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// Copyright 2011 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 V8_BASE_MEMORY_H_
#define V8_BASE_MEMORY_H_
#include "src/base/macros.h"
namespace v8 {
namespace base {
using Address = uintptr_t;
using byte = uint8_t;
// Memory provides an interface to 'raw' memory. It encapsulates the casts
// that typically are needed when incompatible pointer types are used.
// Note that this class currently relies on undefined behaviour. There is a
// proposal (http://wg21.link/p0593r2) to make it defined behaviour though.
template <class T>
inline T& Memory(Address addr) {
DCHECK(IsAligned(addr, alignof(T)));
return *reinterpret_cast<T*>(addr);
}
template <class T>
inline T& Memory(byte* addr) {
return Memory<T>(reinterpret_cast<Address>(addr));
}
template <typename V>
static inline V ReadUnalignedValue(Address p) {
ASSERT_TRIVIALLY_COPYABLE(V);
V r;
memcpy(&r, reinterpret_cast<void*>(p), sizeof(V));
return r;
}
template <typename V>
static inline void WriteUnalignedValue(Address p, V value) {
ASSERT_TRIVIALLY_COPYABLE(V);
memcpy(reinterpret_cast<void*>(p), &value, sizeof(V));
}
template <typename V>
static inline V ReadLittleEndianValue(Address p) {
#if defined(V8_TARGET_LITTLE_ENDIAN)
return ReadUnalignedValue<V>(p);
#elif defined(V8_TARGET_BIG_ENDIAN)
V ret{};
const byte* src = reinterpret_cast<const byte*>(p);
byte* dst = reinterpret_cast<byte*>(&ret);
for (size_t i = 0; i < sizeof(V); i++) {
dst[i] = src[sizeof(V) - i - 1];
}
return ret;
#endif // V8_TARGET_LITTLE_ENDIAN
}
template <typename V>
static inline void WriteLittleEndianValue(Address p, V value) {
#if defined(V8_TARGET_LITTLE_ENDIAN)
WriteUnalignedValue<V>(p, value);
#elif defined(V8_TARGET_BIG_ENDIAN)
byte* src = reinterpret_cast<byte*>(&value);
byte* dst = reinterpret_cast<byte*>(p);
for (size_t i = 0; i < sizeof(V); i++) {
dst[i] = src[sizeof(V) - i - 1];
}
#endif // V8_TARGET_LITTLE_ENDIAN
}
template <typename V>
static inline V ReadLittleEndianValue(V* p) {
return ReadLittleEndianValue<V>(reinterpret_cast<Address>(p));
}
template <typename V>
static inline void WriteLittleEndianValue(V* p, V value) {
WriteLittleEndianValue<V>(reinterpret_cast<Address>(p), value);
}
} // namespace base
} // namespace v8
#endif // V8_BASE_MEMORY_H_
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