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