# HG changeset patch
# User Michael Pavone <pavone@retrodev.com>
# Date 1472616067 25200
# Node ID 506b531cf570efee22ec5fcf92d15acb0820b4e4
# Parent  51672bd41cdd914b3a4f22443095829cec3895e1
Added checkerboard sample

diff -r 51672bd41cdd -r 506b531cf570 checker.s16
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/checker.s16	Tue Aug 30 21:01:07 2016 -0700
@@ -0,0 +1,87 @@
+
+	;set both data banks to VRAM
+	ldim $E1, db
+	ldimh $E0, db
+	
+	;setup palette
+	ldim 2, r0
+	outi $E, r0
+	ldim 0, r0
+	outi $E, r0
+	ldimh $F, r0
+	outi $E, r0
+	
+	;pointer to VRAM
+	ldim 0, r0
+	
+	;black
+	ldim 0, r1
+	
+	;4 pixels of red
+	ldim $11, r2
+	ldimh $11, r2
+	
+	;outer loop counter
+	ldim 8, r4
+
+	;framebuffer offset
+	ldim 0, r5
+outer:
+	;loop counter to do one row of pattern
+	ldim $A0, r3
+	ldimh 0, r3
+	
+blackred:
+	str16 r0, r5, r1
+	addi 2, r5
+	str16 r0, r5, r1
+	addi 2, r5
+	str16 r0, r5, r1
+	addi 2, r5
+	str16 r0, r5, r1
+	addi 2, r5
+	str16 r0, r5, r2
+	addi 2, r5
+	str16 r0, r5, r2
+	addi 2, r5
+	str16 r0, r5, r2
+	addi 2, r5
+	str16 r0, r5, r2
+	addi 2, r5
+	
+	addi -1, r3
+	bne blackred
+	
+	
+	ldim $A0, r3
+	ldimh 0, r3
+redblack:
+	str16 r0, r5, r2
+	addi 2, r5
+	str16 r0, r5, r2
+	addi 2, r5
+	str16 r0, r5, r2
+	addi 2, r5
+	str16 r0, r5, r2
+	addi 2, r5
+	str16 r0, r5, r1
+	addi 2, r5
+	str16 r0, r5, r1
+	addi 2, r5
+	str16 r0, r5, r1
+	addi 2, r5
+	str16 r0, r5, r1
+	addi 2, r5
+	
+	addi -1, r3
+	bne redblack
+	
+	addi -1, r4
+	bne outer
+	
+	ldim 1, r4
+	ldimh $80, r4
+	outi $D, r4
+	
+forever:
+	bra forever
\ No newline at end of file