prepared QTSW flag for proper screen code -> PETSCII conversion

c64/kernal/screen/chrout_screen.s

@@ -86,13 +86,8 @@ chrout_screen_literal:
 	// Toggle quote flag if required
 
 	txa
-	cmp #$22
-	bne !+
+	jsr screen_check_toggle_quote
 
-	lda QTSW
-	eor #$80
-	sta QTSW
-!:
 	// Set colour of the newly printed character
 
 	lda COLOR

c64/kernal/screen/screen_check_toggle_quote.s

@@ -0,0 +1,21 @@
+// #LAYOUT# STD *        #TAKE
+// #LAYOUT# X16 *        #IGNORE
+// #LAYOUT# *   KERNAL_0 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+//
+// Helper routine - check character in .A, toggles quote flag if needed
+//
+
+screen_check_toggle_quote:
+
+	cmp #$22
+	bne !+
+
+	lda QTSW
+	eor #$80
+	sta QTSW
+
+	lda #$22                           // restore previous .A valuee
+!:
+	rts

c64/kernal/screen/screen_code_to_petscii.s

@@ -4,6 +4,9 @@
 // #LAYOUT# *   *        #IGNORE
 
 
+// XXX - conversion should depend on QTSW too
+
+
 screen_code_to_petscii:
 	cmp #$1B
 	bcc s2p_adc_40