Sleep

.assume adl=1

; Sleeps for HL microseconds.
;
; Includes the time to call and return from thus function. Assumes a CPU speed
; of 48MHz and 3 cycles of memory read waitstates (ex. RAM).
;
; It is not possible to sleep for 0 or 1 microsecond. Best effort implementation
; sleeps instead for 1.33 microseconds (repeating, of course).
;
;    I: UHL=microseconds
;   FO: c=0
; If UHL>=2:
;    O: ude=-1, uhl=-1
;   CC: (11*r(PC)+4)*(UHL-2)+14*r(PC)+3*r(SPL)+6
; If UHL<2:
;    O: ude=-2, uhl=UHL-2
;   CC: 7*r(PC)+3*r(SPL)+2
Sleep:
	ld de,-2
	add hl,de
	ret nc
Sleep_Loop:
	ld e,-1
	ret nc
	ret nc
	ret nc
	add hl,de
	ret nc
	nop
	jr Sleep_Loop