hex equivalent of negative numbers

[Former user]

Originally reported on Google Code with ID 506

Steps to reproduce:
hex(-1)
= -0x1

Expected behavior:
It would be very nice if this would show the 2's compliment of any negative numbers.
 So, -1 would yield 0xFFFFFFFF (or 0xFFFFFFFFFFFFFFFF if 64-bit math is being used).

Experienced behavior:

Product version:
0.11

Operating system:
Windows 7 x64 Professional

Additional Information:
For an example of this, switch to "Programmer" mode in the built-in windows calculator.
 Set the radix to decimal, enter -1, then switch the radix to hex.

Reported by [e-mail] on 2014-05-29 12:28:21

[Former user]

Reported by helder.pereira.correia on 2014-12-17 21:45:01 - Labels added: Type-Enhancement

[Former user]

Actually, that's (a side-effect of) what the 'mask' function does. As in,

hex(mask(-1; 32)) == 0xFFFFFFFF

and

unmask(0xFFFFFFFF; 32) == -1

I don't think this could be implemented in the 'hex' function because it wouldn't know
the desired number of bits. I feel the correct solution here would be "document it"...

Reported by fkrull.0 on 2015-01-17 16:37:17

[Former user]

@fkrull: indeed. @nhoch: I don't know the windows calculator but I imagine it uses the
CPU directly instead of an arbitrary precision math engine like SpeedCrunch. Hence
the 0xFFFFFFFF or 0xFFFFFFFFFFFFFFFF results.

Reported by helder.pereira.correia on 2015-01-19 13:45:49 - Status changed: Rejected

[Vedran Grudenic]

Note that it's rather easy to define a user function which does this, using something like:

shex(x; bits) = hex(mask(x; bits))   ? "signed hex"

Or, you can create several functions for common word sizes:

shex16(x) = hex(mask(x; 16))  ? dec -> hex 16-bit signed
shex32(x) = hex(mask(x; 32))  ? dec -> hex 32-bit signed
...
sdec16(x) = unmask(x; 16)  ? hex -> dec 16-bit signed
sdec32(x) = unmask(x; 32)  ? hex -> dec 32-bit signed
...

To use the function, just start typing "shex" and you're set.