small screen code size optimization

c64/kernal/screen/chrout_screen_tab.s

@@ -26,7 +26,6 @@ chrout_screen_TAB_FW:
 chrout_screen_TAB_BW:
 
 	jsr screen_get_clipped_PNTR
-	cpy #$00                           // YYY maybe it's worth to put this inside screen_get_clipped_PNTR?
 	beq !+                             // column 0,  recalculating pointers is not necessary, but this is a rare case nevertheless
 
 	dey

c64/kernal/screen/screen_get_cliped_pntr.s

@@ -1,6 +1,6 @@
 
 //
-// Get PNTR value clipped to 0-39 range in .Y, can trash .A
+// Get PNTR value clipped to 0-39 range in .Y, sets flags to compare with 0, can trash .A
 //
 
 screen_get_clipped_PNTR:
@@ -12,4 +12,5 @@ screen_get_clipped_PNTR:
 	sbc #40
 	tay
 !:
+	cpy #$00
 	rts