Add macros to simplify access to the system registers

[andrew]

Summary

Macros from Svatopluk Kraus and Michal Meloun. May need more cleanup.

[andrew]

I've only compiled this, not tested on hardware or verified the obj files with and without the patch are the same.

[rpaulo]

I think it's a good cleanup and it's easy to verify that nothing changed.

sys/arm/include/sysreg.h

29 ↗

(On Diff #1670)

This file should probably include the header from which __ARM_ARCH comes from.

[• ian]

No objections. Something about this just doesn't thrill me, I think I'd rather see real asm macros, but there's nothing about this that makes it harder to convert to real macros later (in fact, this probably makes it easier). I sure hope all the #defines have been double and tripple checked, this is just the sort of thing where tiny cut and paste errors can make for difficult debugging.

[andrew]

Closed by commit rS272209 (authored by @andrew).