Initial revision

contrib/mntnbi/mntnbi.pl

@@ -0,0 +1,97 @@
+#!/usr/bin/perl -w
+#
+# Quick Perl program to decode and display details about 
+# tagged images created by mknbi, and then mount the contained
+# DOS filesystem using a loop-back mount
+#
+# Martin Atkins, November 1998
+# by hacking disnbi by
+# Ken Yap, September 1998
+#
+#
+
+sub getvendordata {
+	my ($flags) = @_;
+
+	my $vendordata = '';
+	my $vendorlen = ($flags & 0xff) >> 4;
+	if ($vendorlen > 0) {
+		$vendorlen *= 4;
+		$vendordata = unpack("A$vendorlen", substr($imageheader, $curoffset));
+		$curoffset += $vendorlen;
+	}
+	return ($vendordata);
+}
+
+sub decodesegmentflags {
+	my ($flags) = @_;
+
+	$flags >>= 24;
+	$flags &= 0x3;
+	($flags == 0) and $type = "Absolute";
+	($flags == 1) and $type = "Follows last segment";
+	($flags == 2) and $type = "Below end of memory";
+	($flags == 3) and $type = "Below last segment loaded";
+	return ($type);
+}
+
+sub onesegment
+{
+	my ($segnum) = @_;
+	my ($type, $vendordata);
+
+	my ($flags, $loadaddr, $imagelen, $memlength) = unpack("V4", substr($imageheader, $curoffset));
+	$curoffset += 16;
+	print "Segment number $segnum\n";
+	printf "Load address:\t\t%08x\n", $loadaddr;
+	printf "Image length:\t\t%d\n", $imagelen;
+	printf "Memory length:\t\t%d\n", $memlength;
+	$type = &decodesegmentflags($flags);
+	printf "Position:\t\t$type\n";
+	printf "Vendor tag:\t\t%d\n", ($flags >> 8) & 0xff;
+	if (($vendordata = &getvendordata($flags)) ne '') {
+		print "Vendor data:\t\t", $vendordata, "\n";
+	}
+	print "\n";
+	push (@seglengths, $imagelen);
+	return (($flags >> 26) & 1);
+}
+
+@seglengths = ();
+$#ARGV == 1 or die "Usage: mntnbi tagged-image-file dir\n";
+$imagefile= $ARGV[0];
+open(I, $ARGV[0]) or die "$imagefile: $!\n";
+(defined($status = sysread(I, $imageheader, 512)) and $status == 512)
+	or die "$imagefile: Cannot read header\n";
+$headerrecord = substr($imageheader, 0, 16);
+($magic, $flags, $bx, $ds, $ip, $cs) = unpack("a4Vv4", $headerrecord);
+$magic eq "\x36\x13\x03\x1B" or die "$imagefile: Not a tagged image file\n";
+$curoffset = 16;
+
+# Now decode the header
+
+printf "Header location:\t%04x:%04x\n", $ds, $bx;
+printf "Start address:\t\t%04x:%04x\n", $cs, $ip;
+printf "Flags:\n";
+	print "Return to loader after execution (extension)\n" if (($flags >> 8) &  1);
+if (($vendordata = &getvendordata($flags)) ne '') {
+	print "Vendor data:\t\t", $vendordata, "\n";
+}
+print "\n";
+
+# Now decode each segment record
+
+$segnum = 1;
+do {
+	$lastrecord = &onesegment($segnum);
+	++$segnum;
+} while (!$lastrecord);
+
+if ($#seglengths != 1) {
+	die "This is not a DOS image $#seglengths\n";
+}
+$offset = 512 + $seglengths[0];
+print "mounting filesystem at offset $offset in $ARGV[0] on $ARGV[1]\n";
+$rc = system "mount $ARGV[0] $ARGV[1] -t msdos -o loop,offset=$offset";
+print "Done\n" if ($rc == 0);
+exit(0);