Add basic support for ORIC Atmos

git-svn-id: svn://svn.cc65.org/cc65/trunk@2046 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/atmos/chline.s

@@ -0,0 +1,41 @@
+;
+; Ullrich von Bassewitz, 08.08.1998
+;
+; void chlinexy (unsigned char x, unsigned char y, unsigned char length);
+; void chline (unsigned char length);
+;
+
+    	.export		_chlinexy, _chline
+        .import         setscrptr
+        .import         rvs
+	.import		popax
+        .importzp       ptr2
+
+        .include        "atmos.inc"
+
+
+_chlinexy:
+       	pha	    	     	; Save the length
+	jsr	popax	     	; Get X and Y
+        sta     CURS_Y          ; Store Y
+        stx     CURS_X          ; Store X
+       	pla		     	; Restore the length and run into _chline
+
+_chline:
+       	tax                     ; Is the length zero?
+       	beq	@L9  	     	; Jump if done
+        jsr     setscrptr       ; Set ptr2 to screen, won't use X
+        txa                     ; Length into A
+        clc
+        adc     CURS_X
+        sta     CURS_X          ; Correct X position by length
+        lda     #'-'            ; Horizontal line screen code
+        ora     rvs
+@L1:    sta     (ptr2),y        ; Write one char
+        iny                     ; Next char
+        bne     @L2
+        inc     ptr2+1          ; Bump high byte of screen pointer
+@L2:    dex
+        bne     @L1
+@L9:	rts
+