text: //
  // Copyright (c) 2013 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  
  // IndexRangeCache.cpp: Defines the rx::IndexRangeCache class which stores information about
  // ranges of indices.
  
  #include "libGLESv2/renderer/IndexRangeCache.h"
  #include "libGLESv2/formatutils.h"
  
  #include "common/debug.h"
  
  #include <tuple>
  
  namespace rx
  {
  
  template <class IndexType>
  static RangeUI ComputeTypedRange(const IndexType *indices, GLsizei count)
  {
      unsigned int minIndex = indices[0];
      unsigned int maxIndex = indices[0];
  
      for (GLsizei i = 1; i < count; i++)
      {
          if (minIndex > indices[i]) minIndex = indices[i];
          if (maxIndex < indices[i]) maxIndex = indices[i];
      }
  
      return RangeUI(minIndex, maxIndex);
  }
  
  RangeUI IndexRangeCache::ComputeRange(GLenum type, const GLvoid *indices, GLsizei count)
  {
      switch (type)
      {
        case GL_UNSIGNED_BYTE:
          return ComputeTypedRange(static_cast<const GLubyte*>(indices), count);
        case GL_UNSIGNED_INT:
          return ComputeTypedRange(static_cast<const GLuint*>(indices), count);
        case GL_UNSIGNED_SHORT:
          return ComputeTypedRange(static_cast<const GLushort*>(indices), count);
        default:
          UNREACHABLE();
          return RangeUI();
      }
  }
  
  void IndexRangeCache::addRange(GLenum type, unsigned int offset, GLsizei count, const RangeUI &range,
                                 unsigned int streamOffset)
  {
      mIndexRangeCache[IndexRange(type, offset, count)] = IndexBounds(range, streamOffset);
  }
  
  void IndexRangeCache::invalidateRange(unsigned int offset, unsigned int size)
  {
      unsigned int invalidateStart = offset;
      unsigned int invalidateEnd = offset + size;
  
      IndexRangeMap::iterator i = mIndexRangeCache.begin();
      while (i != mIndexRangeCache.end())
      {
          unsigned int rangeStart = i->second.streamOffset;
          unsigned int rangeEnd = i->second.streamOffset + (gl::GetTypeInfo(i->first.type).bytes * i->first.count);
  
          if (invalidateEnd < rangeStart || invalidateStart > rangeEnd)
          {
              ++i;
          }
          else
          {
              i = mIndexRangeCache.erase(i);
          }
      }
  }
  
  bool IndexRangeCache::findRange(GLenum type, unsigned int offset, GLsizei count,
                                  RangeUI *outRange, unsigned int *outStreamOffset) const
  {
      IndexRangeMap::const_iterator i = mIndexRangeCache.find(IndexRange(type, offset, count));
      if (i != mIndexRangeCache.end())
      {
          if (outRange)        *outRange = i->second.range;
          if (outStreamOffset) *outStreamOffset = i->second.streamOffset;
          return true;
      }
      else
      {
          if (outRange)        *outRange = RangeUI(0, 0);
          if (outStreamOffset) *outStreamOffset = 0;
          return false;
      }
  }
  
  void IndexRangeCache::clear()
  {
      mIndexRangeCache.clear();
  }
  
  IndexRangeCache::IndexRange::IndexRange()
      : type(GL_NONE), offset(0), count(0)
  {
  }
  
  IndexRangeCache::IndexRange::IndexRange(GLenum typ, intptr_t off, GLsizei c)
      : type(typ), offset(off), count(c)
  {
  }
  
  bool IndexRangeCache::IndexRange::operator<(const IndexRange& rhs) const
  {
      return std::make_tuple(type, offset, count) < std::make_tuple(rhs.type, rhs.offset, rhs.count);
  }
  
  IndexRangeCache::IndexBounds::IndexBounds()
      : range(0, 0),
        streamOffset(0)
  {
  }
  
  IndexRangeCache::IndexBounds::IndexBounds(const RangeUI &rangeIn, unsigned int offset)
      : range(rangeIn), streamOffset(offset)
  {
  }
  
  }
  