(added PIC tag)

Dwayne, your version is very tricky :-)
You did not say which MCU do you want to do that, but I guess it's not 18F
otherwise you would just simply write this:

  movlw    OFFSET_LOW
  addwf    TIMER3_LOW,w
  movwf    TIMER4_LOW
   movlw    OFFSET_MED
  addwfc   TIMER3_MED,w
  movwf    TIMER4_MED   movlw    OFFSET_HI
  addwfc   TIMER3_HI,w
  movwf    TIMER4_HI

Tamas



---------- Forwarded message ----------
From: Spehro Pefhany <speff@interlog.com>
Date: Dec 23, 2007 2:08 AM
Subject: Re: multi-byte addition with a constant
To: "Microcontroller discussion list - Public." <piclist@mit.edu>

; Untested code -- haven't written asm in a while..
; add 24 bit constant to 24-bit number in result_high:result_mid:result_low
; no registers other than result required, easily expanded to more bytes
; 8-10 instructions depending on constant value
;
; ADDER_LOW   low byte of constant
; ADDER_MID   middle byte of constant
; ADDER_HIGH  high byte of constant

     movlw  (ADDER_LOW)
     addwf  result_low,F          ;LS byte
     movlw  (ADDER_MID)
     #if    ((1+ (ADDER_MID)) & 0xFF)
     skpnc
     movlw  ((1+ (ADDER_MID)) & 0xFF)
     #else
     skpc
     #endif
     addwf   result_mid,F         ; mid byte
     movlw   (ADDER_HIGH)
     #if    ((1+ (ADDER_HIGH)) & 0xFF)
     skpnc
     movlw  ((1+ (ADDER_HIGH)) & 0xFF)
     #else
     skpc
     #endif
     addwf   result_high,F        ; MS byte






Spehro Pefhany --"it's the network..."            "The Journey is the
reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com



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