text: /**
   * By downloading, copying, installing or using the software you agree to this license.
   * If you do not agree to this license, do not download, install,
   * copy or use the software.
   *
   *
   *                           License Agreement
   *                For Open Source Computer Vision Library
   *                        (3-clause BSD License)
   *
   * Copyright (C) 2000-2020, Intel Corporation, all rights reserved.
   * Copyright (C) 2009-2011, Willow Garage Inc., all rights reserved.
   * Copyright (C) 2009-2016, NVIDIA Corporation, all rights reserved.
   * Copyright (C) 2010-2013, Advanced Micro Devices, Inc., all rights reserved.
   * Copyright (C) 2015-2016, OpenCV Foundation, all rights reserved.
   * Copyright (C) 2015-2016, Itseez Inc., all rights reserved.
   * Copyright (C) 2019-2020, Xperience AI, all rights reserved.
   * Third party copyrights are property of their respective owners.
   *
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   *
   *   * Redistributions of source code must retain the above copyright notice,
   *     this list of conditions and the following disclaimer.
   *
   *   * Redistributions in binary form must reproduce the above copyright notice,
   *     this list of conditions and the following disclaimer in the documentation
   *     and/or other materials provided with the distribution.
   *
   *   * Neither the names of the copyright holders nor the names of the contributors
   *     may be used to endorse or promote products derived from this software
   *     without specific prior written permission.
   *
   * This software is provided by the copyright holders and contributors "as is" and
   * any express or implied warranties, including, but not limited to, the implied
   * warranties of merchantability and fitness for a particular purpose are disclaimed.
   * In no event shall copyright holders or contributors be liable for any direct,
   * indirect, incidental, special, exemplary, or consequential damages
   * (including, but not limited to, procurement of substitute goods or services;
   * loss of use, data, or profits; or business interruption) however caused
   * and on any theory of liability, whether in contract, strict liability,
   * or tort (including negligence or otherwise) arising in any way out of
   * the use of this software, even if advised of the possibility of such damage.
   *
   * ---------------------------------------------------------------------------
   * \file dnn/src/common/cv/helper.h
   *
   * MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
   *
   * Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *
   * This file has been modified by Megvii ("Megvii Modifications").
   * All Megvii Modifications are Copyright (C) 2014-2021 Megvii Inc. All rights reserved.
   *
   * ---------------------------------------------------------------------------
   */
  
  #pragma once
  
  #include <cassert>
  #include <climits>
  #include <cmath>
  #include <cstddef>
  
  #include "./aligned_allocator.h"
  #include "./common.h"
  #include "src/common/utils.h"
  
  #include "megdnn/basic_types.h"
  #include "megdnn/opr_param_defs.h"
  
  #if defined(__SSE2__)
  #include <xmmintrin.h>
  #endif
  
  #define MegCVException(expr) \
      do {                     \
          megdnn_throw(#expr); \
      } while (0)
  
  namespace megdnn {
  
  namespace megcv {
  
  template <typename T>
  using AlignedVector = std::vector<T, ah::aligned_allocator<T, 16>>;
  
  static inline size_t align_size(size_t sz, int n) {
      megdnn_assert((n & (n - 1)) == 0);
      return (sz + n - 1) & -n;
  }
  
  static inline int clip(int x, int a, int b) {
      return x >= a ? (x < b ? x : b - 1) : a;
  }
  
  template <typename _Tp>
  static inline _Tp* align_ptr(_Tp* ptr, int n = (int)sizeof(_Tp)) {
      return (_Tp*)(((size_t)ptr + n - 1) & -n);
  }
  
  template <typename T>
  inline T saturate(T x, T lower, T upper) {
      return (x < lower ? lower : (x >= upper ? upper - 1 : x));
  }
  
  // common functions
  template <typename T>
  T modf(T x, T* iptr) {
      T ival;
      T rval(std::modf(x, &ival));
      *iptr = ival;
      return rval;
  }
  
  template <typename T>
  int round(T value) {
      T intpart, fractpart;
      fractpart = modf(value, &intpart);
      if ((fabs(fractpart) != 0.5) || ((((int)intpart) % 2) != 0))
          return (int)(value + (value >= 0 ? 0.5 : -0.5));
      else
          return (int)intpart;
  }
  template <typename DT, typename ST>
  static inline DT saturate_cast(ST x) {
      return x;
  }
  
  template <>
  inline unsigned char saturate_cast<unsigned char, int>(int x) {
      return (unsigned char)((unsigned)x <= UCHAR_MAX ? x : x > 0 ? UCHAR_MAX : 0);
  }
  
  template <>
  inline short saturate_cast<short, int>(int x) {
      return (short)((unsigned)(x - SHRT_MIN) <= (unsigned)USHRT_MAX
                             ? x
                             : x > 0 ? SHRT_MAX : SHRT_MIN);
  }
  
  template <typename ST>
  static inline int cv_round(ST value);
  
  template <>
  inline int cv_round<float>(float value) {
  #if defined(__SSE2__)
      __m128 t = _mm_set_ss(value);
      return _mm_cvtss_si32(t);
  #elif defined(__GNUC__)
      return (int)lrintf(value);
  #else
      /* it's ok if round does not comply with IEEE754 standard;
       the tests should allow +/-1 difference when the tested functions use round
     */
      return (int)(value + (value >= 0 ? 0.5f : -0.5f));
  #endif
  }
  
  template <>
  inline int cv_round<double>(double value) {
  #if defined(__SSE2__)
      __m128d t = _mm_set_sd(value);
      return _mm_cvtsd_si32(t);
  #elif defined(__GNUC__)
      return (int)lrint(value);
  #else
      /* it's ok if round does not comply with IEEE754 standard;
       the tests should allow +/-1 difference when the tested functions use round
     */
      return (int)(value + (value >= 0 ? 0.5f : -0.5f));
  #endif
  }
  
  template <>
  inline int saturate_cast<int, float>(float x) {
      return cv_round(x);
  }
  
  template <>
  inline short saturate_cast<short, float>(float x) {
      return saturate_cast<short, int>(saturate_cast<int, float>(x));
  }
  
  template <>
  inline int saturate_cast<int, double>(double x) {
      return cv_round(x);
  }
  
  template <typename ST, typename DT, int bits>
  struct FixedPtCast {
      typedef ST type1;
      typedef DT rtype;
      enum { SHIFT = bits, DELTA = 1 << (bits - 1) };
  
      DT operator()(ST val) const { return saturate_cast<DT>((val + DELTA) >> SHIFT); }
  };
  
  template <typename ST, typename DT>
  struct FixedPtCastEx {
      typedef ST type1;
      typedef DT rtype;
  
      FixedPtCastEx() : SHIFT(0), DELTA(0) {}
      FixedPtCastEx(int bits) : SHIFT(bits), DELTA(bits ? 1 << (bits - 1) : 0) {}
      DT operator()(ST val) const { return saturate_cast<DT>(val + DELTA); }
      int SHIFT, DELTA;
  };
  
  template <>
  struct FixedPtCastEx<int, uchar> {
      typedef int type1;
      typedef uchar rtype;
  
      FixedPtCastEx() : SHIFT(0), DELTA(0) {}
      FixedPtCastEx(int bits) : SHIFT(bits), DELTA(bits ? 1 << (bits - 1) : 0) {}
      uchar operator()(int val) const {
          return saturate_cast<uchar>((val + DELTA) >> SHIFT);
      }
      int SHIFT, DELTA;
  };
  
  template <typename ST, typename DT>
  struct Cast {
      typedef ST type1;
      typedef DT rtype;
  
      DT operator()(ST val) const { return saturate_cast<DT>(val); }
  };
  
  template <param::WarpPerspective::BorderMode bmode>
  static inline int border_interpolate(int p, int len) {
      using BorderMode = param::WarpPerspective::BorderMode;
      if ((unsigned)p < (unsigned)len)
          ;
      else if (bmode == BorderMode::BORDER_REPLICATE)
          p = p < 0 ? 0 : len - 1;
      else if (
              bmode == BorderMode::BORDER_REFLECT ||
              bmode == BorderMode::BORDER_REFLECT_101) {
          int delta = (bmode == BorderMode::BORDER_REFLECT_101);
          if (len == 1)
              return 0;
          do {
              if (p < 0)
                  p = -p - 1 + delta;
              else
                  p = len - 1 - (p - len) - delta;
          } while ((unsigned)p >= (unsigned)len);
      } else if (bmode == BorderMode::BORDER_WRAP) {
          if (p < 0)
              p -= ((p - len + 1) / len) * len;
          while (p >= len) {
              p -= len;
          }
      } else if (
              bmode == BorderMode::BORDER_CONSTANT ||
              bmode == BorderMode::BORDER_TRANSPARENT)
          p = -1;
      else
          megdnn_throw("Unknown/unsupported border type");
      return p;
  }
  
  namespace gaussian_blur {
  
  using BorderMode = param::GaussianBlur::BorderMode;
  
  #include "./bordermode-inl.h"
  
  }  // namespace gaussian_blur
  
  }  // namespace megcv
  }  // namespace megdnn
  
  // vim: syntax=cpp.doxygen
  