Adding CBM510 support

git-svn-id: svn://svn.cc65.org/cc65/trunk@913 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/cbm510/cgetc.s

@@ -0,0 +1,38 @@
+;
+; Ullrich von Bassewitz, 06.08.1998
+;
+; char cgetc (void);
+;
+
+	.export	   	_cgetc
+	.import	   	plot, write_crtc
+	.import	   	cursor
+
+	.include   	"zeropage.inc"
+	.include	"page3.inc"
+
+
+; ------------------------------------------------------------------------
+
+.proc	_cgetc
+
+L1:    	lda	KeyIndex
+       	beq	L1
+
+L2:    	ldx    	#$00		; Get index
+       	ldy	KeyBuf		; Get first character in the buffer
+       	sei
+L3:    	lda	KeyBuf+1,x	; Move up the remaining chars
+       	sta	KeyBuf,x
+       	inx
+       	cpx	KeyIndex
+       	bne	L3
+       	dec	KeyIndex
+       	cli
+
+       	ldx	#$00		; High byte
+       	tya			; First char from buffer
+       	rts
+
+.endproc
+