@b = unpack('CCCC', pack('I', 0x04030201));

if    ($b[0] == 4 and
       $b[1] == 3 and
       $b[2] == 2 and
       $b[3] == 1 )
  { print "big-endian\n"; }
elsif ($b[0] == 1 and
       $b[1] == 2 and
       $b[2] == 3 and
       $b[3] == 4 )
  { print "little-endian\n"; }
else
  { print "funky-endian\n"; }