RFC: Representation of large hex values
(OK, this isn't strictly a kernel thing - but it seems to be a good place for peoples thoughts on this, and the kernel would be one place to start it off)
The problem: Large (64 bit) hex values are cumbersome - especially when they contain strings of 0's in the middle
Suggestion: Print hex value with a seperator every 4 or 8 nybbles to aid in counting. After some discussion it seems that _ is a decent seperator - e.g.
1000_0000_0000_1234
this is especially useful when you have a pile of numbers like
1000000021771245
and you are trying to see if that is bigger or smaller than the number 1000000232349876, yet it is pretty obvious when you try and compare 1000_0000_2177_1245 and 1000_0002_3234_9876.
I originally thought of using : like IPv6 but this can get in the way on languages which use : for other things. (and I don't think it is worth doing packed numbers like IPv6 does - i.e. 1000_0_2177_1245 would be invalid).
For clarity, it would seem best to use a distinct format character; so perhaps prefix these numbers by 0y (read Oi!) and then you could use %y (and %Y if you REALLY want) in printf. Scanf equivalents would be taught to understand both formats; using 0y and _ makes code that doesn't understand the format fail noisily. So:
0ydead_beef_1ced_ac1d
I don't think there is the necessity to force zero padding, so 1_2177_1245 is valid; but _ shall not be the first character (so as not to construct an identifier). (I'm vaguely remembering that VHDL allows _ padding?)
If people like this then I'd be happy to write a modified printf/scanf, and I suggest that it gets used in limited places until the same could be integrated in gdb/binutils/other tools.
Suggestions and constructive comments welcome and apologies for disturbing your games of wack-the-penguin.
DaveP.S. Thanks go to members of the non-existant cabal on this.
-----Open up your eyes, open up your mind, open up your code -------
/ Dr. David Alan Gilbert | Running GNU/Linux on Alpha,68K| Happy \ \ gro.gilbert @ treblig.org | MIPS,x86,ARM,SPARC,PPC & HPPA | In Hex / \ _________________________|_____ http://www.treblig.org |_______/
Quoted 4 lines · Dr. David Alan Gilbert
(OK, this isn't strictly a kernel thing - but it seems to be a good place for peoples thoughts on this, and the kernel would be one place to start it off)
Quoted 8 lines
The problem: Large (64 bit) hex values are cumbersome - especially when they contain strings of 0's in the middle
Suggestion: Print hex value with a seperator every 4 or 8 nybbles to aid in counting. After some discussion it seems that _ is a decent seperator - e.g.
1000_0000_0000_1234
You'll break people piping output to tools, you must solve this by running the output to your own filter which split hexa number.
regards,
Phil
Quoted 3 lines · Dr. David Alan Gilbert
For clarity, it would seem best to use a distinct format character; so perhaps prefix these numbers by 0y (read Oi!) and then you could use %y (and %Y if you REALLY want) in printf.
POSIX defines the ' flag to enable use of thousand separators for decimal formats. This could easily be extended to hex formats.
Andreas.
Signature · 4 lines
Andreas Schwab, SuSE Labs, [email protected] SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different."