api-constants.h

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// Copyright 2020 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_
#define INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_
 
#include <stddef.h>
#include <stdint.h>
 
#include "v8config.h"              // NOLINT(build/include_directory)
 
namespace cppgc {
namespace internal {
 
// Embedders should not rely on this code!
 
// Internal constants to avoid exposing internal types on the API surface.
namespace api_constants {
// Offset of the uint16_t bitfield from the payload contaning the
// in-construction bit. This is subtracted from the payload pointer to get
// to the right bitfield.
static constexpr size_t kFullyConstructedBitFieldOffsetFromPayload =
    2 * sizeof(uint16_t);
// Mask for in-construction bit.
static constexpr size_t kFullyConstructedBitMask = size_t{1};
 
// Page constants used to align pointers to page begin.
static constexpr size_t kPageSize = size_t{1} << 17;
static constexpr size_t kPageAlignment = kPageSize;
static constexpr size_t kPageBaseMask = ~(kPageAlignment - 1);
static constexpr size_t kGuardPageSize = 4096;
 
// Offset of the Heap backref.
static constexpr size_t kHeapOffset = 0;
 
static constexpr size_t kLargeObjectSizeThreshold = kPageSize / 2;
 
}  // namespace api_constants
 
}  // namespace internal
}  // namespace cppgc
 
#endif  // INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_