Gyruss: Routine at ABFF

ABFF: Update name table to display center enemies

Used by the routine at display_center_enemies.
display_center_enemies_names	ABFF	LD HL,center_enemies_redraw	Test flag
	AC02	BIT 0,(HL)	If not set
	AC04	RET Z	Then return
	AC05	RES 0,(HL)	Else reset flag
	AC07	LD A,(center_map_entries)	Get number of map entries
	AC0A	OR A	Skip ahead if zero
	AC0B	JR Z,erase_center_enemies	...
	AC0D	LD DE,$194E	Name table VDP address
	AC10	LD A,(center_enemies_name_2)	Get first name used for center enemies
	AC13	LD C,$04	4 rows
display_center_enemies_names_0	AC15	LD B,$04	4 columns
display_center_enemies_names_1	AC17	RST $10	Write VDP byte
	AC18	INC A	Next name
	AC19	INC DE	Next VDP address
	AC1A	DJNZ display_center_enemies_names_1	Loop for 4 columns
	AC1C	LD HL,$001C	One row down
	AC1F	ADD HL,DE	...
	AC20	EX DE,HL	...
	AC21	DEC C	Row counter
	AC22	JR NZ,display_center_enemies_names_0	Loop for 4 rows
	AC24	LD HL,(center_enemies_name_1)	Swap center_enemies_name_1 and center_enemies_name_2
	AC27	LD A,L	...
	AC28	LD L,H	...
	AC29	LD H,A	...
	AC2A	LD (center_enemies_name_1),HL	...
	AC2D	XOR A	Reset center enemy to process
	AC2E	LD (center_enemy_processed),A	...
	AC31	RET