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use warnings ;
use strict ;
binmode(STDIN);
my $a ;
read STDIN,$a,8 ;
if( $a ne "\x89PNG\x0d\x0a\x1a\x0a" ) {
die "Malformed PNG header\n" ;
}
sub bv($) {
ord(substr($a,$_[0],1)) ;
}
sub wv($) {
my $a = shift ;
return (bv($a) << 24) + (bv($a+1) << 16) + (bv($a+2)<<8) + bv($a+3);
}
my %all ;
while( !eof STDIN ) {
read STDIN,$a,4 ;
my $len = wv(0);
read STDIN,$a,$len+8 ;
my $type = substr($a,0,4) ;
next if $type eq 'IDAT' ;
last if $type eq 'IEND' ;
if( $type eq 'IHDR' && $len == 13 ) {
print wv(4),"x",wv(8),"x",bv(12),"\n" ;
my $cmode = bv(13) ;
print $cmode & 3 ? "color" : "gray" ;
print "+index" if $cmode & 1 ;
print "+alpha" if $cmode & 4 ;
print "\nz",bv(14)," f",bv(15)," i",bv(16),"\n" ;
next ;
}
my $aref = ($all{$type} ||= []) ;
push @$aref, "$type($len)" ;
{
my $w = 16 ;
$w = 24 if $type eq 'PLTE' ;
$w = 8 if $type eq 'tRNS' ;
for my $i ( 0 .. $len - 1 ) {
push @$aref, sprintf("%s%02X", $i%$w ? " " : "\n ", bv($i+4) ) ;
push @$aref, " " if
$type eq 'PLTE' &&
$i%3 == 2 &&
($i+1)%$w != 0 &&
$i != $len-1 ;
}
push @$aref, "\n" ;
}
}
for my $k ( sort keys %all ) {
print @{$all{$k}} ;
}
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