extmod/modrobotics: bind settings by limits

The settings() just set lower defaults for straight() and turn(). When
they call pbio functions, they are still bound by the control limits.

By limiting the values kept as class attributes, this implicit bound is
made explicit because it makes it possible to see that very large
values are capped.

extmod/modrobotics.c

@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: MIT
 // Copyright (c) 2019 Laurens Valk
 
+#include <stdlib.h>
+
 #include <math.h>
 
 #include <pbio/drivebase.h>
@@ -230,11 +232,15 @@ STATIC mp_obj_t robotics_DriveBase_settings(size_t n_args, const mp_obj_t *pos_a
         pb_assert(PBIO_ERROR_INVALID_OP);
     }
 
-    // If some values are given, set them
-    self->straight_speed = pb_obj_get_default_int(straight_speed, self->straight_speed);
-    self->straight_acceleration = pb_obj_get_default_int(straight_acceleration, self->straight_acceleration);
-    self->turn_rate = pb_obj_get_default_int(turn_rate, self->turn_rate);
-    self->turn_acceleration = pb_obj_get_default_int(turn_acceleration, self->turn_acceleration);
+    // If some values are given, set them, bound by the control limits
+    int32_t straight_speed_limit, straight_acceleration_limit, turn_rate_limit, turn_acceleration_limit, _;
+    pbio_control_settings_get_limits(&self->db->control_distance.settings, &straight_speed_limit, &straight_acceleration_limit, &_);
+    pbio_control_settings_get_limits(&self->db->control_heading.settings, &turn_rate_limit, &turn_acceleration_limit, &_);
+
+    self->straight_speed = min(straight_speed_limit, abs(pb_obj_get_default_int(straight_speed, self->straight_speed)));
+    self->straight_acceleration = min(straight_acceleration_limit, abs(pb_obj_get_default_int(straight_acceleration, self->straight_acceleration)));
+    self->turn_rate = min(turn_rate_limit, abs(pb_obj_get_default_int(turn_rate, self->turn_rate)));
+    self->turn_acceleration = min(turn_acceleration_limit, abs(pb_obj_get_default_int(turn_acceleration, self->turn_acceleration)));
 
     return mp_const_none;
 }