Hi George,
thanks for the tip. However I want to see how far I can go with C. Looking
at my interrupt code there are not that many obvious places where hand
coding would improve things a lot so overall from the maintainability
point of view I first want see if I could do this in C. Having grown
up on 8 bit CPUs (1802,8080,6800,6502,8085,Z80,HC11,HC08, oops this
reveals how old I am ;-) I feel I've done my bit of assembly language
programming. But if it may come to that in the end.
Right now I would just want to get rid of those extra register push/pops,
after discoving '--pno-banksel' option to get rid of all BANKSEL
instructions the compiled code looks actually rather nice to my not
so well trained PIC eye.
br Kusti
> From: "George M. Gallant" <ggallant...@comcast.net>
> Reply-To: <sdcc-user@lists.sourceforge.net>
> Date: Mon, 9 Mar 2009 15:46:22 +0200
> To: <sdcc-user@lists.sourceforge.net>
> Conversation: [Sdcc-user] PIC port, __naked not working, Bus error, signal 11:
> SIGSEGV
> Subject: Re: [Sdcc-user] PIC port, __naked not working, Bus error, signal 11:
> SIGSEGV
>
> Kustaa,
>
> I gave up on using SDCC for interrupts and process UART interrupts in
> assembler.
> I setup 2 queues, one for transmit and one for extraction. Each queue
> has an insert
> pointer, extraction pointer, and byte count. With this scheme I am able
> to reliably
> communicate with a host PC at 38400 on a 40MHz PIC18F2620.
>
> If you allocate 256 bytes for each queue the wrap is handled by the PIC.
> It does
> require some code to manage the transmit interrupt state.
>
> George
>
> Kustaa Nyholm wrote:
>> Hi list,
>>
>>
>> in order to get rid of some longish preamble in my interrupt I tried to
>> define the interrupt as '__naked' but this produced 'Bus error' during
>> compilation.
>>
>> After a lot of pruning I got the code down to:
>>
>> unsigned char x;
>>
>> void test() __naked {
>> if (x) {
>> x = 1;
>> }
>> }
>>
>> which when compiled with parameters:
>>
>> SDCCFLAGS = "-Wl,-m,-s 18f4550.lkr" -mpic16 -p18f4550 --disable-warning 85
>> --std-sdcc99 --obanksel=3 --pno-banksel
>>
>>
>> produces SIGSEGV .
>>
>> If I remove the __naked the problem disappears, but I'm back in square one.
>>
>> So this appears to be compiler bug. I tried to look for this in the list
>> archives but I could not find anything related to that.
>>
>> Now I have specific questions:
>>
>> 1) Should I file a bug?
>>
>> 2) How can I circumvent this?
>>
>> My actual problem is that the compilers emits a lot of code like:
>>
>> 002C C000 FFE5 01503 MOVFF r0x00, POSTDEC1
>> 0030 C000 FFE5 01504 MOVFF r0x01, POSTDEC1
>> 0034 C000 FFE5 01505 MOVFF r0x02, POSTDEC1
>> 0038 C000 FFE5 01506 MOVFF r0x03, POSTDEC1
>> 003C C000 FFE5 01507 MOVFF r0x04, POSTDEC1
>> 0040 C000 FFE5 01508 MOVFF r0x05, POSTDEC1
>>
>> that I would like to avoid, all I want is for the compiler to allocate
>> these are global variables used solely by the interrupt so that there
>> is no need to save/restore them...I know 'naked' alone would not do this
>> but it seems like a necessary step in getting there...?
>>
>> 3) I seem to recall some list discussion relating to PIC / inline assembly
>> and that it does not work or something but I cannot find that
>> discussion. Is there a problem there?
>>
>> br Kusti
>>
>>
>>
>>
>>
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>
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> -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise
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-OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise
-Strategies to boost innovation and cut costs with open source participation
-Receive a $600 discount off the registration fee with the source code: SFAD
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