Gyruss: Routine at 83D0

83D0: Next stage

Used by the routine at stage_completed.
next_stage	83D0	LD HL,status_flags	Flags
	83D3	RES 0,(HL)
	83D5	RES 1,(HL)
	83D7	XOR A
	83D8	LD (wave),A	Clear wave
	83DB	LD (enemies_hit),A	Clear enemies destroyed
	83DE	LD A,(stage)	Stage
	83E1	INC A	Next stage
	83E2	CP $18	Did we reach 24?
	83E4	JR C,next_stage_0	No, skip ahead
	83E6	LD HL,completed_stages	Get the total stages completed
	83E9	ADD A,(HL)	And add 24
	83EA	LD (HL),A	Save again
	83EB	XOR A	And set stage to zero
next_stage_0	83EC	LD (stage),A	Save stage
	83EF	LD HL,status_flags	Flags
	83F2	RES 3,(HL)	Reset bit 3
	83F4	LD A,(stage)	Stage
	83F7	AND $03	Mod 4
	83F9	CP $03	Is it a chance stage?
	83FB	JR NZ,next_stage_1	No, skip ahead
	83FD	SET 3,(HL)	Yes, set flag
next_stage_1	83FF	XOR A	Reset death count
	8400	LD (stage_death_count),A	...
	8403	CALL display_planet	Undraw planet
	8406	LD HL,$201C	Set 4 colors to white/black
	8409	LD DE,$0004	...
	840C	LD A,$F1	...
	840E	CALL $1F82	FILL_VRAM
	8411	LD HL,$0700	Address in pattern table
	8414	LD DE,$0100	256 bytes = 32 patterns
	8417	XOR A	Clear
	8418	CALL $1F82	FILL_VRAM
	841B	LD A,(other_flags)	Save flags
	841E	PUSH AF	...
	841F	CALL init_stage	Init stage
	8422	POP AF	Restore flags
	8423	LD (other_flags),A	...
	8426	JP main_loop	Jump to main loop