Hi,

   I've been thinking about time delays and have read the code posted on the
Fast Forward answers page, but for timing short delays 4 registers seems
enormous overkill. I've devised the following and would appreciate comments
and (more important) improvements.

Apologies if I have reinvented the wheel.

Keith.


; A flexible delay generator.
; ===========================
;
; This should allow delays in the range 18 to 1700 cycles with no missing
; values. It uses only one register, a six step subroutine and four bytes
; of code per call.
;
; Total time is :
;
;       3 cycles (setup)
;       2 cycles (call)
;       3 x contents of 'count'
;       4 x contents of W
;       subtract 2 for nops following bit tests
;       2 cycles (return)
;
;
count   equ 0x10        ; Register used by delay.
        .
        .
        movlw 0x??      ; number of 3 cycle loops
        movwf count
        movlw 0x??      ; number of 4 cycle loops
        call Delay
        .
        .
Delay   addlw -1
        btfss STATUS,Z
        goto $-2
        decfsz count,F
        goto $-1
        return
==========================================================
Keith Dowsett         "Variables won't; constants aren't."

E-mail:      kdowsett@rpms.ac.uk
Phone:       0181-740-3162
Fax:         0181-743-3987

Snail mail:  MRC Clinical Sciences Centre, Cyclotron Unit.
                 Hammersmith Hospital. London W12 0NN.