my $f = unpack('N',  pack('B32', "01000010001111000000000000000000")) ;

printf "0x%08X = %12.9f\n", $f, conv_HFP($f) ;

sub conv_HFP {
  my ($f) = @_ ;

  my $s = ($f & 0x8000_0000) ? -1 : +1 ;
  my $e = (((($f >> 24) & 0x7F) - 0x40) * 4) - 24 ;

  return $s * ($f & 0xFF_FFFF) * (2 ** $e) ;
} ;