From 6c22417d4a05b662ab10f848202916df2501b1f8 Mon Sep 17 00:00:00 2001
From: Martin Haye <martin.haye@ucop.edu>
Date: Thu, 13 Jun 2019 08:50:38 -0700
Subject: [PATCH] More reliable checks for the destruction of 3D rasterizer's
 line table on aux zp.

---
 Platform/Apple/virtual/src/core/mem.s       |  2 ++
 Platform/Apple/virtual/src/include/mem.i    |  1 +
 Platform/Apple/virtual/src/marks/marks.s    |  2 ++
 Platform/Apple/virtual/src/raycast/render.s | 14 ++++++++++++--
 4 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/Platform/Apple/virtual/src/core/mem.s b/Platform/Apple/virtual/src/core/mem.s
index fcee6ce2..214eb6b4 100644
--- a/Platform/Apple/virtual/src/core/mem.s
+++ b/Platform/Apple/virtual/src/core/mem.s
@@ -325,6 +325,7 @@ loMemBegin: !pseudopc $800 {
 	jmp __internalErr
 _fixedRTS:
 	rts			; fixed place to find RTS, for setting V flag
+_diskOpCt !byte 0		; count of disk ops since last render
 
 __aux_dispatch:
 	sec
@@ -411,6 +412,7 @@ _jbrk	jmp $1111		; self-modified by init
 ; Clear carry to call opendir, set carry to call rdwrpart
 ; On return, A contains status (for opendir only)
 callProRWTS:
+	inc _diskOpCt
 	; Copy the parameters to aux zero page
 	ldx #$F
 -	sta clrAuxZP
diff --git a/Platform/Apple/virtual/src/include/mem.i b/Platform/Apple/virtual/src/include/mem.i
index b3c5bda7..6750bd7b 100644
--- a/Platform/Apple/virtual/src/include/mem.i
+++ b/Platform/Apple/virtual/src/include/mem.i
@@ -513,6 +513,7 @@ _crout      = _prY+3
 _waitKey    = _crout+3
 _internalErr = _waitKey+3
 fixedRTS    = _internalErr+3
+diskOpCt    = fixedRTS+1
 
 ; Debug macros
 !macro safeBell {
diff --git a/Platform/Apple/virtual/src/marks/marks.s b/Platform/Apple/virtual/src/marks/marks.s
index a26d3ced..67d19af3 100644
--- a/Platform/Apple/virtual/src/marks/marks.s
+++ b/Platform/Apple/virtual/src/marks/marks.s
@@ -14,6 +14,7 @@
 !convtab "../include/hiBitAscii.ct"
 
 ; Other equates
+!source "../include/mem.i"
 !source "../include/prorwts.i"
 
 target  = $3	; len 1
@@ -256,6 +257,7 @@ _writeMarks: !zone
 	sec
 	; fall through to final ProRWTS command
 callProRWTS:
+	inc diskOpCt
 	stx sizelo
 	sty sizehi
 	sta reqcmd
diff --git a/Platform/Apple/virtual/src/raycast/render.s b/Platform/Apple/virtual/src/raycast/render.s
index 6f6986f7..f160dbcb 100644
--- a/Platform/Apple/virtual/src/raycast/render.s
+++ b/Platform/Apple/virtual/src/raycast/render.s
@@ -1959,9 +1959,19 @@ pl_render: !zone
 	bne +
 	lda $2001
 	cmp $4001
+	bne +
+	lda $2C00
+	cmp $4C00
+	bne +
+	lda $2C01
+	cmp $4C01
+	bne +
+	lda diskOpCt		; check if any disk ops (ProRWTS can use aux zp)
 	beq ++
-+	jsr copyScreen		; if it was, restore by copying hgr1 to hgr2
-	jsr makeLines
++	jsr copyScreen		; restore by copying hgr1 to hgr2
+	jsr makeLines		; and regenerate line pointers on aux zp
+	lda #0
+	sta diskOpCt
 ++	jmp renderFrame		; then go ahead and render
 
 ;-------------------------------------------------------------------------------