Booty: Routine at F618

F618: Sound Generator: White Noise

Used by the routines at SoundHandler_BombFuse and SoundHandler_BombSparks.
SoundGenerator_WhiteNoise	F618	PUSH BC	Stash BC and BC on the stack.
	F619	PUSH BC	Stash BC and BC on the stack.
	F61A	CALL WhiteNoiseGenerator	Call WhiteNoiseGenerator.
	F61D	LD BC,$FFFE	Send *Active_BorderColour to the speaker port.
	F620	LD A,($5BD0)
	F623	OUT (C),A
	F625	POP BC	Restore BC from the stack.
	F626	CALL WhiteNoiseGenerator	Call WhiteNoiseGenerator.
	F629	LD BC,$FFFE	BC=FFFE (C points to the speaker port).
	F62C	LD A,($5BD0)	A=*Active_BorderColour.
	F62F	OR %00010000	Turn on the speaker (set bit 4).
	F631	OUT (C),A	Send A to port *C.
	F633	POP BC	Restore BC from the stack.
	F634	DEC DE	Decrease DE by one.
	F635	LD A,D	Jump to SoundGenerator_WhiteNoise until DE is zero.
	F636	OR E
	F637	JR NZ,SoundGenerator_WhiteNoise
	F639	RET	Return.
WhiteNoiseGenerator	F63A	PUSH BC	Stash BC on the stack.
	F63B	CALL BombTimer	Call BombTimer.
	F63E	AND B	Merge the bits from B.
	F63F	LD B,A	B=A.
	F640	CP $00	Jump to WhiteNoiseHouseKeeping if A is zero.
	F642	JR Z,WhiteNoiseHouseKeeping	Jump to WhiteNoiseHouseKeeping if A is zero.
WhiteNoiseDelay	F644	DJNZ WhiteNoiseDelay	Decrease counter by one and loop back to WhiteNoiseDelay until counter is zero.
WhiteNoiseHouseKeeping	F646	POP BC	Restore BC from the stack.
	F647	RET	Return.