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. Get(unsigned int container)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. MakeValue(unsigned int value)28 static unsigned int MakeValue(unsigned int value) { 29 return (value & kMask) << kShift; 30 } 31 32 // Changes the value of this field. Set(unsigned int * container,unsigned int field_value)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_ 41