further line grow fixes

c64/kernal/screen/chrout_screen_ins.s

@@ -5,7 +5,6 @@
 
 
 // YYY does not work properly on growing logical line
-// YYY implement LNMX
 
 
 chrout_screen_INS:

c64/kernal/screen/screen_grow_logical_line.s

@@ -4,6 +4,9 @@
 screen_grow_logical_line_screen_up:
 
 	jsr screen_scroll_up
+	ldy TBLX
+	lda #$00
+	sta LDTBL+1, y                      // mark the next line as continuation
 
 	// FALLTROUGH
 
@@ -17,7 +20,7 @@ screen_grow_logical_line:
 
 	// Do not grow line if previus one is grown
 	ldy TBLX
-	lda LDTBL,y
+	lda LDTBL+0, y
 	bpl screen_grow_logical_line_done
 
 	// If last line, scroll the screen up
@@ -25,22 +28,35 @@ screen_grow_logical_line:
 	beq screen_grow_logical_line_screen_up
 
 	// Do not grow line if already grown
-	iny
+	lda LDTBL+1, y
-	lda LDTBL,y
 	bpl screen_grow_logical_line_done
 	
-	// Mark current line as grown
-	lda #$00
-	sta LDTBL,y
-
-	// Now we have to scroll lines downwards to make space. We start from the end,
-	// and work backwards. We cannot be as simple and efficient here as we are
-	// for scrolling up, because we do not know how much must be scrolled.
-
 	// Preserve SAL and EAL
 
 	jsr screen_preserve_sal_eal
 
+	// Scroll LDTBL down (start from the end)
+	ldy #23
+!:
+	cpy TBLX
+	beq !+
+	bcc !+
+
+	lda LDTBL+0, y
+	sta LDTBL+1, y
+
+	dey
+	bne !-
+!:
+	// Mark current line as grown
+	ldy TBLX
+	lda #$00
+	sta LDTBL+1, y
+
+	// Now we have to scroll lines downwards to make space. We start from the end,
+	// and work backwards. We cannot be as simple and efficient here as we are
+	// for scrolling up, because we do not know how much must be scrolled.
+
 	// Work out how many physical lines to scroll down
 
 	lda #23
@@ -71,7 +87,6 @@ screen_grow_logical_line:
 screen_grow_logical_line_loop:
 
 	// Scroll down one line each loop iteration
-	// YYY add LDTBL scrolling
 
 	ldy #39
 !: