winch: Add experimental support for cable winch kinematics

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

2 files changed, 47 insertions, 2 deletions

diff --git a/klippy/chelper/__init__.py b/klippy/chelper/__init__.py
index 6427ba0f..fba5eb48 100644
--- a/klippy/chelper/__init__.py
+++ b/klippy/chelper/__init__.py
@@ -17,7 +17,7 @@ COMPILE_CMD = ("gcc -Wall -g -O2 -shared -fPIC"
 SOURCE_FILES = [
     'pyhelper.c', 'serialqueue.c', 'stepcompress.c', 'itersolve.c',
     'kin_cartesian.c', 'kin_corexy.c', 'kin_delta.c', 'kin_polar.c',
-    'kin_extruder.c',
+    'kin_winch.c', 'kin_extruder.c',
 ]
 DEST_LIB = "c_helper.so"
 OTHER_FILES = [
@@ -75,6 +75,11 @@ defs_kin_polar = """
     struct stepper_kinematics *polar_stepper_alloc(char type);
 """
 
+defs_kin_winch = """
+    struct stepper_kinematics *winch_stepper_alloc(double anchor_x
+        , double anchor_y, double anchor_z);
+"""
+
 defs_kin_extruder = """
     struct stepper_kinematics *extruder_stepper_alloc(void);
     void extruder_move_fill(struct move *m, double print_time
@@ -122,7 +127,7 @@ defs_std = """
 defs_all = [
     defs_pyhelper, defs_serialqueue, defs_std, defs_stepcompress, defs_itersolve,
     defs_kin_cartesian, defs_kin_corexy, defs_kin_delta, defs_kin_polar,
-    defs_kin_extruder
+    defs_kin_winch, defs_kin_extruder
 ]
 
 # Return the list of file modification times
diff --git a/klippy/chelper/kin_winch.c b/klippy/chelper/kin_winch.c
new file mode 100644
index 00000000..df894352
--- /dev/null
+++ b/klippy/chelper/kin_winch.c
@@ -0,0 +1,40 @@
+// Cable winch stepper kinematics
+//
+// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include <math.h> // sqrt
+#include <stddef.h> // offsetof
+#include <stdlib.h> // malloc
+#include <string.h> // memset
+#include "compiler.h" // __visible
+#include "itersolve.h" // struct stepper_kinematics
+
+struct winch_stepper {
+    struct stepper_kinematics sk;
+    struct coord anchor;
+};
+
+static double
+winch_stepper_calc_position(struct stepper_kinematics *sk, struct move *m
+                            , double move_time)
+{
+    struct winch_stepper *hs = container_of(sk, struct winch_stepper, sk);
+    struct coord c = move_get_coord(m, move_time);
+    double dx = hs->anchor.x - c.x, dy = hs->anchor.y - c.y;
+    double dz = hs->anchor.z - c.z;
+    return sqrt(dx*dx + dy*dy + dz*dz);
+}
+
+struct stepper_kinematics * __visible
+winch_stepper_alloc(double anchor_x, double anchor_y, double anchor_z)
+{
+    struct winch_stepper *hs = malloc(sizeof(*hs));
+    memset(hs, 0, sizeof(*hs));
+    hs->anchor.x = anchor_x;
+    hs->anchor.y = anchor_y;
+    hs->anchor.z = anchor_z;
+    hs->sk.calc_position = winch_stepper_calc_position;
+    return &hs->sk;
+}