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MOVLF xC5 putting to wrong xC5

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object01

Joined: 13 May 2004
Posts: 90
Location: Nashville, TN

MOVLF xC5 putting to wrong xC5

Posted: Tue May 10, 2005 4:49 pm

This line,

Code:

parserState = opcode;

compiles to

Code:

3D64: MOVLW 04
3D66: MOVWF xC5

.

(opcode is the 5th member of an enum)

The symbol map shows parserState at location 0x0C5. But instead, 0x6C5 is getting assigned the value 4. I can't imagine that this is anything other than a compiler bug, but I don't know how to go about working around it. Truthfully, I don't know enough about indirect addressing to be able to spot the problem.

Any suggestions?

--
Jeff S.

object01

Joined: 13 May 2004
Posts: 90
Location: Nashville, TN


Posted: Tue May 10, 2005 4:57 pm

(ok, so I got the subject line wrong...)

PCM programmer

Joined: 06 Sep 2003
Posts: 21708


Posted: Tue May 10, 2005 5:00 pm

Post a program that we can compile. Post your compiler version.

object01

Joined: 13 May 2004
Posts: 90
Location: Nashville, TN

Posted: Tue May 10, 2005 5:02 pm

PCM programmer wrote:

Post a program that we can compile. Post your compiler version.

I knew you were gonna say that.

I can't reproduce the problem yet using anything other than the ginormous program in question. If I trim it down the problem goes away. My compiler version is 3.223. I'll try reproducing it in something postable.

--
Jeff S.

object01

Joined: 13 May 2004
Posts: 90
Location: Nashville, TN

Posted: Tue May 10, 2005 7:48 pm

It's still tough to get this into a smaller, compilable program, but I found a workaround. The variables stopPoint and i are both unsigned int8.

Here's the listing of the erroneous section:

Code:

.................... // This line caused a compiler bug in PIC-C version 3.223.
.................... // The line below, parserState = opcode, was setting the
.................... // incorrect location in RAM due to a missing MOVLB instruction.
.................... // The compiler moved one value into the BSR to perform this line,
.................... // then didn't reset it to the proper value afterwards.
.................... // Splitting this statement into two lines made the compiler
.................... // execute another MOVLB instruction before the
.................... // parserState = opcode line.
.................... stopPoint = strlen(&(tdif->buffer[i])) + i;
383E: CLRF 03
3840: MOVF xCA,W
3842: ADDLW 7C
3844: MOVWF 01
3846: MOVLW 00
3848: ADDWFC 03,F
384A: MOVF 01,W
384C: MOVLB 5
384E: ADDWF xA4,W
3850: MOVLB 6
3852: MOVWF xA8
3854: MOVLB 5
3856: MOVF xA5,W
3858: ADDWFC 03,W
385A: MOVLB 6
385C: MOVWF xA9
385E: MOVWF xAC
3860: MOVFF 6A8,6AB
3864: MOVLB 0
3866: CALL 2D28
386A: MOVFF 01,6A9
386E: MOVF xCA,W
3870: MOVLB 6
3872: ADDWF 01,W
3874: MOVWF 01
3876: MOVLW 00
3878: ADDWFC 02,W
387A: MOVFF 01,CB
....................
.................... //stopPoint = strlen(&(tdif->buffer[i]));
.................... //stopPoint += i;
....................
.................... // Output one delimiter on next call
.................... outputDelimiter = TRUE;
387E: BSF 20.1
....................
.................... parserState = opcode;
3880: MOVLW 04
3882: MOVWF xC5

And here's the workaround. Breaking apart the stopPoint statement seemed to reintroduce the necessary MOVLB instruction.

Code:

.................... // This line caused a compiler bug in PIC-C version 3.223.
.................... // The line below, parserState = opcode, was setting the
.................... // incorrect location in RAM due to a missing MOVLB instruction.
.................... // The compiler moved one value into the BSR to perform this line,
.................... // then didn't reset it to the proper value afterwards.
.................... // Splitting this statement into two lines made the compiler
.................... // execute another MOVLB instruction before the
.................... // parserState = opcode line.
.................... //stopPoint = strlen(&(tdif->buffer[i])) + i;
....................
.................... stopPoint = strlen(&(tdif->buffer[i]));
383C: CLRF 03
383E: MOVF xCA,W
3840: ADDLW 7C
3842: MOVWF 01
3844: MOVLW 00
3846: ADDWFC 03,F
3848: MOVF 01,W
384A: MOVLB 5
384C: ADDWF xA4,W
384E: MOVLB 6
3850: MOVWF xA8
3852: MOVLB 5
3854: MOVF xA5,W
3856: ADDWFC 03,W
3858: MOVLB 6
385A: MOVWF xA9
385C: MOVWF xAC
385E: MOVFF 6A8,6AB
3862: MOVLB 0
3864: CALL 2D28
3868: MOVFF 01,CB
.................... stopPoint += i;
386C: MOVF xCA,W
386E: ADDWF xCB,F
....................
.................... // Output one delimiter on next call
.................... outputDelimiter = TRUE;
3870: BSF 20.1
....................
.................... parserState = opcode;
3872: MOVLW 04
3874: MOVWF xC5

Hopefully this might lend some insight into the problem. I'm gonna continue to try and get something more concise and compilable, now that I know what's causing the problem. However, it's important to note that this code used to work. Only after recently making a set of changes to separate source files in the project did it exhibit this problem.

--
Jeff S.

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