Gyruss: Routine at 873E

873E: Handle sprite types $15 - $17

Used by the routine at handle_sprite_type_03.

Input
A	Sprite type
IX	Sprite data

handle_sprite_types_15_17

873E

CP $15

Is sprite type < $15

8740

JR C,handle_sprite_types_0E_11

If so, jump ahead

8742

CP $18

Is sprite type >= $18

8744

JR NC,handle_sprite_types_0E_11

If so, jump ahead

sprite types $15 - $17 (laser fence)

8746

LD B,$07

Mask = 7

8748

LD A,(status_flags)

Check if you have died

874B

BIT 2,A

...

874D

JR Z,handle_sprite_types_15_17_0

If not, skip next

874F

LD B,$03

Else set Mask = 3

handle_sprite_types_15_17_0

8751

LD A,(frame_counter)

Frame counter

8754

AND B

AND mask

8755

JR NZ,handle_sprite_types_15_17_1

If not zero, skip next 2

8757

DEC (IX+$01)

Decrement polar y

875A

INC (IX+$05)

Mark for pattern reload

handle_sprite_types_15_17_1

875D

LD HL,other_flags

Flags

8760

SET 4,(HL)

Set laser fence flag

8762

LD A,(IX+$00)

Get sprite type

8765

CP $17

If not laser fence center

8767

RET NZ

Then return to return_from_sprite_handler

8768

LD A,(other_flags)

If bit 3 is reset

876B

BIT 3,A

...

876D

JP Z,deallocate_enemy

Then deallocate

8770

INC (IX+$05)

Mark for pattern reload

8773

LD A,(IX+$02)

Get polar x

8776

ADD A,(IX+$03)

Add velocity

8779

AND $3F

Mod 64

877B

LD (IX+$02),A

Save new polar x

877E

LD HL,laser_fence_2_x

Did center reach end 2?

8781

CP (HL)

...

8782

JR Z,handle_sprite_types_15_17_2

Then skip ahead

8784

INC HL

Did center reach end 1?

8785

CP (HL)

...

8786

RET NZ

If not, return to return_from_sprite_handler

handle_sprite_types_15_17_2

8787

LD A,(IX+$03)

Switch direction

878A

NEG

...

878C

LD (IX+$03),A

...

878F

RET

Return to return_from_sprite_handler