Everyone's a Wally: Routine at 47409

47409: Clear Banner

Used by the routine at PrintBanner.
Clear_Banner	47409	PUSH HL	Stash HL, BC and DE on the stack.
	47410	PUSH BC
	47411	PUSH DE
	47412	LD IX,33272	IX=ScreenBuffer_Locations.
We're not clearing the whole screen buffer, just 32 rows.
	47416	LD C,32	C=32 (row counter).
Fetch the screen buffer location.
Clear_Banner_Vertical_Loop	47418	LD L,(IX+0)	L=*IX+0.
	47421	LD H,(IX+1)	H=*IX+1.
Clear the current row.
	47424	LD B,32	B=32 (column counter).
Clear_Banner_Horizontal_Loop	47426	LD (HL),0	Write 0 to HL.
	47428	INC HL	Increment HL by one.
	47429	DJNZ Clear_Banner_Horizontal_Loop	Decrease column counter by one and loop back to Clear_Banner_Horizontal_Loop until counter is zero.
Move onto the next screen buffer location.
	47431	INC IX	Increment IX by two.
	47433	INC IX	Increment IX by two.
	47435	DEC C	Decrease the row counter held in C by one.
	47436	JR NZ,Clear_Banner_Vertical_Loop	Jump to Clear_Banner_Vertical_Loop until C is zero.
	47438	JP StackRestore	Jump to StackRestore.