$num = 0x01020304;

 $Npacked = pack 'N', $num;
 $Vpacked = pack 'V', $num;

 print map{ vec $Vpacked,      $_, 1 } 0 .. 31
 print map{ vec $Npacked,      $_, 1 } 0 .. 31
 print map{ vec $Vpacked, 31 - $_, 1 } 0 .. 31
 print map{ vec $Npacked, 31 - $_, 1 } 0 .. 31
 
00100000 11000000 01000000 10000000
10000000 01000000 11000000 00100000
00000001 00000010 00000011 00000100
00000100 00000011 00000010 00000001