polar: Experimental support for polar kinematics

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

2 files changed, 49 insertions, 2 deletions

diff --git a/klippy/chelper/__init__.py b/klippy/chelper/__init__.py
index 567807fa..6427ba0f 100644
--- a/klippy/chelper/__init__.py
+++ b/klippy/chelper/__init__.py
@@ -16,7 +16,8 @@ COMPILE_CMD = ("gcc -Wall -g -O2 -shared -fPIC"
                " -o %s %s")
 SOURCE_FILES = [
     'pyhelper.c', 'serialqueue.c', 'stepcompress.c', 'itersolve.c',
-    'kin_cartesian.c', 'kin_corexy.c', 'kin_delta.c', 'kin_extruder.c'
+    'kin_cartesian.c', 'kin_corexy.c', 'kin_delta.c', 'kin_polar.c',
+    'kin_extruder.c',
 ]
 DEST_LIB = "c_helper.so"
 OTHER_FILES = [
@@ -70,6 +71,10 @@ defs_kin_delta = """
         , double tower_x, double tower_y);
 """
 
+defs_kin_polar = """
+    struct stepper_kinematics *polar_stepper_alloc(char type);
+"""
+
 defs_kin_extruder = """
     struct stepper_kinematics *extruder_stepper_alloc(void);
     void extruder_move_fill(struct move *m, double print_time
@@ -116,7 +121,8 @@ 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_extruder
+    defs_kin_cartesian, defs_kin_corexy, defs_kin_delta, defs_kin_polar,
+    defs_kin_extruder
 ]
 
 # Return the list of file modification times
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;
+}