| 1 | // elfcpp_swap.h -- Handle swapping for elfcpp -*- C++ -*- |
| 2 | |
| 3 | // Copyright 2006, 2007, Free Software Foundation, Inc. |
| 4 | // Written by Ian Lance Taylor <iant@google.com>. |
| 5 | |
| 6 | // This file is part of elfcpp. |
| 7 | |
| 8 | // This program is free software; you can redistribute it and/or |
| 9 | // modify it under the terms of the GNU Library General Public License |
| 10 | // as published by the Free Software Foundation; either version 2, or |
| 11 | // (at your option) any later version. |
| 12 | |
| 13 | // In addition to the permissions in the GNU Library General Public |
| 14 | // License, the Free Software Foundation gives you unlimited |
| 15 | // permission to link the compiled version of this file into |
| 16 | // combinations with other programs, and to distribute those |
| 17 | // combinations without any restriction coming from the use of this |
| 18 | // file. (The Library Public License restrictions do apply in other |
| 19 | // respects; for example, they cover modification of the file, and |
| 20 | /// distribution when not linked into a combined executable.) |
| 21 | |
| 22 | // This program is distributed in the hope that it will be useful, but |
| 23 | // WITHOUT ANY WARRANTY; without even the implied warranty of |
| 24 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 25 | // Library General Public License for more details. |
| 26 | |
| 27 | // You should have received a copy of the GNU Library General Public |
| 28 | // License along with this program; if not, write to the Free Software |
| 29 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA |
| 30 | // 02110-1301, USA. |
| 31 | |
| 32 | // This header file defines basic template classes to efficiently swap |
| 33 | // numbers between host form and target form. When the host and |
| 34 | // target have the same endianness, these turn into no-ops. |
| 35 | |
| 36 | #ifndef ELFCPP_SWAP_H |
| 37 | #define ELFCPP_SWAP_H |
| 38 | |
| 39 | #include <stdint.h> |
| 40 | #include <endian.h> |
| 41 | #include <byteswap.h> |
| 42 | |
| 43 | namespace elfcpp |
| 44 | { |
| 45 | |
| 46 | // Endian simply indicates whether the host is big endian or not. |
| 47 | |
| 48 | struct Endian |
| 49 | { |
| 50 | public: |
| 51 | // Used for template specializations. |
| 52 | static const bool host_big_endian = __BYTE_ORDER == __BIG_ENDIAN; |
| 53 | }; |
| 54 | |
| 55 | // Valtype_base is a template based on size (8, 16, 32, 64) which |
| 56 | // defines the type Valtype as the unsigned integer, and |
| 57 | // Signed_valtype as the signed integer, of the specified size. |
| 58 | |
| 59 | template<int size> |
| 60 | struct Valtype_base; |
| 61 | |
| 62 | template<> |
| 63 | struct Valtype_base<8> |
| 64 | { |
| 65 | typedef uint8_t Valtype; |
| 66 | typedef int8_t Signed_valtype; |
| 67 | }; |
| 68 | |
| 69 | template<> |
| 70 | struct Valtype_base<16> |
| 71 | { |
| 72 | typedef uint16_t Valtype; |
| 73 | typedef int16_t Signed_valtype; |
| 74 | }; |
| 75 | |
| 76 | template<> |
| 77 | struct Valtype_base<32> |
| 78 | { |
| 79 | typedef uint32_t Valtype; |
| 80 | typedef int32_t Signed_valtype; |
| 81 | }; |
| 82 | |
| 83 | template<> |
| 84 | struct Valtype_base<64> |
| 85 | { |
| 86 | typedef uint64_t Valtype; |
| 87 | typedef int64_t Signed_valtype; |
| 88 | }; |
| 89 | |
| 90 | // Convert_endian is a template based on size and on whether the host |
| 91 | // and target have the same endianness. It defines the type Valtype |
| 92 | // as Valtype_base does, and also defines a function convert_host |
| 93 | // which takes an argument of type Valtype and returns the same value, |
| 94 | // but swapped if the host and target have different endianness. |
| 95 | |
| 96 | template<int size, bool same_endian> |
| 97 | struct Convert_endian; |
| 98 | |
| 99 | template<int size> |
| 100 | struct Convert_endian<size, true> |
| 101 | { |
| 102 | typedef typename Valtype_base<size>::Valtype Valtype; |
| 103 | |
| 104 | static inline Valtype |
| 105 | convert_host(Valtype v) |
| 106 | { return v; } |
| 107 | }; |
| 108 | |
| 109 | template<> |
| 110 | struct Convert_endian<8, false> |
| 111 | { |
| 112 | typedef Valtype_base<8>::Valtype Valtype; |
| 113 | |
| 114 | static inline Valtype |
| 115 | convert_host(Valtype v) |
| 116 | { return v; } |
| 117 | }; |
| 118 | |
| 119 | template<> |
| 120 | struct Convert_endian<16, false> |
| 121 | { |
| 122 | typedef Valtype_base<16>::Valtype Valtype; |
| 123 | |
| 124 | static inline Valtype |
| 125 | convert_host(Valtype v) |
| 126 | { return bswap_16(v); } |
| 127 | }; |
| 128 | |
| 129 | template<> |
| 130 | struct Convert_endian<32, false> |
| 131 | { |
| 132 | typedef Valtype_base<32>::Valtype Valtype; |
| 133 | |
| 134 | static inline Valtype |
| 135 | convert_host(Valtype v) |
| 136 | { return bswap_32(v); } |
| 137 | }; |
| 138 | |
| 139 | template<> |
| 140 | struct Convert_endian<64, false> |
| 141 | { |
| 142 | typedef Valtype_base<64>::Valtype Valtype; |
| 143 | |
| 144 | static inline Valtype |
| 145 | convert_host(Valtype v) |
| 146 | { return bswap_64(v); } |
| 147 | }; |
| 148 | |
| 149 | // Convert is a template based on size and on whether the target is |
| 150 | // big endian. It defines Valtype and convert_host like |
| 151 | // Convert_endian. That is, it is just like Convert_endian except in |
| 152 | // the meaning of the second template parameter. |
| 153 | |
| 154 | template<int size, bool big_endian> |
| 155 | struct Convert |
| 156 | { |
| 157 | typedef typename Valtype_base<size>::Valtype Valtype; |
| 158 | |
| 159 | static inline Valtype |
| 160 | convert_host(Valtype v) |
| 161 | { |
| 162 | return Convert_endian<size, big_endian == Endian::host_big_endian> |
| 163 | ::convert_host(v); |
| 164 | } |
| 165 | }; |
| 166 | |
| 167 | // Swap is a template based on size and on whether the target is big |
| 168 | // endian. It defines the type Valtype and the functions readval and |
| 169 | // writeval. The functions read and write values of the appropriate |
| 170 | // size out of buffers, swapping them if necessary. readval and |
| 171 | // writeval are overloaded to take pointers to the appropriate type or |
| 172 | // pointers to unsigned char. |
| 173 | |
| 174 | template<int size, bool big_endian> |
| 175 | struct Swap |
| 176 | { |
| 177 | typedef typename Valtype_base<size>::Valtype Valtype; |
| 178 | |
| 179 | static inline Valtype |
| 180 | readval(const Valtype* wv) |
| 181 | { return Convert<size, big_endian>::convert_host(*wv); } |
| 182 | |
| 183 | static inline void |
| 184 | writeval(Valtype* wv, Valtype v) |
| 185 | { *wv = Convert<size, big_endian>::convert_host(v); } |
| 186 | |
| 187 | static inline Valtype |
| 188 | readval(const unsigned char* wv) |
| 189 | { return readval(reinterpret_cast<const Valtype*>(wv)); } |
| 190 | |
| 191 | static inline void |
| 192 | writeval(unsigned char* wv, Valtype v) |
| 193 | { writeval(reinterpret_cast<Valtype*>(wv), v); } |
| 194 | }; |
| 195 | |
| 196 | // We need to specialize the 8-bit version of Swap to avoid |
| 197 | // conflicting overloads, since both versions of readval and writeval |
| 198 | // will have the same type parameters. |
| 199 | |
| 200 | template<bool big_endian> |
| 201 | struct Swap<8, big_endian> |
| 202 | { |
| 203 | typedef typename Valtype_base<8>::Valtype Valtype; |
| 204 | |
| 205 | static inline Valtype |
| 206 | readval(const Valtype* wv) |
| 207 | { return *wv; } |
| 208 | |
| 209 | static inline void |
| 210 | writeval(Valtype* wv, Valtype v) |
| 211 | { *wv = v; } |
| 212 | }; |
| 213 | |
| 214 | // Swap_unaligned is a template based on size and on whether the |
| 215 | // target is big endian. It defines the type Valtype and the |
| 216 | // functions readval and writeval. The functions read and write |
| 217 | // values of the appropriate size out of buffers which may be |
| 218 | // misaligned. |
| 219 | |
| 220 | template<int size, bool big_endian> |
| 221 | struct Swap_unaligned; |
| 222 | |
| 223 | template<bool big_endian> |
| 224 | struct Swap_unaligned<8, big_endian> |
| 225 | { |
| 226 | typedef typename Valtype_base<8>::Valtype Valtype; |
| 227 | |
| 228 | static inline Valtype |
| 229 | readval(const unsigned char* wv) |
| 230 | { return *wv; } |
| 231 | |
| 232 | static inline void |
| 233 | writeval(unsigned char* wv, Valtype v) |
| 234 | { *wv = v; } |
| 235 | }; |
| 236 | |
| 237 | template<> |
| 238 | struct Swap_unaligned<16, false> |
| 239 | { |
| 240 | typedef Valtype_base<16>::Valtype Valtype; |
| 241 | |
| 242 | static inline Valtype |
| 243 | readval(const unsigned char* wv) |
| 244 | { |
| 245 | return (wv[1] << 8) | wv[0]; |
| 246 | } |
| 247 | |
| 248 | static inline void |
| 249 | writeval(unsigned char* wv, Valtype v) |
| 250 | { |
| 251 | wv[1] = v >> 8; |
| 252 | wv[0] = v; |
| 253 | } |
| 254 | }; |
| 255 | |
| 256 | template<> |
| 257 | struct Swap_unaligned<16, true> |
| 258 | { |
| 259 | typedef Valtype_base<16>::Valtype Valtype; |
| 260 | |
| 261 | static inline Valtype |
| 262 | readval(const unsigned char* wv) |
| 263 | { |
| 264 | return (wv[0] << 8) | wv[1]; |
| 265 | } |
| 266 | |
| 267 | static inline void |
| 268 | writeval(unsigned char* wv, Valtype v) |
| 269 | { |
| 270 | wv[0] = v >> 8; |
| 271 | wv[1] = v; |
| 272 | } |
| 273 | }; |
| 274 | |
| 275 | template<> |
| 276 | struct Swap_unaligned<32, false> |
| 277 | { |
| 278 | typedef Valtype_base<32>::Valtype Valtype; |
| 279 | |
| 280 | static inline Valtype |
| 281 | readval(const unsigned char* wv) |
| 282 | { |
| 283 | return (wv[3] << 24) | (wv[2] << 16) | (wv[1] << 8) | wv[0]; |
| 284 | } |
| 285 | |
| 286 | static inline void |
| 287 | writeval(unsigned char* wv, Valtype v) |
| 288 | { |
| 289 | wv[3] = v >> 24; |
| 290 | wv[2] = v >> 16; |
| 291 | wv[1] = v >> 8; |
| 292 | wv[0] = v; |
| 293 | } |
| 294 | }; |
| 295 | |
| 296 | template<> |
| 297 | struct Swap_unaligned<32, true> |
| 298 | { |
| 299 | typedef Valtype_base<32>::Valtype Valtype; |
| 300 | |
| 301 | static inline Valtype |
| 302 | readval(const unsigned char* wv) |
| 303 | { |
| 304 | return (wv[0] << 24) | (wv[1] << 16) | (wv[2] << 8) | wv[3]; |
| 305 | } |
| 306 | |
| 307 | static inline void |
| 308 | writeval(unsigned char* wv, Valtype v) |
| 309 | { |
| 310 | wv[0] = v >> 24; |
| 311 | wv[1] = v >> 16; |
| 312 | wv[2] = v >> 8; |
| 313 | wv[3] = v; |
| 314 | } |
| 315 | }; |
| 316 | |
| 317 | template<> |
| 318 | struct Swap_unaligned<64, false> |
| 319 | { |
| 320 | typedef Valtype_base<64>::Valtype Valtype; |
| 321 | |
| 322 | static inline Valtype |
| 323 | readval(const unsigned char* wv) |
| 324 | { |
| 325 | return ((static_cast<Valtype>(wv[7]) << 56) |
| 326 | | (static_cast<Valtype>(wv[6]) << 48) |
| 327 | | (static_cast<Valtype>(wv[5]) << 40) |
| 328 | | (static_cast<Valtype>(wv[4]) << 32) |
| 329 | | (static_cast<Valtype>(wv[3]) << 24) |
| 330 | | (static_cast<Valtype>(wv[2]) << 16) |
| 331 | | (static_cast<Valtype>(wv[1]) << 8) |
| 332 | | static_cast<Valtype>(wv[0])); |
| 333 | } |
| 334 | |
| 335 | static inline void |
| 336 | writeval(unsigned char* wv, Valtype v) |
| 337 | { |
| 338 | wv[7] = v >> 56; |
| 339 | wv[6] = v >> 48; |
| 340 | wv[5] = v >> 40; |
| 341 | wv[4] = v >> 32; |
| 342 | wv[3] = v >> 24; |
| 343 | wv[2] = v >> 16; |
| 344 | wv[1] = v >> 8; |
| 345 | wv[0] = v; |
| 346 | } |
| 347 | }; |
| 348 | |
| 349 | template<> |
| 350 | struct Swap_unaligned<64, true> |
| 351 | { |
| 352 | typedef Valtype_base<64>::Valtype Valtype; |
| 353 | |
| 354 | static inline Valtype |
| 355 | readval(const unsigned char* wv) |
| 356 | { |
| 357 | return ((static_cast<Valtype>(wv[0]) << 56) |
| 358 | | (static_cast<Valtype>(wv[1]) << 48) |
| 359 | | (static_cast<Valtype>(wv[2]) << 40) |
| 360 | | (static_cast<Valtype>(wv[3]) << 32) |
| 361 | | (static_cast<Valtype>(wv[4]) << 24) |
| 362 | | (static_cast<Valtype>(wv[5]) << 16) |
| 363 | | (static_cast<Valtype>(wv[6]) << 8) |
| 364 | | static_cast<Valtype>(wv[7])); |
| 365 | } |
| 366 | |
| 367 | static inline void |
| 368 | writeval(unsigned char* wv, Valtype v) |
| 369 | { |
| 370 | wv[0] = v >> 56; |
| 371 | wv[1] = v >> 48; |
| 372 | wv[2] = v >> 40; |
| 373 | wv[3] = v >> 32; |
| 374 | wv[4] = v >> 24; |
| 375 | wv[5] = v >> 16; |
| 376 | wv[6] = v >> 8; |
| 377 | wv[7] = v; |
| 378 | } |
| 379 | }; |
| 380 | |
| 381 | } // End namespace elfcpp. |
| 382 | |
| 383 | #endif // !defined(ELFCPP_SWAP_H) |