use strict;
use warnings;
use Devel::Peek;

my $foo = pack("H16", "FFFFFFFFFFFFEF7F" );
Dump($foo);

my $bar = unpack("d", $foo);
Dump($bar);

my $x = $bar;
Dump($x);

my $y = 1.79769313486232e+308;
Dump($y);

__END__
SV = PV(0x99490a0) at 0x995b760
  REFCNT = 1
  FLAGS = (PADMY,POK,pPOK)
  PV = 0x9956ba8 "\377\377\377\377\377\377\357\177"\0
  CUR = 8
  LEN = 12
SV = NV(0x99832d8) at 0x995b7b0
  REFCNT = 1
  FLAGS = (PADMY,NOK,pNOK)
  NV = 1.79769313486232e+308
SV = NV(0x99832d0) at 0x995b740
  REFCNT = 1
  FLAGS = (PADMY,NOK,pNOK)
  NV = 1.79769313486232e+308
SV = NV(0x99832e0) at 0x9968360
  REFCNT = 1
  FLAGS = (PADMY,NOK,pNOK)
  NV = inf

##</code><code>##

179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368