Post by thread:COMF W

Hi, this is not do-able ( like you have written ). COMF W will be compiled as: COMF INDF which means the ram adress pointed at by FSR W will be replaced by '0' by the compiler which inturn is the ramadress for the INDF register, which uses the FSR to point to an memory location ;-) are we having fun yet ? ( just kidding :-) ) To do an COMF on the W reg without using temp ram I belive was mentioned on the list no so long ago ( this month ), cant really remeber the 'best' way so You better do a search to find it. /Tony Tony KŸbek, Flintab AB ÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓ E-mail: spam_OUTtony.kubekTakeThisOuTflintab.com ÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓ

You must be careful not to mix register locations, and the identifiers for where the results of an operation should be put. COMF can only operate on a real file register, either an internal one (like PORTB), or one of your own defined ones. You then specify where the results should go, as either W(0) or F(1) If omitted, there is a default destination (but i can't remember if it is W or F, as I never use this faeture). So normal usage would look like: comf PORTB,W In your case, the W is read as the register to complement. So COMF W compliments register 0 (the value of W), which maps to register INDF (on a 16F84). The real register that INDF refers to depends on the setting of FSR. The result is then stored in the default location. To do what you really want to do, it is 2 instructions: movwf TEMP comf TEMP,W Hope this helps, Andy -----Original Message----- From: .....PDRUNENKILLspam@spam@AOL.COM [PDRUNENKILLspamAOL.COM] Sent: 28 April 2000 13:22 To: .....PICLISTKILLspam.....MITVMA.MIT.EDU Subject: COMF W Hi Group, The MPLAB assembler will compile the COMF W statement but does not work on the simulator. Since it did compile then I assume that the COMF W is doing something, but I am not sure what it does? Anyone provide a bit of light on this? Paul

Paul: the directive < comf W > will assemble to < comf 0,1 >. This complements the register file 00h, which is normally the INDF register and stores the result back in INDF, whereever INDF is pointing to. The W-orking register can be complemented by < xorlw 0xFF >. martin ;********************************************** ;** name: Martin Schaefer ** ;** company: elektronik 21 GmbH, Germany ** ;** e-mail: EraseMEschaeferspam_OUTTakeThisOuTelektronik21.de ** ;**********************************************

The W register is really one of the harder working registers in the PIC, and it deserves a good compliment every now and then! I say we should stop asking for so much efficiency, and put xorlw 0xFF xorlw 0xFF in our main program loop so the W register knows it's doing a good job! _ / \ The Rouge Ribbon \ / Campaign: X Complement your W / \ register often! Of course, a REAL programmer would be able to compliment their hardest working register without problems: PC! It would be really neat to have a program which would take an ASM source file and insert COMF PC,1 randomly, rearranging the program as needed so it jumps to the correct location after a COMF PC,1, and still have the program run correctly (albiet a bit more slowly) Can you imagine the look on someone's face who's just dissassembled your code? "WHAT THE...?!?" Now there's real code protection. Anyone who can follow that code could rewrite it themselves. -Adam Martin Schdfer wrote: {Quote hidden}> > Paul: > > the directive < comf W > will assemble to < comf 0,1 >. This complements > the register file 00h, which is normally the INDF register and stores the > result back in INDF, whereever INDF is pointing to. > > The W-orking register can be complemented by < xorlw 0xFF >. > > martin > > ;********************************************** > ;** name: Martin Schaefer ** > ;** company: elektronik 21 GmbH, Germany ** > ;** e-mail: schaeferspam_OUTelektronik21.de ** > ;**********************************************

Try XORLW 0xFF instead. On Fri, 28 Apr 2000, KŸbek Tony wrote: {Quote hidden}> Date: Fri, 28 Apr 2000 15:19:36 +0200 > From: KŸbek Tony <@spam@tony.kubekKILLspamFLINTAB.COM> > Reply-To: pic microcontroller discussion list <KILLspamPICLISTKILLspamMITVMA.MIT.EDU> > To: RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU > Subject: Re: COMF W > > Hi, > this is not do-able ( like you have written ). > COMF W will be compiled as: > COMF INDF which means the ram adress pointed at by FSR > > W will be replaced by '0' by the compiler which inturn is the ramadress > for the INDF register, which uses the FSR to point to an memory location > ;-) > are we having fun yet ? ( just kidding :-) ) > > To do an COMF on the W reg without using temp ram I belive was mentioned > on the list no so long ago ( this month ), cant really remeber the > 'best' way so You better do a search to find it. > > /Tony > > > > Tony KŸbek, Flintab AB > ÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓ > E-mail: spamBeGonetony.kubekspamBeGoneflintab.com > ÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓ >

Hi Paul. Ok. Step by step explanation what you are doing. It is wrong at all but why it can be compiled successfully ? 1. W is defined in include file as 0 (see .inc file for more info) 2. comf operation takes data from register, invert it and put back to destination, destination can be the same reg itself or W reg In your case : COMF W is compiled as : COMF 0 which means that pic has to take data from INDF (0) reg. Looks like destination is omitted. By MPLAB defaults it means put data back in register ( ,F or ,1 ) if you didn't redefined it. So in you example processor will take value from INDF, invert it and put back to INDF. INDF is register that for some magical reason becomes the data memory cell which address is specified by FSR register in some strange way ;) (read your pic docs about that) Good luck in research ! ;) (Better to read some real working progs, it really can help, search inside of piclist archive for that) WBR Dmitry. ----- TakeThisOuTPDRUNENEraseMEspam_OUTAOL.COM wrote: > > Hi Group, > > The MPLAB assembler will compile the COMF W statement but does not work on > the simulator. Since it did compile then I assume that the COMF W is doing > something, but I am not sure what it does? > > Anyone provide a bit of light on this? Paul

On Fri, 28 Apr 2000 PDRUNENEraseME.....AOL.COM wrote: > Date: Fri, 28 Apr 2000 14:06:21 EDT > From: EraseMEPDRUNENAOL.COM > Reply-To: pic microcontroller discussion list <RemoveMEPICLISTEraseMEEraseMEMITVMA.MIT.EDU> > To: RemoveMEPICLISTspam_OUTKILLspamMITVMA.MIT.EDU > Subject: Re: COMF W > > In a message dated 4/28/00 11:45:31 AM Central Daylight Time, > RemoveMErleggittTakeThisOuTspamCONCENTRIC.NET writes: > > << Try XORLW 0xFF instead. >> > > Thanks!! > > But still, why not the COMF W, I also tried COMF W,W but that just put the > value > into w as $FF, so something else was read as $00. File register instructions have a destination code, 0 or 1, i.e. MOVLW REG,0. But saying '0' or '1' is a pain, so the assembler has predefined: #define W 0 #define F 1 The address of the INDF file register is 0, so the definition of 'INDF' is: #define INDF 0 The COMF instruction works with a register address, i.e. COMF 0. The symbol you used to plug the '0' in there is irrelevant. You could also say 'COMF C' and get the same result, because the carry bit is bit 0 of the status register, thus: #define C 0 Remember that symbols don't exist to the PIC, these are for your edification only. Take a look at the listing file and you'll see the actual opcodes being generated, you can reference back to the spec to see what's going on. These are the only things that the micro sees (although not in hex :). -- Rich

The real issue is that the assembler (as with most) does not assign types. It doesn't know that "IND" is a "register" or that "C" is a "statusbit" or that "W" (and "F") is an "accumulator" or a "destination" which is not a "register". If it did, then the definition COMF register could throw an error like COMF W ERROR ^- COMF expects a register. W is a destination. or COMF W, W ERROR ^- COMF expects a register. W is a destination. ERROR ^- COMF expects 1 parameter. Also, if you tried to do ADDWF PCL, PCL ERROR ^- ADDWF has PCL as register but needs a destination. PCL is a register. As Rich says, all the assembler knows is number. Every symbol gets translated to a number first, then plugged in. COMF W becomes COMF 0 which complements IND. --- James Newton (PICList Admin #3) EraseMEjamesnewtonspamspamBeGonepiclist.com 1-619-652-0593 PIC/PICList FAQ: http://www.piclist.com or .org {Original Message removed}

James Newton <RemoveMEjamesnewtonKILLspampiclist.com> wrote: > COMF W, W > ERROR ^- COMF expects a register. W is a destination. > ERROR ^- COMF expects 1 parameter. Uh... Why the second error, James? -Andy === Andrew Warren - fastfwdSTOPspamspam_OUTix.netcom.com === Fast Forward Engineering - San Diego, California === http://www.geocities.com/SiliconValley/2499

<x-flowed>At 08:21 AM 4/28/00 -0400, KILLspamPDRUNENspamBeGoneAOL.COM wrote: >Hi Group, > >The MPLAB assembler will compile the COMF W statement but does not work on >the simulator. Since it did compile then I assume that the COMF W is doing >something, but I am not sure what it does? W is not a physical register, so you can't compliment it that way. But you can do: comw MACRO xorlw 0xFF endm and then just use 'comw' where you need it dwayne Dwayne Reid <EraseMEdwaynerEraseMEplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 16 years of Engineering Innovation (1984 - 2000) * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. </x-flowed>

Thanks for everyone's help! Paul In a message dated 4/29/00 3:05:07 PM Central Daylight Time, @spam@dwayner@spam@spam_OUTPLANET.EON.NET writes: << W is not a physical register, so you can't compliment it that way. But you can do: comw MACRO xorlw 0xFF endm and then just use 'comw' where you need it dwayne >>

On Fri, 28 Apr 2000 14:06:21 EDT spamBeGonePDRUNENKILLspamAOL.COM writes: > In a message dated 4/28/00 11:45:31 AM Central Daylight Time, > .....rleggittspam_OUTCONCENTRIC.NET writes: > > << Try XORLW 0xFF instead. >> > > Thanks!! > > But still, why not the COMF W, I also tried COMF W,W but that just > put the > value > into w as $FF, so something else was read as $00. Cuz W is not in the "file register" address space on most PICs. Some (the 17c and 18c) DO put w in the file register address space, but, since the include files have w defined as 0 (and f defined as 1) to set the destination bit in most instructions, these include files instead use the name WREG to hold the address of W when it IS in the file register address map. Harold ________________________________________________________________ YOU'RE PAYING TOO MUCH FOR THE INTERNET! Juno now offers FREE Internet Access! Try it today - there's no risk! For your FREE software, visit: dl.http://www.juno.com/get/tagj.

<x-flowed>Hi, folks! What about XORLW 0x'FF' ?? It complements each bit in W.... Bye! >Tony KŸbeck has written: >Hi, >this is not do-able ( like you have written ). >COMF W will be compiled as: >COMF INDF which means the ram adress pointed at by FSR >W will be replaced by '0' by the compiler which inturn is the ramadress >for the INDF register, which uses the FSR to point to an memory location >;-) >are we having fun yet ? ( just kidding :-) ) >To do an COMF on the W reg without using temp ram I belive was mentioned >on the list no so long ago ( this month ), cant really remeber the >'best' way so You better do a search to find it. >/Tony > > >Tony KŸbek, Flintab AB >ÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓ >E-mail: TakeThisOuTtony.kubek.....TakeThisOuTflintab.com >ÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓ > ---------------- o --------------------- Name: Alejandro Lavarello ICQ: 35 764 596 alejol e-mail: TakeThisOuTalejolKILLspamspamadinet.com.uy Address: Zapican 2560 apto 308 City: Montevideo Country: Uruguay Work title: Electronic Technician Work organization: Intendencia Municipal de Montevideo Work address: Palacio Municipal - Subsuelo- Seccion Senales Luminosas Work e-mail: .....semaforosRemoveMEimm.gub.uy Work tel/fax: +598 2 9011930 ----------------- o -------------------- </x-flowed>