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RE: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os
From: |
Stu Bell |
Subject: |
RE: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os |
Date: |
Fri, 16 May 2008 14:16:29 -0600 |
>> The PORTA bits are used for hardware control. I want to use the
>> atan2(), etc. calls as pulse stretching.
>>
>> Then I recommend using the calls in <util/delay.h> to get exact
delays
>> instead of monkeying around with floating point routine calls.
>> They'll be a lot more exact as well as being a boatlad smaller!
>
>Perhaps the atan2() call are accomplishing useful work...
Perhaps so. However, if all they are doing is "pulse stretching" as was
indicated, a flat delay is better.
That said, I thought the OP was originally using the PORTA bit flipping
as a simple way to time how long each given function takes, perhaps as a
calibration or benchmarking exercise. I found the fact that sin, cos,
and so on worked, but atan2 didn't, the most interesting part of the
discussion.
And I think the answer to that has been adequately explained (look-up
tables not affecting volatility, etc.). Then we branched off into
whether "clobber memory" is the best way to handle sei() and cli().
Again, a fun discussion.
Enough explanation of my comments. Back to the argument, which is
already in progress... ;-)
Stu
- Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, (continued)
- Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, Andy H, 2008/05/22
- Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, David Brown, 2008/05/23
- Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, Paulo Marques, 2008/05/16
- Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, John Regehr, 2008/05/16
- Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, Thomas D. Dean, 2008/05/16
- RE: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, Stu Bell, 2008/05/16
- RE: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, John Regehr, 2008/05/16
- RE: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os,
Stu Bell <=
- Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, Thomas D. Dean, 2008/05/16
- Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, David Brown, 2008/05/17
Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, Thomas D. Dean, 2008/05/15
Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, Thomas D. Dean, 2008/05/15
Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, hutchinsonandy, 2008/05/15
Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, Alex Wenger, 2008/05/15
Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os, David Brown, 2008/05/15