G80: Handle crash detection

At a higher level, crash detection will repeat the last gcode command.

Some commands such as G28 or G80 need to be repeated in full and require
special handling.

In such cases, do not store the saved target coordinate (which is fake
in such cases) and invalidate the saved position.

This fixes the last coordinate of the first G1 move after recovery.

We also avoid moving from the origin when the saved position is
invalidated, which is not strictly necessary, but saves some time.

Firmware/Marlin_main.cpp

@@ -219,7 +219,7 @@ unsigned int heating_status;
 unsigned int heating_status_counter;
 bool loading_flag = false;
 
-
+#define XY_NO_RESTORE_FLAG (mesh_bed_leveling_flag || homing_flag)
 
 char snmm_filaments_used = 0;
 
@@ -305,7 +305,12 @@ bool no_response = false;
 uint8_t important_status;
 uint8_t saved_filament_type;
 
-#define SAVED_TARGET_UNSET (X_MIN_POS-1)
+// Define some coordinates outside the clamp limits (making them invalid past the parsing stage) so
+// that they can be used later for various logical checks
+#define X_COORD_INVALID (X_MIN_POS-1)
+#define Y_COORD_INVALID (Y_MIN_POS-1)
+
+#define SAVED_TARGET_UNSET X_COORD_INVALID
 float saved_target[NUM_AXIS] = {SAVED_TARGET_UNSET, 0, 0, 0};
 
 // save/restore printing in case that mmu was not responding 
@@ -375,7 +380,7 @@ boolean chdkActive = false;
 bool saved_printing = false; //!< Print is paused and saved in RAM
 static uint32_t saved_sdpos = 0; //!< SD card position, or line number in case of USB printing
 uint8_t saved_printing_type = PRINTING_TYPE_SD;
-static float saved_pos[4] = { 0, 0, 0, 0 };
+static float saved_pos[4] = { X_COORD_INVALID, 0, 0, 0 };
 static uint16_t saved_feedrate2 = 0; //!< Default feedrate (truncated from float)
 static int saved_feedmultiply2 = 0;
 static uint8_t saved_active_extruder = 0;
@@ -11460,7 +11465,8 @@ void stop_and_save_print_to_ram(float z_move, float e_move)
 #endif
 
   // save the global state at planning time
-  if (current_block)
+  bool pos_invalid = XY_NO_RESTORE_FLAG;
+  if (current_block && !pos_invalid)
   {
       memcpy(saved_target, current_block->gcode_target, sizeof(saved_target));
       saved_feedrate2 = current_block->gcode_feedrate;
@@ -11472,7 +11478,10 @@ void stop_and_save_print_to_ram(float z_move, float e_move)
   }
 
 	planner_abort_hard(); //abort printing
+
 	memcpy(saved_pos, current_position, sizeof(saved_pos));
+    if (pos_invalid) saved_pos[X_AXIS] = X_COORD_INVALID;
+
     saved_feedmultiply2 = feedmultiply; //save feedmultiply
 	saved_active_extruder = active_extruder; //save active_extruder
 	saved_extruder_temperature = degTargetHotend(active_extruder);
@@ -11566,6 +11575,13 @@ void restore_print_from_ram_and_continue(float e_move)
     fans_check_enabled = false;
   #endif
 
+    // do not restore XY for commands that do not require that
+    if (saved_pos[X_AXIS] == X_COORD_INVALID)
+    {
+        saved_pos[X_AXIS] = current_position[X_AXIS];
+        saved_pos[Y_AXIS] = current_position[Y_AXIS];
+    }
+
 	//first move print head in XY to the saved position:
 	plan_buffer_line(saved_pos[X_AXIS], saved_pos[Y_AXIS], current_position[Z_AXIS], saved_pos[E_AXIS] - e_move, homing_feedrate[Z_AXIS]/13, active_extruder);
 	//then move Z