Import grbl v1.1h
diff --git a/grbl/motion_control.h b/grbl/motion_control.h
new file mode 100644
index 0000000..0f7531e
--- /dev/null
+++ b/grbl/motion_control.h
@@ -0,0 +1,66 @@
+/*
+ motion_control.h - high level interface for issuing motion commands
+ Part of Grbl
+
+ Copyright (c) 2011-2016 Sungeun K. Jeon for Gnea Research LLC
+ Copyright (c) 2009-2011 Simen Svale Skogsrud
+
+ Grbl is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ Grbl is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with Grbl. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef motion_control_h
+#define motion_control_h
+
+
+// System motion commands must have a line number of zero.
+#define HOMING_CYCLE_LINE_NUMBER 0
+#define PARKING_MOTION_LINE_NUMBER 0
+
+#define HOMING_CYCLE_ALL 0 // Must be zero.
+#define HOMING_CYCLE_X bit(X_AXIS)
+#define HOMING_CYCLE_Y bit(Y_AXIS)
+#define HOMING_CYCLE_Z bit(Z_AXIS)
+
+
+// Execute linear motion in absolute millimeter coordinates. Feed rate given in millimeters/second
+// unless invert_feed_rate is true. Then the feed_rate means that the motion should be completed in
+// (1 minute)/feed_rate time.
+void mc_line(float *target, plan_line_data_t *pl_data);
+
+// Execute an arc in offset mode format. position == current xyz, target == target xyz,
+// offset == offset from current xyz, axis_XXX defines circle plane in tool space, axis_linear is
+// the direction of helical travel, radius == circle radius, is_clockwise_arc boolean. Used
+// for vector transformation direction.
+void mc_arc(float *target, plan_line_data_t *pl_data, float *position, float *offset, float radius,
+ uint8_t axis_0, uint8_t axis_1, uint8_t axis_linear, uint8_t is_clockwise_arc);
+
+// Dwell for a specific number of seconds
+void mc_dwell(float seconds);
+
+// Perform homing cycle to locate machine zero. Requires limit switches.
+void mc_homing_cycle(uint8_t cycle_mask);
+
+// Perform tool length probe cycle. Requires probe switch.
+uint8_t mc_probe_cycle(float *target, plan_line_data_t *pl_data, uint8_t parser_flags);
+
+// Handles updating the override control state.
+void mc_override_ctrl_update(uint8_t override_state);
+
+// Plans and executes the single special motion case for parking. Independent of main planner buffer.
+void mc_parking_motion(float *parking_target, plan_line_data_t *pl_data);
+
+// Performs system reset. If in motion state, kills all motion and sets system alarm.
+void mc_reset();
+
+#endif