| // elfcpp_swap.h -- Handle swapping for elfcpp -*- C++ -*- |
| |
| // Copyright (C) 2006-2024 Free Software Foundation, Inc. |
| // Written by Ian Lance Taylor <iant@google.com>. |
| |
| // This file is part of elfcpp. |
| |
| // This program is free software; you can redistribute it and/or |
| // modify it under the terms of the GNU Library General Public License |
| // as published by the Free Software Foundation; either version 2, or |
| // (at your option) any later version. |
| |
| // In addition to the permissions in the GNU Library General Public |
| // License, the Free Software Foundation gives you unlimited |
| // permission to link the compiled version of this file into |
| // combinations with other programs, and to distribute those |
| // combinations without any restriction coming from the use of this |
| // file. (The Library Public License restrictions do apply in other |
| // respects; for example, they cover modification of the file, and |
| /// distribution when not linked into a combined executable.) |
| |
| // This program is distributed in the hope that it will be useful, but |
| // WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| // Library General Public License for more details. |
| |
| // You should have received a copy of the GNU Library General Public |
| // License along with this program; if not, write to the Free Software |
| // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA |
| // 02110-1301, USA. |
| |
| // This header file defines basic template classes to efficiently swap |
| // numbers between host form and target form. When the host and |
| // target have the same endianness, these turn into no-ops. |
| |
| #ifndef ELFCPP_SWAP_H |
| #define ELFCPP_SWAP_H |
| |
| #include <stdint.h> |
| |
| // We need an autoconf-generated config.h file for endianness and |
| // swapping. We check two macros: WORDS_BIGENDIAN and |
| // HAVE_BYTESWAP_H. |
| |
| #include "config.h" |
| |
| #ifdef HAVE_BYTESWAP_H |
| #include <byteswap.h> |
| #endif // defined(HAVE_BYTESWAP_H) |
| |
| // Provide our own versions of the byteswap functions. |
| #if !HAVE_DECL_BSWAP_16 |
| static inline uint16_t |
| bswap_16(uint16_t v) |
| { |
| return ((v >> 8) & 0xff) | ((v & 0xff) << 8); |
| } |
| #endif // !HAVE_DECL_BSWAP16 |
| |
| #if !HAVE_DECL_BSWAP_32 |
| static inline uint32_t |
| bswap_32(uint32_t v) |
| { |
| return ( ((v & 0xff000000) >> 24) |
| | ((v & 0x00ff0000) >> 8) |
| | ((v & 0x0000ff00) << 8) |
| | ((v & 0x000000ff) << 24)); |
| } |
| #endif // !HAVE_DECL_BSWAP32 |
| |
| #if !HAVE_DECL_BSWAP_64 |
| static inline uint64_t |
| bswap_64(uint64_t v) |
| { |
| return ( ((v & 0xff00000000000000ULL) >> 56) |
| | ((v & 0x00ff000000000000ULL) >> 40) |
| | ((v & 0x0000ff0000000000ULL) >> 24) |
| | ((v & 0x000000ff00000000ULL) >> 8) |
| | ((v & 0x00000000ff000000ULL) << 8) |
| | ((v & 0x0000000000ff0000ULL) << 24) |
| | ((v & 0x000000000000ff00ULL) << 40) |
| | ((v & 0x00000000000000ffULL) << 56)); |
| } |
| #endif // !HAVE_DECL_BSWAP64 |
| |
| // gcc 4.3 and later provides __builtin_bswap32 and __builtin_bswap64. |
| |
| #if defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)) |
| #undef bswap_32 |
| #define bswap_32 __builtin_bswap32 |
| #undef bswap_64 |
| #define bswap_64 __builtin_bswap64 |
| #endif |
| |
| namespace elfcpp |
| { |
| |
| // Endian simply indicates whether the host is big endian or not. |
| |
| struct Endian |
| { |
| public: |
| // Used for template specializations. |
| static const bool host_big_endian = |
| #ifdef WORDS_BIGENDIAN |
| true |
| #else |
| false |
| #endif |
| ; |
| }; |
| |
| // Valtype_base is a template based on size (8, 16, 32, 64) which |
| // defines the type Valtype as the unsigned integer, and |
| // Signed_valtype as the signed integer, of the specified size. |
| |
| template<int size> |
| struct Valtype_base; |
| |
| template<> |
| struct Valtype_base<8> |
| { |
| typedef uint8_t Valtype; |
| typedef int8_t Signed_valtype; |
| }; |
| |
| template<> |
| struct Valtype_base<16> |
| { |
| typedef uint16_t Valtype; |
| typedef int16_t Signed_valtype; |
| }; |
| |
| template<> |
| struct Valtype_base<32> |
| { |
| typedef uint32_t Valtype; |
| typedef int32_t Signed_valtype; |
| }; |
| |
| template<> |
| struct Valtype_base<64> |
| { |
| typedef uint64_t Valtype; |
| typedef int64_t Signed_valtype; |
| }; |
| |
| // Convert_endian is a template based on size and on whether the host |
| // and target have the same endianness. It defines the type Valtype |
| // as Valtype_base does, and also defines a function convert_host |
| // which takes an argument of type Valtype and returns the same value, |
| // but swapped if the host and target have different endianness. |
| |
| template<int size, bool same_endian> |
| struct Convert_endian; |
| |
| template<int size> |
| struct Convert_endian<size, true> |
| { |
| typedef typename Valtype_base<size>::Valtype Valtype; |
| |
| static inline Valtype |
| convert_host(Valtype v) |
| { return v; } |
| }; |
| |
| template<> |
| struct Convert_endian<8, false> |
| { |
| typedef Valtype_base<8>::Valtype Valtype; |
| |
| static inline Valtype |
| convert_host(Valtype v) |
| { return v; } |
| }; |
| |
| template<> |
| struct Convert_endian<16, false> |
| { |
| typedef Valtype_base<16>::Valtype Valtype; |
| |
| static inline Valtype |
| convert_host(Valtype v) |
| { return bswap_16(v); } |
| }; |
| |
| template<> |
| struct Convert_endian<32, false> |
| { |
| typedef Valtype_base<32>::Valtype Valtype; |
| |
| static inline Valtype |
| convert_host(Valtype v) |
| { return bswap_32(v); } |
| }; |
| |
| template<> |
| struct Convert_endian<64, false> |
| { |
| typedef Valtype_base<64>::Valtype Valtype; |
| |
| static inline Valtype |
| convert_host(Valtype v) |
| { return bswap_64(v); } |
| }; |
| |
| // Convert is a template based on size and on whether the target is |
| // big endian. It defines Valtype and convert_host like |
| // Convert_endian. That is, it is just like Convert_endian except in |
| // the meaning of the second template parameter. |
| |
| template<int size, bool big_endian> |
| struct Convert |
| { |
| typedef typename Valtype_base<size>::Valtype Valtype; |
| |
| static inline Valtype |
| convert_host(Valtype v) |
| { |
| return Convert_endian<size, big_endian == Endian::host_big_endian> |
| ::convert_host(v); |
| } |
| }; |
| |
| // Swap is a template based on size and on whether the target is big |
| // endian. It defines the type Valtype and the functions readval and |
| // writeval. The functions read and write values of the appropriate |
| // size out of buffers, swapping them if necessary. readval and |
| // writeval are overloaded to take pointers to the appropriate type or |
| // pointers to unsigned char. |
| |
| template<int size, bool big_endian> |
| struct Swap |
| { |
| typedef typename Valtype_base<size>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const Valtype* wv) |
| { return Convert<size, big_endian>::convert_host(*wv); } |
| |
| static inline void |
| writeval(Valtype* wv, Valtype v) |
| { *wv = Convert<size, big_endian>::convert_host(v); } |
| |
| static inline Valtype |
| readval(const unsigned char* wv) |
| { return readval(reinterpret_cast<const Valtype*>(wv)); } |
| |
| static inline void |
| writeval(unsigned char* wv, Valtype v) |
| { writeval(reinterpret_cast<Valtype*>(wv), v); } |
| }; |
| |
| // We need to specialize the 8-bit version of Swap to avoid |
| // conflicting overloads, since both versions of readval and writeval |
| // will have the same type parameters. |
| |
| template<bool big_endian> |
| struct Swap<8, big_endian> |
| { |
| typedef typename Valtype_base<8>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const Valtype* wv) |
| { return *wv; } |
| |
| static inline void |
| writeval(Valtype* wv, Valtype v) |
| { *wv = v; } |
| }; |
| |
| // Swap_unaligned is a template based on size and on whether the |
| // target is big endian. It defines the type Valtype and the |
| // functions readval and writeval. The functions read and write |
| // values of the appropriate size out of buffers which may be |
| // misaligned. |
| |
| template<int size, bool big_endian> |
| struct Swap_unaligned; |
| |
| template<bool big_endian> |
| struct Swap_unaligned<8, big_endian> |
| { |
| typedef typename Valtype_base<8>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const unsigned char* wv) |
| { return *wv; } |
| |
| static inline void |
| writeval(unsigned char* wv, Valtype v) |
| { *wv = v; } |
| }; |
| |
| template<> |
| struct Swap_unaligned<16, false> |
| { |
| typedef Valtype_base<16>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const unsigned char* wv) |
| { |
| return (wv[1] << 8) | wv[0]; |
| } |
| |
| static inline void |
| writeval(unsigned char* wv, Valtype v) |
| { |
| wv[1] = v >> 8; |
| wv[0] = v; |
| } |
| }; |
| |
| template<> |
| struct Swap_unaligned<16, true> |
| { |
| typedef Valtype_base<16>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const unsigned char* wv) |
| { |
| return (wv[0] << 8) | wv[1]; |
| } |
| |
| static inline void |
| writeval(unsigned char* wv, Valtype v) |
| { |
| wv[0] = v >> 8; |
| wv[1] = v; |
| } |
| }; |
| |
| template<> |
| struct Swap_unaligned<32, false> |
| { |
| typedef Valtype_base<32>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const unsigned char* wv) |
| { |
| return (wv[3] << 24) | (wv[2] << 16) | (wv[1] << 8) | wv[0]; |
| } |
| |
| static inline void |
| writeval(unsigned char* wv, Valtype v) |
| { |
| wv[3] = v >> 24; |
| wv[2] = v >> 16; |
| wv[1] = v >> 8; |
| wv[0] = v; |
| } |
| }; |
| |
| template<> |
| struct Swap_unaligned<32, true> |
| { |
| typedef Valtype_base<32>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const unsigned char* wv) |
| { |
| return (wv[0] << 24) | (wv[1] << 16) | (wv[2] << 8) | wv[3]; |
| } |
| |
| static inline void |
| writeval(unsigned char* wv, Valtype v) |
| { |
| wv[0] = v >> 24; |
| wv[1] = v >> 16; |
| wv[2] = v >> 8; |
| wv[3] = v; |
| } |
| }; |
| |
| template<> |
| struct Swap_unaligned<64, false> |
| { |
| typedef Valtype_base<64>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const unsigned char* wv) |
| { |
| return ((static_cast<Valtype>(wv[7]) << 56) |
| | (static_cast<Valtype>(wv[6]) << 48) |
| | (static_cast<Valtype>(wv[5]) << 40) |
| | (static_cast<Valtype>(wv[4]) << 32) |
| | (static_cast<Valtype>(wv[3]) << 24) |
| | (static_cast<Valtype>(wv[2]) << 16) |
| | (static_cast<Valtype>(wv[1]) << 8) |
| | static_cast<Valtype>(wv[0])); |
| } |
| |
| static inline void |
| writeval(unsigned char* wv, Valtype v) |
| { |
| wv[7] = v >> 56; |
| wv[6] = v >> 48; |
| wv[5] = v >> 40; |
| wv[4] = v >> 32; |
| wv[3] = v >> 24; |
| wv[2] = v >> 16; |
| wv[1] = v >> 8; |
| wv[0] = v; |
| } |
| }; |
| |
| template<> |
| struct Swap_unaligned<64, true> |
| { |
| typedef Valtype_base<64>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const unsigned char* wv) |
| { |
| return ((static_cast<Valtype>(wv[0]) << 56) |
| | (static_cast<Valtype>(wv[1]) << 48) |
| | (static_cast<Valtype>(wv[2]) << 40) |
| | (static_cast<Valtype>(wv[3]) << 32) |
| | (static_cast<Valtype>(wv[4]) << 24) |
| | (static_cast<Valtype>(wv[5]) << 16) |
| | (static_cast<Valtype>(wv[6]) << 8) |
| | static_cast<Valtype>(wv[7])); |
| } |
| |
| static inline void |
| writeval(unsigned char* wv, Valtype v) |
| { |
| wv[0] = v >> 56; |
| wv[1] = v >> 48; |
| wv[2] = v >> 40; |
| wv[3] = v >> 32; |
| wv[4] = v >> 24; |
| wv[5] = v >> 16; |
| wv[6] = v >> 8; |
| wv[7] = v; |
| } |
| }; |
| |
| // Swap_aligned32 is a template based on size and on whether the |
| // target is big endian. It defines the type Valtype and the |
| // functions readval and writeval. The functions read and write |
| // values of the appropriate size out of buffers which may not be |
| // 64-bit aligned, but are 32-bit aligned. |
| |
| template<int size, bool big_endian> |
| struct Swap_aligned32 |
| { |
| typedef typename Valtype_base<size>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const unsigned char* wv) |
| { return Swap<size, big_endian>::readval( |
| reinterpret_cast<const Valtype*>(wv)); } |
| |
| static inline void |
| writeval(unsigned char* wv, Valtype v) |
| { Swap<size, big_endian>::writeval(reinterpret_cast<Valtype*>(wv), v); } |
| }; |
| |
| template<> |
| struct Swap_aligned32<64, true> |
| { |
| typedef Valtype_base<64>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const unsigned char* wv) |
| { |
| return ((static_cast<Valtype>(Swap<32, true>::readval(wv)) << 32) |
| | static_cast<Valtype>(Swap<32, true>::readval(wv + 4))); |
| } |
| |
| static inline void |
| writeval(unsigned char* wv, Valtype v) |
| { |
| typedef Valtype_base<32>::Valtype Valtype32; |
| |
| Swap<32, true>::writeval(wv, static_cast<Valtype32>(v >> 32)); |
| Swap<32, true>::writeval(wv + 4, static_cast<Valtype32>(v)); |
| } |
| }; |
| |
| template<> |
| struct Swap_aligned32<64, false> |
| { |
| typedef Valtype_base<64>::Valtype Valtype; |
| |
| static inline Valtype |
| readval(const unsigned char* wv) |
| { |
| return ((static_cast<Valtype>(Swap<32, false>::readval(wv + 4)) << 32) |
| | static_cast<Valtype>(Swap<32, false>::readval(wv))); |
| } |
| |
| static inline void |
| writeval(unsigned char* wv, Valtype v) |
| { |
| typedef Valtype_base<32>::Valtype Valtype32; |
| |
| Swap<32, false>::writeval(wv + 4, static_cast<Valtype32>(v >> 32)); |
| Swap<32, false>::writeval(wv, static_cast<Valtype32>(v)); |
| } |
| }; |
| |
| } // End namespace elfcpp. |
| |
| #endif // !defined(ELFCPP_SWAP_H) |