Initial commit.

rle.pl

@@ -0,0 +1,86 @@
+#!/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;