From ad615f1eb4febb59f5148ba356d9ad91dc72db09 Mon Sep 17 00:00:00 2001
From: "B. Watson" <yalhcru@gmail.com>
Date: Wed, 6 Jan 2016 01:55:41 -0500
Subject: compressed title image, loads faster

---
 titlecomp.pl | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100644 titlecomp.pl

(limited to 'titlecomp.pl')

diff --git a/titlecomp.pl b/titlecomp.pl
new file mode 100644
index 0000000..2e17a92
--- /dev/null
+++ b/titlecomp.pl
@@ -0,0 +1,95 @@
+#!/usr/bin/perl -w
+
+$datasize = 0x1700;
+
+use bytes;
+
+# skip xex header
+read(STDIN, our $junk, 6);
+
+read(STDIN, $data, $datasize);
+
+for(split //, $data) {
+	$got{ord($_)}++;
+}
+
+$firstcode = shift || 128; # must be >=128
+for($firstcode..255) {
+	push @available_codes, $_ unless $got{$_};
+}
+print scalar keys %got, " unique byte values\n";
+print scalar @available_codes . " available run codes >= $firstcode\n";
+
+sub allocate_code {
+	if(!@available_codes) {
+		die "out of run codes!\n";
+	}
+
+	return shift @available_codes;
+}
+
+# add a $ff to the end, to force the last run to be written
+# if the file ends in a run. Remove it afterwards.
+$run = 0;
+$output = "";
+for(split //, $data . chr(0xff)) {
+	if($_ eq "\0") {
+		if($run) {
+			$run++;
+		} else {
+			$run = 1;
+		}
+	} else {
+		if($run > 1) {
+			if($runlengths{$run}) {
+				$output .= chr($runlengths{$run});
+			} else {
+				my $code = allocate_code();
+				$runlengths{$run} = $code;
+				$used_codes{$code} = $run;
+				$output .= chr($code);
+				$lastcode = $code;
+			}
+		} elsif($run == 1) {
+			$output .= "\0";
+		}
+		$run = 0;
+		$output .= $_;
+	}
+}
+
+# remove the $ff we added above.
+substr($output, -1) = "";
+
+open $out, ">comptitle.dat";
+print $out $output;
+close $out;
+
+$pct = int(length($output) * 1000 / length($data))/ 10;
+print "1st code $firstcode, last $lastcode, table size " . ($lastcode - $firstcode + 1) . "\n";
+print length($output) . " bytes compressed data, $pct% ratio\n";
+print "used " . keys(%runlengths) . " codes\n";
+
+
+for($firstcode..$lastcode) {
+	$table .= " .byte ";
+	if(exists($used_codes{$_})) {
+		$table .= '$' . sprintf("%02x", $used_codes{$_}) . " ; " . sprintf("%02x", $_);
+	} else {
+		$table .= "\$00 ; SELF";
+	}
+	$table .= "\n";
+}
+
+open $in, "<comptitle.s.in" or die $!;
+open $out, ">comptitle.s" or die $!;
+
+while(<$in>) {
+	s/__TABLE__/$table/;
+	s/__FIRSTCODE__/$firstcode/g;
+	s/__LASTCODE__/$lastcode/g;
+	print $out $_;
+}
+
+close $in;
+close $out;
-- 
cgit v1.2.3