From 7d7dfa87d8fc3499b48906ae457c858983aee864 Mon Sep 17 00:00:00 2001
From: FeralChild64 <you@example.com>
Date: Sun, 30 Aug 2020 23:20:06 +0200
Subject: [PATCH] initial code for clearing screen with DMAgic, does not work
 yet

---
 src/kernal/board_m65/mega65_dmagic.s  |  4 +--
 src/kernal/screen_m65/mega65_clrscr.s | 48 +++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/src/kernal/board_m65/mega65_dmagic.s b/src/kernal/board_m65/mega65_dmagic.s
index 773c0711..76d45d06 100644
--- a/src/kernal/board_m65/mega65_dmagic.s
+++ b/src/kernal/board_m65/mega65_dmagic.s
@@ -25,7 +25,7 @@ m65_dmagic_oper_fill:
 
 	// Set operation type
 
-	lda #$03                           // operation: FILL
+	lda #($03 + $08)                   // operation: FILL + allow interrupts
 	sta M65_DMAGIC_LIST+6
 
 	// Go to common part
@@ -42,7 +42,7 @@ m65_dmagic_oper_copy:
 
 	// Set operation type
 
-	lda #$00                           // operation: COPY
+	lda #($00 + $08)                   // operation: COPY + allow interrupts
 	sta M65_DMAGIC_LIST+6
 
 	// Adapt the source addresses, go to common part
diff --git a/src/kernal/screen_m65/mega65_clrscr.s b/src/kernal/screen_m65/mega65_clrscr.s
index f297c469..bb43dfcb 100644
--- a/src/kernal/screen_m65/mega65_clrscr.s
+++ b/src/kernal/screen_m65/mega65_clrscr.s
@@ -1,6 +1,7 @@
 // #LAYOUT# M65 KERNAL_1 #TAKE
 // #LAYOUT# *   *        #IGNORE
 
+// #define DMAGIC_CLRSCR
 
 
 M65_CLRSCR:
@@ -30,6 +31,51 @@ m65_clrscr_takeover: // .A has to be 0
 	sta M65_TXTROW_OFF+0
 	sta M65_TXTROW_OFF+1
 
+#if DMAGIC_CLRSCR
+
+	// XXX for some reason this does not work - find out, why
+
+	// Clear the whole screen + colour memory
+
+	// Screen size
+	sec
+	lda M65_COLGUARD+0
+	sbc #$01
+	sta M65_DMAJOB_SIZE_0
+	lda M65_COLGUARD+1
+	sbc #$00
+	sta M65_DMAJOB_SIZE_1
+
+	// Screen start address
+	lda M65_SCRBASE+0
+	sta M65_DMAJOB_DST_0
+	lda M65_SCRBASE+1
+	sta M65_DMAJOB_DST_1
+	lda M65_SCRSEG+0
+	sta M65_DMAJOB_DST_2
+	lda M65_SCRSEG+1
+	sta M65_DMAJOB_DST_3
+
+	// Fill with spaces
+	lda #$20
+	jsr m65_dmagic_oper_fill
+
+	// Colour RAM start address
+	lda #$00
+	sta M65_DMAJOB_DST_0
+	sta M65_DMAJOB_DST_1
+	lda #$F8
+	sta M65_DMAJOB_DST_2
+	lda #$0F
+	sta M65_DMAJOB_DST_3
+
+	// Fill with colour, without attributes
+	lda COLOR
+	and #$0F
+	jsr m65_dmagic_oper_fill
+
+#else
+
 	// Clear the whole screen+color memory
 	// XXX consider using DMAgic for this - FILL command
 
@@ -92,6 +138,8 @@ m65_clrscr_loop_done:
 
 	plz
 
+#endif // no DMAGIC_CLRSCR
+
 	// Set screen+color base address in VIC IV
 	// XXX deduplicate with mode setting routine