From b9d19b000864ba73962278a30eab4896d0d96562 Mon Sep 17 00:00:00 2001
From: Scott Lahteine <sourcetree@thinkyhead.com>
Date: Thu, 15 Sep 2016 03:40:34 -0500
Subject: [PATCH] Tweak extrapolate_one_point

---
 Marlin/Marlin_main.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index e03c35419d..dcfa84a226 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -2122,9 +2122,9 @@ static void clean_up_after_endstop_or_probe_move() {
 #elif ENABLED(AUTO_BED_LEVELING_NONLINEAR)
 
   /**
-   * All DELTA leveling in the Marlin uses NONLINEAR_BED_LEVELING
+   * Extrapolate a single point from its neighbors
    */
-  static void extrapolate_one_point(uint8_t x, uint8_t y, int xdir, int ydir) {
+  static void extrapolate_one_point(uint8_t x, uint8_t y, int8_t xdir, int8_t ydir) {
     if (bed_level_grid[x][y]) return;  // Don't overwrite good values.
     float a = 2 * bed_level_grid[x + xdir][y] - bed_level_grid[x + xdir * 2][y], // Left to right.
           b = 2 * bed_level_grid[x][y + ydir] - bed_level_grid[x][y + ydir * 2], // Front to back.