Avalon: Routine at D651

D651: Determine whether a warlock should materialize in the room

Used by the routine at D63A.
A warlock can appear in the room: After a certain time, based on a slowly decrementing counter byte at EBB4 along with a pseudo-random adjustment As long as there aren't already 3 creatures in the room On levels 1-7 (based on room numbers in the table at C6A4) No warlock appears on level 8 (Chambers of Chaos). On level 9 (High Temple of Chaos), DEMONS materialize in rooms instead of warlocks.
D651	LD A,($EAC9)	Get the current level text number (1-9) - calculated from lookup table at C6A4
D654	LD B,A	Store in B register
There are only 7 warlocks, so we need to do something for levels 8 and 9
D655	CP $08	Are we in the Chambers of Chaos (level 8)?
D657	JP Z,$D6CF	If so there's no warlock on this level - jump to the end of this check routine
D65A	CP $09	Are we in the High Temple of Chaos (level 9)?
D65C	JR Z,$D6A4	If so, jump out and generate a DEMON instead of a WARLOCK
D65E	LD A,($EAAA)	Game cycle timer
D661	AND $3F	Check bits 0-5 (values = 0-63)
D663	JP NZ,$D6CF	Check bits 0-5 (values = 0-63)
Every 64 game cycles, reduce the timer counter for a warlock appearing in the room
D666	LD A,($EBB4)	Get warlock appearance timer
D669	DEC A	Decrement it
D66A	LD ($EBB4),A	...and re-store
D66D	LD C,A	...and re-store
D66E	CALL $DB06	Run pseudo-random number generator to produce a random number (returned in A register)
D671	CP C	Compare it against the warlock appearance timer
D672	JR C,$D6CF	If random number < warlock timer, jump out here
D674	LD A,($EBAD)	Random number > warlock timer. Get byte 6 of warlock data set
D677	CP $00
D679	JR NZ,$D6CF	If this byte isn't 0, there's already a warlock so we can jump out at this point