; drill - peck-drilling subroutine
; Requires globals: #<_z_top>, #<_z_bot>
; Optional global:  #<_z_clearance>
o<drill> sub
	; x, y, peck
	; #1 #2 #3

	G90   ; absolute x,y,z
	M101  ; enable Z-axis (M102 disables)

	o2 if [EXISTS[#<_z_clearance>]]
		#<z_clearance> = #<_z_clearance>
	o2 else
		#<z_clearance> = #<_z_top>
	o2 endif

	G0 Z#<z_clearance>
	G0 X#1 Y#2
	G0 Z#<_z_top>

	o104 if [#3 NE 0]   ; peck drilling
		#<h> = [#<_z_top> - #3]    ; first peck target (one peck below top)
		o101 while [#<h> GT #<_z_bot>]
			G1 Z#<h>
			G0 Z#<_z_top>          ; full retract
			G0 Z[#<h>+.02]         ; rapid back to just above previous depth
			#<h> = [#<h>-#3]
		o101 endwhile
	o104 endif

	G1 Z#<_z_bot>
	G0 Z#<z_clearance>

o<drill> endsub

M2