[avr-libc-dev] [bug #30363] _delay_xx() functions in <util/delay.h> are broken

[Bill Perry]

Follow-up Comment #5, bug #30363 (project avr-libc):

Eric,
Totally agree with your comments over on avrfreaks
thread:
http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&p=725947#725947

The part about delaying the release process was actually kind of funny.
:lol:

On a serious note,
issues with <util/delay.h> and proposed fixes have actually been going on for
several years now. The original posting about Han's better delay routines were
made a couple of years ago.

My overall feeling is that library supplied delay routines need to "just
work" and work for hardware type setup timing type of delays as there is no
alternative to cycle delays for those types of very short delays.

[b]What can I do to help this along?[/b]

BTW, in testing between Han's delay code sequences and the
__builtin_avr_delay_cycles() code, Han's code actually generates smaller code
in some cases. It looks like there are some instructions that Han's used that
are not being used by GCC. At some point this also might be something to look
at.

In the big picture I think the <util/delay.h> routines need to deal with the
cycle rounding better.
My opinion is that f you can't pick your rounding style, "always up" seems
like the way to go as it ensures that the delays can b e used for hardware
setup time delays.

[b]But I'll offer to help in any way.
>From creating patches, to updating the doxygen doucmenation.
Just let me know.[/b]
Also, is the "mailing list" you refered to different from posting comments to
the savannah bug report?


--- bill

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