From 5959fd1bde3e1b04c0197138b512460070fb840d Mon Sep 17 00:00:00 2001
From: =?utf8?q?=EB=B0=95=EC=A2=85=ED=98=84/=EB=8F=99=EC=9E=91=EC=A0=9C?=
 =?utf8?q?=EC=96=B4Lab=28SR=29/Senior=20Engineer/=EC=82=BC=EC=84=B1?=
 =?utf8?q?=EC=A0=84=EC=9E=90?= <jh1302.park@samsung.com>
Date: Mon, 9 Apr 2018 11:28:58 +0900
Subject: [PATCH] Introduce tensor::NonIncreasingStride (#499)

This commit extracts stride-related code from TensorView in nnfw::support::tflite
as NonIncreasingStride utility class (in nnfw::util::tensor).

Signed-off-by: Jonghyun Park <jh1302.park@samsung.com>
---
 include/support/tflite/TensorView.h         |  6 ++---
 include/util/tensor/NonIncreasingStride.h   | 42 +++++++++++++++++++++++++++++
 src/support/tflite/src/TensorView.cpp       | 26 +++---------------
 src/util/CMakeLists.txt                     |  1 +
 src/util/src/tensor/NonIncreasingStride.cpp | 30 +++++++++++++++++++++
 5 files changed, 78 insertions(+), 27 deletions(-)
 create mode 100644 include/util/tensor/NonIncreasingStride.h
 create mode 100644 src/util/src/tensor/NonIncreasingStride.cpp

diff --git a/include/support/tflite/TensorView.h b/include/support/tflite/TensorView.h
index 8aeb325..18de5df 100644
--- a/include/support/tflite/TensorView.h
+++ b/include/support/tflite/TensorView.h
@@ -6,6 +6,7 @@
 #include "util/tensor/Shape.h"
 #include "util/tensor/Index.h"
 #include "util/tensor/Reader.h"
+#include "util/tensor/NonIncreasingStride.h"
 
 namespace nnfw
 {
@@ -29,14 +30,11 @@ public:
   float &at(const nnfw::util::tensor::Index &index);
 
 private:
-  uint32_t offsetOf(const nnfw::util::tensor::Index &index) const;
-
-private:
   nnfw::util::tensor::Shape _shape;
 
 public:
   float *_base;
-  std::vector<uint32_t> _stride;
+  nnfw::util::tensor::NonIncreasingStride _stride;
 
 public:
   // TODO Introduce Operand ID class
diff --git a/include/util/tensor/NonIncreasingStride.h b/include/util/tensor/NonIncreasingStride.h
new file mode 100644
index 0000000..30a5c1e
--- /dev/null
+++ b/include/util/tensor/NonIncreasingStride.h
@@ -0,0 +1,42 @@
+#ifndef __NNFW_UTIL_TENSOR_NON_INCREASING_STRIDE_H__
+#define __NNFW_UTIL_TENSOR_NON_INCREASING_STRIDE_H__
+
+#include "util/tensor/Shape.h"
+#include "util/tensor/Index.h"
+
+#include <vector>
+
+namespace nnfw
+{
+namespace util
+{
+namespace tensor
+{
+
+// As its name suggests, stride[N-1] >= stride[N] holds for all N < rank in NonIncreasingStride.
+class NonIncreasingStride
+{
+public:
+  void init(const Shape &shape)
+  {
+    _stride.resize(shape.rank());
+    _stride.at(shape.rank() - 1) = 1;
+
+    for (uint32_t axis = shape.rank() - 1; axis > 0; --axis)
+    {
+      _stride.at(axis - 1) = _stride.at(axis) * shape.dim(axis);
+    }
+  }
+
+public:
+  uint32_t offset(const Index &index) const;
+
+private:
+  std::vector<uint32_t> _stride;
+};
+
+} // namespace tensor
+} // namespace util
+} // namespace nnfw
+
+#endif // __NNFW_UTIL_TENSOR_NON_INCREASING_STRIDE_H__
diff --git a/src/support/tflite/src/TensorView.cpp b/src/support/tflite/src/TensorView.cpp
index 18acfe6..774d0cf 100644
--- a/src/support/tflite/src/TensorView.cpp
+++ b/src/support/tflite/src/TensorView.cpp
@@ -12,39 +12,19 @@ namespace tflite
 TensorView<float>::TensorView(const nnfw::util::tensor::Shape &shape, float *base) : _shape{shape}, _base{base}
 {
   // Set 'stride'
-  _stride.resize(_shape.rank());
-  _stride.at(_shape.rank() - 1) = 1;
-
-  for (uint32_t axis = _shape.rank() - 1; axis > 0; --axis)
-  {
-    _stride.at(axis - 1) = _stride.at(axis) * _shape.dim(axis);
-  }
-}
-
-uint32_t TensorView<float>::offsetOf(const nnfw::util::tensor::Index &index) const
-{
-  assert(index.rank() == _shape.rank());
-
-  uint32_t offset = 0;
-
-  for (size_t axis = 0; axis < _shape.rank(); ++axis)
-  {
-    offset += _stride.at(axis) * index.at(axis);
-  }
-
-  return offset;
+  _stride.init(_shape);
 }
 
 float TensorView<float>::at(const nnfw::util::tensor::Index &index) const
 {
-  const auto offset = offsetOf(index);
+  const auto offset = _stride.offset(index);
 
   return *(_base + offset);
 }
 
 float &TensorView<float>::at(const nnfw::util::tensor::Index &index)
 {
-  const auto offset = offsetOf(index);
+  const auto offset = _stride.offset(index);
 
   return *(_base + offset);
 }
diff --git a/src/util/CMakeLists.txt b/src/util/CMakeLists.txt
index 97ab891..046f01d 100644
--- a/src/util/CMakeLists.txt
+++ b/src/util/CMakeLists.txt
@@ -1,6 +1,7 @@
 # Library `nnfw_util`
 set(NNFW_UTILITY_SRCS src/environment.cpp)
 list(APPEND NNFW_UTILITY_SRCS src/tensor/Shape.cpp)
+list(APPEND NNFW_UTILITY_SRCS src/tensor/NonIncreasingStride.cpp)
 
 set(NNFW_INCLUDE_DIR ${CMAKE_SOURCE_DIR}/include)
 
diff --git a/src/util/src/tensor/NonIncreasingStride.cpp b/src/util/src/tensor/NonIncreasingStride.cpp
new file mode 100644
index 0000000..54b6f41
--- /dev/null
+++ b/src/util/src/tensor/NonIncreasingStride.cpp
@@ -0,0 +1,30 @@
+#include "util/tensor/NonIncreasingStride.h"
+
+#include <cassert>
+
+namespace nnfw
+{
+namespace util
+{
+namespace tensor
+{
+
+uint32_t NonIncreasingStride::offset(const Index &index) const
+{
+  const size_t rank = _stride.size();
+
+  assert(index.rank() == rank);
+
+  uint32_t offset = 0;
+
+  for (size_t axis = 0; axis < rank; ++axis)
+  {
+    offset += _stride.at(axis) * index.at(axis);
+  }
+
+  return offset;
+}
+
+} // namespace tensor
+} // namespace util
+} // namespace nnfw
-- 
2.7.4