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author Chris Cannam
date Mon, 07 Sep 2015 11:13:41 +0100
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1 // boost/endian/buffers.hpp ----------------------------------------------------------//
2
3 // (C) Copyright Darin Adler 2000
4 // (C) Copyright Beman Dawes 2006, 2009, 2014
5
6 // Distributed under the Boost Software License, Version 1.0.
7 // See http://www.boost.org/LICENSE_1_0.txt
8
9 // See library home page at http://www.boost.org/libs/endian
10
11 //--------------------------------------------------------------------------------------//
12
13 // Original design developed by Darin Adler based on classes developed by Mark
14 // Borgerding. Four original class templates were combined into a single endian
15 // class template by Beman Dawes, who also added the unrolled_byte_loops sign
16 // partial specialization to correctly extend the sign when cover integer size
17 // differs from endian representation size.
18
19 // TODO: When a compiler supporting constexpr becomes available, try possible uses.
20
21 #ifndef BOOST_ENDIAN_BUFFERS_HPP
22 #define BOOST_ENDIAN_BUFFERS_HPP
23
24 #if defined(_MSC_VER)
25 # pragma warning(push)
26 # pragma warning(disable:4365) // conversion ... signed/unsigned mismatch
27 #endif
28
29 #ifdef BOOST_ENDIAN_LOG
30 # include <iostream>
31 #endif
32
33 #if defined(__BORLANDC__) || defined( __CODEGEARC__)
34 # pragma pack(push, 1)
35 #endif
36
37 #include <boost/config.hpp>
38 #include <boost/predef/detail/endian_compat.h>
39 #include <boost/endian/conversion.hpp>
40 #include <boost/type_traits/is_signed.hpp>
41 #include <boost/cstdint.hpp>
42 #include <boost/static_assert.hpp>
43 #include <boost/core/scoped_enum.hpp>
44 #include <iosfwd>
45 #include <climits>
46
47 # if CHAR_BIT != 8
48 # error Platforms with CHAR_BIT != 8 are not supported
49 # endif
50
51 # ifdef BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
52 # define BOOST_ENDIAN_DEFAULT_CONSTRUCT {} // C++03
53 # else
54 # define BOOST_ENDIAN_DEFAULT_CONSTRUCT = default; // C++0x
55 # endif
56
57 # if defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS) && defined(BOOST_ENDIAN_FORCE_PODNESS)
58 # define BOOST_ENDIAN_NO_CTORS
59 # endif
60
61 //---------------------------------- synopsis ----------------------------------------//
62
63 namespace boost
64 {
65 namespace endian
66 {
67
68 BOOST_SCOPED_ENUM_START(align)
69 {no, yes
70 # ifdef BOOST_ENDIAN_DEPRECATED_NAMES
71 , unaligned = no, aligned = yes
72 # endif
73 }; BOOST_SCOPED_ENUM_END
74
75 template <BOOST_SCOPED_ENUM(order) Order, class T, std::size_t n_bits,
76 BOOST_SCOPED_ENUM(align) A = align::no>
77 class endian_buffer;
78
79 // aligned big endian signed integer buffers
80 typedef endian_buffer<order::big, int8_t, 8, align::yes> big_int8_buf_at;
81 typedef endian_buffer<order::big, int16_t, 16, align::yes> big_int16_buf_at;
82 typedef endian_buffer<order::big, int32_t, 32, align::yes> big_int32_buf_at;
83 typedef endian_buffer<order::big, int64_t, 64, align::yes> big_int64_buf_at;
84
85 // aligned big endian unsigned integer buffers
86 typedef endian_buffer<order::big, uint8_t, 8, align::yes> big_uint8_buf_at;
87 typedef endian_buffer<order::big, uint16_t, 16, align::yes> big_uint16_buf_at;
88 typedef endian_buffer<order::big, uint32_t, 32, align::yes> big_uint32_buf_at;
89 typedef endian_buffer<order::big, uint64_t, 64, align::yes> big_uint64_buf_at;
90
91 // aligned little endian signed integer buffers
92 typedef endian_buffer<order::little, int8_t, 8, align::yes> little_int8_buf_at;
93 typedef endian_buffer<order::little, int16_t, 16, align::yes> little_int16_buf_at;
94 typedef endian_buffer<order::little, int32_t, 32, align::yes> little_int32_buf_at;
95 typedef endian_buffer<order::little, int64_t, 64, align::yes> little_int64_buf_at;
96
97 // aligned little endian unsigned integer buffers
98 typedef endian_buffer<order::little, uint8_t, 8, align::yes> little_uint8_buf_at;
99 typedef endian_buffer<order::little, uint16_t, 16, align::yes> little_uint16_buf_at;
100 typedef endian_buffer<order::little, uint32_t, 32, align::yes> little_uint32_buf_at;
101 typedef endian_buffer<order::little, uint64_t, 64, align::yes> little_uint64_buf_at;
102
103 // aligned native endian typedefs are not provided because
104 // <cstdint> types are superior for this use case
105
106 // unaligned big endian signed integer buffers
107 typedef endian_buffer<order::big, int_least8_t, 8> big_int8_buf_t;
108 typedef endian_buffer<order::big, int_least16_t, 16> big_int16_buf_t;
109 typedef endian_buffer<order::big, int_least32_t, 24> big_int24_buf_t;
110 typedef endian_buffer<order::big, int_least32_t, 32> big_int32_buf_t;
111 typedef endian_buffer<order::big, int_least64_t, 40> big_int40_buf_t;
112 typedef endian_buffer<order::big, int_least64_t, 48> big_int48_buf_t;
113 typedef endian_buffer<order::big, int_least64_t, 56> big_int56_buf_t;
114 typedef endian_buffer<order::big, int_least64_t, 64> big_int64_buf_t;
115
116 // unaligned big endian unsigned integer buffers
117 typedef endian_buffer<order::big, uint_least8_t, 8> big_uint8_buf_t;
118 typedef endian_buffer<order::big, uint_least16_t, 16> big_uint16_buf_t;
119 typedef endian_buffer<order::big, uint_least32_t, 24> big_uint24_buf_t;
120 typedef endian_buffer<order::big, uint_least32_t, 32> big_uint32_buf_t;
121 typedef endian_buffer<order::big, uint_least64_t, 40> big_uint40_buf_t;
122 typedef endian_buffer<order::big, uint_least64_t, 48> big_uint48_buf_t;
123 typedef endian_buffer<order::big, uint_least64_t, 56> big_uint56_buf_t;
124 typedef endian_buffer<order::big, uint_least64_t, 64> big_uint64_buf_t;
125
126 // unaligned little endian signed integer buffers
127 typedef endian_buffer<order::little, int_least8_t, 8> little_int8_buf_t;
128 typedef endian_buffer<order::little, int_least16_t, 16> little_int16_buf_t;
129 typedef endian_buffer<order::little, int_least32_t, 24> little_int24_buf_t;
130 typedef endian_buffer<order::little, int_least32_t, 32> little_int32_buf_t;
131 typedef endian_buffer<order::little, int_least64_t, 40> little_int40_buf_t;
132 typedef endian_buffer<order::little, int_least64_t, 48> little_int48_buf_t;
133 typedef endian_buffer<order::little, int_least64_t, 56> little_int56_buf_t;
134 typedef endian_buffer<order::little, int_least64_t, 64> little_int64_buf_t;
135
136 // unaligned little endian unsigned integer buffers
137 typedef endian_buffer<order::little, uint_least8_t, 8> little_uint8_buf_t;
138 typedef endian_buffer<order::little, uint_least16_t, 16> little_uint16_buf_t;
139 typedef endian_buffer<order::little, uint_least32_t, 24> little_uint24_buf_t;
140 typedef endian_buffer<order::little, uint_least32_t, 32> little_uint32_buf_t;
141 typedef endian_buffer<order::little, uint_least64_t, 40> little_uint40_buf_t;
142 typedef endian_buffer<order::little, uint_least64_t, 48> little_uint48_buf_t;
143 typedef endian_buffer<order::little, uint_least64_t, 56> little_uint56_buf_t;
144 typedef endian_buffer<order::little, uint_least64_t, 64> little_uint64_buf_t;
145
146 # ifdef BOOST_BIG_ENDIAN
147 // unaligned native endian signed integer buffers
148 typedef big_int8_buf_t native_int8_buf_t;
149 typedef big_int16_buf_t native_int16_buf_t;
150 typedef big_int24_buf_t native_int24_buf_t;
151 typedef big_int32_buf_t native_int32_buf_t;
152 typedef big_int40_buf_t native_int40_buf_t;
153 typedef big_int48_buf_t native_int48_buf_t;
154 typedef big_int56_buf_t native_int56_buf_t;
155 typedef big_int64_buf_t native_int64_buf_t;
156
157 // unaligned native endian unsigned integer buffers
158 typedef big_uint8_buf_t native_uint8_buf_t;
159 typedef big_uint16_buf_t native_uint16_buf_t;
160 typedef big_uint24_buf_t native_uint24_buf_t;
161 typedef big_uint32_buf_t native_uint32_buf_t;
162 typedef big_uint40_buf_t native_uint40_buf_t;
163 typedef big_uint48_buf_t native_uint48_buf_t;
164 typedef big_uint56_buf_t native_uint56_buf_t;
165 typedef big_uint64_buf_t native_uint64_buf_t;
166 # else
167 // unaligned native endian signed integer buffers
168 typedef little_int8_buf_t native_int8_buf_t;
169 typedef little_int16_buf_t native_int16_buf_t;
170 typedef little_int24_buf_t native_int24_buf_t;
171 typedef little_int32_buf_t native_int32_buf_t;
172 typedef little_int40_buf_t native_int40_buf_t;
173 typedef little_int48_buf_t native_int48_buf_t;
174 typedef little_int56_buf_t native_int56_buf_t;
175 typedef little_int64_buf_t native_int64_buf_t;
176
177 // unaligned native endian unsigned integer buffers
178 typedef little_uint8_buf_t native_uint8_buf_t;
179 typedef little_uint16_buf_t native_uint16_buf_t;
180 typedef little_uint24_buf_t native_uint24_buf_t;
181 typedef little_uint32_buf_t native_uint32_buf_t;
182 typedef little_uint40_buf_t native_uint40_buf_t;
183 typedef little_uint48_buf_t native_uint48_buf_t;
184 typedef little_uint56_buf_t native_uint56_buf_t;
185 typedef little_uint64_buf_t native_uint64_buf_t;
186 # endif
187
188 // Stream inserter
189 template <class charT, class traits, BOOST_SCOPED_ENUM(order) Order, class T,
190 std::size_t n_bits, BOOST_SCOPED_ENUM(align) A>
191 std::basic_ostream<charT, traits>&
192 operator<<(std::basic_ostream<charT, traits>& os,
193 const endian_buffer<Order, T, n_bits, A>& x)
194 {
195 return os << x.value();
196 }
197
198 // Stream extractor
199 template <class charT, class traits, BOOST_SCOPED_ENUM(order) Order, class T,
200 std::size_t n_bits, BOOST_SCOPED_ENUM(align) A>
201 std::basic_istream<charT, traits>&
202 operator>>(std::basic_istream<charT, traits>& is,
203 endian_buffer<Order, T, n_bits, A>& x)
204 {
205 T i;
206 if (is >> i)
207 x = i;
208 return is;
209 }
210
211 //---------------------------------- end synopsis ------------------------------------//
212
213 namespace detail
214 {
215
216 // Unrolled loops for loading and storing streams of bytes.
217
218 template <typename T, std::size_t n_bytes,
219 bool sign=boost::is_signed<T>::value >
220 struct unrolled_byte_loops
221 {
222 typedef unrolled_byte_loops<T, n_bytes - 1, sign> next;
223
224 static T load_big(const unsigned char* bytes) BOOST_NOEXCEPT
225 { return static_cast<T>(*(bytes - 1) | (next::load_big(bytes - 1) << 8)); }
226 static T load_little(const unsigned char* bytes) BOOST_NOEXCEPT
227 { return static_cast<T>(*bytes | (next::load_little(bytes + 1) << 8)); }
228
229 static void store_big(char* bytes, T value) BOOST_NOEXCEPT
230 {
231 *(bytes - 1) = static_cast<char>(value);
232 next::store_big(bytes - 1, static_cast<T>(value >> 8));
233 }
234 static void store_little(char* bytes, T value) BOOST_NOEXCEPT
235 {
236 *bytes = static_cast<char>(value);
237 next::store_little(bytes + 1, static_cast<T>(value >> 8));
238 }
239 };
240
241 template <typename T>
242 struct unrolled_byte_loops<T, 1, false>
243 {
244 static T load_big(const unsigned char* bytes) BOOST_NOEXCEPT
245 { return *(bytes - 1); }
246 static T load_little(const unsigned char* bytes) BOOST_NOEXCEPT
247 { return *bytes; }
248 static void store_big(char* bytes, T value) BOOST_NOEXCEPT
249 { *(bytes - 1) = static_cast<char>(value); }
250 static void store_little(char* bytes, T value) BOOST_NOEXCEPT
251 { *bytes = static_cast<char>(value); }
252
253 };
254
255 template <typename T>
256 struct unrolled_byte_loops<T, 1, true>
257 {
258 static T load_big(const unsigned char* bytes) BOOST_NOEXCEPT
259 { return *reinterpret_cast<const signed char*>(bytes - 1); }
260 static T load_little(const unsigned char* bytes) BOOST_NOEXCEPT
261 { return *reinterpret_cast<const signed char*>(bytes); }
262 static void store_big(char* bytes, T value) BOOST_NOEXCEPT
263 { *(bytes - 1) = static_cast<char>(value); }
264 static void store_little(char* bytes, T value) BOOST_NOEXCEPT
265 { *bytes = static_cast<char>(value); }
266 };
267
268 template <typename T, std::size_t n_bytes>
269 inline
270 T load_big_endian(const void* bytes) BOOST_NOEXCEPT
271 {
272 return unrolled_byte_loops<T, n_bytes>::load_big
273 (static_cast<const unsigned char*>(bytes) + n_bytes);
274 }
275
276 template <typename T, std::size_t n_bytes>
277 inline
278 T load_little_endian(const void* bytes) BOOST_NOEXCEPT
279 {
280 # if defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
281 // On x86 (which is little endian), unaligned loads are permitted
282 if (sizeof(T) == n_bytes) // GCC 4.9, VC++ 14.0, and probably others, elide this
283 // test and generate code only for the applicable return
284 // case since sizeof(T) and n_bytes are known at compile
285 // time.
286 {
287 return *reinterpret_cast<T const *>(bytes);
288 }
289 # endif
290 return unrolled_byte_loops<T, n_bytes>::load_little
291 (static_cast<const unsigned char*>(bytes));
292 }
293
294 template <typename T, std::size_t n_bytes>
295 inline
296 void store_big_endian(void* bytes, T value) BOOST_NOEXCEPT
297 {
298 unrolled_byte_loops<T, n_bytes>::store_big
299 (static_cast<char*>(bytes) + n_bytes, value);
300 }
301
302 template <typename T, std::size_t n_bytes>
303 inline
304 void store_little_endian(void* bytes, T value) BOOST_NOEXCEPT
305 {
306 # if defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
307 // On x86 (which is little endian), unaligned stores are permitted
308 if (sizeof(T) == n_bytes) // GCC 4.9, VC++ 14.0, and probably others, elide this
309 // test and generate code only for the applicable return
310 // case since sizeof(T) and n_bytes are known at compile
311 // time.
312 {
313 *reinterpret_cast<T *>(bytes) = value;
314 return;
315 }
316 # endif
317 unrolled_byte_loops<T, n_bytes>::store_little
318 (static_cast<char*>(bytes), value);
319 }
320
321 } // namespace detail
322
323 # ifdef BOOST_ENDIAN_LOG
324 bool endian_log(true);
325 # endif
326
327 // endian_buffer class template specializations --------------------------------------//
328
329 // Specializations that represent unaligned bytes.
330 // Taking an integer type as a parameter provides a nice way to pass both
331 // the size and signedness of the desired integer and get the appropriate
332 // corresponding integer type for the interface.
333
334 // Q: Should endian_buffer supply "value_type operator value_type() const noexcept"?
335 // A: No. The rationale for endian_buffers is to prevent high-cost hidden
336 // conversions. If an implicit conversion operator is supplied, hidden conversions
337 // can occur.
338
339 // unaligned big endian_buffer specialization
340 template <typename T, std::size_t n_bits>
341 class endian_buffer< order::big, T, n_bits, align::no >
342 {
343 BOOST_STATIC_ASSERT( (n_bits/8)*8 == n_bits );
344 public:
345 typedef T value_type;
346 # ifndef BOOST_ENDIAN_NO_CTORS
347 endian_buffer() BOOST_ENDIAN_DEFAULT_CONSTRUCT
348 explicit endian_buffer(T val) BOOST_NOEXCEPT
349 {
350 # ifdef BOOST_ENDIAN_LOG
351 if ( endian_log )
352 std::cout << "big, unaligned, "
353 << n_bits << "-bits, construct(" << val << ")\n";
354 # endif
355 detail::store_big_endian<T, n_bits/8>(m_value, val);
356 }
357 # endif
358 endian_buffer & operator=(T val) BOOST_NOEXCEPT
359 {
360 # ifdef BOOST_ENDIAN_LOG
361 if (endian_log)
362 std::cout << "big, unaligned, " << n_bits << "-bits, assign(" << val << ")\n";
363 # endif
364 detail::store_big_endian<T, n_bits/8>(m_value, val);
365 return *this;
366 }
367 value_type value() const BOOST_NOEXCEPT
368 {
369 # ifdef BOOST_ENDIAN_LOG
370 if ( endian_log )
371 std::cout << "big, unaligned, " << n_bits << "-bits, convert("
372 << detail::load_big_endian<T, n_bits/8>(m_value) << ")\n";
373 # endif
374 return detail::load_big_endian<T, n_bits/8>(m_value);
375 }
376 const char* data() const BOOST_NOEXCEPT { return m_value; }
377 protected:
378 char m_value[n_bits/8];
379 };
380
381 // unaligned little endian_buffer specialization
382 template <typename T, std::size_t n_bits>
383 class endian_buffer< order::little, T, n_bits, align::no >
384 {
385 BOOST_STATIC_ASSERT( (n_bits/8)*8 == n_bits );
386 public:
387 typedef T value_type;
388 # ifndef BOOST_ENDIAN_NO_CTORS
389 endian_buffer() BOOST_ENDIAN_DEFAULT_CONSTRUCT
390 explicit endian_buffer(T val) BOOST_NOEXCEPT
391 {
392 # ifdef BOOST_ENDIAN_LOG
393 if ( endian_log )
394 std::cout << "little, unaligned, " << n_bits << "-bits, construct("
395 << val << ")\n";
396 # endif
397 detail::store_little_endian<T, n_bits/8>(m_value, val);
398 }
399 # endif
400 endian_buffer & operator=(T val) BOOST_NOEXCEPT
401 { detail::store_little_endian<T, n_bits/8>(m_value, val); return *this; }
402 value_type value() const BOOST_NOEXCEPT
403 {
404 # ifdef BOOST_ENDIAN_LOG
405 if ( endian_log )
406 std::cout << "little, unaligned, " << n_bits << "-bits, convert("
407 << detail::load_little_endian<T, n_bits/8>(m_value) << ")\n";
408 # endif
409 return detail::load_little_endian<T, n_bits/8>(m_value);
410 }
411 const char* data() const BOOST_NOEXCEPT { return m_value; }
412 protected:
413 char m_value[n_bits/8];
414 };
415
416 // align::yes specializations; only n_bits == 16/32/64 supported
417
418 // aligned big endian_buffer specialization
419 template <typename T, std::size_t n_bits>
420 class endian_buffer<order::big, T, n_bits, align::yes>
421 {
422 BOOST_STATIC_ASSERT( (n_bits/8)*8 == n_bits );
423 BOOST_STATIC_ASSERT( sizeof(T) == n_bits/8 );
424 public:
425 typedef T value_type;
426 # ifndef BOOST_ENDIAN_NO_CTORS
427 endian_buffer() BOOST_ENDIAN_DEFAULT_CONSTRUCT
428 explicit endian_buffer(T val) BOOST_NOEXCEPT
429 {
430 # ifdef BOOST_ENDIAN_LOG
431 if ( endian_log )
432 std::cout << "big, aligned, " << n_bits
433 << "-bits, construct(" << val << ")\n";
434 # endif
435 m_value = ::boost::endian::native_to_big(val);
436 }
437
438 # endif
439 endian_buffer& operator=(T val) BOOST_NOEXCEPT
440 {
441 m_value = ::boost::endian::native_to_big(val);
442 return *this;
443 }
444 //operator value_type() const BOOST_NOEXCEPT
445 //{
446 // return ::boost::endian::big_to_native(m_value);
447 //}
448 value_type value() const BOOST_NOEXCEPT
449 {
450 # ifdef BOOST_ENDIAN_LOG
451 if ( endian_log )
452 std::cout << "big, aligned, " << n_bits << "-bits, convert("
453 << ::boost::endian::big_to_native(m_value) << ")\n";
454 # endif
455 return ::boost::endian::big_to_native(m_value);
456 }
457 const char* data() const BOOST_NOEXCEPT
458 {return reinterpret_cast<const char*>(&m_value);}
459 protected:
460 T m_value;
461 };
462
463 // aligned little endian_buffer specialization
464 template <typename T, std::size_t n_bits>
465 class endian_buffer<order::little, T, n_bits, align::yes>
466 {
467 BOOST_STATIC_ASSERT( (n_bits/8)*8 == n_bits );
468 BOOST_STATIC_ASSERT( sizeof(T) == n_bits/8 );
469 public:
470 typedef T value_type;
471 # ifndef BOOST_ENDIAN_NO_CTORS
472 endian_buffer() BOOST_ENDIAN_DEFAULT_CONSTRUCT
473 explicit endian_buffer(T val) BOOST_NOEXCEPT
474 {
475 # ifdef BOOST_ENDIAN_LOG
476 if ( endian_log )
477 std::cout << "little, aligned, " << n_bits
478 << "-bits, construct(" << val << ")\n";
479 # endif
480 m_value = ::boost::endian::native_to_little(val);
481 }
482
483 # endif
484 endian_buffer& operator=(T val) BOOST_NOEXCEPT
485 {
486 m_value = ::boost::endian::native_to_little(val);
487 return *this;
488 }
489 value_type value() const BOOST_NOEXCEPT
490 {
491 # ifdef BOOST_ENDIAN_LOG
492 if ( endian_log )
493 std::cout << "little, aligned, " << n_bits << "-bits, convert("
494 << ::boost::endian::little_to_native(m_value) << ")\n";
495 # endif
496 return ::boost::endian::little_to_native(m_value);
497 }
498 const char* data() const BOOST_NOEXCEPT
499 {return reinterpret_cast<const char*>(&m_value);}
500 protected:
501 T m_value;
502 };
503
504 } // namespace endian
505 } // namespace boost
506
507 #if defined(__BORLANDC__) || defined( __CODEGEARC__)
508 # pragma pack(pop)
509 #endif
510
511 #if defined(_MSC_VER)
512 # pragma warning(pop)
513 #endif
514
515 #endif // BOOST_ENDIAN_BUFFERS_HPP