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2 lines of code greedy on ROM

 
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uni_student



Joined: 01 Aug 2007
Posts: 38
Location: AUckland, NEW ZEALAND

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2 lines of code greedy on ROM
PostPosted: Fri Oct 09, 2009 10:45 pm     Reply with quote

Pic 16f716

Before adding these 2 lines ROm usage is 78%

Code:

dist=dist + (atof(temp)/3600);
printf("%1.2fkm  ", dist);
 


After "Out of ROM" Error mesage.

How can I fix this? Any help appreciated.
andrewg



Joined: 17 Aug 2005
Posts: 316
Location: Perth, Western Australia

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PostPosted: Fri Oct 09, 2009 11:46 pm     Reply with quote

Floating point code takes up a lot of space. Stick to integer math wherever possible.

From the code you've given, you're only needing to track distance in kilometers to 2 decimal places, i.e. to 10m. So count in multiples of 10m.
Code:
dist = dist + temp / 36;
printf("%ld0m", dist);

There are other things to try. You could shift the "/36" to the printf to maintain precision. You could print to a buffer (see sprintf), allowing you to shuffle characters around and insert a decimal place for kms before displaying.
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Andrew
uni_student



Joined: 01 Aug 2007
Posts: 38
Location: AUckland, NEW ZEALAND

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PostPosted: Sat Oct 10, 2009 12:18 am     Reply with quote

andrewg

I used a less precise measurement in conjunction with atoi instead of atof which has certainly fixed the problem.

Cheers
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