Create ay-test.asm

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Source/Apps/TEST/sound/ay-test.asm

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+;*****************************************************************************
+;*****************************************************************************
+;**                                                                         **
+;**	AY-3-8910 Sound Test Program                                        **
+;**	Author: Wayne Warthen -- 10/8/2017                                  **
+;**                                                                         **
+;*****************************************************************************
+;*****************************************************************************
+;
+;=============================================================================
+; Constants Section
+;=============================================================================
+;
+; Hardware port addresses
+;
+rsel	.equ	$9A		; Register seelection port address
+rdat	.equ	$9B		; Register data port address
+acr	.equ	$9C		; Aux control register port address
+;
+; CPU speed for delay scaling
+;
+cpuspd	.equ	4		; CPU speed in MHz
+;
+; BDOS invocation constants
+;
+bdos	.equ	$0005		; BDOS invocation vector
+print	.equ	9		; BDOS print function number
+conwrt	.equ	2		; BDOS console write char
+;
+;=============================================================================
+; Code Section
+;=============================================================================
+;
+	.org	$100
+;
+	ld	(stksav),sp	; save incoming stack frame
+	ld	sp,stack	; setup our private stack
+;
+	ld	de,banner	; load banner string address
+	ld	c,print		; BDOS print function number
+	call	bdos		; do it
+;
+	ld	a,$FF		; SCG board activation value
+	out	(acr),a		; write value to ACR
+;
+	xor	a		; zero accum
+	ld	(chan),a	; init channel number
+;
+chloop:
+	; Test each channel
+	call	tstchan		; test the current channel
+	ld	hl,chan		; point to channel number
+	ld	a,(chan)	; get current channel
+	inc	a		; bump to next
+	ld	(chan),a	; save it
+	cp	3		; end of channels?
+	jr	nz,chloop	; loop if not done
+;
+	ld	de,crlf		; newline
+	ld	c,print		; BDOS print function
+	call	bdos		; do it
+;
+	ld	sp,(stksav)	; restore stack
+;
+	ret			; end of program
+;
+tstchan:
+	; Display channel being tested
+	ld	de,chmsg	; point to channel message
+	ld	c,print		; BDOS print function number
+	call	bdos		; do it
+	ld	a,(chan)	; get current channel number
+	add	a,'A'		; offset to print as alpha
+	ld	e,a		; put in E
+	ld	c,conwrt	; BDOS console out function number
+	call	bdos		; do it
+	ld	de,chmsg2	; point to channel message
+	ld	c,print		; BDOS print function number
+	call	bdos		; do it
+;
+	ld	hl,0		; initial pitch value
+	ld	(pitch),hl	; save it
+;
+	; Setup mixer register
+	ld	a,(chan)	; get channel num (0-2)
+	inc	a		; adjust index (1-3)
+	ld	b,a		; and use as loop counter
+	xor	a		; clear accum
+	scf			; set carry
+mixloop:
+	rla			; rotate bit
+	djnz	mixloop		; loop based on channel num
+	cpl			; invert bits
+	and	$FF		; so only target bit is cleared
+	push	af		; save value
+	ld	a,7		; mixer register
+	out	(rsel),a	; select it
+	pop	af		; recover value
+	out	(rdat),a	; and set register value
+;
+	; Set channel volume to max
+	ld	a,(chan)	; get channel
+	add	a,8		; adjust for start of vol regs
+	out	(rsel),a	; select register
+	ld	a,$0F		; max volume
+	out	(rdat),a	; write it
+;
+pitloop:
+	; Pitch loop
+	ld	a,(chan)	; get channel
+	sla	a		; A := channel pitch reg, 2 bytes per chan
+	out	(rsel),a	; select low byte register
+	push	af		; save register
+	ld	a,l		; get low byte of pitch value
+	out	(rdat),a	; and write it to register
+	pop	af		; recover register index
+	inc	a		; inc to high byte pitch register
+	out	(rsel),a	; select high byte register
+	ld	a,h		; get high byte of pitch value
+	out	(rdat),a	; and write it to register
+;
+	; Delay
+	ld	b,cpuspd	; cpu speed scalar
+dlyloop:
+	call	dly64		; arbitrary delay
+	djnz	dlyloop		; loop based on cpu speed
+;
+	; Next pitch value
+	ld	hl,(pitch)	; get current pitch
+	inc	hl		; increment
+	ld	(pitch),hl	; save new value
+	ld	a,h		; get high byte
+	;cp	16		; end of max range?
+	cp	4		; end of max range?
+	jr	nz,pitloop	; loop till done
+;
+	; Clean up
+	call	clrpsg		; shut down psg
+;
+	ret			; done
+;
+; Clear PSG registers to default
+;
+clrpsg:
+	ld	b,16		; loop for 18 registers
+	ld	c,0		; init register index
+clrpsg1:
+	ld	a,c		; register num to accum
+	out	(rsel),a	; select it
+	xor	a		; clear accum
+	out	(rdat),a	; and write to register
+	inc	c		; next register
+	djnz	clrpsg1		; loop through all registers
+	ret			; return
+;
+; Program PSG registers from list at HL
+;
+setpsg:
+	ld	a,(hl)		; get psg reg number
+	inc	hl		; bump index
+	cp	$FF		; check for end
+	ret	z		; return if end marker $FF
+	out	(rsel),a	; select psg register
+	ld	a,(hl)		; get register value
+	inc	hl		; bump index
+	out	(rdat),a	; set register value
+	jr	setpsg		; loop till done
+;
+; Short delay functions.  No clock speed compensation, so they
+; will run longer on slower systems.  The number indicates the
+; number of call/ret invocations.  A single call/ret is
+; 27 t-states on a z80, 25 t-states on a z180
+;
+dly256:	call	dly128
+dly128:	call	dly64
+dly64:	call	dly32
+dly32:	call	dly16
+dly16:	call	dly8
+dly8:	call	dly4
+dly4:	call	dly2
+dly2:	call	dly1
+dly1:	ret
+;
+;=============================================================================
+; Data Section
+;=============================================================================
+;
+chan	.db	0		; active audio channel
+pitch	.dw	0		; current pitch
+;
+banner	.text	"\r\nRetroBrew Computers SCG AY-3-8910 Sound Test\r\n"
+	.text	"Set SCG board base I/O address to 0x98\r\n$"
+chmsg	.text	"\r\nPlaying descending tones on channel $"
+chmsg2	.text	"...$"
+crlf	.text	"\r\n$"
+;
+stksav	.dw	0		; saved stack frame
+	.fill	80,$FF		; 40 level private stack
+stack	.equ	$		; start of stack
+;
+	.end