The Hobbit: Routine at 7F78

7F78: Drawing Routine

Used by the routine at YouSeeStart. Draws a location picture from its line, fill and attribute commands. Nothing is drawn when the picture switch is off, and a dark place is forced black. See Location Graphics Decoding.
Drawing	7F78	PUSH AF	Save AF and jump to Drawing_Check if the picture switch at B707 is not zero.
	7F79	LD A,($B707)
	7F7C	AND A
	7F7D	JR NZ,Drawing_Check
	7F7F	LD A,$FF	Write FF to LocationID.
	7F81	LD ($7F77),A	Write FF to LocationID.
	7F84	POP AF	Restore AF from the stack.
	7F85	RET	Return.
Drawing Check
Drawing_Check	7F86	POP AF	Keep the saved flags, save the registers, and point IX at the location graphics table.
	7F87	PUSH AF
	7F88	PUSH HL
	7F89	PUSH BC
	7F8A	PUSH DE
	7F8B	PUSH IX
	7F8D	LD IX,$CC00
	7F91	CALL IndexIdTable	Call IndexIdTable to look this id up. The zero flag is set when nothing matches.
	7F94	LD ($7F77),A	Store the location ID at LocationID.
	7F97	LD L,(IX+$01)	Read the low byte of this location's graphics address.
	7F9A	LD H,(IX+$02)	Read the high byte of this location's graphics address.
	7F9D	CALL NZ,DrawingSetup	If there is graphics data for this location then call DrawingSetup.
	7FA0	POP IX	Restore IX, DE, BC, HL and AF from the stack.
	7FA2	POP DE
	7FA3	POP BC
	7FA4	POP HL
	7FA5	POP AF
	7FA6	RET	Return.