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compiler operation across ROM pages

 
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jack11
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compiler operation across ROM pages
PostPosted: Tue Apr 06, 2004 8:44 am     Reply with quote
Is there a method to force the compiler to use all (or most) of a ROM segment? Using 16f877 with PCM 3.169. After compiling, the resulting code has large gaps of unused memory. It appears that the compiler fills a ROM segment to some point and then abandons it and moves to the next ROM segment. I'd like to use the ROM more efficiently.

Any Thoughts

Thanks
Ttelmah
Guest
Re: compiler operation across ROM pages
PostPosted: Tue Apr 06, 2004 10:12 am     Reply with quote
jack11 wrote:
Is there a method to force the compiler to use all (or most) of a ROM segment? Using 16f877 with PCM 3.169. After compiling, the resulting code has large gaps of unused memory. It appears that the compiler fills a ROM segment to some point and then abandons it and moves to the next ROM segment. I'd like to use the ROM more efficiently.

Any Thoughts

Thanks

The answer, is to keep functions small.
Basically, if all the functions in the code are very small, the waste on a page will be tiny. However if when fitting things in, the next function is larger than the remaining space in a page, the compier will immediately jump to the next page to put it into. Then even if the following functions are small again, it'll only go back to the earlier page, if it finds something too large to fit in the new page, and either has to re-organise, and start looking for holes elsewhere.
If you have several smaller functions, that are declared after the first one that jumps into the second page, try declaring them in front of this function instead. This may delay the selection of the second page.

Best Wishes
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