sergei Fedosov <eleksir@gmail.com>
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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README.md Normal file
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## RLE
Another simplified implementation of the ideas of Run Length Encoding
algorhythm. Instead of bit manipulation, it manipulates bytes. Output
data stream have no header or tail where metadata can be stored, so
no integrity checks are implemented.
This code licensed under BSD 2 clause license.

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rle.pl Normal file
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#!/usr/bin/perl
use strict;
use warnings "all";
use Fcntl;
my $fname = undef;
if(defined($ARGV[0])){
if($ARGV[0] eq "--help"){
syswrite STDOUT, "Usage: $0 <filename>\n";
syswrite STDOUT, "or pipe data thrugh $0's STDIN to $0 STDOUT\n";
exit 0;
}
$fname = $ARGV[0];
}
my $byte;
my $counter = 1;
my $block_size = 65536;
my $first_remembered_byte = undef;
my $second_remembered_byte = undef;
if (defined($fname)){
sysopen(STDIN, $fname, O_RDONLY) or die "Can not open file $fname!\n";
sysopen(STDOUT, "$fname.rle", O_WRONLY|O_TRUNC|O_CREAT) or die "Can not open file $fname.rle!\n";
}
binmode(STDIN);
binmode(STDOUT);
exit 0 if ((sysread(STDIN, $byte, 1)) == 0);
$first_remembered_byte = $byte;
my $output_buf_byte_counter = 0;
my $output_buf = '';
my $input_buf = '';
while ( 1 ) {
my $read_bytes = sysread(STDIN, $input_buf, $block_size);
last if($read_bytes == 0);
my $i = 0;
for ( $i = 0; $i < $read_bytes; $i++ ) {
$byte = substr( $input_buf, $i, 1);
last unless(defined($byte));
$second_remembered_byte = $first_remembered_byte;
$first_remembered_byte = $byte;
if(($first_remembered_byte eq $second_remembered_byte) and ($counter <= 254)){
$counter++;
next;
}
if ($output_buf_byte_counter == $block_size){
syswrite STDOUT, $output_buf || die "Cannot write output stream!\n";
$output_buf = '';
$output_buf_byte_counter = 0;
}else{
$output_buf_byte_counter++;
}
$output_buf .= chr($counter) . $second_remembered_byte;
$second_remembered_byte = $first_remembered_byte;
$counter = 1;
}
undef $i;
undef $read_bytes;
}
close(STDIN);
# 0-byte string
exit 0 unless (defined($first_remembered_byte));
# 1-byte string
unless(defined($second_remembered_byte)){
$output_buf = chr($counter) . $first_remembered_byte;
}else{
# 2+ bytes string
$output_buf .= chr($counter) . $second_remembered_byte;
}
syswrite STDOUT, $output_buf || die "Cannot write output stream!\n";
close(STDOUT);
undef $fname;
undef $counter;
undef $first_remembered_byte;
undef $second_remembered_byte;
undef $byte;
undef $input_buf;
undef $output_buf;

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unrle.pl Normal file
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#!/usr/bin/perl
use strict;
use warnings "all";
use Fcntl;
my $fname = undef;
if(defined($ARGV[0])){
if($ARGV[0] eq "--help"){
syswrite STDOUT, "Usage: $0 <filename>\n";
syswrite STDOUT, "or pipe data thrugh $0's STDIN to $0 STDOUT\n";
exit 0;
}
exit unless ($ARGV[0] =~ /\.rle$/);
$fname = $ARGV[0];
$fname = substr($fname, 0, -4);
}
my $byte = '';
my $dbyte = '';
my $block_size = 65536;
if (defined($fname)){
sysopen(STDIN, "$fname.rle", O_RDONLY) or die "Can not open file $fname!\n";
sysopen(STDOUT, $fname, O_WRONLY|O_TRUNC|O_CREAT) or die "Can not open file $fname.rle!\n";
}
binmode(STDIN);
binmode(STDOUT);
my $output_buf_byte_counter = 0;
my $output_buf = '';
my $input_buf ='';
while ( 1 ) {
my $read_bytes = sysread(STDIN, $input_buf, $block_size);
last unless(defined($read_bytes));
last if($read_bytes == 0);
my $i = 0;
for ( $i = 0; $i < $read_bytes; $i++ ) {
$dbyte = substr( $input_buf, $i, 1);
last unless(defined($dbyte));
$i++;
$byte = substr( $input_buf, $i, 1);
last unless(defined($byte));
for(my $i = 0; $i < ord($dbyte); $i++){
if ($output_buf_byte_counter == $block_size){
syswrite STDOUT, $output_buf || die "Cannot write output stream!\n";
$output_buf = '';
$output_buf_byte_counter = 0;
}else{
$output_buf_byte_counter++;
}
$output_buf .= $byte;
}
}
undef $i;
undef $read_bytes;
}
close(STDIN);
syswrite STDOUT, $output_buf || die "Cannot write output stream!\n";
close(STDOUT);
undef $fname;
undef $byte;
undef $dbyte;
undef $block_size;
undef $output_buf_byte_counter;
undef $output_buf;
undef $input_buf;