COMPMID-1107: Add support for ChannelShuffle in CL

Change-Id: I56d2a02b316f0c69ff1fd7220e732f775414fe69
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/129709
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Tested-by: Jenkins <bsgcomp@arm.com>
Reviewed-by: Giorgio Arena <giorgio.arena@arm.com>
Reviewed-by: Gian Marco Iodice <gianmarco.iodice@arm.com>
diff --git a/tests/validation/reference/ChannelShuffle.cpp b/tests/validation/reference/ChannelShuffle.cpp
new file mode 100644
index 0000000..790eff5
--- /dev/null
+++ b/tests/validation/reference/ChannelShuffle.cpp
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2018 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.
+ */
+#include "ChannelShuffle.h"
+
+#include "arm_compute/core/Types.h"
+#include "tests/validation/Helpers.h"
+
+namespace arm_compute
+{
+namespace test
+{
+namespace validation
+{
+namespace reference
+{
+// Refence implementation for channel shuffle taken from https://github.com/pytorch/pytorch/blob/master/caffe2/operators/channel_shuffle_op.h
+template <typename T>
+SimpleTensor<T> channel_shuffle(const SimpleTensor<T> &src, int num_groups)
+{
+    // Create reference
+    SimpleTensor<T> dst{ src.shape(), src.data_type(), src.num_channels(), src.fixed_point_position(), src.quantization_info() };
+
+    const int M                 = src.shape()[0];
+    const int N                 = src.shape()[1];
+    const int num_channels      = src.shape()[2];
+    const int batches           = src.shape()[3];
+    const int MxN               = M * N;
+    const int channels_in_group = num_channels / num_groups;
+
+    const T *src_ref = src.data();
+    T       *dst_ref = dst.data();
+
+    for(int n = 0; n < batches; ++n)
+    {
+        for(int g = 0; g < num_groups; ++g)
+        {
+            // Gather the group g block (of size channels_in_group * MxN) from output channels
+            // g + 0 * G, g + 1 * G, g + 2 * G, g + G * (K - 1) etc.
+            const T *src_ptr = src_ref + g * MxN + n * num_channels * MxN;
+            T       *dst_ptr = dst_ref + g * channels_in_group * MxN + n * num_channels * MxN;
+            for(int i = 0; i < channels_in_group; ++i)
+            {
+                std::copy(src_ptr + i * num_groups * MxN,
+                          src_ptr + (i * num_groups + 1) * MxN,
+                          dst_ptr + i * MxN);
+            }
+        }
+    }
+
+    return dst;
+}
+
+template SimpleTensor<uint8_t> channel_shuffle(const SimpleTensor<uint8_t> &src, int num_groups);
+template SimpleTensor<uint16_t> channel_shuffle(const SimpleTensor<uint16_t> &src, int num_groups);
+template SimpleTensor<uint32_t> channel_shuffle(const SimpleTensor<uint32_t> &src, int num_groups);
+template SimpleTensor<half> channel_shuffle(const SimpleTensor<half> &src, int num_groups);
+template SimpleTensor<float> channel_shuffle(const SimpleTensor<float> &src, int num_groups);
+} // namespace reference
+} // namespace validation
+} // namespace test
+} // namespace arm_compute