Gunfright: Routine at 43221

Type 23: a tumbleweed rolling about next to the sheriff. It follows one of two routes, stepping through the route one byte at a time; the high nibble of each byte is the vertical speed and the low nibble the horizontal speed, both signed. Bits 6 and 7 of byte 5 mirror the route, and they change every time a route ends, so the tumbleweed wanders in a different way each time. It spins by flipping its sprite every frame, and it hurts the sheriff if they touch. It goes away when the sheriff is two cells away.

Type 23: a tumbleweed rolling about next to the sheriff. It follows one of two routes, stepping through the route one byte at a time; the high nibble of each byte is the vertical speed and the low nibble the horizontal speed, both signed. Bits 6 and 7 of byte 5 mirror the route, and they change every time a route ends, so the tumbleweed wanders in a different way each time. It spins by flipping its sprite every frame, and it hurts the sheriff if they touch. It goes away when the sheriff is two cells away.
Disappear if the sheriff is more than two cells away.
HandleTumbleweed	43221	LD C,2	Set the distance to two cells.
	43223	CALL CheckDistance	Check how close the sheriff is.
	43226	JP NC,HandleBody_Remove	Remove the tumbleweed if the sheriff has moved away.
Fetch the next step of the route.
	43229	LD A,(IX+10)	Fetch the number of the route, zero or one.
	43232	LD BC,43339	Point BC at TumbleweedRoutes.
	43235	CALL GetTableEntry	Point HL at the start of the route.
	43238	LD A,(IX+11)	Fetch the position in the route.
	43241	INC (IX+11)	Move on to the next step.
	43244	CALL AddAToHL	Point HL at the step.
	43247	LD A,(HL)	Fetch the step.
	43248	CP 128	Jump to HandleTumbleweed_RouteEnd if this is the end of the route.
	43250	JR Z,HandleTumbleweed_RouteEnd
Work out the vertical speed from the high nibble.
	43252	SRA A	Shift the high nibble into the bottom of the byte, keeping the sign.
	43254	SRA A
	43256	SRA A
	43258	SRA A
	43260	BIT 6,(IX+5)	Jump to HandleTumbleweed_DoubleVertical unless the route is mirrored vertically.
	43264	JR Z,HandleTumbleweed_DoubleVertical
	43266	NEG	Negate the speed to mirror the route.
HandleTumbleweed_DoubleVertical	43268	SLA A	Double the speed.
	43270	LD (41493),A	Store it as the vertical speed.
Work out the horizontal speed from the low nibble.
	43273	LD A,(HL)	Fetch the step again.
	43274	LD C,A	Keep the tumbleweed step in C.
	43275	AND %00001111	Keep the low nibble.
	43277	BIT 3,C	Jump to HandleTumbleweed_TestHorizontal unless the nibble is negative.
	43279	JR Z,HandleTumbleweed_TestHorizontal
	43281	OR %11110000	Extend the sign of the nibble into the top half.
HandleTumbleweed_TestHorizontal	43283	BIT 7,(IX+5)	Jump to HandleTumbleweed_DoubleHorizontal unless the route is mirrored horizontally.
	43287	JR Z,HandleTumbleweed_DoubleHorizontal
	43289	NEG	Negate the speed to mirror the route.
HandleTumbleweed_DoubleHorizontal	43291	SLA A	Double the speed.
	43293	LD (41492),A	Store it as the horizontal speed.
Move the tumbleweed.
	43296	CALL CheckWallsEachWay	Set the direction the tumbleweed is facing from its speed.
	43299	CALL MoveObject	Move the tumbleweed.
	43302	LD A,(IX+7)	Fetch the flags of the object.
	43305	XOR %01000000	Flip the sprite horizontally.
	43307	LD (IX+7),A	Store the flags.
	43310	CALL CheckSheriffTouch	Check whether the tumbleweed is touching the sheriff.
	43313	JP C,KillSheriff	Hurt the sheriff if it is.
	43316	RET	Return.
The route has ended, so choose the next one.
HandleTumbleweed_RouteEnd	43317	LD A,(41496)	Fetch a random number.
	43320	AND %00000001	Keep bit 0.
	43322	LD (IX+10),A	Choose the route with it.
	43325	LD (IX+11),0	Write 0 to byte 11 to go back to the first step.
	43329	LD A,(IX+5)	Fetch the mirror flags.
	43332	ADD A,64	Add 64 to change how the route is mirrored.
	43334	LD (IX+5),A	Store the flags.
	43337	JR HandleTumbleweed	Start again with the new route.