tracker6: make it interrupt-run

music/tiny_tracker6/Makefile

@@ -37,7 +37,8 @@ d4.o:	d4.s \
 	zp.inc hardware.inc \
 	mA2E_4.s \
 	mockingboard_init.s play_frame.s \
-	tracker_init.s ay3_write_regs.s
+	tracker_init.s ay3_write_regs.s interrupt_handler.s \
+	mockingboard_constants.s
 	ca65 -o d4.o d4.s -l d4.lst
 
 
@@ -53,4 +54,4 @@ text_to_tiny.o:	text_to_tiny.c
 ####
 
 clean:
-	rm -f *~ *.o *.lst D2 HELLO text_to_tiny mA2E_2.s mA2E_3.s mA2E_4.s
+	rm -f *~ *.o *.lst D4 HELLO text_to_tiny mA2E_2.s mA2E_3.s mA2E_4.s

music/tiny_tracker6/d4.s

@@ -6,21 +6,8 @@
 	.include "zp.inc"
 	.include "hardware.inc"
 
-; for a 256 entry we need to fit in 252 bytes
 
-; 310 bytes -- initial
-; 268 bytes -- strip out interrupts
-; 262 bytes -- simplify init
-; 261 bytes -- optimize init more
-; 253 bytes -- optimize var init
-; 252 bytes -- bne vs jmp
-; 250 bytes -- song only has 16 notes so can never be negative
-; 249 bytes -- make terminating value $80 instead of $FF
-; 247 bytes -- combine note loop.  makes song a bit faster
-; 245 bytes -- try to optimize writing out volume
-; 255 bytes -- add in some visualization
-; 252 bytes -- re-arrange decode code
-d2:
+d4:
 
 	;===================
 	; music Player Setup
@@ -37,26 +24,14 @@ tracker_song = peasant_song
 
 	jsr	SETGR			; enable lo-res graphics
 
+	cli				; enable music
 game_loop:
-	; typically A=0, X=FF, Y=0 here
 
-	; play a frame of music
 
-.include "play_frame.s"
-.include "ay3_write_regs.s"
+	jmp	game_loop
 
-	; delay 20Hz, or 1/20s = 50ms
-
-	lda	#140
-	jsr	WAIT
-
-	lda	#140
-	jsr	WAIT
-
-	lda	#140
-	jsr	WAIT
-
-	beq	game_loop
+.include "interrupt_handler.s"
+.include "mockingboard_constants.s"
 
 ; music
 .include	"mA2E_4.s"

music/tiny_tracker6/interrupt_handler.s

@@ -0,0 +1,68 @@
+	;================================
+	;================================
+	; mockingboard interrupt handler
+	;================================
+	;================================
+	; On Apple II/6502 the interrupt handler jumps to address in 0xfffe
+	; This is in the ROM, which saves the registers
+	;   on older IIe it saved A to $45 (which could mess with DISK II)
+	;   newer IIe doesn't do that.
+	; It then calculates if it is a BRK or not (which trashes A)
+	; Then it sets up the stack like an interrupt and calls 0x3fe
+
+	; Note: the IIc is much more complicated
+	;	its firmware tries to decode the proper source
+	;	based on various things, including screen hole values
+	;	we bypass that by switching out ROM and replacing the
+	;	$fffe vector with this, but that does mean we have
+	;	to be sure status flag and accumulator set properly
+
+interrupt_handler:
+	php			; save status flags
+	cld			; clear decimal mode
+	pha			; save A				; 3
+				; A is saved in $45 by firmware
+	txa
+	pha			; save X
+	tya
+	pha			; save Y
+
+	inc	$0404		; debug (flashes char onscreen)
+
+
+ay3_irq_handler:
+	bit	MOCK_6522_T1CL	; clear 6522 interrupt by reading T1C-L	; 4
+
+
+.include "play_frame.s"
+.include "ay3_write_regs.s"
+
+	;=================================
+	; Finally done with this interrupt
+	;=================================
+
+done_ay3_irq_handler:
+
+	pla
+	tay			; restore Y
+	pla
+	tax			; restore X
+	pla			; restore a				; 4
+
+	; on II+/IIe (but not IIc) we need to do this?
+interrupt_smc:
+	lda	$45		; restore A
+	plp			; restore flags
+
+	rti			; return from interrupt			; 6
+
+								;============
+								; typical
+								; ???? cycles
+
+
+
+
+
+
+

music/tiny_tracker6/mockingboard_constants.s

@@ -0,0 +1,21 @@
+init_addresses:
+	.byte <MOCK_6522_DDRB1,<MOCK_6522_DDRA1		; set the data direction for all pins of PortA/PortB to be output
+	.byte <MOCK_6522_ACR,<MOCK_6522_IER		; Continuous interrupts, clear all interrupts
+	.byte <MOCK_6522_IFR,<MOCK_6522_IER		; enable interrupt on timer overflow
+	.byte <MOCK_6522_T1CL,<MOCK_6522_T1CH		; set oflow value, start counting
+	.byte <MOCK_6522_ORB1,<MOCK_6522_ORB1		; reset ay-3-8910
+
+	; note, terminated by the $ff below
+
+init_values:
+	.byte $ff,$ff	; set the data direction for all pins of PortA/PortB to be output
+	.byte $40,$7f
+	.byte $C0,$C0
+	.byte $e7,$4f	; c7ce / 1.023e6 = .050s, 20Hz
+	.byte MOCK_AY_RESET,MOCK_AY_INACTIVE
+
+	; c7ce / 1.023e6 = .050s, 20Hz
+	; 9c40 / 1.023e6 = .040s, 25Hz
+	; 4fe7 / 1.023e6 = .020s, 50Hz
+	; 411a / 1.023e6 = .016s, 60Hz
+

music/tiny_tracker6/mockingboard_init.s

@@ -66,12 +66,54 @@ mockingboard_init:
 	; Reset Left AY-3-8910
 	;===========================
 
-	ldx	#$FF
-	stx	MOCK_6522_DDRB1
-	stx	MOCK_6522_DDRA1
+;	ldx	#$FF
+;	stx	MOCK_6522_DDRB1
+;	stx	MOCK_6522_DDRA1
 
-	inx				;	#MOCK_AY_RESET $0
-	stx	MOCK_6522_ORB1
-	ldx	#MOCK_AY_INACTIVE	;	$4
-	stx	MOCK_6522_ORB1
+;	inx				;	#MOCK_AY_RESET $0
+;	stx	MOCK_6522_ORB1
+;	ldx	#MOCK_AY_INACTIVE	;	$4
+;	stx	MOCK_6522_ORB1
 
+
+;	sei			; disable interrupts, is this necessary?
+
+	;=========================
+	; Setup Interrupt Handler
+	;=========================
+
+	; NOTE: we don't support IIc as it's a hack
+	;	traditionally Mockingboard on IIc was rare
+
+	;========================
+	; set up interrupt
+	; Vector address goes to 0x3fe/0x3ff
+
+	; can save 10 bytes if we load in memory so this
+	; is in the right place automatically
+
+	lda	#<interrupt_handler	; 2
+	sta	$03fe			; 3
+	lda	#>interrupt_handler	; 2
+	sta	$03ff			; 3
+					;=========
+					; 10
+	;=========================
+	; Initialize the 6522s
+	; Reset Left AY-3-8910
+	;===========================
+
+	; entries=10
+	; 14 + 2*entries = 34 bytes
+
+;	assume Y=0 on entry?
+
+	ldy	#0			; 2
+init_it_loop:
+	lda	init_values,Y		; 3
+	ldx	init_addresses,Y	; 3
+	bmi	doneit			; 2
+	iny				; 1
+	sta	$c400,X			; 3
+	bne	init_it_loop		; 2
+doneit:

music/tiny_tracker6/play_frame.s

@@ -3,6 +3,15 @@ play_frame:
 	;============================
 	; see if still counting down
 
+	lda	SONG_COUNTDOWN
+	; rotate through channel A volume
+
+	tya
+	and	#$7
+	tay
+	lda	channel_a_volume,Y
+	sta	AY_REGS+8
+
 	lda	SONG_COUNTDOWN
 	bpl	done_update_song
 
@@ -17,9 +26,8 @@ set_notes_loop:
 	;==================
 	; see if hit end
 
-	; this song only 16 notes so valid notes always positive
-;	cmp	#$80
-	bpl	not_end
+	cmp	#$ff
+	bne	not_end
 
 	;====================================
 	; if at end, loop back to beginning
@@ -30,14 +38,15 @@ set_notes_loop:
 
 not_end:
 
+
 	; NNNNNNEC -- c=channel, e=end, n=note
 
 	pha				; save note
 
 	and	#1
-	tax
-	ldy	#$0E
-	sty	AY_REGS+8,X		; $08 set volume A,B
+;	tax
+;	ldy	#$0E
+;	sty	AY_REGS+8,X		; $08 set volume A,B
 
 	asl
 	tax				; put channel offset in X
@@ -46,6 +55,9 @@ not_end:
 	pla				; restore note
 	tay
 	and	#$2
+	asl
+	asl
+	asl
 	sta	SONG_COUNTDOWN		; always 2 long?
 
 	tya
@@ -76,3 +88,9 @@ blah_urgh:
 done_update_song:
 	dec	SONG_COUNTDOWN
 	bmi	set_notes_loop
+	bpl	skip_data
+
+channel_a_volume:
+	.byte 14,14,14,14,11,11,10,10
+
+skip_data: