From c0b0123313d8a4895d1c42c8f74675a2be5b6e08 Mon Sep 17 00:00:00 2001
From: Mischa Poslawsky <wormy@shiar.org>
Date: Fri, 27 Feb 2009 00:38:20 +0100
Subject: [PATCH] parse-wormedit: guess specific variant of v95 levels

There were 3 different level formats all with the same version 95.
Try to autodetect which by looking at some conflicting byte offsets;
the only other way is manual specification, which hopefully isn't
needed in any practical cases.
---
 parse-wormedit | 55 +++++++++++++++++++++++++++++++-------------------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/parse-wormedit b/parse-wormedit
index 26d6cbd..bc0d926 100755
--- a/parse-wormedit
+++ b/parse-wormedit
@@ -97,39 +97,52 @@ my @FORMAT = (
 
 sub read {
 	my ($self, $input) = @_;
-	my ($id, $subid) = (substr($input, 0, 15), ord substr($input, 15, 1));
-	my $version = $opt{version} // $MAGICID{$id}
+	my ($id, $version) = (substr($input, 0, 15), ord substr($input, 15, 1));
+	my $fileversion = $MAGICID{$id}
 		or die "File does not match any known WormEdit level header\n";
-	$subid == $version
-		or warn "Unsupported version $subid (expecting $version)\n";
-	given ($version) {
-		when (53) {
-			# current @FORMAT
+
+	if ($opt{version}) {
+		warn "Override version $version to $opt{version}\n";
+		$version = $opt{version};
+	}
+	elsif ($version != $fileversion) {
+		warn "Unexpected version $version (expecting $fileversion)\n";
+	}
+	elsif ($version == 95) {
+		# auto-detect exact variant
+		if (ord substr($input, 70, 1) ~~ [1 .. 8]) {
+			# valid sprite length instead of description byte
+			# (which is usually a letter or nul)
+			$version = 94;
 		}
-		when ($_ <= 95 and $_ > 90) {
-			ref $_ and pop @$_ for @{ $FORMAT[11] }; # only 8 moderefs
-			$FORMAT[-1]->[-1]->[0] = '32C'; # less objects
-			continue;
+		elsif (ord substr($input, 147, 1) == 0) {
+			# nul of end type is 2 bytes later (unlike first char of endstr)
+			$version = 96;
 		}
-		when (95) {
+		warn "Ambiguous file version 95; guessing subversion $version\n";
+	};
+
+	$fileversion += 100 if $fileversion < 90;  # 93..95 came before 50..53
+	given ($fileversion) {
+		when (153) { } # current @FORMAT
 			$FORMAT[7] = 'Ca64'; # no reserved space after description
-			#ref $_ and $_->[-1] = 'C' for @{ $FORMAT[11] }; # only 9 moderefs
 			$FORMAT[19] = 'Ca255'; # enddata
-			splice @FORMAT, 6, 2 if $subid < 95;  # early (sub)version without description
+			$FORMAT[-1]->[-1]->[0] = '32C'; # less objects
+		when ($version == 96) {
+			ref $_ and $_->[-1] = 'C' for @{ $FORMAT[11] }; # 9 moderefs
 		}
-		when ($_ <= 94 and $_ > 90) {
-			splice @FORMAT, 6, 2;  # no description
+			ref $_ and pop @$_ for @{ $FORMAT[11] }; # only 8 moderefs
+			splice @FORMAT, 6, 2 if $version <= 94;  # earlier version without description
+		when (95) { }
 			splice @{ $FORMAT[7] }, 4, 2;  # no race
 			splice @FORMAT, 16, 2; # no enddata
 			splice @{ $FORMAT[-1] }, 1, 2; # no name
-			continue if $_ < 94;
-		}
-		when (93) {
+		when (94) { }
 			splice @FORMAT, 16, 2; # no hiname
 			$FORMAT[-1]->[0] = 64; # constant amount of levels
-		}
+		when (93) { }
 		default {
-			die "Cannot parse data for Wormedit $version\n";
+			die "Cannot parse data for Wormedit $fileversion/$version\n";
 		}
 	}
 
-- 
2.30.0