From b52890bfeb3d159d8b32df20062e0e36d4b446a4 Mon Sep 17 00:00:00 2001
From: Vince Weaver <vince@deater.net>
Date: Wed, 3 May 2017 00:40:33 -0400
Subject: [PATCH] tfv: more commenting of duet

---
 tfv/duet.s  |  56 ++++++++++++++++++++++++++++------------------------
 tfv/tfv.dsk | Bin 143360 -> 143360 bytes
 2 files changed, 30 insertions(+), 26 deletions(-)

diff --git a/tfv/duet.s b/tfv/duet.s
index 1d728a0f..d4dac092 100644
--- a/tfv/duet.s
+++ b/tfv/duet.s
@@ -25,14 +25,15 @@
 ; These are all "Free" zero page locations
 LOC6	EQU	$06
 LOC7	EQU	$07
-LOC8	EQU	$08
+DURATION	EQU	$08
 LOC9	EQU	$09
 LOC1D	EQU	$1D
-LOC1E	EQU	$1E
-LOC1F	EQU	$1F
+MADDRL	EQU	$1E
+MADDRH	EQU	$1F
 LOC4E	EQU	$4E
 LOC4F	EQU	$4F
 
+play_ed:
 	LDA	#$01		; 900: A9 01	; 2 *!*
 	STA	LOC9		; 902: 85 09	; 3
 	STA	LOC1D		; 904: 85 1D	; 3
@@ -42,39 +43,41 @@ LOC4F	EQU	$4F
 	BNE	label1		; 909: D0 15	; 4 *!*
 label2:
 	INY			; 90B: C8	; 2
-	LDA	(LOC1E),Y	; 90C: B1 1E	; 5 *!*
+	LDA	(MADDRL),Y	; 90C: B1 1E	; 5 *!*
 	STA	LOC9		; 90E: 85 09	; 3
 	INY			; 910: C8	; 2
-	LDA	(LOC1E),Y	; 911: B1 1E	; 5 *!*
+	LDA	(MADDRL),Y	; 911: B1 1E	; 5 *!*
 	STA	LOC1D		; 913: 85 1D	; 3
 loop:
-	LDA	LOC1E		; 915: A5 1E	; 3 *!*
+	LDA	MADDRL		; 915: A5 1E	; 3 *!*
 	CLC			; 917: 18	; 2
 	ADC	#$03		; 918: 69 03	; 2 *!*
-	STA	LOC1E		; 91A: 85 1E	; 3
+	STA	MADDRL		; 91A: 85 1E	; 3
 	BCC	label1		; 91C: 90 02	; 4 *!*
-	INC	LOC1F		; 91E: E6 1F	; 5
+	INC	MADDRH		; 91E: E6 1F	; 5
 label1:
-	LDY	#$00		; 920: A0 00	; 2 *!*
-	LDA	(LOC1E),Y	; 922: B1 1E	; 5 *!*
-	CMP	#$01		; 924: C9 01	; 2
-	BEQ	label2		; 926: F0 E3	; 4 *!*
-	BCS	label3		; 928: B0 0D	; 4 *!*
-	PLA			; 92A: 68	; 4
-	PLA			; 92B: 68	; 4
-	PLA			; 92C: 68	; 4
+	LDY	#$00		; 920: A0 00	; 2 *!*	Set Y to zero
+	LDA	(MADDRL),Y	; 922: B1 1E	; 5 *!*	Load first byte
+	CMP	#$01		; 924: C9 01	; 2	Compare to 1
+	BEQ	label2		; 926: F0 E3	; 4 *!* If one ?
+	BCS	play_note	; 928: B0 0D	; 4 *!* If >1, then duration
+	PLA			; 92A: 68	; 4	POP
+	PLA			; 92B: 68	; 4	POP
+	PLA			; 92C: 68	; 4	POP
+
 sub1:
-	LDX	#$49		; 92D: A2 49	; 2 *!*
-	INY			; 92F: C8	; 2
-	LDA	(LOC1E),Y	; 930: B1 1E	; 5 *!*
-	BNE	label4		; 932: D0 02	; 4 *!*
-	LDX	#$C9		; 934: A2 C9	; 2 *!*
+	LDX	#$49		; 92D: A2 49	; 2 *!*	X=0x49 (EOR opcode)
+	INY			; 92F: C8	; 2	increment to next byte
+	LDA	(MADDRL),Y	; 930: B1 1E	; 5 *!*	load next byte
+	BNE	label4		; 932: D0 02	; 4 *!* if not zero
+	LDX	#$C9		; 934: A2 C9	; 2 *!* X=0xC9 (CMP opcode)
 label4:
-	RTS			; 936: 60	; 6
-label3:
-	STA	LOC8		; 937: 85 08	; 3
+	RTS			; 936: 60	; 6	return
+
+play_note:
+	STA	DURATION	; 937: 85 08	; 3
 	JSR	sub1		; 939: 20 2D09	; 6
-	STX	$0983		; 93C: 8E 8309	; 4		; self-modify
+	STX	$0983		; 93C: 8E 8309	; 4	self-modify EOR/CMP
 	STA	LOC6		; 93F: 85 06	; 3
 	LDX	LOC9		; 941: A6 09	; 3 *!*
 label5:
@@ -139,7 +142,7 @@ label16:
 label17:
 	DEC	LOC4F		; 999: C6 4F	; 5
 	BNE	label18		; 99B: D0 11	; 4 *!*
-	DEC	LOC8		; 99D: C6 08	; 5
+	DEC	DURATION	; 99D: C6 08	; 5
 	BNE	label18		; 99F: D0 0D	; 4 *!*
 	BVC	label19		; 9A1: 50 03	; 4 *!*
 	BIT	$C030		; 9A3: 2C 30C0	; 4		SPEAKER
@@ -166,3 +169,4 @@ label23:
 	BVS	label99		; 9BD: 70 A3	; 4 *!*
 	NOP			; 9BF: EA	; 2
 	BVC	label8		; 9C0: 50 A3	; 4 *!*
+
diff --git a/tfv/tfv.dsk b/tfv/tfv.dsk
index 18d460b432e49875b211c73d6ab26708f29cff5e..7dbb5d54bad0d12a465e902ddc45f2449c34fedd 100644
GIT binary patch
delta 556
zcmZXPL2DC17=~vyYceCPjO{MnV6z>{no}3{2Nbj*Wg`-E&&5+%Pxc2C5-AI%pe*!I
zk0r68<{&L}$id52ZOL{F488Ok6g=b<v_}uljM^d{US{6;zImUIX^l`z>IiNUxV*DM
z;Di2vz#n&RS$Xs1^Y+W)ylnsrnZx(lP@J4+$6t1b$LF60JG})s-=CuJg$GCd^+zy)
zhE>>xw|_SANAM2DI4*@@DD1(Z8)LPV_FU(AE_M^+`@$|bbTc^lb}$`9QM)4B!f0pD
zVnluXdIQJ#E`EF_e!W`9s_+5Fg>Fd~j&QUe^&*j53epS&xiL{Lt}cNzNH>Ks$)~Ge
zVhZzZzVgtk)(UHY;Bg?Oo(_Zb^r^Ueio|qH<-)D-P58vdXDT?-xo)A-TI-B!9r=}2
z!@}~oY+eFDCjjP5ns|TYFds2j`YWUB4o#FCHmAC*{C{`GNj#(o(#)d7Lfl4tj&PfB
zK=>l%MTg%*yd<-TQNmop0AW6D{son3;yTRJgY_gfqpvrJ4NYt;5?&;YB9YLB)IV-r
hbL&1~Wl}H80jMseKXc)u3uUCh_3BLBH@j8%^*6^UwtoNs

delta 59
zcmZp8z|jCiTNpb8nCuTsc2u_7T(4}yxJ`(07w<F$MxM!hTyEQW6d3bW7(Z;UabcXm
OxLH8;3;QxZ#zz2Ow-eC-