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With #OPT compress on 18f27j13 int16 shift problem

 
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mjdale2003



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Posts: 21
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With #OPT compress on 18f27j13 int16 shift problem
PostPosted: Mon Jan 25, 2016 5:54 am     Reply with quote

Hi, I seem to be having a problem with shifting a 16bit integer when using the #opt compress switch

I am trying to store a 16bit integer in to internal flash.

i have tried both |= (1<<val) method and bit_set()

compiler version
PCH 5.051

the output to the function is
Quote:
save 8 00FF


here is the function

Code:


#OPT compress

void save_16_eeprom(unsigned int16 val){
   unsigned int16 dat_val;
   
   value = read_ee16(active_output_cam);

01198:  MOVFF  AA8,C68
0119C:  RCALL  0E68
0119E:  MOVFF  02,C67
011A2:  MOVFF  01,C66

   // use bit_set as optimization
   // changes this to a char shift
   // for some reason even though
   // printf shows val as 8 - 16 ???
   //dat_val |= ((unsigned int16)1<<val);
   bit_set(dat_val, val);

011A6:  CLRF   03
011A8:  MOVLW  01
011AA:  MOVWF  02
011AC:  MOVLB  C
011AE:  MOVF   x64,W
011B0:  MOVWF  00
011B2:  BZ    11BE
011B4:  BCF    FD8.0
011B6:  RLCF   02,F
011B8:  RLCF   03,F
011BA:  DECFSZ 00,F
011BC:  BRA    11B4
011BE:  MOVF   02,W
011C0:  IORWF  x66,F
011C2:  MOVF   03,W
011C4:  IORWF  x67,F
   
   write_ee16(active_output_cam, dat_val);
   
011C6:  MOVFF  AA8,C84
011CA:  MOVFF  C67,C86
011CE:  MOVFF  C66,C85
011D2:  MOVLB  0
011D4:  RCALL  0ECC

   printf(TxData2, "save %lu %04X \n\r", val, dat_val); TXIE = 1;

011D6:  MOVLW  AE
011D8:  MOVWF  FF6
011DA:  MOVLW  BE
011DC:  MOVWF  FF7
011DE:  MOVLW  00
011E0:  MOVWF  FF8
011E2:  MOVLW  05
011E4:  RCALL  10C8
011E6:  MOVLW  10
011E8:  MOVWF  FE9
011EA:  MOVFF  C65,C69
011EE:  MOVFF  C64,C68
011F2:  RCALL  10D2
011F4:  MOVLW  20
011F6:  MOVLB  C
011F8:  RCALL  122C
011FA:  MOVLW  02
011FC:  MOVLB  C
011FE:  MOVWF  x68
01200:  MOVLW  30
01202:  RCALL  122C
01204:  MOVLB  C
01206:  DECFSZ x68,F
01208:  BRA    1200
0120A:  MOVFF  C66,C68
0120E:  MOVLW  37
01210:  MOVWF  x69
01212:  MOVLB  0
01214:  RCALL  0F46
01216:  MOVLW  BB
01218:  MOVWF  FF6
0121A:  MOVLW  BE
0121C:  MOVWF  FF7
0121E:  MOVLW  00
01220:  MOVWF  FF8
01222:  MOVLW  03
01224:  RCALL  10C8
01226:  BSF    F9D.4
*
0122C:  MOVWF  x73
0122E:  MOVLB  0
01230:  RCALL  0C66
01232:  RETURN 0
   
   update_eeprom();
   
01228:  RCALL  1010
0122A:  RETURN 0
}
temtronic



Joined: 01 Jul 2010
Posts: 9226
Location: Greensville,Ontario

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PostPosted: Mon Jan 25, 2016 7:30 am     Reply with quote

I don't use that PIC but you should post a small,compilable program that shows us the problem. Most C guys don't know ASM. Could be a 'casting' problem or something 'before' your function.
Also post test data before and after as well as expected results


Jay
Ttelmah



Joined: 11 Mar 2010
Posts: 19513

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PostPosted: Mon Jan 25, 2016 8:47 am     Reply with quote

Bit set has to do a rotation. The processor doesn't have a variable based bit_set function, so while a bit set on a fixed bit is efficient, a bit_set using a variable has to be done by rotating a mask.

I can't actually work out what you are trying to do?. If you are rotating a value to get bytes from it, then use the make8 function. Far more efficient than any rotation based method, since the compiler can just do a byte fetch.
mjdale2003



Joined: 10 Oct 2004
Posts: 21
Location: UK

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PostPosted: Mon Jan 25, 2016 9:45 am     Reply with quote

hi and thanks for the fast response, i have stripped down the function to a simple routine that assigns a value to the top byte prints, sets a bit then prints again, there is no reason this should fail surely

Code:

void save_pre_eeprom(unsigned int16 pre){
   unsigned int16 value;
   
   if(pre <=16){
      value = 0xAA00;
      printf(TxData2, "save %u %lu %04X \n\r", active_output, pre, value);
      bit_set(value, 8);
      printf(TxData2, "save %u %lu %04X \n\r", active_output, pre, value);
   }
}


and the output remains as

save 0 2 0000
save 0 2 0000

call it from main the "pre" value changes if i use another value but the "value" value is always 0000 even if i change it to a int32

the .lst file seems to set the bit but it is never displayed, could it be the printf function becoming corrupt after the #compress part of the compilation.




Code:

.................... void save_pre_eeprom(unsigned int16 pre){
....................    unsigned int16 value;
....................    
....................    if(pre <=16){
*
01316:  MOVLB  C
01318:  MOVF   xE5,F
0131A:  BTFSS  FD8.2
0131C:  BRA    137A
0131E:  MOVF   xE4,W
01320:  SUBLW  10
01322:  BTFSS  FD8.0
01324:  BRA    137A
....................       
....................       value = 0xAA00;
01326:  MOVLW  AA
01328:  MOVWF  xE7
0132A:  CLRF   xE6
....................       
....................       printf(TxData2, "save %u %lu %04X \n\r", active_output_cam, pre, value);
0132C:  MOVLW  DA
0132E:  MOVWF  FF6
01330:  MOVLW  C0
01332:  MOVWF  FF7
01334:  MOVLW  00
01336:  RCALL  137E
01338:  MOVLW  30
0133A:  RCALL  1246
0133C:  MOVLB  C
0133E:  DECFSZ xE8,F
01340:  BRA    1338
01342:  RCALL  13AC
01344:  MOVLW  EA
01346:  MOVWF  FF6
01348:  MOVLW  C0
0134A:  MOVWF  FF7
0134C:  MOVLW  00
0134E:  RCALL  13B8
*
0137E:  MOVWF  FF8
01380:  MOVLW  05
01382:  RCALL  1024
01384:  MOVFF  B28,D09
01388:  MOVLW  1B
0138A:  RCALL  102E
0138C:  RCALL  0EC0
0138E:  MOVLW  20
01390:  RCALL  1246
01392:  MOVLW  10
01394:  MOVWF  FE9
01396:  MOVFF  CE5,CE9
0139A:  MOVFF  CE4,CE8
0139E:  RCALL  1250
013A0:  MOVLW  20
013A2:  RCALL  1246
013A4:  MOVLW  02
013A6:  MOVLB  C
013A8:  MOVWF  xE8
013AA:  RETURN 0
013AC:  MOVFF  CE6,D09
013B0:  MOVLW  37
013B2:  RCALL  102E
013B4:  RCALL  0F34
013B6:  RETURN 0
013B8:  MOVWF  FF8
013BA:  MOVLW  03
013BC:  RCALL  1024
013BE:  RETURN 0
....................       
....................       bit_set(value, 8);
01350:  MOVLB  C
01352:  BSF    xE7.0
....................       
....................       printf(TxData2, "save %u %lu %04X \n\r", active_output_cam, pre, value);
01354:  MOVLW  EE
01356:  MOVWF  FF6
01358:  MOVLW  C0
0135A:  MOVWF  FF7
0135C:  MOVLW  00
0135E:  RCALL  137E
01360:  MOVLW  30
01362:  RCALL  1246
01364:  MOVLB  C
01366:  DECFSZ xE8,F
01368:  BRA    1360
0136A:  RCALL  13AC
0136C:  MOVLW  FE
0136E:  MOVWF  FF6
01370:  MOVLW  C0
01372:  MOVWF  FF7
01374:  MOVLW  00
01376:  RCALL  13B8
01378:  MOVLB  C
....................       
....................    }
0137A:  MOVLB  0
0137C:  RETURN 0
.................... }
RF_Developer



Joined: 07 Feb 2011
Posts: 839

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PostPosted: Mon Jan 25, 2016 10:45 am     Reply with quote

Its nothing to do with shifting or optimisation. Check your format specifiers:

From the manual:
Quote:

x Hex int (lower case)
X Hex int (upper case)
Lx Hex long int (lower case)
LX Hex long int (upper case)


To format your int16, you need %LX. What your format is doing is formatting the lower byte and padding it to four characters with zeros: the upper byte is always going to be 00.
mjdale2003



Joined: 10 Oct 2004
Posts: 21
Location: UK

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PostPosted: Mon Jan 25, 2016 11:27 am     Reply with quote

Well spotted thank you, silly me :/
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