From 1c3d849cc309d3d1a5ed1ca6a6fd56acacd5ce3f Mon Sep 17 00:00:00 2001
From: Bobbi Webber-Manners <bobbi.manners@gmail.com>
Date: Sun, 27 Nov 2022 21:55:40 -0500
Subject: [PATCH] Adds support for Mockingboard noise channel. WIP!

---
 applecorn.po   | Bin 819200 -> 819200 bytes
 mainmem.mock.s |  71 ++++++++++++++++++++++++++++++++++---------------
 mame_applecorn |   4 +--
 3 files changed, 52 insertions(+), 23 deletions(-)

diff --git a/applecorn.po b/applecorn.po
index 754b08b8f8e0346a8a062f860b5517e8adbf9217..432cc70e77c60128271accb608da94270750d9b4 100644
GIT binary patch
delta 301
zcmZo@FluNp+K|p7(Cfuet!pmI(D0Z+0mNu7XK62IVFY3(AZ7+)5T6x@*?^cGh&h0m
zb9*@p*SCwRFVj8NPV)S~lHt>wlHv0&9mHYwQBU>Z%78H4Qhl_xPrAm%&&udEebH?$
zBjMl-g@TMz0^e6!EMiv(&R8j;P%!=eZ7#`WceviwuTbF1s8Z0%$Vj;LfZ>C1mlfBl
zoxPbrWiNL2W&o*Q35(cf0QLU@%ky_hWU{ZC;ROT`IW7nrB!5GP<%mLKqC`SeALEe)
w>^%%e7O((`ULc1J#;F2IHi9G@K#~nddO3kSHZX5{#wl(MmhBtPaR+P!05Jx3S^xk5

delta 315
zcmZo@FluNp+K|p7kn6=zt;;6D(D0Z+0mNu7XK62IVFY3(AZ7+)5T6x@*?^cGh&h0m
zb9*@p*SCwR57Rx?PV)S~lHt>wlHv0$9mHYwQBU<@%78H4QhlVhPrAm%&&sGbebH?$
zBOSYpQv$zMS}bB$u**nLIG?_<zL)RF+LqYfj#veT{f_Oi2_8`^6qquq6r?hi-Qjvy
zpOJ9u0mBEuE-S88J99IEx?b$e%>Yurz~a1J5}E9)W_SSsSnP%l?-2tgiv%5(BMOa)
z5(!a#j7Rz!k1SyCVK~y$aAW}sgzjZL(hC%2Llvz`U}0fK1Ka1H;ud6?EWo6&eZx8K
GfQ<l3$8+BR

diff --git a/mainmem.mock.s b/mainmem.mock.s
index a314982..4cca602 100644
--- a/mainmem.mock.s
+++ b/mainmem.mock.s
@@ -83,12 +83,15 @@ MOCKINIT    LDA   #$FF                      ; All VIA pins output
 * Silence all channels
 MOCKSILENT  LDX  #13                        ; Clear all 14 AY-3 regs
             LDA  #$00
-:L0         JSR  MOCKWRT
+:L0         JSR  MOCKWRT1
+            JSR  MOCKWRT2
             DEX
             BPL  :L0
             LDA  #$38                       ; Turn off noise
             LDX  #07
-            JSR  MOCKWRT
+            JSR  MOCKWRT1                   ; First AY-3
+            LDA  #$14                       ; A,B=tone; C=noise
+            JSR  MOCKWRT2                   ; Second AY-3
             RTS
 
 
@@ -122,17 +125,22 @@ MOCKNOTE    PHA
 * Preserves X & Y
 MOCKFREQ    PHX
             CPX   #$00                      ; Noise channel
-            BEQ   :DONE                     ; TODO: IGNORE NOISE FOR NOW
+            BEQ   :NOISE
             TXA
             DEC   A                         ; Subtract 1
             ASL                             ; Double to get fine register
             TAX
             LDA   MFREQLOW,Y                ; LSB of divider
-            JSR   MOCKWRT                   ; Write value to AY-3 register
+            JSR   MOCKWRT1                  ; Write value to AY-3 register
             INX                             ; Add one for course register
             LDA   MFREQHIGH,Y               ; MSB of divider
-            JSR   MOCKWRT                   ; Write value to AY-3 register
-:DONE       PLX
+            JSR   MOCKWRT1                  ; Write value to AY-3 register
+            PLX
+            RTS
+:NOISE      LDX   #6                        ; Noise period register
+            TYA                             ; TODO TEMPORARY HACK
+            JSR   MOCKWRT2                  ; Write value to AY-3 register
+            PLX
             RTS
 
 
@@ -141,7 +149,7 @@ MOCKFREQ    PHX
 * Preserves X & Y
 MOCKAMP     PHX
             CPX   #$00                      ; Noise channel
-            BEQ   :DONE                     ; Has no amplitude
+            BEQ   :NOISE
             TXA                             ; Add 7 to get register
             CLC
             ADC   #7
@@ -151,18 +159,24 @@ MOCKAMP     PHX
             LSR
             LSR
             LSR                             ; Now 0..15
-            JSR   MOCKWRT                   ; Write value to AY-3 register
-:DONE       PLX
+            JSR   MOCKWRT1                  ; Write value to AY-3 register
+            PLX
+            RTS
+:NOISE      LDX   #10                       ; Chan C
+            TYA                             ; Amplitude 0..255
+            LSR                             ; Divide by 16
+            LSR
+            LSR
+            LSR                             ; Now 0..15
+            JSR   MOCKWRT2                  ; Write value to AY-3 register
+            PLX
             RTS
 
 
 * Mockingboard interrupt service routine - just calls generic audio ISR
 MOCKISR     CLD
-            BIT   MOCK_6522_IFR            ; See if interrupt was from MB
-            BMI   :MOCK                    ; Yes
-            SEC                            ; We did not service irc
-            RTS
-:MOCK       BIT   MOCK_6522_T1CL           ; Clear interrupt
+* TODO: Check whether interrupt is from Mockingboard or not
+            BIT   MOCK_6522_T1CL           ; Clear interrupt
             JSR   AUDIOISR
             CLC                            ; CC indicates we serviced irq
             RTS
@@ -172,28 +186,43 @@ MOCKISR     CLD
 ** Private functions follow (ie: not part of driver API)
 **
 
-* Write to both AY-3s
+* Write to first AY-3
 * On entry: A - value, X - register
 * On exit: All regs preserved.
-MOCKWRT     PHY
+MOCKWRT1    PHY
             STX   MOCK_6522_ORA1            ; Latch the address
-            STX   MOCK_6522_ORA2
             LDY   #MOCK_AY_LATCH_ADDR
             STY   MOCK_6522_ORB1
-            STY   MOCK_6522_ORB2
 
             LDY   #MOCK_AY_INACTIVE         ; Go inactive
             STY   MOCK_6522_ORB1
-            STY   MOCK_6522_ORB2
 
             STA   MOCK_6522_ORA1            ; Write data
-            STA   MOCK_6522_ORA2
             LDY   #MOCK_AY_WRITE
             STY   MOCK_6522_ORB1
-            STY   MOCK_6522_ORB2
 
             LDY   #MOCK_AY_INACTIVE         ; Go inactive
             STY   MOCK_6522_ORB1
+            PLY
+            RTS
+
+
+* Write to second AY-3
+* On entry: A - value, X - register
+* On exit: All regs preserved.
+MOCKWRT2    PHY
+            STX   MOCK_6522_ORA2            ; Latch the address
+            LDY   #MOCK_AY_LATCH_ADDR
+            STY   MOCK_6522_ORB2
+
+            LDY   #MOCK_AY_INACTIVE         ; Go inactive
+            STY   MOCK_6522_ORB2
+
+            STA   MOCK_6522_ORA2            ; Write data
+            LDY   #MOCK_AY_WRITE
+            STY   MOCK_6522_ORB2
+
+            LDY   #MOCK_AY_INACTIVE         ; Go inactive
             STY   MOCK_6522_ORB2
             PLY
             RTS
diff --git a/mame_applecorn b/mame_applecorn
index a21de9b..05ac8af 100755
--- a/mame_applecorn
+++ b/mame_applecorn
@@ -1,2 +1,2 @@
-#mame -w apple2ee -debug -sl5 mouse -sl7 cffa2 -harddisk1 ~/Personal/Development/Applecorn/applecorn.po
-mame -w apple2gs -debug -sl7 cffa2 -harddisk1 ~/Personal/Development/Applecorn/applecorn.po -harddisk2 tests/JGHMusic2.po
+mame -w apple2ee -debug -sl5 mouse -sl7 cffa2 -harddisk1 ~/Personal/Development/Applecorn/applecorn.po
+#mame -w apple2gs -debug -sl7 cffa2 -harddisk1 ~/Personal/Development/Applecorn/applecorn.po -harddisk2 tests/JGHMusic2.po