Dudes:

The following QuickBASIC program generates PIC source code for precise
delays of from 1 to over 12,918,587,911 cycles.  For a delay of
600,000,000 cycles (10 minutes at 4 MHz), the output looks like this:

               list r=dec

        r1     equ     [any file register]
        r2     equ     r1+1
        r3     equ     r2+1
        r4     equ     r3+1
                            ___________________
        delay: movlw 213   |                   |
               movwf  r1   |                   V
               movlw 205   |       loop:  decfsz r1
               movwf  r2   |              goto   loop
               movlw 228   |              decfsz r2
               movwf  r3   |              goto   loop
               movlw  12   |              decfsz r3
               movwf  r4   |              goto   loop
                   |       |              decfsz r4
                   |_______|              goto   loop



Here's the program:


' ===================================================================
'
' Four-Variable PIC Delay Calculator
' Written by Andy Warren, 31 Jan 1995
'
' (C) 1995 Fast Forward Engineering
'
' Permission is hereby granted for all
' non-commercial use.
'

        defdbl a-z

        x = 0

        input "Number of cycles to delay:",delay
        delay = int(delay)

        if delay < 32 then goto inline

        x = delay-16

                               d = int(x/50463234)
        x = x - d * 50463234:  c = int (x/197122)
        x = x - c * 197122:    b = int (x/770)
        x = x - b * 770:       a = int (x/3)

        a = a + 1: b = b + 1: c = c + 1: d = d + 1

        if a > 256 then a = 256
        if b > 256 then b = 256
        if c > 256 then c = 256
        if d > 256 then d = 256

        x = 3*a + 770*b + 197122*c + 50463234*d - 50661121 + 8

        a$=right$("   "+str$(a),3): if a$ = "256" then a$ = "  0"
        b$=right$("   "+str$(b),3): if b$ = "256" then b$ = "  0"
        c$=right$("   "+str$(c),3): if c$ = "256" then c$ = "  0"
        d$=right$("   "+str$(d),3): if d$ = "256" then d$ = "  0"

        print
        print"       list r=dec"
        print
        print"r1     equ     [any file register]"
        print"r2     equ     r1+1"
        print"r3     equ     r2+1"
        print"r4     equ     r3+1"
        print"                    ___________________
        print"delay: movlw ";a$;"   |                   |"
        print"       movwf  r1   |                   V"
        print"       movlw ";b$;"   |       loop:  decfsz r1"
        print"       movwf  r2   |              goto   loop"
        print"       movlw ";c$;"   |              decfsz r2"
        print"       movwf  r3   |              goto   loop"
        print"       movlw ";d$;"   |              decfsz r3"
        print"       movwf  r4   |              goto   loop"
        print"           |       |              decfsz r4"
        print"           |_______|              goto   loop"

inline:

        x = delay - x

        g = int(x/2): if g = 0 then goto inline1

        for y = 1 to g
        print"                                  goto   $+1"
        next

inline1:

        if x/2 = int(x/2) then goto finis

        print"                                  nop"

finis:

        end

'====================================================================

Enjoy...

-Andy


--
Andrew Warren - fastfwd@ix.netcom.com
Fast Forward Engineering, Vista, California