COMPMID-571: Implement reference and CL/NEON validation for Erode

Change-Id: I7cc6acc4947f77412230e286ab9b14304f35b025
Reviewed-on: http://mpd-gerrit.cambridge.arm.com/90869
Tested-by: Kaizen <jeremy.johnson+kaizengerrit@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Reviewed-by: Pablo Tello <pablo.tello@arm.com>
diff --git a/tests/validation/CPP/Erode.cpp b/tests/validation/CPP/Erode.cpp
new file mode 100644
index 0000000..5e8b36f
--- /dev/null
+++ b/tests/validation/CPP/Erode.cpp
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2017 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 "Erode.h"
+
+#include "Utils.h"
+#include "tests/validation/Helpers.h"
+
+#include <algorithm>
+#include <array>
+
+namespace arm_compute
+{
+namespace test
+{
+namespace validation
+{
+namespace reference
+{
+template <typename T>
+SimpleTensor<T> erode(const SimpleTensor<T> &src, BorderMode border_mode, T constant_border_value)
+{
+    /*
+             -1   x  +1
+         -1 [tl][tc][tr] -1
+          y [ml][xy][mr]  y
+         +1 [bl][bc][br] +1
+             -1   x  +1
+        erode:
+        dst(x, y) = min[ src(x', y') for x-1<=x'<=x+1, y-1<=y'<=y+1 ] = min({tl, tc, tr, ml, xy, mr, bl, bc, br})
+    */
+    SimpleTensor<T> dst(src.shape(), src.data_type());
+
+    for(int i = 0; i < src.num_elements(); ++i)
+    {
+        Coordinates coord = index2coord(src.shape(), i);
+        const int   x     = coord.x();
+        const int   y     = coord.y();
+
+        std::array<T, 9> neighbours = { { 0 } };
+        for(int row = y - 1, j = 0; row <= y + 1; ++row)
+        {
+            for(int col = x - 1; col <= x + 1; ++col, ++j)
+            {
+                coord.set(0, col);
+                coord.set(1, row);
+                neighbours[j] = tensor_elem_at(src, coord, border_mode, constant_border_value);
+            }
+        }
+
+        dst[i] = *std::min_element(neighbours.cbegin(), neighbours.cend());
+    }
+
+    return dst;
+}
+
+template SimpleTensor<uint8_t> erode(const SimpleTensor<uint8_t> &src, BorderMode border_mode, uint8_t constant_border_value);
+} // namespace reference
+} // namespace validation
+} // namespace test
+} // namespace arm_compute
diff --git a/tests/validation/CPP/Erode.h b/tests/validation/CPP/Erode.h
new file mode 100644
index 0000000..5e27513
--- /dev/null
+++ b/tests/validation/CPP/Erode.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2017 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_TEST_ERODE_H__
+#define __ARM_COMPUTE_TEST_ERODE_H__
+
+#include "tests/SimpleTensor.h"
+
+namespace arm_compute
+{
+namespace test
+{
+namespace validation
+{
+namespace reference
+{
+template <typename T>
+SimpleTensor<T> erode(const SimpleTensor<T> &src, BorderMode border_mode, T constant_border_value = 0);
+} // namespace reference
+} // namespace validation
+} // namespace test
+} // namespace arm_compute
+#endif /* __ARM_COMPUTE_TEST_ERODE_H__ */