Sabre Wulf: Routine at 39338

Used by the routine at UpdateCounters.

Every actor (the player, the animals, the tribesmen, the objects and so on) is held in a 12 byte record in the actor table, which runs from ImmortalData to StoredActorTable. The first byte of each record is the sprite ID, and this is also the index into the jump table at JumpTable which selects the handler routine for the actor.

The handler for one actor is run per pass of MainLoop_NextActor. When the frame counter changes the actor currently being processed is remembered in SavedActorPointer (this happens every frame, 50 times a second), the player's actor (ImmortalData) is processed straight away and then the loop carries on from where it was interrupted. Once every actor has been processed, UpdateCounters runs.

Used by the routine at UpdateCounters. Every actor (the player, the animals, the tribesmen, the objects and so on) is held in a 12 byte record in the actor table, which runs from ImmortalData to StoredActorTable. The first byte of each record is the sprite ID, and this is also the index into the jump table at JumpTable which selects the handler routine for the actor. The handler for one actor is run per pass of MainLoop_NextActor. When the frame counter changes the actor currently being processed is remembered in SavedActorPointer (this happens every frame, 50 times a second), the player's actor (ImmortalData) is processed straight away and then the loop carries on from where it was interrupted. Once every actor has been processed, UpdateCounters runs.
MainLoop	39338	LD SP,24576	Set the stack pointer to GameEntry.
	39341	EI	Enable interrupts.
	39342	LD IX,38670	Point IX at the first actor after the player, at ImmortalData_Actors.
This entry point is used by the routine at NextActor. Check if the frame counter has changed since the last time through.
MainLoop_NextActor	39346	LD A,(23672)	Fetch the low byte of the frame counter from FRAMES into C.
	39349	LD C,A	Fetch the low byte of the frame counter from FRAMES into C.
	39350	LD A,(38550)	Fetch the frame counter from the previous pass from LastFrame.
	39353	CP C	Jump to MainLoop_RunHandler if the frame counter has not changed.
	39354	JR Z,MainLoop_RunHandler
FrameUpdate	39356	DI	Disable interrupts.
	39357	LD A,(23672)	Remember the new frame counter in LastFrame.
	39360	LD (38550),A	Remember the new frame counter in LastFrame.
	39363	LD A,1	Set the frame updated flag in FrameUpdated.
	39365	LD (38551),A	Set the frame updated flag in FrameUpdated.
	39368	LD (38569),IX	Remember which actor was being processed in SavedActorPointer.
	39372	LD IX,38658	Point IX at the player's actor at ImmortalData.
Update the random number seed using the Z80 refresh register.
MainLoop_RunHandler	39376	LD A,R	Fetch the Z80 refresh register as a source of randomness.
	39378	LD C,A	Stash it in C.
	39379	LD A,(38549)	Fetch the random seed from RandomNumber.
	39382	ADC A,C	Mix in the refresh register value and the carry flag.
	39383	LD (38549),A	Store the new random seed in RandomNumber.
Run the handler for this actor. The handler returns to NextActor, so push that address first, then use the sprite ID to find the handler in the jump table.
	39386	LD HL,39408	Stash the return address NextActor on the stack so the handler returns to it.
	39389	PUSH HL
	39390	LD BC,39742	Point BC at the handler jump table at JumpTable.
See See Ending.
	39393	LD A,(IX+0)	Fetch the sprite ID of the actor into HL.
	39396	LD L,A
	39397	LD H,0
	39399	ADD HL,HL	Double the sprite ID to get the offset into the jump table.
	39400	ADD HL,BC	Add the jump table address to get the address of the actor's entry.
	39401	LD A,(HL)	Fetch the address of the handler from the jump table.
	39402	INC HL
	39403	LD H,(HL)
	39404	LD L,A
	39405	JP IndirectJump	Jump to IndirectJump, which jumps to the address held in HL.