idex_modes: COPY and MIRROR mode implementation (#6297)

COPY and MIRROR mode implementation

Correctly apply input shaper params to new dual_carriage

Added SAVE_/RESTORE_IDEX_STATE commands

Documentation updates for the new IDEX modes

Signed-off-by: Dmitry Butyugin <dmbutyugin@google.com>

4 files changed, 237 insertions, 179 deletions

diff --git a/klippy/kinematics/cartesian.py b/klippy/kinematics/cartesian.py
index 0cd7849a..59604197 100644
--- a/klippy/kinematics/cartesian.py
+++ b/klippy/kinematics/cartesian.py
@@ -5,6 +5,7 @@
 # This file may be distributed under the terms of the GNU GPLv3 license.
 import logging
 import stepper
+from . import idex_modes
 
 class CartKinematics:
     def __init__(self, toolhead, config):
@@ -16,6 +17,25 @@ class CartKinematics:
                       for n in 'xyz']
         for rail, axis in zip(self.rails, 'xyz'):
             rail.setup_itersolve('cartesian_stepper_alloc', axis.encode())
+        ranges = [r.get_range() for r in self.rails]
+        self.axes_min = toolhead.Coord(*[r[0] for r in ranges], e=0.)
+        self.axes_max = toolhead.Coord(*[r[1] for r in ranges], e=0.)
+        self.dc_module = None
+        if config.has_section('dual_carriage'):
+            dc_config = config.getsection('dual_carriage')
+            dc_axis = dc_config.getchoice('axis', {'x': 'x', 'y': 'y'})
+            self.dual_carriage_axis = {'x': 0, 'y': 1}[dc_axis]
+            # setup second dual carriage rail
+            self.rails.append(stepper.LookupMultiRail(dc_config))
+            self.rails[3].setup_itersolve('cartesian_stepper_alloc',
+                                          dc_axis.encode())
+            dc_rail_0 = idex_modes.DualCarriagesRail(
+                    self.rails[0], axis=self.dual_carriage_axis, active=True)
+            dc_rail_1 = idex_modes.DualCarriagesRail(
+                    self.rails[3], axis=self.dual_carriage_axis, active=False)
+            self.dc_module = idex_modes.DualCarriages(
+                    dc_config, dc_rail_0, dc_rail_1,
+                    axis=self.dual_carriage_axis)
         for s in self.get_steppers():
             s.set_trapq(toolhead.get_trapq())
             toolhead.register_step_generator(s.generate_steps)
@@ -28,31 +48,18 @@ class CartKinematics:
         self.max_z_accel = config.getfloat('max_z_accel', max_accel,
                                            above=0., maxval=max_accel)
         self.limits = [(1.0, -1.0)] * 3
-        ranges = [r.get_range() for r in self.rails]
-        self.axes_min = toolhead.Coord(*[r[0] for r in ranges], e=0.)
-        self.axes_max = toolhead.Coord(*[r[1] for r in ranges], e=0.)
-        # Check for dual carriage support
-        if config.has_section('dual_carriage'):
-            dc_config = config.getsection('dual_carriage')
-            dc_axis = dc_config.getchoice('axis', {'x': 'x', 'y': 'y'})
-            self.dual_carriage_axis = {'x': 0, 'y': 1}[dc_axis]
-            dc_rail = stepper.LookupMultiRail(dc_config)
-            dc_rail.setup_itersolve('cartesian_stepper_alloc', dc_axis.encode())
-            for s in dc_rail.get_steppers():
-                toolhead.register_step_generator(s.generate_steps)
-            self.dual_carriage_rails = [
-                self.rails[self.dual_carriage_axis], dc_rail]
-            self.printer.lookup_object('gcode').register_command(
-                'SET_DUAL_CARRIAGE', self.cmd_SET_DUAL_CARRIAGE,
-                desc=self.cmd_SET_DUAL_CARRIAGE_help)
     def get_steppers(self):
-        rails = self.rails
-        if self.dual_carriage_axis is not None:
-            dca = self.dual_carriage_axis
-            rails = rails[:dca] + self.dual_carriage_rails + rails[dca+1:]
-        return [s for rail in rails for s in rail.get_steppers()]
+        return [s for rail in self.rails for s in rail.get_steppers()]
     def calc_position(self, stepper_positions):
         return [stepper_positions[rail.get_name()] for rail in self.rails]
+    def update_limits(self, i, range):
+        l, h = self.limits[i]
+        # Only update limits if this axis was already homed,
+        # otherwise leave in un-homed state.
+        if l <= h:
+            self.limits[i] = range
+    def override_rail(self, i, rail):
+        self.rails[i] = rail
     def set_position(self, newpos, homing_axes):
         for i, rail in enumerate(self.rails):
             rail.set_position(newpos)
@@ -61,7 +68,7 @@ class CartKinematics:
     def note_z_not_homed(self):
         # Helper for Safe Z Home
         self.limits[2] = (1.0, -1.0)
-    def _home_axis(self, homing_state, axis, rail):
+    def home_axis(self, homing_state, axis, rail):
         # Determine movement
         position_min, position_max = rail.get_range()
         hi = rail.get_homing_info()
@@ -77,16 +84,10 @@ class CartKinematics:
     def home(self, homing_state):
         # Each axis is homed independently and in order
         for axis in homing_state.get_axes():
-            if axis == self.dual_carriage_axis:
-                dc1, dc2 = self.dual_carriage_rails
-                altc = self.rails[axis] == dc2
-                self._activate_carriage(0)
-                self._home_axis(homing_state, axis, dc1)
-                self._activate_carriage(1)
-                self._home_axis(homing_state, axis, dc2)
-                self._activate_carriage(altc)
+            if self.dc_module is not None and axis == self.dual_carriage_axis:
+                self.dc_module.home(homing_state)
             else:
-                self._home_axis(homing_state, axis, self.rails[axis])
+                self.home_axis(homing_state, axis, self.rails[axis])
     def _motor_off(self, print_time):
         self.limits = [(1.0, -1.0)] * 3
     def _check_endstops(self, move):
@@ -119,24 +120,6 @@ class CartKinematics:
             'axis_minimum': self.axes_min,
             'axis_maximum': self.axes_max,
         }
-    # Dual carriage support
-    def _activate_carriage(self, carriage):
-        toolhead = self.printer.lookup_object('toolhead')
-        toolhead.flush_step_generation()
-        dc_rail = self.dual_carriage_rails[carriage]
-        dc_axis = self.dual_carriage_axis
-        self.rails[dc_axis].set_trapq(None)
-        dc_rail.set_trapq(toolhead.get_trapq())
-        self.rails[dc_axis] = dc_rail
-        pos = toolhead.get_position()
-        pos[dc_axis] = dc_rail.get_commanded_position()
-        toolhead.set_position(pos)
-        if self.limits[dc_axis][0] <= self.limits[dc_axis][1]:
-            self.limits[dc_axis] = dc_rail.get_range()
-    cmd_SET_DUAL_CARRIAGE_help = "Set which carriage is active"
-    def cmd_SET_DUAL_CARRIAGE(self, gcmd):
-        carriage = gcmd.get_int('CARRIAGE', minval=0, maxval=1)
-        self._activate_carriage(carriage)
 
 def load_kinematics(toolhead, config):
     return CartKinematics(toolhead, config)
diff --git a/klippy/kinematics/hybrid_corexy.py b/klippy/kinematics/hybrid_corexy.py
index 62dccc26..26032039 100644
--- a/klippy/kinematics/hybrid_corexy.py
+++ b/klippy/kinematics/hybrid_corexy.py
@@ -33,17 +33,13 @@ class HybridCoreXYKinematics:
             self.rails.append(stepper.PrinterRail(dc_config))
             self.rails[1].get_endstops()[0][0].add_stepper(
                 self.rails[3].get_steppers()[0])
-            self.rails[3].setup_itersolve('cartesian_stepper_alloc', b'y')
+            self.rails[3].setup_itersolve('corexy_stepper_alloc', b'+')
             dc_rail_0 = idex_modes.DualCarriagesRail(
-                self.printer, self.rails[0], axis=0, active=True,
-                stepper_alloc_active=('corexy_stepper_alloc', b'-'),
-                stepper_alloc_inactive=('cartesian_reverse_stepper_alloc',b'y'))
+                    self.rails[0], axis=0, active=True)
             dc_rail_1 = idex_modes.DualCarriagesRail(
-                self.printer, self.rails[3], axis=0, active=False,
-                stepper_alloc_active=('corexy_stepper_alloc', b'+'),
-                stepper_alloc_inactive=('cartesian_stepper_alloc', b'y'))
-            self.dc_module = idex_modes.DualCarriages(self.printer,
-                        dc_rail_0, dc_rail_1, axis=0)
+                    self.rails[3], axis=0, active=False)
+            self.dc_module = idex_modes.DualCarriages(
+                    dc_config, dc_rail_0, dc_rail_1, axis=0)
         for s in self.get_steppers():
             s.set_trapq(toolhead.get_trapq())
             toolhead.register_step_generator(s.generate_steps)
@@ -60,8 +56,8 @@ class HybridCoreXYKinematics:
         return [s for rail in self.rails for s in rail.get_steppers()]
     def calc_position(self, stepper_positions):
         pos = [stepper_positions[rail.get_name()] for rail in self.rails]
-        if (self.dc_module is not None and 'CARRIAGE_1' == \
-                    self.dc_module.get_status()['active_carriage']):
+        if (self.dc_module is not None and 'PRIMARY' == \
+                    self.dc_module.get_status()['carriage_1']):
             return [pos[0] - pos[1], pos[1], pos[2]]
         else:
             return [pos[0] + pos[1], pos[1], pos[2]]
@@ -81,7 +77,7 @@ class HybridCoreXYKinematics:
     def note_z_not_homed(self):
         # Helper for Safe Z Home
         self.limits[2] = (1.0, -1.0)
-    def _home_axis(self, homing_state, axis, rail):
+    def home_axis(self, homing_state, axis, rail):
         position_min, position_max = rail.get_range()
         hi = rail.get_homing_info()
         homepos = [None, None, None, None]
@@ -95,14 +91,10 @@ class HybridCoreXYKinematics:
         homing_state.home_rails([rail], forcepos, homepos)
     def home(self, homing_state):
         for axis in homing_state.get_axes():
-            if (self.dc_module is not None and axis == 0):
-                self.dc_module.save_idex_state()
-                for i in [0,1]:
-                    self.dc_module.toggle_active_dc_rail(i)
-                    self._home_axis(homing_state, axis, self.rails[0])
-                self.dc_module.restore_idex_state()
+            if self.dc_module is not None and axis == 0:
+                self.dc_module.home(homing_state)
             else:
-                self._home_axis(homing_state, axis, self.rails[axis])
+                self.home_axis(homing_state, axis, self.rails[axis])
     def _motor_off(self, print_time):
         self.limits = [(1.0, -1.0)] * 3
     def _check_endstops(self, move):
diff --git a/klippy/kinematics/hybrid_corexz.py b/klippy/kinematics/hybrid_corexz.py
index a92a2194..e13c9aa4 100644
--- a/klippy/kinematics/hybrid_corexz.py
+++ b/klippy/kinematics/hybrid_corexz.py
@@ -33,17 +33,13 @@ class HybridCoreXZKinematics:
             self.rails.append(stepper.PrinterRail(dc_config))
             self.rails[2].get_endstops()[0][0].add_stepper(
                 self.rails[3].get_steppers()[0])
-            self.rails[3].setup_itersolve('cartesian_stepper_alloc', b'z')
+            self.rails[3].setup_itersolve('corexz_stepper_alloc', b'+')
             dc_rail_0 = idex_modes.DualCarriagesRail(
-                self.printer, self.rails[0], axis=0, active=True,
-                stepper_alloc_active=('corexz_stepper_alloc', b'-'),
-                stepper_alloc_inactive=('cartesian_reverse_stepper_alloc',b'z'))
+                self.rails[0], axis=0, active=True)
             dc_rail_1 = idex_modes.DualCarriagesRail(
-                self.printer, self.rails[3], axis=0, active=False,
-                stepper_alloc_active=('corexz_stepper_alloc', b'+'),
-                stepper_alloc_inactive=('cartesian_stepper_alloc', b'z'))
-            self.dc_module = idex_modes.DualCarriages(self.printer,
-                        dc_rail_0, dc_rail_1, axis=0)
+                self.rails[3], axis=0, active=False)
+            self.dc_module = idex_modes.DualCarriages(
+                    dc_config, dc_rail_0, dc_rail_1, axis=0)
         for s in self.get_steppers():
             s.set_trapq(toolhead.get_trapq())
             toolhead.register_step_generator(s.generate_steps)
@@ -60,8 +56,8 @@ class HybridCoreXZKinematics:
         return [s for rail in self.rails for s in rail.get_steppers()]
     def calc_position(self, stepper_positions):
         pos = [stepper_positions[rail.get_name()] for rail in self.rails]
-        if (self.dc_module is not None and 'CARRIAGE_1' == \
-                    self.dc_module.get_status()['active_carriage']):
+        if (self.dc_module is not None and 'PRIMARY' == \
+                    self.dc_module.get_status()['carriage_1']):
             return [pos[0] - pos[2], pos[1], pos[2]]
         else:
             return [pos[0] + pos[2], pos[1], pos[2]]
@@ -81,7 +77,7 @@ class HybridCoreXZKinematics:
     def note_z_not_homed(self):
         # Helper for Safe Z Home
         self.limits[2] = (1.0, -1.0)
-    def _home_axis(self, homing_state, axis, rail):
+    def home_axis(self, homing_state, axis, rail):
         position_min, position_max = rail.get_range()
         hi = rail.get_homing_info()
         homepos = [None, None, None, None]
@@ -95,14 +91,10 @@ class HybridCoreXZKinematics:
         homing_state.home_rails([rail], forcepos, homepos)
     def home(self, homing_state):
         for axis in homing_state.get_axes():
-            if (self.dc_module is not None and axis == 0):
-                self.dc_module.save_idex_state()
-                for i in [0,1]:
-                    self.dc_module.toggle_active_dc_rail(i)
-                    self._home_axis(homing_state, axis, self.rails[0])
-                self.dc_module.restore_idex_state()
+            if self.dc_module is not None and axis == 0:
+                self.dc_module.home(homing_state)
             else:
-                self._home_axis(homing_state, axis, self.rails[axis])
+                self.home_axis(homing_state, axis, self.rails[axis])
     def _motor_off(self, print_time):
         self.limits = [(1.0, -1.0)] * 3
     def _check_endstops(self, move):
diff --git a/klippy/kinematics/idex_modes.py b/klippy/kinematics/idex_modes.py
index 73fac776..ec8944bb 100644
--- a/klippy/kinematics/idex_modes.py
+++ b/klippy/kinematics/idex_modes.py
@@ -1,23 +1,48 @@
 # Support for duplication and mirroring modes for IDEX printers
 #
 # Copyright (C) 2021  Fabrice Gallet <tircown@gmail.com>
+# Copyright (C) 2023  Dmitry Butyugin <dmbutyugin@google.com>
 #
 # This file may be distributed under the terms of the GNU GPLv3 license.
 import math
 import chelper
 
+INACTIVE = 'INACTIVE'
+PRIMARY = 'PRIMARY'
+COPY = 'COPY'
+MIRROR = 'MIRROR'
+
 class DualCarriages:
-    def __init__(self, printer, rail_0, rail_1, axis):
-        self.printer = printer
+    VALID_MODES = [PRIMARY, COPY, MIRROR]
+    def __init__(self, dc_config, rail_0, rail_1, axis):
+        self.printer = dc_config.get_printer()
         self.axis = axis
         self.dc = (rail_0, rail_1)
-        self.saved_state = None
+        self.saved_states = {}
+        safe_dist = dc_config.getfloat('safe_distance', None, minval=0.)
+        if safe_dist is None:
+            dc0_rail = rail_0.get_rail()
+            dc1_rail = rail_1.get_rail()
+            safe_dist = min(abs(dc0_rail.position_min - dc1_rail.position_min),
+                            abs(dc0_rail.position_max - dc1_rail.position_max))
+        self.safe_dist = safe_dist
         self.printer.add_object('dual_carriage', self)
+        self.printer.register_event_handler("klippy:ready", self._handle_ready)
         gcode = self.printer.lookup_object('gcode')
         gcode.register_command(
                    'SET_DUAL_CARRIAGE', self.cmd_SET_DUAL_CARRIAGE,
                    desc=self.cmd_SET_DUAL_CARRIAGE_help)
-    def toggle_active_dc_rail(self, index):
+        gcode.register_command(
+                   'SAVE_DUAL_CARRIAGE_STATE',
+                   self.cmd_SAVE_DUAL_CARRIAGE_STATE,
+                   desc=self.cmd_SAVE_DUAL_CARRIAGE_STATE_help)
+        gcode.register_command(
+                   'RESTORE_DUAL_CARRIAGE_STATE',
+                   self.cmd_RESTORE_DUAL_CARRIAGE_STATE,
+                   desc=self.cmd_RESTORE_DUAL_CARRIAGE_STATE_help)
+    def get_rails(self):
+        return self.dc
+    def toggle_active_dc_rail(self, index, override_rail=False):
         toolhead = self.printer.lookup_object('toolhead')
         toolhead.flush_step_generation()
         pos = toolhead.get_position()
@@ -27,104 +52,170 @@ class DualCarriages:
             if i != index:
                 if dc.is_active():
                     dc.inactivate(pos)
-                kin.override_rail(3, dc_rail)
-            elif dc.is_active() is False:
-                newpos = pos[:self.axis] + [dc.axis_position] \
-                            + pos[self.axis+1:]
-                dc.activate(newpos)
-                kin.override_rail(self.axis, dc_rail)
-                toolhead.set_position(newpos)
-                kin.update_limits(self.axis, dc_rail.get_range())
+                if override_rail:
+                    kin.override_rail(3, dc_rail)
+        target_dc = self.dc[index]
+        if target_dc.mode != PRIMARY:
+            newpos = pos[:self.axis] + [target_dc.get_axis_position(pos)] \
+                        + pos[self.axis+1:]
+            target_dc.activate(PRIMARY, newpos, old_position=pos)
+            if override_rail:
+                kin.override_rail(self.axis, target_dc.get_rail())
+            toolhead.set_position(newpos)
+        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):
+            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
+        self.toggle_active_dc_rail(0, override_rail=True)
     def get_status(self, eventtime=None):
-        dc0, dc1 = self.dc
-        if (dc0.is_active() is True):
-            return { 'mode': 'FULL_CONTROL', 'active_carriage': 'CARRIAGE_0' }
+        return {('carriage_%d' % (i,)) : dc.mode
+                for (i, dc) in enumerate(self.dc)}
+    def get_kin_range(self, toolhead, mode):
+        pos = toolhead.get_position()
+        axes_pos = [dc.get_axis_position(pos) for dc in self.dc]
+        dc0_rail = self.dc[0].get_rail()
+        dc1_rail = self.dc[1].get_rail()
+        range_min = dc0_rail.position_min
+        range_max = dc0_rail.position_max
+        safe_dist = self.safe_dist
+
+        if mode == COPY:
+            range_min = max(range_min,
+                            axes_pos[0] - axes_pos[1] + dc1_rail.position_min)
+            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:
+                range_min = max(range_min,
+                                0.5 * (sum(axes_pos) + safe_dist))
+                range_max = min(range_max,
+                                sum(axes_pos) - dc1_rail.position_min)
+            else:
+                range_max = min(range_max,
+                                0.5 * (sum(axes_pos) - safe_dist))
+                range_min = max(range_min,
+                                sum(axes_pos) - dc1_rail.position_max)
         else:
-            return { 'mode': 'FULL_CONTROL', 'active_carriage': 'CARRIAGE_1' }
-    def save_idex_state(self):
-        dc0, dc1 = self.dc
-        if (dc0.is_active() is True):
-            mode, active_carriage = ('FULL_CONTROL', 'CARRIAGE_0')
+            # mode == PRIMARY
+            active_idx = 1 if self.dc[1].is_active() else 0
+            inactive_idx = 1 - active_idx
+            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:
+                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 activate_dc_mode(self, index, mode):
+        toolhead = self.printer.lookup_object('toolhead')
+        toolhead.flush_step_generation()
+        kin = toolhead.get_kinematics()
+        if mode == INACTIVE:
+            self.dc[index].inactivate(toolhead.get_position())
+        elif mode == PRIMARY:
+            self.toggle_active_dc_rail(index)
         else:
-            mode, active_carriage = ('FULL_CONTROL', 'CARRIAGE_1')
-        self.saved_state = {
-            'mode': mode,
-            'active_carriage': active_carriage,
-            'axis_positions': (dc0.axis_position, dc1.axis_position)
-            }
-    def restore_idex_state(self):
-        if self.saved_state is not None:
-            # set carriage 0 active
-            if (self.saved_state['active_carriage'] == 'CARRIAGE_0'
-                        and self.dc[0].is_active() is False):
-                self.toggle_active_dc_rail(0)
-            # set carriage 1 active
-            elif (self.saved_state['active_carriage'] == 'CARRIAGE_1'
-                        and self.dc[1].is_active() is False):
-                self.toggle_active_dc_rail(1)
-    cmd_SET_DUAL_CARRIAGE_help = "Set which carriage is active"
+            self.toggle_active_dc_rail(0)
+            self.dc[index].activate(mode, toolhead.get_position())
+        kin.update_limits(self.axis, self.get_kin_range(toolhead, mode))
+    def _handle_ready(self):
+        # Apply the transform later during Klipper initialization to make sure
+        # that input shaping can pick up the correct stepper kinematic flags.
+        for dc in self.dc:
+            dc.apply_transform()
+    cmd_SET_DUAL_CARRIAGE_help = "Configure the dual carriages mode"
     def cmd_SET_DUAL_CARRIAGE(self, gcmd):
         index = gcmd.get_int('CARRIAGE', minval=0, maxval=1)
-        if (not(self.dc[0].is_active() == self.dc[1].is_active() == True)
-                    and self.dc[index].is_active() is False):
-            self.toggle_active_dc_rail(index)
+        mode = gcmd.get('MODE', PRIMARY).upper()
+        if mode not in self.VALID_MODES:
+            raise gcmd.error("Invalid mode=%s specified" % (mode,))
+        if mode in [COPY, MIRROR]:
+            if index == 0:
+                raise gcmd.error(
+                        "Mode=%s is not supported for carriage=0" % (mode,))
+            curtime = self.printer.get_reactor().monotonic()
+            kin = self.printer.lookup_object('toolhead').get_kinematics()
+            axis = 'xyz'[self.axis]
+            if axis not in kin.get_status(curtime)['homed_axes']:
+                raise gcmd.error(
+                        "Axis %s must be homed prior to enabling mode=%s" %
+                        (axis, mode))
+        self.activate_dc_mode(index, mode)
+    cmd_SAVE_DUAL_CARRIAGE_STATE_help = \
+            "Save dual carriages modes and positions"
+    def cmd_SAVE_DUAL_CARRIAGE_STATE(self, gcmd):
+        state_name = gcmd.get('NAME', 'default')
+        pos = self.printer.lookup_object('toolhead').get_position()
+        self.saved_states[state_name] = {
+            'carriage_modes': [dc.mode for dc in self.dc],
+            'axes_positions': [dc.get_axis_position(pos) for dc in self.dc],
+        }
+    cmd_RESTORE_DUAL_CARRIAGE_STATE_help = \
+            "Restore dual carriages modes and positions"
+    def cmd_RESTORE_DUAL_CARRIAGE_STATE(self, gcmd):
+        state_name = gcmd.get('NAME', 'default')
+        saved_state = self.saved_states.get(state_name)
+        if saved_state is None:
+            raise gcmd.error("Unknown DUAL_CARRIAGE state: %s" % (state_name,))
+        move_speed = gcmd.get('MOVE_SPEED', 0., above=0.)
+        toolhead = self.printer.lookup_object('toolhead')
+        toolhead.flush_step_generation()
+        pos = toolhead.get_position()
+        if gcmd.get_int('MOVE', 1):
+            for i, dc in enumerate(self.dc):
+                self.toggle_active_dc_rail(i)
+                saved_pos = saved_state['axes_positions'][i]
+                toolhead.manual_move(
+                        pos[:self.axis] + [saved_pos] + pos[self.axis+1:],
+                        move_speed or dc.get_rail().homing_speed)
+        for i, dc in enumerate(self.dc):
+            saved_mode = saved_state['carriage_modes'][i]
+            self.activate_dc_mode(i, saved_mode)
 
 class DualCarriagesRail:
-    ACTIVE=1
-    INACTIVE=2
-    def __init__(self, printer, rail, axis, active, stepper_alloc_active,
-                 stepper_alloc_inactive=None):
-        self.printer = printer
+    ENC_AXES = [b'x', b'y']
+    def __init__(self, rail, axis, active):
         self.rail = rail
         self.axis = axis
-        self.status = (self.INACTIVE, self.ACTIVE)[active]
-        self.stepper_alloc_active = stepper_alloc_active
-        self.stepper_alloc_inactive = stepper_alloc_inactive
-        self.axis_position = -1
-        self.stepper_active_sk = {}
-        self.stepper_inactive_sk = {}
-        for s in rail.get_steppers():
-            self._save_sk(self.status, s, s.get_stepper_kinematics())
-    def _alloc_sk(self, alloc_func, *params):
+        self.mode = (INACTIVE, PRIMARY)[active]
+        self.offset = 0.
+        self.scale = 1. if active else 0.
         ffi_main, ffi_lib = chelper.get_ffi()
-        return ffi_main.gc(getattr(ffi_lib, alloc_func)(*params), ffi_lib.free)
-    def _get_sk(self, status, stepper):
-        sk = None
-        if status == self.ACTIVE:
-            sk = self.stepper_active_sk.get(stepper, None)
-            if sk is None and self.stepper_alloc_active:
-                sk = self._alloc_sk(*self.stepper_alloc_active)
-                self._save_sk(status, stepper, sk)
-        elif status == self.INACTIVE:
-            sk = self.stepper_inactive_sk.get(stepper, None)
-            if sk is None and self.stepper_alloc_inactive:
-                sk = self._alloc_sk(*self.stepper_alloc_inactive)
-                self._save_sk(status, stepper, sk)
-        return sk
-    def _save_sk(self, status, stepper, sk):
-        if status == self.ACTIVE:
-            self.stepper_active_sk[stepper] = sk
-        elif status == self.INACTIVE:
-            self.stepper_inactive_sk[stepper] = sk
-    def _update_stepper_alloc(self, position, active=True):
-        toolhead = self.printer.lookup_object('toolhead')
-        self.axis_position = position[self.axis]
-        self.rail.set_trapq(None)
-        old_status = self.status
-        self.status = (self.INACTIVE, self.ACTIVE)[active]
-        for s in self.rail.get_steppers():
-            sk = self._get_sk(self.status, s)
-            if sk is None:
-                return
-            old_sk = s.set_stepper_kinematics(sk)
-            self._save_sk(old_status, s, old_sk)
-        self.rail.set_position(position)
-        self.rail.set_trapq(toolhead.get_trapq())
+        self.dc_stepper_kinematics = []
+        self.orig_stepper_kinematics = []
+        for s in rail.get_steppers():
+            sk = ffi_main.gc(ffi_lib.dual_carriage_alloc(), ffi_lib.free)
+            orig_sk = s.get_stepper_kinematics()
+            ffi_lib.dual_carriage_set_sk(sk, orig_sk)
+            # Set the default transform for the other axis
+            ffi_lib.dual_carriage_set_transform(
+                    sk, self.ENC_AXES[1 - axis], 1., 0.)
+            self.dc_stepper_kinematics.append(sk)
+            self.orig_stepper_kinematics.append(orig_sk)
+            s.set_stepper_kinematics(sk)
     def get_rail(self):
         return self.rail
     def is_active(self):
-        return self.status == self.ACTIVE
-    def activate(self, position):
-        self._update_stepper_alloc(position, active=True)
+        return self.mode != INACTIVE
+    def get_axis_position(self, position):
+        return position[self.axis] * self.scale + self.offset
+    def apply_transform(self):
+        ffi_main, ffi_lib = chelper.get_ffi()
+        for sk in self.dc_stepper_kinematics:
+            ffi_lib.dual_carriage_set_transform(
+                    sk, self.ENC_AXES[self.axis], self.scale, self.offset)
+    def activate(self, mode, position, old_position=None):
+        old_axis_position = self.get_axis_position(old_position or position)
+        self.scale = -1. if mode == MIRROR else 1.
+        self.offset = old_axis_position - position[self.axis] * self.scale
+        self.apply_transform()
+        self.mode = mode
     def inactivate(self, position):
-        self._update_stepper_alloc(position, active=False)
+        self.offset = self.get_axis_position(position)
+        self.scale = 0.
+        self.apply_transform()
+        self.mode = INACTIVE