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PODefining a function (high interrupt) within or outside a macro C
 

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  1. PODefining a function (high interrupt) within or outside a macro C
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    <p>For starter, Im using the C18 compiler for my PIC. When I create the function like high_ISR without any calls in it, my compiler adds code to it, code I can only see in a Disassembly listing view. This makeing my high_ISR function have a cycle time of say 160 cycles (but it appears to be empty looking at the C code).</p> <p>Instead if I define it as a macro, I will have it empty of "secret" code. Will I somehow have a problem with other functions cause removing code that my compiler secretly puts there, will it cope with that in other ways?</p> <p>I mean, I want the ISRs to be fast. Is there a way to make the ISR function fast when writing the function in a c file, could I somehow supress the "secret code".</p> <p>See code examples below:</p> <p>Proper creation of my high_ISR function in a .c file but with a long cycle time</p> <pre><code>#pragma interrupt highISR void highISR(void) { SomeFunction(); } </code></pre> <p>Macro created function for instance in my header file (say cycle time of 16 cycles)</p> <pre><code>#define FAST_INTERRUPT \ void highISR(void) \ { \ SomeFunction(); \ } </code></pre> <p>Just for clarification, If I use the macro, I implement it as:</p> <pre><code>#pragma interrupt higISR FAST_INTERRUPT </code></pre> <p>The First highISR declaration produces this:</p> <pre><code> #pragma interrupt highISR 323: void highISR(void) 12B12 CFDA MOVFF 0xfda, 0xfe4 12B14 FFE4 NOP 12B16 CFE2 MOVFF 0xfe2, 0xfda 12B18 FFDA NOP 12B1A CFE9 MOVFF 0xfe9, 0xfe4 12B1C FFE4 NOP 12B1E CFEA MOVFF 0xfea, 0xfe4 12B20 FFE4 NOP 12B22 CFD9 MOVFF 0xfd9, 0xfe4 12B24 FFE4 NOP 12B26 CFDA MOVFF 0xfda, 0xfe4 12B28 FFE4 NOP 12B2A C1FB MOVFF 0x1fb, 0xfe4 12B2C FFE4 NOP 12B2E C1FC MOVFF 0x1fc, 0xfe4 12B30 FFE4 NOP 12B32 C1FD MOVFF 0x1fd, 0xfe4 12B34 FFE4 NOP 12B36 C1FE MOVFF 0x1fe, 0xfe4 12B38 FFE4 NOP 12B3A CFF6 MOVFF 0xff6, 0xfe4 12B3C FFE4 NOP 12B3E CFF7 MOVFF 0xff7, 0xfe4 12B40 FFE4 NOP 12B42 CFF8 MOVFF 0xff8, 0xfe4 12B44 FFE4 NOP 12B46 CFF5 MOVFF 0xff5, 0xfe4 12B48 FFE4 NOP 12B4A CFF3 MOVFF 0xff3, 0xfe4 12B4C FFE4 NOP 12B4E CFF4 MOVFF 0xff4, 0xfe4 12B50 FFE4 NOP 12B52 CFFA MOVFF 0xffa, 0xfe4 12B54 FFE4 NOP 12B56 CFFB MOVFF 0xffb, 0xfe4 12B58 FFE4 NOP 12B5A EE05 LFSR 0, 0x500 12B5C F000 NOP 12B5E 0E12 MOVLW 0x12 12B60 04E8 DECF 0xfe8, W, ACCESS 12B62 E303 BNC 0x12b6a 12B64 CFEE MOVFF 0xfee, 0xfe4 12B66 FFE4 NOP 12B68 D7FB BRA 0x12b60 12B6A 52E6 MOVF 0xfe6, F, ACCESS 324: { 325: SomeFunction(); 12B6C EC48 CALL 0x14090, 0 12B6E F0A0 NOP 327: } 12B70 52E5 MOVF 0xfe5, F, ACCESS 12B72 EE05 LFSR 0, 0x511 12B74 F011 NOP 12B76 0E12 MOVLW 0x12 12B78 04E8 DECF 0xfe8, W, ACCESS 12B7A E303 BNC 0x12b82 12B7C CFE5 MOVFF 0xfe5, 0xfed 12B7E FFED NOP 12B80 D7FB BRA 0x12b78 12B82 CFE5 MOVFF 0xfe5, 0xffb 12B84 FFFB NOP 12B86 CFE5 MOVFF 0xfe5, 0xffa 12B88 FFFA NOP 12B8A CFE5 MOVFF 0xfe5, 0xff4 12B8C FFF4 NOP 12B8E CFE5 MOVFF 0xfe5, 0xff3 12B90 FFF3 NOP 12B92 CFE5 MOVFF 0xfe5, 0xff5 12B94 FFF5 NOP 12B96 CFE5 MOVFF 0xfe5, 0xff8 12B98 FFF8 NOP 12B9A CFE5 MOVFF 0xfe5, 0xff7 12B9C FFF7 NOP 12B9E CFE5 MOVFF 0xfe5, 0xff6 12BA0 FFF6 NOP 12BA2 CFE5 MOVFF 0xfe5, 0x1fe 12BA4 F1FE NOP 12BA6 CFE5 MOVFF 0xfe5, 0x1fd 12BA8 F1FD NOP 12BAA CFE5 MOVFF 0xfe5, 0x1fc 12BAC F1FC NOP 12BAE CFE5 MOVFF 0xfe5, 0x1fb 12BB0 F1FB NOP 12BB2 CFE5 MOVFF 0xfe5, 0xfda 12BB4 FFDA NOP 12BB6 CFE5 MOVFF 0xfe5, 0xfd9 12BB8 FFD9 NOP 12BBA CFE5 MOVFF 0xfe5, 0xfea 12BBC FFEA NOP 12BBE CFE5 MOVFF 0xfe5, 0xfe9 12BC0 FFE9 NOP 12BC2 CFE5 MOVFF 0xfe5, 0xfda 12BC4 FFDA NOP 12BC6 0011 RETFIE 0x1 </code></pre> <p>The Second Function only produce this -></p> <pre><code>322: #pragma interrupt highISR 323: FAST_INTERRUPT 13742 CFDA MOVFF 0xfda, 0xfe4 13744 FFE4 NOP 13746 CFE2 MOVFF 0xfe2, 0xfda 13748 FFDA NOP 1374A 52E6 MOVF 0xfe6, F, ACCESS 1374C 0105 MOVLB 0x5 1374E 5140 MOVF 0x40, W, BANKED 13750 1A77 XORWF 0xf77, F, ACCESS 13752 96A4 BCF 0xfa4, 0x3, ACCESS 13754 2877 INCF 0xf77, W, ACCESS 13756 6078 CPFSLT 0xf78, ACCESS 13758 86A4 BSF 0xfa4, 0x3, ACCESS 1375A 7E8B BTG 0xf8b, 0x7, ACCESS 1375C 0011 RETFIE 0x1 1375E 52E5 MOVF 0xfe5, F, ACCESS 13760 CFE5 MOVFF 0xfe5, 0xfda 13762 FFDA NOP 13764 0011 RETFIE 0x1 </code></pre> <p>Further more clarification just to show that the functions them self is written the same: For the first rutine -></p> <pre><code>void SomeFunction(void) { if(PIR3bits.TMR4IF) { PIR3bits.TMR4IF = 0; PR4 ^= _SoftPWM_Toggle; _asm INCF PR4,0,ACCESS CPFSLT TMR4,ACCESS _endasm PIR3bits.TMR4IF = 1; SOFT_PWM_PIN ^= 1; } } </code></pre> <p>The Second one in header as a macro -></p> <pre><code>#define FAST_INTERRUPT \ void highISR(void) \ { \ PR4 ^= _SoftPWM_Toggle; \ \ PIR3bits.TMR4IF = 0; \ \ _asm \ INCF PR4,0,ACCESS \ CPFSLT TMR4,ACCESS \ _endasm \ \ PIR3bits.TMR4IF = 1; \ \ SOFT_PWM_PIN ^= 1; \ \ _asm \ RETFIE 1 \ _endasm \ } </code></pre>
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      1. PODefining a function (high interrupt) within or outside a macro C
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    1. COWHat makes you think that defining the ISR within a macro will make any difference at all ? Ultimately you'll get the same code. Note that you have left out `#pragma interrupt highISR` in the macro case, for obvious reasons.
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      1. PODefining a function (high interrupt) within or outside a macro C
      1. USPaul R
    2. COWhen Im debugging my code within the ISR function, in the first case the compiler put some extra lines of code there not visable until I disassembly, thous making my ISR taking a longer time executing. In the second case when Dissassembly the code the compiler is forced not to put any "secret code" right there, thous speeding up my ISR function.
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      1. PODefining a function (high interrupt) within or outside a macro C
      1. USChristian
    3. COYes, but your second "macro" version does not have `#pragma interrupt highISR` so you're probably not saving/restoring context around the ISR correctly in that case - that's probably the missing "secret code" that you're getting hung up about.
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      1. PODefining a function (high interrupt) within or outside a macro C
      1. USPaul R
 

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