polar: Experimental support for polar kinematics

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

1 files changed, 41 insertions, 0 deletions

diff --git a/klippy/chelper/kin_polar.c b/klippy/chelper/kin_polar.c
new file mode 100644
index 00000000..cc1f2eab
--- /dev/null
+++ b/klippy/chelper/kin_polar.c
@@ -0,0 +1,41 @@
+// Polar kinematics stepper pulse time generation
+//
+// 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 <stdlib.h> // malloc
+#include <string.h> // memset
+#include "compiler.h" // __visible
+#include "itersolve.h" // struct stepper_kinematics
+
+static double
+polar_stepper_radius_calc_position(struct stepper_kinematics *sk, struct move *m
+                                   , double move_time)
+{
+    struct coord c = move_get_coord(m, move_time);
+    return sqrt(c.x*c.x + c.y*c.y);
+}
+
+static double
+polar_stepper_angle_calc_position(struct stepper_kinematics *sk, struct move *m
+                                  , double move_time)
+{
+    struct coord c = move_get_coord(m, move_time);
+    // XXX - handle x==y==0
+    // XXX - handle angle wrapping
+    return atan2(c.y, c.x);
+}
+
+struct stepper_kinematics * __visible
+polar_stepper_alloc(char type)
+{
+    struct stepper_kinematics *sk = malloc(sizeof(*sk));
+    memset(sk, 0, sizeof(*sk));
+    if (type == 'r')
+        sk->calc_position = polar_stepper_radius_calc_position;
+    else if (type == 'a')
+        sk->calc_position = polar_stepper_angle_calc_position;
+    return sk;
+}