vdiv: Added vdiv C source.

Multiple changes related to building the vdiv c source w/c example.

    * Renamed GroveVdiv to vdiv (all cases) throughout source, examples,
    directory names, and documentation.

    * Added C source.

    * Tested C sensor code on edison

    * Updated CMakeLists.txt for examples-c to build from
    <sensorname>-c.  This was a small change to get c examples to build
    for sensors in which the C++ does NOT wrap the C.

    * Added C example for vdiv.

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/vdiv/vdiv_fti.c

@@ -0,0 +1,118 @@
+/*
+ * Author:
+ * Copyright (c) 2015 Intel Corporation.
+ *
+ * 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 <string.h>
+#include <stdlib.h>
+
+#include "vdiv.h"
+#include "fti/upm_sensor.h"
+#include "fti/upm_voltage.h"
+
+/** 
+ * This file implements the Function Table Interface (FTI) for this sensor
+ */
+
+const char upm_vdiv_name[] = "VDIV";
+const char upm_vdiv_description[] = "Analog voltage divider sensor";
+const upm_protocol_t upm_vdiv_protocol[] = {UPM_ANALOG};
+const upm_sensor_t upm_vdiv_category[] = {UPM_VOLTAGE};
+
+// forward declarations
+const void* upm_vdiv_get_ft(upm_sensor_t sensor_type);
+void* upm_vdiv_init_str(const char* protocol, const char* params);
+void upm_vdiv_close(void* dev);
+const upm_sensor_descriptor_t upm_vdiv_get_descriptor();
+upm_result_t upm_vdiv_set_offset(const void* dev, float offset);
+upm_result_t upm_vdiv_set_scale(const void* dev, float scale);
+upm_result_t upm_vdiv_get_value(const void* dev, float *value);
+
+/* This sensor implementes 2 function tables */
+/* 1. Generic base function table */
+static const upm_sensor_ft ft_gen =
+{
+    .upm_sensor_init_name = &upm_vdiv_init_str,
+    .upm_sensor_close = &upm_vdiv_close,
+    .upm_sensor_get_descriptor = &upm_vdiv_get_descriptor
+};
+
+/* 2. VOLTAGE function table */
+static const upm_voltage_ft ft_voltage =
+{
+    .upm_voltage_set_offset = &upm_vdiv_set_offset,
+    .upm_voltage_set_scale = &upm_vdiv_set_scale,
+    .upm_voltage_get_value = &upm_vdiv_get_value
+};
+
+const void* upm_vdiv_get_ft(upm_sensor_t sensor_type)
+{
+    switch(sensor_type)
+    {
+        case UPM_SENSOR:
+            return &ft_gen;
+        case UPM_VOLTAGE:
+            return &ft_voltage;
+        default:
+            return NULL;
+    }
+}
+
+void* upm_vdiv_init_str(const char* protocol, const char* params)
+{
+    fprintf(stderr, "String initialization - not implemented, using ain0: %s\n", __FILENAME__);
+    return vdiv_init(0, 5.0);
+}
+
+void upm_vdiv_close(void* dev)
+{
+    vdiv_close((vdiv_context)dev);
+}
+
+const upm_sensor_descriptor_t upm_vdiv_get_descriptor()
+{
+    /* Fill in the descriptor */
+    upm_sensor_descriptor_t usd;
+    usd.name = upm_vdiv_name;
+    usd.description = upm_vdiv_description;
+    usd.protocol_size = 1;
+    usd.protocol = upm_vdiv_protocol;
+    usd.category_size = 1;
+    usd.category = upm_vdiv_category;
+
+    return usd;
+}
+
+upm_result_t upm_vdiv_set_offset(const void* dev, float offset)
+{
+    return vdiv_set_offset((vdiv_context)dev, offset);
+}
+
+upm_result_t upm_vdiv_set_scale(const void* dev, float scale)
+{
+    return vdiv_set_scale((vdiv_context)dev, scale);
+}
+
+upm_result_t upm_vdiv_get_value(const void* dev, float *value)
+{
+    return vdiv_get_computed_volts((vdiv_context)dev, value);
+}