my $bytes = pack 'C*', 0x00, 0x00, 0x01, 0x16, 0x7A, 0x53, 0x7C, 0x80;

##</code><code>##

print unpack 'Q', scalar reverse $bytes;;
1196053200000

##</code><code>##

print unpack 'Q', pack 'C8',  reverse 0x00, 0x00, 0x01, 0x16, 0x7A, 0x53, 0x7C, 0x80;;
1196053200000

##</code><code>##

print unpack 'Q>', pack 'C8',  0x00, 0x00, 0x01, 0x16, 0x7A, 0x53, 0x7C, 0x80;;
1196053200000

##</code><code>##

( $hi, $lo ) = unpack 'NN', $bytes;;
print +($hi * 2**32 ) + $lo;;
1196053200000