The Sidney Affair: Routine at 64455

64455: Sound: Noise

Makes a short noise on the speaker by toggling bit 4 of port 254 for 0128 pulses. Called by BASIC as "noi" (64455).
Sound_Noise	64455	DI	Disable interrupts.
	64456	LD BC,128
	64459	LD A,(23624)
	64462	RRCA
	64463	RRCA
	64464	RRCA
	64465	EX AF,AF'
	64466	LD H,0
Sound_Noise_0	64468	EX AF,AF'
	64469	OUT (254),A
	64471	XOR 16
	64473	EX AF,AF'
	64474	LD L,0
	64476	LD D,L
	64477	LD E,H
	64478	AND A
	64479	SBC HL,DE
	64481	SBC HL,DE
	64483	LD DE,254
	64486	ADD HL,DE
	64487	LD A,L
	64488	SUB H
	64489	JR C,Sound_Noise_1
	64491	DEC A
Sound_Noise_1	64492	LD H,A
Sound_Noise_2	64493	DEC A
	64494	JR NZ,Sound_Noise_2
	64496	DEC BC
	64497	LD A,B
	64498	OR C
	64499	JR NZ,Sound_Noise_0
	64501	RET