work on character inserting

c64/kernal/screen/screen_get_logical_line_end_ptr.s

@@ -0,0 +1,26 @@
+
+
+screen_get_logical_line_end_ptr:
+
+	ldy TBLX
+	cpy #24
+	bcs screen_get_logical_line_end_39 // last line of the screen
+	
+	lda LDTBL, y
+	bpl screen_get_logical_line_end_39 // current line continues previous one
+	
+	iny
+	lda LDTBL, y
+	bmi screen_get_logical_line_end_39 // current line is not continued
+	
+	// FALLTROUGH
+	
+screen_get_logical_line_end_79:
+
+	ldy #79
+	rts
+	
+screen_get_logical_line_end_39:
+
+	ldy #39
+	rts