Cyberun: Routine at A8D9

A8D9: Build Stack Graphic

Used by the routines at BuildShip and BeginLife. Builds the graphic of the stack that hangs below the ship, as a sprite that is two bytes wide in a buffer with seven bytes to a row, by copying one row of the stack for each unit of its height. This is a best reading of the code.
BuildStackGraphic	A8D9	LD HL,$F6BB	Use the buffer.
	A8DC	LD DE,$7721	Use the graphic of the stack.
	A8DF	LD A,($C905)	Fetch the height of the stack.
	A8E2	AND A	Return if the stack is empty.
	A8E3	RET Z	Return if the stack is empty.
	A8E4	LD B,A	Use the height as a counter.
BuildStackGraphic_Loop	A8E5	LD A,(DE)	Copy a row of the stack...
	A8E6	LD (HL),A	Write A where HL points.
	A8E7	INC DE	Advance DE.
	A8E8	INC HL	Advance HL.
	A8E9	LD A,(DE)	...two bytes wide.
	A8EA	LD (HL),A	Write A where HL points.
	A8EB	INC DE	Advance DE.
	A8EC	LD A,$05	Move on to the next row of the buffer.
	A8EE	CALL AddAToHL	Call AddAToHL.
	A8F1	DJNZ BuildStackGraphic_Loop	Loop back to BuildStackGraphic_Loop for each row.
	A8F3	RET	Return.