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/KernelDescriptors.h b/arm_compute/core/KernelDescriptors.h
new file mode 100644
index 0000000..186dbfb
--- /dev/null
+++ b/arm_compute/core/KernelDescriptors.h
@@ -0,0 +1,38 @@
+/*
+ * 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_CORE_KERNEL_DESCRIPTORS_H__
+#define __ARM_COMPUTE_CORE_KERNEL_DESCRIPTORS_H__
+
+namespace arm_compute
+{
+/** Descriptor used by the FFT core kernels */
+struct FFTRadixStageKernelDescriptor
+{
+    unsigned int axis{ 0 };               /**< Axis to run the FFT on. */
+    unsigned int radix{ 0 };              /**< Radix to use. */
+    unsigned int Nx{ 0 };                 /**< Nx coefficient. */
+    bool         is_first_stage{ false }; /**< Flags if the FFT kernels is the first stage of a decomposed FFT. */
+};
+} // namespace arm_compute
+#endif /* __ARM_COMPUTE_CORE_KERNEL_DESCRIPTORS_H__ */