| // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| #ifndef VM_BOOLFIELD_H_ |
| #define VM_BOOLFIELD_H_ |
| |
| #include "vm/globals.h" |
| |
| namespace dart { |
| |
| // BoolField is a template for encoding and decoding a bit inside an |
| // unsigned machine word. |
| template<int position> |
| class BoolField { |
| public: |
| // Returns a uword with the bool value encoded. |
| static uword encode(bool value) { |
| ASSERT(position < sizeof(uword)); |
| return static_cast<uword>((value ? 1U : 0) << position); |
| } |
| |
| // Extracts the bool from the value. |
| static bool decode(uword value) { |
| ASSERT(position < sizeof(uword)); |
| return (value & (1U << position)) != 0; |
| } |
| |
| // Returns a uword with the bool field value encoded based on the |
| // original value. Only the single bit corresponding to this bool |
| // field will be changed. |
| static uword update(bool value, uword original) { |
| ASSERT(position < sizeof(uword)); |
| const uword mask = 1U << position; |
| return value ? original | mask : original & ~mask; |
| } |
| }; |
| |
| } // namespace dart |
| |
| #endif // VM_BOOLFIELD_H_ |