setcolor, getcolor and setcolor_low functions

git-svn-id: svn://svn.cc65.org/cc65/trunk@93 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/atari/setcolor.s

@@ -0,0 +1,51 @@
+;
+; Christian Groessler, June 2000
+;
+; this file provides a setcolor() function similar to BASIC SETCOLOR
+;
+; void __fastcall__ setcolor     (unsigned char color_reg, unsigned char hue, unsigned char luminace);
+; void __fastcall__ setcolor_low (unsigned char color_reg, unsigned char color_value);
+; unsigned char __fastcall__ getcolor (unsigned char color_reg);
+;
+
+
+ 	.export		_setcolor, _setcolor_low, _getcolor
+	.import		popa
+	.include	"atari.inc"
+
+.proc	_getcolor
+
+	tax
+	lda	COLOR0,x	; get current value
+	ldx	#0
+	rts
+
+.endproc
+
+.proc	_setcolor
+
+;	asl	a		; not -> BASIC compatible
+	sta	lum		; remember luminance
+	jsr	popa		; get hue
+	asl	a
+	asl	a
+	asl	a
+	asl	a
+	ora	lum
+;	jmp	_setcolor_low
+
+.endproc
+
+.proc	_setcolor_low
+
+	pha
+	jsr	popa
+	tax
+	pla
+	sta	COLOR0,x
+	rts
+
+.endproc
+
+	.bss
+lum:	.res	1