minor size optimisation

src/libsrc/dgr.pla

@@ -263,53 +263,49 @@ asm _dgrSetPix
 	BCS	+
 end
 asm _dgrSetEvnEvn
+	SEC
+	!byte	$90		; mask CLC
+asm _dgrSetOddEvn
+	CLC
 	; EVEN PIXEL
-	LDA	$2000,X
-	AND	#$0F
+-	JSR	$0100		; LDA AUX (DST),Y
 	STA	TMP
-	JSR	$0100		; LDA AUX (DST),Y
-	AND	#$F0
+	LDA	#$FF
+	ADC	#$00
+	EOR	#$F0			; #$F0 if even, #$0F if odd
+	PHA
+	AND	TMP
+	STA	TMP
+	PLA
+	EOR	#$FF			; #$0F if even, #$F0 if odd
+	AND	$2000,X
 	ORA	TMP
 	STA	$C005		; WRITE AUX MEM
 	STA	(GBASE),Y
 	STA	$C004		; WRITE MAIN MEM
 	RTS
 end
-asm _dgrSetEvnOdd
-	; ODD PIXEL
-+	LDA	$1000,X
-	AND	#$0F
-	STA	TMP
-	LDA	(GBASE),Y
-	AND	#$F0
-	ORA	TMP
-	STA	(GBASE),Y
-	RTS
+
 	; ODD ROW
 ++	LSR
 	TAY
-	BCS	+++
-end
-asm _dgrSetOddEvn
-	; EVEN PIXEL
-	LDA	$2000,X
-	AND	#$F0
-	STA	TMP
-	JSR	$0100		; LDA AUX (DST),Y
-	AND	#$0F
-	ORA	TMP
-	STA	$C005		; WRITE AUX MEM
-	STA	(GBASE),Y
-	STA	$C004		; WRITE MAIN MEM
-	RTS
-end
+	BCC	-
+
 asm _dgrSetOddOdd
+	CLC
+	!byte	$B0		; mask SEC
+asm _dgrSetEvnOdd
+	SEC
 	; ODD PIXEL
-+++	LDA	$1000,X
-	AND	#$F0
++	LDA	#$FF
+	ADC	#$00
+	EOR	#$0F			; #$F0 if odd, #$0F if even
+	PHA
+	AND	$1000,X
 	STA	TMP
-	LDA	(GBASE),Y
-	AND	#$0F
+	PLA
+	EOR	#$FF			; #$0F if odd, #$F0 if even
+	AND	(GBASE),Y
 	ORA	TMP
 	STA	(GBASE),Y
 	RTS