gpu/command_buffer/common/bitfield_helpers.h

   1 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This file contains a helper template class used to access bit fields in
   6 // unsigned int_ts.
   7
   8 #ifndef GPU_COMMAND_BUFFER_COMMON_BITFIELD_HELPERS_H_
   9 #define GPU_COMMAND_BUFFER_COMMON_BITFIELD_HELPERS_H_
  10
  11 namespace gpu {
  12
  13 // Bitfield template class, used to access bit fields in unsigned int_ts.
  14 template<int shift, int length> class BitField {
  15  public:
  16   static const unsigned int kShift = shift;
  17   static const unsigned int kLength = length;
  18   // the following is really (1<<length)-1 but also work for length == 32
  19   // without compiler warning.
  20   static const unsigned int kMask = 1U + ((1U << (length-1)) - 1U) * 2U;
  21
  22   // Gets the value contained in this field.
  23   static unsigned int Get(unsigned int container) {
  24     return (container >> kShift) & kMask;
  25   }
  26
  27   // Makes a value that can be or-ed into this field.
  28   static unsigned int MakeValue(unsigned int value) {
  29     return (value & kMask) << kShift;
  30   }
  31
  32   // Changes the value of this field.
  33   static void Set(unsigned int *container, unsigned int field_value) {
  34     *container = (*container & ~(kMask << kShift)) | MakeValue(field_value);
  35   }
  36 };
  37
  38 }  // namespace gpu
  39
  40 #endif  // GPU_COMMAND_BUFFER_COMMON_BITFIELD_HELPERS_H_