forked from KolibriOS/kolibrios
110 lines
2.1 KiB
Perl
110 lines
2.1 KiB
Perl
|
#!/usr/bin/perl
|
||
|
|
#
|
||
|
|
# Disassemble a GIF file and display the sections and chunks within.
|
||
|
|
#
|
||
|
|
# Warning: only part of the specification is implemented.
|
||
|
|
#
|
||
|
|
|
||
|
|
use strict;
|
||
|
|
use warnings;
|
||
|
|
|
||
|
|
die "Usage: $0 IMAGE\n" unless @ARGV == 1;
|
||
|
|
my ($image) = @ARGV;
|
||
|
|
|
||
|
|
open IMAGE, '<', $image or die "$0: open $image: $!\n";
|
||
|
|
undef $/;
|
||
|
|
my $gif = <IMAGE>;
|
||
|
|
close IMAGE;
|
||
|
|
|
||
|
|
print "$image: ", length $gif, " bytes\n\n";
|
||
|
|
|
||
|
|
my @gif = unpack 'C*', $gif;
|
||
|
|
my $z = 0;
|
||
|
|
|
||
|
|
output_chunk('Header', 6);
|
||
|
|
output_chunk('Logical Screen Descriptor', 7);
|
||
|
|
|
||
|
|
my $global_colors = $gif[10] & 0x80;
|
||
|
|
my $color_table_size = 2 << ($gif[10] & 0x07);
|
||
|
|
|
||
|
|
if ($global_colors) {
|
||
|
|
output_chunk('Global Color Table', $color_table_size * 3);
|
||
|
|
}
|
||
|
|
|
||
|
|
while (1) {
|
||
|
|
while ($gif[$z] == 0x21) {
|
||
|
|
if ($gif[$z + 1] == 0xf9) {
|
||
|
|
output_chunk('Graphic Control Extension', 5 + 2);
|
||
|
|
} elsif ($gif[$z + 1] == 0xfe) {
|
||
|
|
output_chunk('Comment Extension', 2);
|
||
|
|
} elsif ($gif[$z + 1] == 0x01) {
|
||
|
|
output_chunk('Plain Text Extension', 13 + 2);
|
||
|
|
} elsif ($gif[$z + 1] == 0xff) {
|
||
|
|
output_chunk('Application Extension', 12 + 2);
|
||
|
|
} else {
|
||
|
|
output_chunk((sprintf 'Unknown Extension 0x%.2x',
|
||
|
|
$gif[$z + 1]), $gif[$z + 2] + 3);
|
||
|
|
}
|
||
|
|
|
||
|
|
while ($gif[$z] != 0) {
|
||
|
|
output_chunk('Data Sub-block', $gif[$z] + 1);
|
||
|
|
}
|
||
|
|
output_chunk('Block Terminator', 1);
|
||
|
|
}
|
||
|
|
|
||
|
|
if ($gif[$z] == 0x3b) {
|
||
|
|
output_chunk('Trailer', 1);
|
||
|
|
last;
|
||
|
|
}
|
||
|
|
|
||
|
|
if ($gif[$z] != 0x2c) {
|
||
|
|
last;
|
||
|
|
}
|
||
|
|
|
||
|
|
output_chunk('Image Descriptor', 10);
|
||
|
|
|
||
|
|
output_chunk('Table Based Image Data', 1);
|
||
|
|
|
||
|
|
while ($gif[$z] != 0) {
|
||
|
|
output_chunk('Data Sub-block', $gif[$z] + 1);
|
||
|
|
}
|
||
|
|
output_chunk('Block Terminator', 1);
|
||
|
|
}
|
||
|
|
|
||
|
|
if ($z != @gif) {
|
||
|
|
output_chunk('*** Junk on End ***', @gif - $z);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
#
|
||
|
|
# Output a chunk of data as hex and characters.
|
||
|
|
#
|
||
|
|
sub output_chunk
|
||
|
|
{
|
||
|
|
my ($description, $length) = @_;
|
||
|
|
|
||
|
|
print "$description";
|
||
|
|
for (my $i = 0; $i != $length; $i++) {
|
||
|
|
if ($i % 8 == 0) {
|
||
|
|
print "\n";
|
||
|
|
printf "%8i: ", $z + $i;
|
||
|
|
}
|
||
|
|
if ($z + $i == @gif) {
|
||
|
|
print "EOF\n\n";
|
||
|
|
print "Unexpected end of file\n";
|
||
|
|
exit;
|
||
|
|
}
|
||
|
|
my $c = $gif[$z + $i];
|
||
|
|
printf "%.2x ", $c;
|
||
|
|
if (32 <= $c and $c <= 126) {
|
||
|
|
printf "'%c'", $c;
|
||
|
|
} else {
|
||
|
|
print " ";
|
||
|
|
}
|
||
|
|
print " ";
|
||
|
|
}
|
||
|
|
print "\n\n";
|
||
|
|
|
||
|
|
$z += $length;
|
||
|
|
}
|