COMPMID-1958: Implements 1D FFT in OpenCL.

Forward complex FFT implementation.

Change-Id: Ia0ba8740072e5adb06f8ead462a47abc8b5dd125
Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Reviewed-on: https://review.mlplatform.org/c/904
Reviewed-by: Gian Marco Iodice <gianmarco.iodice@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
diff --git a/arm_compute/core/CL/kernels/CLFFTDigitReverseKernel.h b/arm_compute/core/CL/kernels/CLFFTDigitReverseKernel.h
new file mode 100644
index 0000000..10652cd
--- /dev/null
+++ b/arm_compute/core/CL/kernels/CLFFTDigitReverseKernel.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2019 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * 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.
+ */
+#ifndef __ARM_COMPUTE_CLFFTDIGITREVERSEKERNEL_H__
+#define __ARM_COMPUTE_CLFFTDIGITREVERSEKERNEL_H__
+
+#include "arm_compute/core/CL/ICLKernel.h"
+
+namespace arm_compute
+{
+// Forward declarations
+class ICLTensor;
+
+/** Interface for the digit reverse operation kernel. */
+class CLFFTDigitReverseKernel : public ICLKernel
+{
+public:
+    /** Constructor */
+    CLFFTDigitReverseKernel();
+    /** Prevent instances of this class from being copied (As this class contains pointers) */
+    CLFFTDigitReverseKernel(const CLFFTDigitReverseKernel &) = delete;
+    /** Prevent instances of this class from being copied (As this class contains pointers) */
+    CLFFTDigitReverseKernel &operator=(const CLFFTDigitReverseKernel &) = delete;
+    /** Default Move Constructor. */
+    CLFFTDigitReverseKernel(CLFFTDigitReverseKernel &&) = default;
+    /** Default move assignment operator */
+    CLFFTDigitReverseKernel &operator=(CLFFTDigitReverseKernel &&) = default;
+    /** Default destructor */
+    ~CLFFTDigitReverseKernel() = default;
+    /** Set the input and output tensors.
+     *
+     * @param[in]  input  Source tensor. Data types supported: F32.
+     * @param[out] output Destination tensor. Data type supported: same as @p input
+     * @param[in]  idx    Digit reverse index tensor. Data type supported: U32
+     * @param[in]  axis   Axis to perform digit reverse on.
+     */
+    void configure(const ICLTensor *input, ICLTensor *output, const ICLTensor *idx, unsigned int axis);
+    /** Static function to check if given info will lead to a valid configuration of @ref CLFFTDigitReverseKernel
+     *
+     * @param[in] input  Source tensor info. Data types supported: F32.
+     * @param[in] output Destination tensor info. Data type supported: same as @p input
+     * @param[in] idx    Digit reverse index tensor info. Data type supported: U32
+     * @param[in] axis   Axis to perform digit reverse on.
+     *
+     * @return a status
+     */
+    static Status validate(const ITensorInfo *input, const ITensorInfo *output, const ITensorInfo *idx, unsigned int axis);
+
+    // Inherited methods overridden:
+    void run(const Window &window, cl::CommandQueue &queue) override;
+
+private:
+    const ICLTensor *_input;
+    ICLTensor       *_output;
+    const ICLTensor *_idx;
+};
+} // namespace arm_compute
+#endif /*__ARM_COMPUTE_CLFFTDIGITREVERSEKERNEL_H__ */