idex_modes: Fixed the case when carriages home in the same direction

Previous version of the code assumed that dual carriages home away
from each other, which is not true on some machines, which have the
second dual carriage homing on the first carriage. The new code
correctly identifies the relative order of the carriages now.

Signed-off-by: Dmitry Butyugin <[email protected]>

klippy/kinematics/idex_modes.py

@@ -65,7 +65,13 @@ def toggle_active_dc_rail(self, index, override_rail=False):
         kin.update_limits(self.axis, target_dc.get_rail().get_range())
     def home(self, homing_state):
         kin = self.printer.lookup_object('toolhead').get_kinematics()
-        for i, dc_rail in enumerate(self.dc):
+        enumerated_dcs = list(enumerate(self.dc))
+        if (self.get_dc_order(0, 1) > 0) != \
+                self.dc[0].get_rail().get_homing_info().positive_dir:
+            # The second carriage must home first, because the carriages home in
+            # the same direction and the first carriage homes on the second one
+            enumerated_dcs.reverse()
+        for i, dc_rail in enumerated_dcs:
             self.toggle_active_dc_rail(i, override_rail=True)
             kin.home_axis(homing_state, self.axis, dc_rail.get_rail())
         # Restore the original rails ordering
@@ -88,7 +94,7 @@ def get_kin_range(self, toolhead, mode):
             range_max = min(range_max,
                             axes_pos[0] - axes_pos[1] + dc1_rail.position_max)
         elif mode == MIRROR:
-            if dc0_rail.get_homing_info().positive_dir:
+            if self.get_dc_order(0, 1) > 0:
                 range_min = max(range_min,
                                 0.5 * (sum(axes_pos) + safe_dist))
                 range_max = min(range_max,
@@ -105,11 +111,28 @@ def get_kin_range(self, toolhead, mode):
             if active_idx:
                 range_min = dc1_rail.position_min
                 range_max = dc1_rail.position_max
-            if self.dc[active_idx].get_rail().get_homing_info().positive_dir:
+            if self.get_dc_order(active_idx, inactive_idx) > 0:
                 range_min = max(range_min, axes_pos[inactive_idx] + safe_dist)
             else:
                 range_max = min(range_max, axes_pos[inactive_idx] - safe_dist)
         return (range_min, range_max)
+    def get_dc_order(self, first, second):
+        if first == second:
+            return 0
+        # Check the relative order of the first and second carriages and
+        # return -1 if the first carriage position is always smaller
+        # than the second one and 1 otherwise
+        first_rail = self.dc[first].get_rail()
+        second_rail = self.dc[second].get_rail()
+        first_homing_info = first_rail.get_homing_info()
+        second_homing_info = second_rail.get_homing_info()
+        if first_homing_info.positive_dir != second_homing_info.positive_dir:
+            # Carriages home away from each other
+            return 1 if first_homing_info.positive_dir else -1
+        # Carriages home in the same direction
+        if first_rail.position_endstop > second_rail.position_endstop:
+            return 1
+        return -1
     def activate_dc_mode(self, index, mode):
         toolhead = self.printer.lookup_object('toolhead')
         toolhead.flush_step_generation()