HEX format

[input]-48357032784590233537827831608 in hex[/input]

This wrong answer..
0xFFFFFFFF63BFFFFFFFEE0000000000C8 <- this true

in two's complement:

[input]48357032784590233537827831608 in hex[/input]
[input]ceil(log2( 48357032784590233537827831608 ))[/input]
[input]2^128-1 in hex[/input]
[input](2^128-48357032784590233537827831608) in hex[/input]

0xffffffff63bfffffffee0000000000c8

All right. I wish that this was accomplished at once, if it possible.