[REBOL] Bitwise manipulation Re:
From: joel:neely:fedex at: 11-Oct-2000 10:50
Hi, Phil...
[Philip--Hayes--btcellnet--net] wrote:
> An interesting one ...
>
> I have a integer value that I must convert to binary:
>
> Nice and easy for values <= 127
>
> int1: 56
>
> b1: to-binary to-block int1
>
> HOWEVER, if int1 is greater than 127, say 2037, I have to perform the
>
> following task:
>
> 2037 which is equivalent to 0000100001011000 must be split into 2 bytes as
>
> follows
>
> b1: -> 00001000 effectively b1: to-binary to-block 8
>
> b2: -> 01011000 effectively b2: to-binary to-block 24
>
> Any suggestions..
>
Two suggestions:
1) Try using
big-endian: func [n [integer!] /local r] [
r: copy #{}
until [
insert r to-binary to-char (n // 256)
0 = n: to-integer n / 256
]
r
]
>> big-endian 56
== #{38}
>> big-endian 2037
== #{07F5}
However, *DANGER, WILL ROBINSON!*,
1.1) This assumes byte order for values requiring more than 8 bits.
1.2) It breaks for negative values! (Explaining why and proposing
a repair are left as exercises for the reader... ;-)
2) Check your math. Last time I looked, 2037 was odd, which means that
its binary representation MUST end in a one! ;-)
-jn-
--
; Joel Neely [joel--neely--fedex--com] 901-263-4460 38017/HKA/9677
REBOL [] print to-string debase decompress #{
789C0BCE0BAB4A7176CA48CAB53448740FABF474F3720BCC
B6F4F574CFC888342AC949CE74B50500E1710C0C24000000}
