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// 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_