Sabre Wulf: Routine at 45447

45447: Enter Room Left

Used by the routine at MoveActorLeft.

Used by MoveActor when an actor has gone off the left of the screen. The actor is put at the right of the room to the left (the room number is one less, but the room stays in the same row of the map) and its X position is set so that its right edge is at the edge of the screen.

Input
IX	Actor record

Output
E	New X position

EnterRoomLeft

45447

LD A,(38573)

Fetch the width of the actor from Actor_Width.

45450

NEG

Negate the width.

45452

DEC A

Subtract one.

45453

LD E,A

Stash the new X position in E.

45454

LD A,(IX+1)

Fetch the room of the actor.

45457

LD C,A

Stash the room in C.

45458

DEC A

Move to the room on the left.

This entry point is used by the routine at EnterRoomRight.

EnterRoomLeft_Row

45459

AND %00001111

Keep only bits 0-3 (the column).

45461

LD B,A

Stash the column in B.

45462

LD A,C

Fetch the old room.

45463

AND %11110000

Keep only bits 4-7 (the row).

45465

OR B

Merge in the new column.

45466

LD (IX+1),A

Set the new room of the actor.

45469

JR EnterRoom

Jump to EnterRoom.