The Trap Door: Routine at FD99

FD99: Build Music Delay Count

Used by the routine at Continue_MenuMusicTick. Build a delay count from the shared phase at FC8F.
Build_MusicDelayCount	FD99	PUSH AF	Stash AF on the stack.
	FD9A	LD A,($FC8F)	Load FC8F, complement it, and copy the result into B and C.
	FD9D	CPL
	FD9E	LD B,A
	FD9F	LD C,A
	FDA0	ADD A,$01	Add 01 so a zero phase still yields a positive count.
	FDA2	SRA A	Divide A by 04 with two arithmetic shifts right.
	FDA4	SRA A	Divide A by 04 with two arithmetic shifts right.
	FDA6	LD E,A	Copy the scaled count into E.
	FDA7	CP $00	If the scaled count is zero, force E to 01.
	FDA9	JR NZ,Build_MusicDelayCount_Return	If the scaled count is zero, force E to 01.
	FDAB	INC E
Restore AF and return the delay count.
Build_MusicDelayCount_Return	FDAC	POP AF	Restore AF from the stack and return.
	FDAD	RET	Restore AF from the stack and return.