X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?a=blobdiff_plain;f=xortest.s;h=9a32dc2f29d5392d10b84eecbe68b5bf1f07bcb0;hb=e4183cdb16f93005e6fe930ccd4613bae8a83e3b;hp=b876059c3bffbc4fab1555b514addbd88961535a;hpb=71180a72d4e205696eb3b0f6db03a56c65a845b5;p=a2gs_xortest

diff --git a/xortest.s b/xortest.s
index b876059..9a32dc2 100644
--- a/xortest.s
+++ b/xortest.s
@@ -1,5 +1,7 @@
 	org $800
 
+LARGE = 0
+
 REG_NEWVID = $c029
 FB_BASE	= $e12000
 
@@ -12,15 +14,15 @@ FB_BASE	= $e12000
 	rep #$30	; accum/index 16bit
 	lda #$0000
 	ldx #$0000
-fillrest
+fillrest		; @30f
 	stal $e19d00,x
 	inx
 	inx
-	cpx #$300
+	cpx #$100
 	bne fillrest
 	
 	lda #$0000
-cmap	pha
+cmap	pha		; @31d
 	sta 0
 	asl
 	tax	; offset = i * 2
@@ -38,29 +40,53 @@ cmap	pha
 	bne cmap
 
 YVAL	= 0
-COLIDX	= 1
+TMPVAL	= 1
+YNIB	= 2
 
-	sep #$20	; accum 8bit
-	ldx #0		; fb index
+	sep #$20	; accum 8bit  @337
+	ldx #0000	; fb index
 	stz YVAL
-yloop	lda YVAL
-	and #$f
-	sta COLIDX
+yloop	ldy #0000	; column/2 on Y reg  @33e
+xloop	lda YVAL	; @341
+
+	DO LARGE
+	lsr
+	FIN
+
+	and #$0f
+	sta YNIB
+	tya
+
+	DO LARGE = 0
 	asl
+	inc		; increment X, next pixel on low nibble
+	FIN
+
+	and #$0f
+	sta TMPVAL	; save first pixel X coordinate
+
+	DO LARGE = 0
+	dec		; decrement back for high nibble pixel
+	FIN
+
+	eor YNIB
+	asl		; move next pixel value to high nibble
 	asl
 	asl
 	asl
-	ora COLIDX
-	ldy #160	; 160 bytes across
-xloop	stal FB_BASE,x
+	ora TMPVAL	; first pixel X -> low nibble
+	eor YNIB
+
+	stal FB_BASE, x	; write the pixel pair
 	inx
-	dey
+	iny
+	cpy #160
 	bne xloop
 	inc YVAL
 	lda YVAL
 	cmp #200
 	bne yloop
 
-infloop	bra infloop
+infloop	bra infloop	; @36d
 
 	; vi:ft=asm_ca65