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+/*
+ * Copyright (C) 2012 Jamie Bullock
+ *
+ * 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.
+ *
+ */
+
+/** \file xtract_helper.h: helper functions for making life with libxtract a bit more bearable */
+
+#ifndef XTRACT_HELPER_H
+#define XTRACT_HELPER_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef _MSC_VER
+	#ifndef __cplusplus
+		typedef int bool;
+		#define false 0
+		#define true 1
+	#endif
+#else
+	#include <stdbool.h>
+#endif
+
+
+/**
+  * \defgroup helper helper functions
+  *
+  * Declares helper functions, and their parameters. 
+  *
+  * \note These functions don't necessarily conform to the prototype used in xtract_scalar.h and xtract_vector.h etc, and as such are intended to be called 'directly' rather than via the xtract[] function pointer array (libxtract.h)
+  *
+  * @{
+  */
+
+/** \brief Apply a window function to an array of length N
+ *
+ * \param *data a pointer to an array of doubles
+ * \param N the number of elements in the array pointed to by *data
+ * \param *argv a pointer to a window function as returned by xtract_make_window()
+ * \param *result a pointer to the first element an array containing the windowed data
+ *
+ * It is up to the caller to generate and free the array containing the window, and to allocate and free memory of size N to hold the data pointed to by *result
+ *
+ */
+int xtract_windowed(const double *data, const int N, const void *argv, double *result);
+
+/** \brief Divides the array pointed to by *data into two subframes, and applies a given feature to each subframe, returning them in a single array pointed to by result
+ *
+ * \param *data an array of doubles
+ * \param N the number of elements in the array pointed by *data
+ * \param feature an integer representing the feature to be applied to each subframe in data. This will be a value as given in the enumeration xtract_features_ (libxtract.h)
+ * \param *argv a pointer to the argument vector to be passed to the feature extraction function as determined by feature
+ * \param *result a pointer to the 'packed' results of the feature calculation. This may be passed in as *data to xtract_features_from_subframes() to calculate further features on the subframes, or xtract_difference_vector(), to get the difference between the subframes.
+ *
+ *
+ * It is important to ensure that any _init_*() functions that are called in preparation for functions that are called on subframes are given the subframe size as 'N', and not the frame size. i.e. if xtract_features_from_subframes() is called with N=64, and feature=XTRACT_SPECTRUM, then xtract_init_fft() should be called with N=32.
+ *
+ */
+int xtract_features_from_subframes(const double *data, const int N, const int feature, const void *argv, double *result);
+
+/** \brief Test whether a number is denormal */
+int xtract_is_denormal(double const d);
+
+/** \brief Test whether a number is a power of two */
+bool xtract_is_poweroftwo(unsigned int x);
+
+    
+/** \brief Smooth a vector
+ *
+ * \param *data a pointer to an array of doubles
+ * \param N the number of elements in the array pointed to by *data to be smoothed
+ * \param *argv a pointer to a double giving the smoothing gain
+ * \param *result a pointer to the first element an array containing the smoothed data
+ *
+ * \note if passing in a spectrum e.g. *result from xtract_spectrum(), then N for xtract_smoothed() should be N / 2 with respect to the N for xtract_spectrum() so only amplitude components are smoothed, not frequencies!
+ *
+ */
+    int xtract_smoothed(const double *data, const int N, const void *argv, double *result);
+    
+    
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+
+