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vin
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| optimization |
 Posted: Thu Nov 03, 2005 2:33 am |
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Dear Sir,
anyone can a brief description about optimisation techniques in CCS C. during programming i encountered with a peculier problem. when my total rom used reaches 75% compiler shows the message "OUT OF ROM". but when i include functions used in submodules in main file(file which contains main declaration) this eoor message is not shown. any one can help me?. |
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Foppie
Joined: 16 Sep 2005
Posts: 138
Location: The Netherlands
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MikeValencia
Joined: 04 Aug 2004
Posts: 238
Location: Chicago
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| Posted: Thu Nov 03, 2005 7:43 am |
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Though it's not always a cure-all to your out-of-rom problems, it does help to break up long functions into smaller ones. And also to use the #separate directive in front of each function, as was mentioned in the first reply. I use #separate the following way:
| Code: |
#separate
void my_fxn(void); // function prototype
#separate
void my_fxn2(void); // function prototype
...
void my_fxn(void)
{
...
}
#separate
void my_fxn2(void)
{
...
}
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Furthermore, are you using a 16F series PIC? That architecture seems to be notorious for those out-of-rom problems as your code grows. I never have that problem with PIC18F series chips. You might want to consider using an equivalent 18F chip. In fact, with an 18F, i never found the need to use #separate. |
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Foppie
Joined: 16 Sep 2005
Posts: 138
Location: The Netherlands
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| Posted: Thu Nov 03, 2005 8:03 am |
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| MikeValencia wrote: | | Furthermore, are you using a 16F series PIC? That architecture seems to be notorious for those out-of-rom problems as your code grows. I never have that problem with PIC18F series chips. You might want to consider using an equivalent 18F chip. In fact, with an 18F, i never found the need to use #separate. |
Is this not just because the 18F has more ROM??? |
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MikeValencia
Joined: 04 Aug 2004
Posts: 238
Location: Chicago
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| Posted: Thu Nov 03, 2005 8:25 am |
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| I've always been told that the 18F is geared more towards C programming than the 16F. I don't think it's a ROM issue. You say you have only 75% of ROM filled up. It's just that the 16F isn't so tolerant of having long functions that cross "page" boundaries. I haven't written in assembly nor read the datasheets for several years now, so i can't give a concise description. |
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asmallri
Joined: 12 Aug 2004
Posts: 1635
Location: Perth, Australia
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| Posted: Thu Nov 03, 2005 8:35 am |
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| MikeValencia wrote: | | I've always been told that the 18F is geared more towards C programming than the 16F. I don't think it's a ROM issue. You say you have only 75% of ROM filled up. It's just that the 16F isn't so tolerant of having long functions that cross "page" boundaries. I haven't written in assembly nor read the datasheets for several years now, so i can't give a concise description. |
The 16F family has a brain dead memory architecture (RAM and Program Memory) that should never have been brought to market - but that's the world we live in :-)
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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dyeatman
Joined: 06 Sep 2003
Posts: 1934
Location: Norman, OK
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vin
Guest
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| Posted: Thu Nov 03, 2005 11:29 pm |
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dear Sir,
Thank all for the valuble information. I am just going to experiment with code. ok we will see again. |
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