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Nigel
Joined: 25 Sep 2003
Posts: 4
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| Problems with MPASM & C |
 Posted: Thu Dec 18, 2003 3:08 am |
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Hi folks,
Have been using CCS C for approx 2 months. Now I need to put some assembler in and cannot compile the code !
Could someone give me an idea as to what I'm doing wrong ?
I'm Using :
MPLAB v6.32
Microchip ICD2 with PICDEM 2 plus board
PIC18F452 chip installed
CCS PCWH C compiler v3.179,
All running under Windows XP professional (service pack 1) on an Athlon 1500+ PC with 320Mb ram.
This is an example of what I cannot compile. I get "Expecting an opcode mnemonic" error.
| Code: | /* ASMTest.c
Test for including MPASM assembler code in CCS C */
#include <18f452.h>
#fuses NOWDT,NOPROTECT,NOLVP,NOWRT,NOEBTR
#DEVICE ICD=TRUE
#use delay (clock=4000000)
// Declare three 8 bit integers
int count;
int count2;
int result;
// Put them at RAM locations 0x420 to 0x422
#byte count=0x420
#byte count2=0x421
#byte result=0x422
void main(void)
{ count=1;
count2=2;
#ASM
// Move 4 into BSR to access Bank 4
MOVLB 4
// Move contents of 0x420 into WREG (1)
MOVF 0x20, 0, 1
// Add WREG to contents of 0x421 (2), store result (3) in WREG,
ADDWF 0x21, 0, 1
// Copy WREG to 0x422
MOVWF 0x22,1
#ENDASM
}
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Thu Dec 18, 2003 9:25 am |
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CCS doesn't like the RAM access bit. Try this
| Code: |
/* ASMTest.c
Test for including MPASM assembler code in CCS C */
#include <18f452.h>
#fuses NOWDT,NOPROTECT,NOLVP,NOWRT,NOEBTR
#DEVICE ICD=TRUE
#use delay (clock=4000000)
// Declare three 8 bit integers
int count;
int count2;
int result;
// Put them at RAM locations 0x420 to 0x422
#byte count=0x420
#byte count2=0x421
#byte result=0x422
void main(void)
{ count=1;
count2=2;
#ASM
// Move 4 into BSR to access Bank 4
MOVLB 4
// Move contents of 0x420 into WREG (1)
MOVF 0x20, 0
// Add WREG to contents of 0x421 (2), store result (3) in WREG,
ADDWF 0x21, 0
// Copy WREG to 0x422
MOVWF 0x22
#ENDASM
}
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Nigel
Joined: 25 Sep 2003
Posts: 4
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| Thanks Mark |
| Posted: Thu Dec 18, 2003 9:42 am |
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| Thanks for your help, that's fixed it ! |
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Ttelmah
Guest
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| Re: Thanks Mark |
| Posted: Thu Dec 18, 2003 10:02 am |
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| Nigel wrote: | | Thanks for your help, that's fixed it ! |
Worth adding, that you don't actually have to do the bank switching!.
You can code as:
#ASM
// Move contents of 0x420 into WREG (1)
MOVF count, 0
// Add WREG to contents of 0x421 (2), store result (3) in WREG,
ADDWF count2, 0
// Copy WREG to 0x422
MOVWF result
#ENDASM
The compiler supports, a sort of 'C hybrid' compiler syntax, and will automatically bank switch for you, if you use the symbolic names (in the example as given the compiler will not actually code a bank switch, since bank 4 is allready selected to initialise the variables). If you don't want this 'auto switching' to take place, add 'asis', to the #ASM directive.
Best Wishes |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Thu Dec 18, 2003 10:57 am |
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One more thing, if you do use the variable name and the variable is bigger than 8 bits, the syntax is
&counter+1
and not
counter+1 |
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