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Function won't return anything other than 0.

 
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object01



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

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Function won't return anything other than 0.
PostPosted: Fri Jun 04, 2004 9:53 am     Reply with quote

I've been wrestling with what seems like a compiler bug. I'm hoping somebody can point out something I've missed.

The following code fragment from my program generates the listing that follows. There are two things I don't understand: first, the instruction at 0xA3A, GOTO 23B, actually goes to 0xA3B. Second, the only return statement in any of this is the RETLW 00, which according to the PIC16F88 data sheet will return 0. Sure enough, the function this code fragment comes from never returns anything but 0.

Notice the two commented return statements. If I uncomment those statements and comment out the return (matchFound), I get the same problem. The program eventually flows to the RETLW 00.

I'm using PCM v3.189.

--
Jeff S.

Code:
if (!matchFound) {
   fprintf(DEBUGGER, "\nDid not match ");
   fprintf(DEBUGGER, ATINFO.response);
   fprintf(DEBUGGER, "\n");
   //return FALSE;         // Would just return matchFound, but there seems to be a bug in the compiler.
} else {
   fprintf(DEBUGGER, "\nMatched ");
   fprintf(DEBUGGER, ATINFO.response);
   fprintf(DEBUGGER, "\n");
   //return TRUE;         // Would just return matchFound, but there seems to be a bug in the compiler.
}
return (matchFound);


Code:
....................       if (!matchFound) {
*
09C8:  BSF    03.6
09C9:  BTFSC  56.0
09CA:  GOTO   201
....................          fprintf(DEBUGGER, "\nDid not match ");
09CB:  CLRF   57
09CC:  MOVF   57,W
09CD:  BCF    0A.3
09CE:  BCF    03.6
09CF:  CALL   087
09D0:  BSF    0A.3
09D1:  BSF    03.6
09D2:  INCF   57,F
09D3:  MOVWF  77
09D4:  MOVWF  65
09D5:  BCF    0A.3
09D6:  BCF    03.6
09D7:  CALL   320
09D8:  BSF    0A.3
09D9:  MOVLW  0F
09DA:  BSF    03.6
09DB:  SUBWF  57,W
09DC:  BTFSS  03.2
09DD:  GOTO   1CC
....................          fprintf(DEBUGGER, ATINFO.response);
09DE:  MOVLW  63
09DF:  MOVWF  04
09E0:  BCF    03.7
09E1:  MOVLW  00
09E2:  IORWF  00,W
09E3:  BTFSC  03.2
09E4:  GOTO   1F9
09E5:  CLRF   58
09E6:  MOVF   04,W
09E7:  MOVWF  57
09E8:  BCF    58.0
09E9:  BTFSC  03.7
09EA:  BSF    58.0
09EB:  MOVF   00,W
09EC:  MOVWF  65
09ED:  BCF    0A.3
09EE:  BCF    03.6
09EF:  CALL   320
09F0:  BSF    0A.3
09F1:  BSF    03.6
09F2:  MOVF   57,W
09F3:  MOVWF  04
09F4:  BCF    03.7
09F5:  BTFSC  58.0
09F6:  BSF    03.7
09F7:  INCF   04,F
09F8:  GOTO   1E1
....................          fprintf(DEBUGGER, "\n");
09F9:  MOVLW  0A
09FA:  MOVWF  65
09FB:  BCF    0A.3
09FC:  BCF    03.6
09FD:  CALL   320
09FE:  BSF    0A.3
....................          //return FALSE;         // Would just return matchFound, but there seems to be a bug in the compiler.
....................       } else {
09FF:  GOTO   235
0A00:  BSF    03.6
....................          fprintf(DEBUGGER, "\nMatched ");
0A01:  CLRF   57
0A02:  MOVF   57,W
0A03:  BCF    0A.3
0A04:  BCF    03.6
0A05:  CALL   09B
0A06:  BSF    0A.3
0A07:  BSF    03.6
0A08:  INCF   57,F
0A09:  MOVWF  77
0A0A:  MOVWF  65
0A0B:  BCF    0A.3
0A0C:  BCF    03.6
0A0D:  CALL   320
0A0E:  BSF    0A.3
0A0F:  MOVLW  09
0A10:  BSF    03.6
0A11:  SUBWF  57,W
0A12:  BTFSS  03.2
0A13:  GOTO   202
....................          fprintf(DEBUGGER, ATINFO.response);
0A14:  MOVLW  63
0A15:  MOVWF  04
0A16:  BCF    03.7
0A17:  MOVLW  00
0A18:  IORWF  00,W
0A19:  BTFSC  03.2
0A1A:  GOTO   22F
0A1B:  CLRF   58
0A1C:  MOVF   04,W
0A1D:  MOVWF  57
0A1E:  BCF    58.0
0A1F:  BTFSC  03.7
0A20:  BSF    58.0
0A21:  MOVF   00,W
0A22:  MOVWF  65
0A23:  BCF    0A.3
0A24:  BCF    03.6
0A25:  CALL   320
0A26:  BSF    0A.3
0A27:  BSF    03.6
0A28:  MOVF   57,W
0A29:  MOVWF  04
0A2A:  BCF    03.7
0A2B:  BTFSC  58.0
0A2C:  BSF    03.7
0A2D:  INCF   04,F
0A2E:  GOTO   217
....................          fprintf(DEBUGGER, "\n");
0A2F:  MOVLW  0A
0A30:  MOVWF  65
0A31:  BCF    0A.3
0A32:  BCF    03.6
0A33:  CALL   320
0A34:  BSF    0A.3
....................          //return TRUE;         // Would just return matchFound, but there seems to be a bug in the compiler.
....................       }
....................       return (matchFound);
0A35:  MOVLW  00
0A36:  BSF    03.6
0A37:  BTFSC  56.0
0A38:  MOVLW  01
0A39:  MOVWF  78
0A3A:  GOTO   23B
....................    }
.................... }
0A3B:  BCF    03.6
0A3C:  RETLW  00
rnielsen



Joined: 23 Sep 2003
Posts: 852
Location: Utah

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PostPosted: Fri Jun 04, 2004 10:09 am     Reply with quote

I thought that a return() (or return;) would break out of the function and not execute the remaining code of the function. If you un-comment the first two return's then the third one would never be executed. Plus, I think if you want to return a value you need to have return(value) stated. Just a simple 'return true;' or 'return false;' will simply return with no value being returned. You might want to change it to return(true); and return(false);. But, then again, if you do, the third return(matchFound) would not be executed.

Ronald
William H. Conley III



Joined: 27 May 2004
Posts: 17
Location: Tucson, AZ

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PostPosted: Fri Jun 04, 2004 10:20 am     Reply with quote

Try..........



if (!matchFound)
{
fprintf(DEBUGGER, "\nDid not match ");
fprintf(DEBUGGER, ATINFO.response);
fprintf(DEBUGGER, "\n");
return (FALSE);
}
else
{
fprintf(DEBUGGER, "\nMatched ");
fprintf(DEBUGGER, ATINFO.response);
fprintf(DEBUGGER, "\n");
return (TRUE);
}
return (matchFound);
object01



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

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PostPosted: Fri Jun 04, 2004 11:10 am     Reply with quote

Including the commented "return TRUE" and "return FALSE" statements results in the same problem. In fact, they cause the program to eventually flow to the same RETLW 00 statement. And parentheses around any of the return statements' parameters don't seem to affect it either. The assembly listing just keeps coming down to that RETLW 00 statement.

--
Jeff S.
Guest








PostPosted: Fri Jun 04, 2004 11:25 am     Reply with quote

It has to be a bug? Your code is nothing I haven't used my self Question
Guest








PostPosted: Sat Jun 05, 2004 11:57 am     Reply with quote

>> first, the instruction at 0xA3A, GOTO 23B, actually goes to 0xA3B.

This is the effect of ... 0A36: BSF 03.6

>> Second, the only return statement in any of this is the RETLW 00,

The return value is ... 0A39: MOVWF 78 ... CCS use RAM 0x78 for return value instead of the W.

read the SYM file:

078 @SCRATCH
078 _RETURN_
079 @SCRATCH

and read the LST file after the function call, there will be a line ... MOVF 78,W ... right after the CALL xxx.
Ed Arnold



Joined: 02 Nov 2003
Posts: 18

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same problem
PostPosted: Sat Jun 05, 2004 1:20 pm     Reply with quote

I have had the same problem with my code. I ended up scraping the code. I am using version 3.148? Keep us posted with any new finding you may have.
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