Sabre Wulf: Routine at A922

A922: Choose Wulf Direction

Used by the routine at HandlerWulf.

Sets the direction of the Wulf. If the Wulf is not in the same row of rooms as the player then nothing happens, except that IX+02 is reset. Otherwise, if IX+02 is zero, it is set to 01 and the Wulf is sent to the left or the right depending on whether the player is in a room to its left or right. If they are in the same room then the X positions are used instead (see CompareWulfPosition).

Input
IX	Actor record of the Wulf

ChooseWulfDirection

A922

LD A,($9703)

Fetch the room of the player from 9703.

A925

AND %11110000

Keep only bits 4-7.

A927

LD C,A

Stash the row of the player in C.

A928

LD A,(IX+$01)

Fetch the room of the Wulf.

A92B

AND %11110000

Keep only bits 4-7.

A92D

CP C

Jump to ChooseWulfDirection_SameRow if the Wulf is in the same row as the player.

A92E

JR Z,ChooseWulfDirection_SameRow

A930

LD (IX+$02),$00

Clear the direction chosen flag of the Wulf.

A934

RET

Return.

ChooseWulfDirection_SameRow

A935

LD A,(IX+$02)

Fetch the direction chosen flag of the Wulf.

A938

AND A

Return if the direction has already been chosen.

A939

RET NZ

A93A

LD (IX+$02),$01

Set the direction chosen flag of the Wulf.

A93E

LD A,($9703)

Fetch the room of the player from 9703.

A941

CP (IX+$01)

Jump to CompareWulfPosition if the Wulf is in the same room as the player.

A944

JR Z,CompareWulfPosition

A946

JR NC,SendWulfRight

Jump to SendWulfRight if the player is to the right of the Wulf.

This entry point is used by the routine at CompareWulfPosition.

ChooseWulfDirection_Left

A948

LD (IX+$06),$C0

Set the X velocity of the Wulf to C0 (moving left).

A94C

RES 2,(IX+$00)

Reset bit 2 of the sprite ID so that the Wulf faces left.

A950

RET

Return.