mailto: blog -at- heyrick -dot- eu

SharedCLibrary versions

On the RISC OS forum, the question was raised as to what library versions should an application ask for?

Well, a compiled program has a "stubs" part stuck at the end which does all the interfacing with the library, and part of it looks like this:

What we can see from this is that the minimum that is required is to have SharedCLibrary 5.17 and FPEmulator 4.03.

The current library version is something like 6.03, and it looks as if a good many programs ask for 5.34 (but not all, some want later) so what is actually different and why would you want to specify a version?

The answer is simple - you'd want to require a version of the library that offers the features that you need.

Briefly:

  • Versions prior to 5.27 have a variety of serious 32 bit issues. Probably shouldn't be used.
    If you're interested in a useful 32 bit friendly version, you should ask for 5.44 or newer.

  • Versions prior to 5.52 contain no or partial support for C99 features such as long long, complex numbers, etc etc.
    If you use these things, you'll probably want 5.52 or later.

Versions following are less "major change", so will simply be listed with the salient points. No mention is made of RISC_OSLib changes, as you ought to have the latest version if you're using a recent DDE.

  • 5.60 now looks up the location of the special CLib words, instead of hacking around in page zero.
  • 5.61 uses SMULL/UMULL/CLZ in the maths code. This probably only applies to ROM builds as legacy hardware (probably everything pre-StrongARM) won't have those instructions.
  • 5.64 includes support internally for 64 bit file pointers, in readiness for when the filing system is able to cope with it...
  • 5.69 supports locale support for selecting timezones (done in 5.68) and changes to mktime() to support this.
  • 5.76 fixes scanf() so it'll fail when no match occurs.
  • 5.88 has an option to use LDREXB/STREXB instead of SWP and SWPB. Soft load versions will look at the processor to determine whether or not it's safe to use swap, ROM builds will be built for the specific architecture.
  • 5.90 fixes localtime() to return the correct time if the timezone is not the first for the territory (my fix ☺).
  • 5.91 provides enhancements so clients can receive optimal routines (where possible) according to their processor type.
  • 5.93 removes some unnecessary cache sync calls, to optimise on SMP ROMs.
  • 5.95 fixes some "abort while in abort handler" problems due to stack pointer/limit values being invalid.
  • 5.97 includes enhancements to try to avoid blocking callbacks (the unkillable while(1) {} loop in a TasWindow...

With this in mind, everybody ought to be using the latest version of CLib, however for your own programs...

  • 5.44 should be the absolute minimum that you ask for in your RMEnsure.
  • 5.52 if you want C99's enhancements, 64 bit integers, etc.
  • 5.90 if you need working support for alternative timezones.

 

 

Your comments:

Please note that while I check this page every so often, I am not able to control what users write; therefore I disclaim all liability for unpleasant and/or infringing and/or defamatory material. Undesired content will be removed as soon as it is noticed. By leaving a comment, you agree not to post material that is illegal or in bad taste, and you should be aware that the time and your IP address are both recorded, should it be necessary to find out who you are. Oh, and don't bother trying to inline HTML. I'm not that stupid! ☺
 
You can now follow comment additions with the comment RSS feed. This is distinct from the b.log RSS feed, so you can subscribe to one or both as you wish.

Gavin Wraith, 18th March 2020, 22:40
Many thanks for this, Rick. Let us hope it will not be too long before CLib also supports VFP and Neon.
David Pilling, 22nd March 2020, 02:42
I never seem to do the right thing - perils of being involved for so long - RMEnsure a version and someone will decide one should not. Interesting to read of the differences though - I did not appreciate those.
Rick, 24th March 2020, 21:42
Yes, I hope CLib soon supports VFP, as emulating FP on a machine with it in hardware (and hundreds of times faster) is rather untenable. 
 
Unfortunately it is not as simple as plugging in a different set of instructions. Unlike FPE which only requires some registers to be preserved, VFP uses contexts. Also, the byte ordering of the FP values in memory is the other way around, so anything that works directly with that (casting, printf, etc) will need versions that understands both VFP (for new apps) and FPE (for everything else). 
Rick, 24th March 2020, 21:48
FP values are defined by IEEE aren't they? Aside from byte order, they're the same thing, yes? 
Assuming so... 
 
Personally, the way I'd do it is to write all the FP routines to work with VFP values. And have a flag set by the application if it supports VFP. 
Then, upon dealing with an FP value, if the flag is NOT set, then flip the byte ordering. In this way, the default is for direct support of VFP for speed, and any time lost due to constant byte flipping for FPE will be negligible compared to using the maths emulator itself... 

Add a comment (v0.10) [help?] . . . try the comment feed!
Your name
Your email (optional)
Validation Are you real? Please type 17934 backwards.
Your comment
Calendar
«   March 2020   »
MonTueWedThuFriSatSun
      
23568
9101114
171921
27
31     

Last 5 entries

List all b.log entries

Return to the site index

Search

Search Rick's b.log!

PS: Don't try to be clever.
It's a simple substring match.

Etc...

Thank you:
  • Fred
  • Bernard
  • Michael
  • David

Last read at 23:32 on 2020/04/02.

QR code


Valid HTML 4.01 Transitional
Valid CSS
Valid RSS 2.0

 

© 2020 Rick Murray
This web page is licenced for your personal, private, non-commercial use only. No automated processing by advertising systems is permitted.
RIPA notice: No consent is given for interception of page transmission.

 

Have you noticed the watermarks on pictures?
Next entry - 2020/03/20
Return to top of page