urm37: Add C library for this sensor

Added a C implementation for this sensor.  The C++ library was changed
to just wrap the C library calls.

Signed-off-by: Jon Trulson <jtrulson@ics.com>

src/urm37/urm37_fti.c

@@ -0,0 +1,109 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ *         Abhishek Malik <abhishek.malik@intel.com>
+ * Copyright (c) 2016 Intel Corporation.
+ *
+ * Thanks to Adafruit for supplying a google translated version of the
+ * Chinese datasheet and some clues in their code.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include "urm37.h"
+#include "upm_fti.h"
+
+/** 
+ * This file implements the Function Table Interface (FTI) for this sensor
+ */
+
+const char upm_light_name[] = "URM37";
+const char upm_light_description[] = "Ultrasonic Ranger";
+// problem here is it's an either/or analog vs. uart.  So we will just
+// only support analog for now
+// 1st gpio is reset, 2nd is trigger
+const upm_protocol_t upm_light_protocol[] = {UPM_ANALOG, UPM_GPIO, UPM_GPIO};
+const upm_sensor_t upm_light_category[] = {UPM_DISTANCE};
+
+// forward declarations
+const void* upm_urm37_get_ft(upm_sensor_t sensor_type);
+void* upm_urm37_init_name();
+void upm_urm37_close(void* dev);
+upm_result_t upm_urm37_get_distance(void* dev, float* distance,
+                                    upm_distance_u unit);
+
+static const upm_sensor_ft ft =
+{
+    .upm_sensor_init_name = &upm_urm37_init_name,
+    .upm_sensor_close = &upm_urm37_close,
+};
+
+static const upm_distance_ft dft =
+{
+    .upm_distance_get_value = &upm_urm37_get_distance
+};
+
+const void* upm_urm37_get_ft(upm_sensor_t sensor_type)
+{
+  switch(sensor_type)
+    {
+    case UPM_SENSOR:
+      return &ft;
+      
+    case UPM_DISTANCE:
+      return &dft;
+      
+    default:
+      return NULL;
+    }
+}
+
+void* upm_urm37_init_name()
+{
+    return NULL;
+}
+
+
+void upm_urm37_close(void* dev)
+{
+    urm37_close((urm37_context)dev);
+}
+
+upm_result_t upm_urm37_get_distance(void* dev, float* distance,
+                                    upm_distance_u unit)
+{
+  // only cm returned by sensor
+  float dist;
+  urm37_get_distance((urm37_context)dev, &dist, 0);
+
+  switch(unit)
+    {
+    case CENTIMETER:
+      *distance = dist;
+      return UPM_SUCCESS;
+
+    case INCH:
+      *distance = dist / 2.54;
+      return UPM_SUCCESS;
+
+    default:
+      return UPM_ERROR_INVALID_PARAMETER;
+    }
+}
+