Optimising tricks of the trade !

[darren logan]

Hello,

Im fairly new to PIC C, but have just completed my first project involving many of the more advanced features of a PIC (such as timer and UART interrupts).

My budget was to used a PIC16F870 and several times during the project I was faced with the dreaded OUT OF ROM message.
When this happened, I would go back through my code and check to see if I could cut down or optimise to trim down the code size, and sure enough I did.

I learnt several tricks along the way to save space and Im sure it would be of benefit to share mine, and you share yours. Here are a couple that made a big difference for me...

(Note that these may not apply to you, depending on your setup but I should imagine they will come in handy at some point!):

Instead of using:
output_low(whatever)
Use:
bit_clear(*x,y)
(also use bit_set instead of output_high)

Instead of using:
delay_ms(xxx)
Use:
for(i=0;i (I.e., use a for/loop. However a for loop instead of delay_us on the other hand does not save space)

Please post your handy tips !

Cheers,
Darren
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Original Post ID: 11198

[mark r. hahn]

:=Hello,
--- snip ---
:=Please post your handy tips !
:=
:=Cheers,
:=Darren

I wrote a review of the CCS PCM compiler a few years back. I included several tips on how to make your programs smaller. Most of what I wrote then still holds. You might wish to check out my web page: <a href="http://home.hvc.rr.com/mhahn/HahnTronix.html" TARGET="_blank">http://home.hvc.rr.com/mhahn/HahnTronix.html</a>

Happy crunching,

Mark Hahn
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This message was ported from CCS's old forum
Original Post ID: 11214

[Darren Logan]

Hello,

My program contained several write_eeprom and read_eeprom commands.

I replaced them with my own read/writes thus:

void writetoeeprom(int addr, int data) {

write_eeprom(addr,data);

}

int readfromeeprom(int addr) {

return(read_eeprom(addr));

}

This made a significant difference.

Regards,
Darren
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This message was ported from CCS's old forum
Original Post ID: 12149