mirror of
https://github.com/classilla/tenfourfox.git
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698 lines
19 KiB
C++
698 lines
19 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* Functions for reading and writing integers in various endiannesses. */
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/*
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* The classes LittleEndian and BigEndian expose static methods for
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* reading and writing 16-, 32-, and 64-bit signed and unsigned integers
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* in their respective endianness. The naming scheme is:
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*
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* {Little,Big}Endian::{read,write}{Uint,Int}<bitsize>
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*
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* For instance, LittleEndian::readInt32 will read a 32-bit signed
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* integer from memory in little endian format. Similarly,
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* BigEndian::writeUint16 will write a 16-bit unsigned integer to memory
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* in big-endian format.
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*
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* The class NativeEndian exposes methods for conversion of existing
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* data to and from the native endianness. These methods are intended
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* for cases where data needs to be transferred, serialized, etc.
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* swap{To,From}{Little,Big}Endian byteswap a single value if necessary.
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* Bulk conversion functions are also provided which optimize the
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* no-conversion-needed case:
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*
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* - copyAndSwap{To,From}{Little,Big}Endian;
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* - swap{To,From}{Little,Big}EndianInPlace.
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*
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* The *From* variants are intended to be used for reading data and the
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* *To* variants for writing data.
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*
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* Methods on NativeEndian work with integer data of any type.
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* Floating-point data is not supported.
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*
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* For clarity in networking code, "Network" may be used as a synonym
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* for "Big" in any of the above methods or class names.
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*
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* As an example, reading a file format header whose fields are stored
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* in big-endian format might look like:
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*
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* class ExampleHeader
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* {
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* private:
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* uint32_t mMagic;
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* uint32_t mLength;
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* uint32_t mTotalRecords;
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* uint64_t mChecksum;
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*
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* public:
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* ExampleHeader(const void* data)
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* {
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* const uint8_t* ptr = static_cast<const uint8_t*>(data);
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* mMagic = BigEndian::readUint32(ptr); ptr += sizeof(uint32_t);
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* mLength = BigEndian::readUint32(ptr); ptr += sizeof(uint32_t);
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* mTotalRecords = BigEndian::readUint32(ptr); ptr += sizeof(uint32_t);
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* mChecksum = BigEndian::readUint64(ptr);
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* }
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* ...
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* };
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*/
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#ifndef mozilla_Endian_h
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#define mozilla_Endian_h
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#include "mozilla/Assertions.h"
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#include "mozilla/Attributes.h"
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#include "mozilla/Compiler.h"
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#include "mozilla/DebugOnly.h"
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#include "mozilla/TypeTraits.h"
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#include <stdint.h>
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#include <string.h>
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#if defined(_MSC_VER)
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# include <stdlib.h>
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# pragma intrinsic(_byteswap_ushort)
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# pragma intrinsic(_byteswap_ulong)
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# pragma intrinsic(_byteswap_uint64)
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#endif
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#if defined(_WIN64)
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# if defined(_M_X64) || defined(_M_AMD64) || defined(_AMD64_)
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# define MOZ_LITTLE_ENDIAN 1
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# else
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# error "CPU type is unknown"
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# endif
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#elif defined(_WIN32)
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# if defined(_M_IX86)
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# define MOZ_LITTLE_ENDIAN 1
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# elif defined(_M_ARM)
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# define MOZ_LITTLE_ENDIAN 1
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# else
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# error "CPU type is unknown"
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# endif
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#elif defined(__APPLE__) || defined(__powerpc__) || defined(__ppc__)
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# if __LITTLE_ENDIAN__
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# define MOZ_LITTLE_ENDIAN 1
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# elif __BIG_ENDIAN__
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# define MOZ_BIG_ENDIAN 1
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# endif
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#elif defined(__GNUC__) && \
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defined(__BYTE_ORDER__) && \
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defined(__ORDER_LITTLE_ENDIAN__) && \
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defined(__ORDER_BIG_ENDIAN__)
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/*
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* Some versions of GCC provide architecture-independent macros for
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* this. Yes, there are more than two values for __BYTE_ORDER__.
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*/
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# if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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# define MOZ_LITTLE_ENDIAN 1
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# elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
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# define MOZ_BIG_ENDIAN 1
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# else
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# error "Can't handle mixed-endian architectures"
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# endif
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/*
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* We can't include useful headers like <endian.h> or <sys/isa_defs.h>
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* here because they're not present on all platforms. Instead we have
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* this big conditional that ideally will catch all the interesting
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* cases.
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*/
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#elif defined(__sparc) || defined(__sparc__) || \
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defined(_POWER) || defined(__hppa) || \
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defined(_MIPSEB) || defined(__ARMEB__) || \
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defined(__s390__) || defined(__AARCH64EB__) || \
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(defined(__sh__) && defined(__LITTLE_ENDIAN__)) || \
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(defined(__ia64) && defined(__BIG_ENDIAN__))
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# define MOZ_BIG_ENDIAN 1
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#elif defined(__i386) || defined(__i386__) || \
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defined(__x86_64) || defined(__x86_64__) || \
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defined(_MIPSEL) || defined(__ARMEL__) || \
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defined(__alpha__) || defined(__AARCH64EL__) || \
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(defined(__sh__) && defined(__BIG_ENDIAN__)) || \
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(defined(__ia64) && !defined(__BIG_ENDIAN__))
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# define MOZ_LITTLE_ENDIAN 1
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#endif
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#if MOZ_BIG_ENDIAN
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# define MOZ_LITTLE_ENDIAN 0
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#elif MOZ_LITTLE_ENDIAN
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# define MOZ_BIG_ENDIAN 0
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#else
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# error "Cannot determine endianness"
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#endif
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#if defined(__clang__)
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# if __has_builtin(__builtin_bswap16)
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# define MOZ_HAVE_BUILTIN_BYTESWAP16 __builtin_bswap16
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# endif
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#elif defined(__GNUC__)
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# if MOZ_GCC_VERSION_AT_LEAST(4, 8, 0)
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# define MOZ_HAVE_BUILTIN_BYTESWAP16 __builtin_bswap16
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# endif
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#elif defined(_MSC_VER)
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# define MOZ_HAVE_BUILTIN_BYTESWAP16 _byteswap_ushort
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#endif
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namespace mozilla {
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namespace detail {
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/*
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* We need wrappers here because free functions with default template
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* arguments and/or partial specialization of function templates are not
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* supported by all the compilers we use.
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*/
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template<typename T, size_t Size = sizeof(T)>
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struct Swapper;
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template<typename T>
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struct Swapper<T, 2>
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{
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static T swap(T aValue)
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{
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#if defined(MOZ_HAVE_BUILTIN_BYTESWAP16)
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return MOZ_HAVE_BUILTIN_BYTESWAP16(aValue);
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#else
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return T(((aValue & 0x00ff) << 8) | ((aValue & 0xff00) >> 8));
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#endif
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}
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};
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template<typename T>
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struct Swapper<T, 4>
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{
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static T swap(T aValue)
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{
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#if defined(__clang__) || defined(__GNUC__)
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return T(__builtin_bswap32(aValue));
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#elif defined(_MSC_VER)
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return T(_byteswap_ulong(aValue));
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#else
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return T(((aValue & 0x000000ffU) << 24) |
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((aValue & 0x0000ff00U) << 8) |
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((aValue & 0x00ff0000U) >> 8) |
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((aValue & 0xff000000U) >> 24));
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#endif
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}
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};
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template<typename T>
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struct Swapper<T, 8>
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{
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static inline T swap(T aValue)
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{
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#if defined(__clang__) || defined(__GNUC__)
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return T(__builtin_bswap64(aValue));
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#elif defined(_MSC_VER)
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return T(_byteswap_uint64(aValue));
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#else
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return T(((aValue & 0x00000000000000ffULL) << 56) |
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((aValue & 0x000000000000ff00ULL) << 40) |
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((aValue & 0x0000000000ff0000ULL) << 24) |
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((aValue & 0x00000000ff000000ULL) << 8) |
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((aValue & 0x000000ff00000000ULL) >> 8) |
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((aValue & 0x0000ff0000000000ULL) >> 24) |
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((aValue & 0x00ff000000000000ULL) >> 40) |
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((aValue & 0xff00000000000000ULL) >> 56));
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#endif
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}
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};
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enum Endianness { Little, Big };
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#if MOZ_BIG_ENDIAN
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# define MOZ_NATIVE_ENDIANNESS detail::Big
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#else
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# define MOZ_NATIVE_ENDIANNESS detail::Little
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#endif
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class EndianUtils
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{
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/**
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* Assert that the memory regions [aDest, aDest+aCount) and
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* [aSrc, aSrc+aCount] do not overlap. aCount is given in bytes.
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*/
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static void assertNoOverlap(const void* aDest, const void* aSrc,
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size_t aCount)
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{
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DebugOnly<const uint8_t*> byteDestPtr = static_cast<const uint8_t*>(aDest);
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DebugOnly<const uint8_t*> byteSrcPtr = static_cast<const uint8_t*>(aSrc);
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MOZ_ASSERT((byteDestPtr <= byteSrcPtr &&
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byteDestPtr + aCount <= byteSrcPtr) ||
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(byteSrcPtr <= byteDestPtr &&
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byteSrcPtr + aCount <= byteDestPtr));
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}
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template<typename T>
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static void assertAligned(T* aPtr)
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{
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MOZ_ASSERT((uintptr_t(aPtr) % sizeof(T)) == 0, "Unaligned pointer!");
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}
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protected:
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/**
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* Return |aValue| converted from SourceEndian encoding to DestEndian
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* encoding.
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*/
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template<Endianness SourceEndian, Endianness DestEndian, typename T>
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static inline T maybeSwap(T aValue)
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{
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if (SourceEndian == DestEndian) {
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return aValue;
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}
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return Swapper<T>::swap(aValue);
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}
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/**
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* Convert |aCount| elements at |aPtr| from SourceEndian encoding to
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* DestEndian encoding.
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*/
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template<Endianness SourceEndian, Endianness DestEndian, typename T>
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static inline void maybeSwapInPlace(T* aPtr, size_t aCount)
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{
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assertAligned(aPtr);
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if (SourceEndian == DestEndian) {
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return;
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}
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for (size_t i = 0; i < aCount; i++) {
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aPtr[i] = Swapper<T>::swap(aPtr[i]);
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}
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}
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/**
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* Write |aCount| elements to the unaligned address |aDest| in DestEndian
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* format, using elements found at |aSrc| in SourceEndian format.
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*/
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template<Endianness SourceEndian, Endianness DestEndian, typename T>
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static void copyAndSwapTo(void* aDest, const T* aSrc, size_t aCount)
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{
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assertNoOverlap(aDest, aSrc, aCount * sizeof(T));
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assertAligned(aSrc);
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if (SourceEndian == DestEndian) {
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memcpy(aDest, aSrc, aCount * sizeof(T));
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return;
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}
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uint8_t* byteDestPtr = static_cast<uint8_t*>(aDest);
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for (size_t i = 0; i < aCount; ++i) {
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union
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{
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T mVal;
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uint8_t mBuffer[sizeof(T)];
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} u;
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u.mVal = maybeSwap<SourceEndian, DestEndian>(aSrc[i]);
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memcpy(byteDestPtr, u.mBuffer, sizeof(T));
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byteDestPtr += sizeof(T);
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}
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}
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/**
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* Write |aCount| elements to |aDest| in DestEndian format, using elements
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* found at the unaligned address |aSrc| in SourceEndian format.
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*/
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template<Endianness SourceEndian, Endianness DestEndian, typename T>
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static void copyAndSwapFrom(T* aDest, const void* aSrc, size_t aCount)
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{
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assertNoOverlap(aDest, aSrc, aCount * sizeof(T));
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assertAligned(aDest);
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if (SourceEndian == DestEndian) {
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memcpy(aDest, aSrc, aCount * sizeof(T));
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return;
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}
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const uint8_t* byteSrcPtr = static_cast<const uint8_t*>(aSrc);
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for (size_t i = 0; i < aCount; ++i) {
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union
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{
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T mVal;
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uint8_t mBuffer[sizeof(T)];
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} u;
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memcpy(u.mBuffer, byteSrcPtr, sizeof(T));
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aDest[i] = maybeSwap<SourceEndian, DestEndian>(u.mVal);
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byteSrcPtr += sizeof(T);
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}
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}
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};
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template<Endianness ThisEndian>
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class Endian : private EndianUtils
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{
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protected:
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/** Read a uint16_t in ThisEndian endianness from |aPtr| and return it. */
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static MOZ_WARN_UNUSED_RESULT uint16_t readUint16(const void* aPtr)
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{
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return read<uint16_t>(aPtr);
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}
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/** Read a uint32_t in ThisEndian endianness from |aPtr| and return it. */
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static MOZ_WARN_UNUSED_RESULT uint32_t readUint32(const void* aPtr)
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{
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return read<uint32_t>(aPtr);
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}
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/** Read a uint64_t in ThisEndian endianness from |aPtr| and return it. */
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static MOZ_WARN_UNUSED_RESULT uint64_t readUint64(const void* aPtr)
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{
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return read<uint64_t>(aPtr);
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}
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/** Read an int16_t in ThisEndian endianness from |aPtr| and return it. */
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static MOZ_WARN_UNUSED_RESULT int16_t readInt16(const void* aPtr)
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{
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return read<int16_t>(aPtr);
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}
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/** Read an int32_t in ThisEndian endianness from |aPtr| and return it. */
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static MOZ_WARN_UNUSED_RESULT int32_t readInt32(const void* aPtr)
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{
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return read<uint32_t>(aPtr);
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}
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/** Read an int64_t in ThisEndian endianness from |aPtr| and return it. */
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static MOZ_WARN_UNUSED_RESULT int64_t readInt64(const void* aPtr)
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{
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return read<int64_t>(aPtr);
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}
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/** Write |aValue| to |aPtr| using ThisEndian endianness. */
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static void writeUint16(void* aPtr, uint16_t aValue)
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{
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write(aPtr, aValue);
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}
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/** Write |aValue| to |aPtr| using ThisEndian endianness. */
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static void writeUint32(void* aPtr, uint32_t aValue)
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{
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write(aPtr, aValue);
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}
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/** Write |aValue| to |aPtr| using ThisEndian endianness. */
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static void writeUint64(void* aPtr, uint64_t aValue)
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{
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write(aPtr, aValue);
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}
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/** Write |aValue| to |aPtr| using ThisEndian endianness. */
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static void writeInt16(void* aPtr, int16_t aValue)
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{
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write(aPtr, aValue);
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}
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/** Write |aValue| to |aPtr| using ThisEndian endianness. */
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static void writeInt32(void* aPtr, int32_t aValue)
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{
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write(aPtr, aValue);
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}
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/** Write |aValue| to |aPtr| using ThisEndian endianness. */
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static void writeInt64(void* aPtr, int64_t aValue)
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{
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write(aPtr, aValue);
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}
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/*
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* Converts a value of type T to little-endian format.
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*
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* This function is intended for cases where you have data in your
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* native-endian format and you need it to appear in little-endian
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* format for transmission.
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*/
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template<typename T>
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MOZ_WARN_UNUSED_RESULT static T swapToLittleEndian(T aValue)
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{
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return maybeSwap<ThisEndian, Little>(aValue);
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}
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/*
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* Copies |aCount| values of type T starting at |aSrc| to |aDest|, converting
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* them to little-endian format if ThisEndian is Big.
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* As with memcpy, |aDest| and |aSrc| must not overlap.
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*/
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template<typename T>
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static void copyAndSwapToLittleEndian(void* aDest, const T* aSrc,
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size_t aCount)
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{
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copyAndSwapTo<ThisEndian, Little>(aDest, aSrc, aCount);
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}
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/*
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* Likewise, but converts values in place.
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*/
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template<typename T>
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static void swapToLittleEndianInPlace(T* aPtr, size_t aCount)
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{
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maybeSwapInPlace<ThisEndian, Little>(aPtr, aCount);
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}
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/*
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* Converts a value of type T to big-endian format.
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*/
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template<typename T>
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MOZ_WARN_UNUSED_RESULT static T swapToBigEndian(T aValue)
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{
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return maybeSwap<ThisEndian, Big>(aValue);
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}
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/*
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* Copies |aCount| values of type T starting at |aSrc| to |aDest|, converting
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* them to big-endian format if ThisEndian is Little.
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* As with memcpy, |aDest| and |aSrc| must not overlap.
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*/
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template<typename T>
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static void copyAndSwapToBigEndian(void* aDest, const T* aSrc,
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size_t aCount)
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{
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copyAndSwapTo<ThisEndian, Big>(aDest, aSrc, aCount);
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}
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/*
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* Likewise, but converts values in place.
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*/
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template<typename T>
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static void swapToBigEndianInPlace(T* aPtr, size_t aCount)
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{
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maybeSwapInPlace<ThisEndian, Big>(aPtr, aCount);
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}
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/*
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* Synonyms for the big-endian functions, for better readability
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* in network code.
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*/
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template<typename T>
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MOZ_WARN_UNUSED_RESULT static T swapToNetworkOrder(T aValue)
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{
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return swapToBigEndian(aValue);
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}
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template<typename T>
|
|
static void
|
|
copyAndSwapToNetworkOrder(void* aDest, const T* aSrc, size_t aCount)
|
|
{
|
|
copyAndSwapToBigEndian(aDest, aSrc, aCount);
|
|
}
|
|
|
|
template<typename T>
|
|
static void
|
|
swapToNetworkOrderInPlace(T* aPtr, size_t aCount)
|
|
{
|
|
swapToBigEndianInPlace(aPtr, aCount);
|
|
}
|
|
|
|
/*
|
|
* Converts a value of type T from little-endian format.
|
|
*/
|
|
template<typename T>
|
|
MOZ_WARN_UNUSED_RESULT static T swapFromLittleEndian(T aValue)
|
|
{
|
|
return maybeSwap<Little, ThisEndian>(aValue);
|
|
}
|
|
|
|
/*
|
|
* Copies |aCount| values of type T starting at |aSrc| to |aDest|, converting
|
|
* them to little-endian format if ThisEndian is Big.
|
|
* As with memcpy, |aDest| and |aSrc| must not overlap.
|
|
*/
|
|
template<typename T>
|
|
static void copyAndSwapFromLittleEndian(T* aDest, const void* aSrc,
|
|
size_t aCount)
|
|
{
|
|
copyAndSwapFrom<Little, ThisEndian>(aDest, aSrc, aCount);
|
|
}
|
|
|
|
/*
|
|
* Likewise, but converts values in place.
|
|
*/
|
|
template<typename T>
|
|
static void swapFromLittleEndianInPlace(T* aPtr, size_t aCount)
|
|
{
|
|
maybeSwapInPlace<Little, ThisEndian>(aPtr, aCount);
|
|
}
|
|
|
|
/*
|
|
* Converts a value of type T from big-endian format.
|
|
*/
|
|
template<typename T>
|
|
MOZ_WARN_UNUSED_RESULT static T swapFromBigEndian(T aValue)
|
|
{
|
|
return maybeSwap<Big, ThisEndian>(aValue);
|
|
}
|
|
|
|
/*
|
|
* Copies |aCount| values of type T starting at |aSrc| to |aDest|, converting
|
|
* them to big-endian format if ThisEndian is Little.
|
|
* As with memcpy, |aDest| and |aSrc| must not overlap.
|
|
*/
|
|
template<typename T>
|
|
static void copyAndSwapFromBigEndian(T* aDest, const void* aSrc,
|
|
size_t aCount)
|
|
{
|
|
copyAndSwapFrom<Big, ThisEndian>(aDest, aSrc, aCount);
|
|
}
|
|
|
|
/*
|
|
* Likewise, but converts values in place.
|
|
*/
|
|
template<typename T>
|
|
static void swapFromBigEndianInPlace(T* aPtr, size_t aCount)
|
|
{
|
|
maybeSwapInPlace<Big, ThisEndian>(aPtr, aCount);
|
|
}
|
|
|
|
/*
|
|
* Synonyms for the big-endian functions, for better readability
|
|
* in network code.
|
|
*/
|
|
template<typename T>
|
|
MOZ_WARN_UNUSED_RESULT static T swapFromNetworkOrder(T aValue)
|
|
{
|
|
return swapFromBigEndian(aValue);
|
|
}
|
|
|
|
template<typename T>
|
|
static void copyAndSwapFromNetworkOrder(T* aDest, const void* aSrc,
|
|
size_t aCount)
|
|
{
|
|
copyAndSwapFromBigEndian(aDest, aSrc, aCount);
|
|
}
|
|
|
|
template<typename T>
|
|
static void swapFromNetworkOrderInPlace(T* aPtr, size_t aCount)
|
|
{
|
|
swapFromBigEndianInPlace(aPtr, aCount);
|
|
}
|
|
|
|
private:
|
|
/**
|
|
* Read a value of type T, encoded in endianness ThisEndian from |aPtr|.
|
|
* Return that value encoded in native endianness.
|
|
*/
|
|
template<typename T>
|
|
static T read(const void* aPtr)
|
|
{
|
|
union
|
|
{
|
|
T mVal;
|
|
uint8_t mBuffer[sizeof(T)];
|
|
} u;
|
|
memcpy(u.mBuffer, aPtr, sizeof(T));
|
|
return maybeSwap<ThisEndian, MOZ_NATIVE_ENDIANNESS>(u.mVal);
|
|
}
|
|
|
|
/**
|
|
* Write a value of type T, in native endianness, to |aPtr|, in ThisEndian
|
|
* endianness.
|
|
*/
|
|
template<typename T>
|
|
static void write(void* aPtr, T aValue)
|
|
{
|
|
T tmp = maybeSwap<MOZ_NATIVE_ENDIANNESS, ThisEndian>(aValue);
|
|
memcpy(aPtr, &tmp, sizeof(T));
|
|
}
|
|
|
|
Endian() = delete;
|
|
Endian(const Endian& aTther) = delete;
|
|
void operator=(const Endian& aOther) = delete;
|
|
};
|
|
|
|
template<Endianness ThisEndian>
|
|
class EndianReadWrite : public Endian<ThisEndian>
|
|
{
|
|
private:
|
|
typedef Endian<ThisEndian> super;
|
|
|
|
public:
|
|
using super::readUint16;
|
|
using super::readUint32;
|
|
using super::readUint64;
|
|
using super::readInt16;
|
|
using super::readInt32;
|
|
using super::readInt64;
|
|
using super::writeUint16;
|
|
using super::writeUint32;
|
|
using super::writeUint64;
|
|
using super::writeInt16;
|
|
using super::writeInt32;
|
|
using super::writeInt64;
|
|
};
|
|
|
|
} /* namespace detail */
|
|
|
|
class LittleEndian final : public detail::EndianReadWrite<detail::Little>
|
|
{};
|
|
|
|
class BigEndian final : public detail::EndianReadWrite<detail::Big>
|
|
{};
|
|
|
|
typedef BigEndian NetworkEndian;
|
|
|
|
class NativeEndian final : public detail::Endian<MOZ_NATIVE_ENDIANNESS>
|
|
{
|
|
private:
|
|
typedef detail::Endian<MOZ_NATIVE_ENDIANNESS> super;
|
|
|
|
public:
|
|
/*
|
|
* These functions are intended for cases where you have data in your
|
|
* native-endian format and you need the data to appear in the appropriate
|
|
* endianness for transmission, serialization, etc.
|
|
*/
|
|
using super::swapToLittleEndian;
|
|
using super::copyAndSwapToLittleEndian;
|
|
using super::swapToLittleEndianInPlace;
|
|
using super::swapToBigEndian;
|
|
using super::copyAndSwapToBigEndian;
|
|
using super::swapToBigEndianInPlace;
|
|
using super::swapToNetworkOrder;
|
|
using super::copyAndSwapToNetworkOrder;
|
|
using super::swapToNetworkOrderInPlace;
|
|
|
|
/*
|
|
* These functions are intended for cases where you have data in the
|
|
* given endianness (e.g. reading from disk or a file-format) and you
|
|
* need the data to appear in native-endian format for processing.
|
|
*/
|
|
using super::swapFromLittleEndian;
|
|
using super::copyAndSwapFromLittleEndian;
|
|
using super::swapFromLittleEndianInPlace;
|
|
using super::swapFromBigEndian;
|
|
using super::copyAndSwapFromBigEndian;
|
|
using super::swapFromBigEndianInPlace;
|
|
using super::swapFromNetworkOrder;
|
|
using super::copyAndSwapFromNetworkOrder;
|
|
using super::swapFromNetworkOrderInPlace;
|
|
};
|
|
|
|
#undef MOZ_NATIVE_ENDIANNESS
|
|
|
|
} /* namespace mozilla */
|
|
|
|
#endif /* mozilla_Endian_h */
|