Post by thread:Inline Assembly in CCS

I'm trying to do some inline assembly, specifically manipulating the program counter to jump through a table based on a variable value. There are 2 asm commands in the book that don't appear in the PIC data books along with the rest of the commands. They are movplw and movphw. movplw implies move pl to w based on the syntax of the rest of the PIC commands. Is this correct? If so, how do I move w to pl or add w to pl. First, I tried : #byte PCL =2 #asm movf bit,W addwf PCL,F ... #endasm I got: Error: expression must evaluate to a constant Then I tried: #byte PCL=2 #asm movplw addwf bit,W movwf PCL ... #endasm I got: Error: undefined identifier

Darlene wrote: -----Original Message----- From: Darlene Magnusson <spam_OUTdarleneTakeThisOuTZIRCON.COM> >First, I tried : >#byte PCL =2 > >#asm >movf bit,W >addwf PCL,F >... >#endasm > >I got: >Error: expression must evaluate to a constant Usually I find that error when I have not defined a variable. When I tried this code, CCS returned "UNDEFINED ERROR" and then MPLAB crashed! Are you defining BIT as an integer variable ( int bit; ), or as a bit location (#DEFINE bit 5) ? If bit is not an integer variable, all hell might break loose. {Quote hidden}> >Then I tried: >#byte PCL=2 > >#asm >movplw >addwf bit,W >movwf PCL >... >#endasm > >I got: >Error: undefined identifier Still sounds like a variable not defined. I still can't figure out what the movplw is supposed to do. Forget inline assembly and use standard C. A standard C syntax way of making a lookup table is this: (and it works in CCS!) This is copied directly from one of my programs that really does compile, BTW. int time; int index = [ some number between 0 and 32] static const int lookup[33] = { 9, 10, 11, 12, 13, 13, 14, 15, 16, 16, 17, 18, 19, 20, 21, 22, 23, 23, 24, 25, 26, 27, 28, 29, 29, 29, 30, 31, 31, 31, 31, 31, 31 }; time = lookup[index];

At 09:32 AM 4/14/99 -0500, you wrote: {Quote hidden}>Darlene wrote: >-----Original Message----- >From: Darlene Magnusson <.....darleneKILLspam@spam@ZIRCON.COM> >>First, I tried : >>#byte PCL =2 >> >>#asm >>movf bit,W >>addwf PCL,F >>... >>#endasm >> >>I got: >>Error: expression must evaluate to a constant > > >Usually I find that error when I have not defined a variable. When I tried >this code, CCS returned "UNDEFINED ERROR" and then MPLAB crashed! > >Are you defining BIT as an integer variable ( int bit; ), or as a bit >location (#DEFINE bit 5) ? If bit is not an integer variable, all hell >might break loose. > bit is declared as an integer (int bit;) , sorry I left that line out. {Quote hidden}>> >>Then I tried: >>#byte PCL=2 >> >>#asm >>movplw >>addwf bit,W >>movwf PCL >>... >>#endasm >> >>I got: >>Error: undefined identifier > >Still sounds like a variable not defined. I still can't figure out what the >movplw is supposed to do. Forget inline assembly and use standard C. > >A standard C syntax way of making a lookup table is this: (and it works in >CCS!) This is copied directly from one of my programs that really does >compile, BTW. > >int time; >int index = [ some number between 0 and 32] > >static const int lookup[33] = { 9, 10, 11, 12, 13, 13, 14, >15, 16, 16, 17, 18, 19, 20, 21, 22, > 23, 23, 24, 25, 26, 27, 28, 29, 29, 29, 30, 31, >31, 31, 31, 31, 31 }; > >time = lookup[index]; > Thank you for the suggestion but I don't think this type of table won't work for my application, my table is more like a switch statement (ie. if bit is equal to 5, set the 5th bit). I was trying to find the most efficient way of doing this.