From 60117f47bd1a93ed87a7b2b7f2da240612d4b5f9 Mon Sep 17 00:00:00 2001
From: Peter Ferrie <peter.ferrie@gmail.com>
Date: Wed, 12 Jul 2017 15:26:19 -0700
Subject: [PATCH] write-combine without intermediate var

---
 src/libsrc/dgr.pla | 38 ++++++++++++++------------------------
 1 file changed, 14 insertions(+), 24 deletions(-)

diff --git a/src/libsrc/dgr.pla b/src/libsrc/dgr.pla
index 198b58e..142be5a 100755
--- a/src/libsrc/dgr.pla
+++ b/src/libsrc/dgr.pla
@@ -206,9 +206,8 @@ export asm dgrBLT(buff, x, y, width, height, src)
 	CLC
 	ADC	ESTKL+2,X	; WIDTH
 	STA	SRCL
-	LDA	SRCH
-	ADC	#$00
-	STA	SRCH
+	BCC	+++
+	INC	SRCH
 	BNE	+++
 +	AND	#$FE
 	TAY
@@ -268,12 +267,10 @@ asm _dgrSetPix
 end
 asm _dgrSetEvnEvn
 	; EVEN PIXEL
-	LDA	$2000,X
-	AND	#$0F
-	STA	TMP
 	JSR	$0100		; LDA AUX (DST),Y
+	EOR	$2000,X
 	AND	#$F0
-	ORA	TMP
+	EOR	$2000,X
 	STA	$C005		; WRITE AUX MEM
 	STA	(GBASE),Y
 	STA	$C004		; WRITE MAIN MEM
@@ -281,12 +278,10 @@ asm _dgrSetEvnEvn
 end
 asm _dgrSetEvnOdd
 	; ODD PIXEL
-+	LDA	$1000,X
-	AND	#$0F
-	STA	TMP
-	LDA	(GBASE),Y
++	LDA	(GBASE),Y
+	EOR	$1000,X
 	AND	#$F0
-	ORA	TMP
+	EOR	$1000,X
 	STA	(GBASE),Y
 	RTS
 	; ODD ROW
@@ -296,12 +291,10 @@ asm _dgrSetEvnOdd
 end
 asm _dgrSetOddEvn
 	; EVEN PIXEL
-	LDA	$2000,X
-	AND	#$F0
-	STA	TMP
 	JSR	$0100		; LDA AUX (DST),Y
+	EOR	$2000,X
 	AND	#$0F
-	ORA	TMP
+	EOR	$2000,X
 	STA	$C005		; WRITE AUX MEM
 	STA	(GBASE),Y
 	STA	$C004		; WRITE MAIN MEM
@@ -309,12 +302,10 @@ asm _dgrSetOddEvn
 end
 asm _dgrSetOddOdd
 	; ODD PIXEL
-+++	LDA	$1000,X
-	AND	#$F0
-	STA	TMP
-	LDA	(GBASE),Y
++++	LDA	(GBASE),Y
+	EOR	$1000,X
 	AND	#$0F
-	ORA	TMP
+	EOR	$1000,X
 	STA	(GBASE),Y
 	RTS
 end
@@ -358,9 +349,8 @@ export asm dgrTile(buff, x, y, src)
 	LDA	SRCL		; SKIP TO NEXT ROW
 	ADC	#$07		; CARRY = 1
 	STA	SRCL
-	LDA	SRCH
-	ADC	#$00
-	STA	SRCH
+	BCC	+++
+	INC	SRCH
 	BNE	+++
 +	AND	#$FE
 	TAY