Tranz Am: Routine at 6949

6949: Plot Map Points

Used by the routine at CreateWindow.
PlotMapPoints	6949	LD BC,$7811	BC=MapPoints.
PlotMapPoints_Loop	694C	LD HL,$4708	HL=4708 (screen buffer location).
Handle the X co-ordinate.
	694F	LD A,(BC)	A=X co-ordinate of map point.
	6950	INC BC	Increment the map pointer in BC by one.
Scale the X co-ordinate for the smaller map display output.
	6951	SRL A	A=A / 04.
	6953	SRL A	A=A / 04.
	6955	LD E,A	Store the result in E.
Handle the Y co-ordinate.
	6956	LD A,(BC)	A=Y co-ordinate of map point.
	6957	INC BC	Increment the map pointer in BC by one.
Scale the Y co-ordinate for the smaller map display output.
	6958	SRL A	A=A / 08.
	695A	SRL A
	695C	SRL A
	695E	LD D,A	Store the result in D.
Calculate the map screen address of our currently processed map point.
	695F	LD A,H	H=H - D.
	6960	SUB D
	6961	LD H,A
	6962	LD A,L	L=L + E.
	6963	ADD A,E
	6964	LD L,A
Handle the map point "type" - place names are excluded.
	6965	LD A,(BC)	A=sprite ID of map point.
	6966	INC BC	Increment the map pointer in BC by one. Now pointing to the next record.
	6967	PUSH BC	Stash BC on the stack.
	6968	LD BC,$0101	BC=0101 (used in HandlerTerrainDots_1).
Skip place names - they don't show a marker on the map.
	696B	BIT 6,A	If bit 6 is set then this is a place name so skip and jump to PlotMapPoints_Continue.
	696D	JR Z,PlotMapPoints_Continue
	696F	CP $60	If A is 60 jump to PlotMapPoints_Continue.
	6971	JR Z,PlotMapPoints_Continue	If A is 60 jump to PlotMapPoints_Continue.
	6973	CALL HandlerTerrainDots_1	Call HandlerTerrainDots_1.
Check if finished. The stack contains the start of the next record, or the first byte past the end of the map points.
PlotMapPoints_Continue	6976	POP BC	Restore BC from the stack.
	6977	LD HL,$7CD6	HL=7CD6 (one byte past the end of MapPoints).
	697A	AND A	Reset the carry flag.
	697B	SBC HL,BC	HL=HL - BC.
	697D	JR NZ,PlotMapPoints_Loop	If the result is not zero then jump to PlotMapPoints_Loop.
	697F	RET	Return.