hmc5883l: C port; FTI; C++ wraps C

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

src/hmc5883l/hmc5883l.h

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+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2017 Intel Corporation.
+ *
+ * Ported based on original C++ code by:
+ * Author: Brendan Le Foll <brendan.le.foll@intel.com>
+ * Contributions: Mihai Tudor Panu <mihai.tudor.panu@intel.com>
+ * Copyright (c) 2014 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.
+ */
+#pragma once
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <upm.h>
+#include <mraa/i2c.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+    /**
+     * @file hmc5883l.h
+     * @library hmc5883l
+     * @brief HMC5883L 3-Axis Digital Compass
+     *
+     */
+
+    /**
+     * Device context
+     */
+    typedef struct _hmc5883l_context {
+        mraa_i2c_context i2c;
+
+        int16_t coords[3];
+        float   declination;
+    } *hmc5883l_context;
+
+
+    /**
+     * Initialize an Hmc5883l device
+     *
+     * @param bus Number of the used I2C bus
+     * @return Device context, or NULL on error
+     */
+    hmc5883l_context hmc5883l_init(int bus);
+
+    /**
+     * Close the device
+     *
+     * @param Device context
+     */
+    void hmc5883l_close(hmc5883l_context dev);
+
+    /**
+     * Updates the values by reading from I2C
+     *
+     * @param Device context
+     * @return UPM result
+     */
+    upm_result_t hmc5883l_update(const hmc5883l_context dev);
+
+    /*
+     * Returns the direction.  hmc5883l_update() must have been called
+     * prior to calling this function.
+     *
+     * @param Device context
+     * @return Direction
+     */
+    float hmc5883l_direction(const hmc5883l_context dev);
+
+    /*
+     * Returns the heading.  hmc5883l_update() must have been called
+     * prior to calling this function.
+     *
+     * @param Device context
+     * @return Heading
+     */
+    float hmc5883l_heading(const hmc5883l_context dev);
+
+    /**
+     * Returns a pointer to an int[3] that contains the coordinates as
+     * integers.  hmc5883l_update() must have been called prior to calling
+     * this function.
+     *
+     * @param Device context
+     * @return *int to an int[3] (X, Y, Z)
+     */
+    const int16_t *hmc5883l_coordinates(const hmc5883l_context dev);
+
+    /**
+     * Sets the magnetic declination for better accuracy.
+     * hmc5883l_update() must have been called prior to calling this
+     * function.
+     *
+     * @param Device context
+     * @param dec The magnetic declination
+     */
+    void hmc5883l_set_declination(const hmc5883l_context dev, float dec);
+
+    /**
+     * Gets the current magnetic declination value.  hmc5883l_update()
+     * must have been called prior to calling this function.
+     *
+     * @param Device context
+     * @return Magnetic declination as a floating-point value
+     */
+    float hmc5883l_get_declination(const hmc5883l_context dev);
+
+#ifdef __cplusplus
+}
+#endif