contrib/llvm-project/libcxx/include/__bit_reference

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___BIT_REFERENCE
  11 #define _LIBCPP___BIT_REFERENCE
  12
  13 #include <__config>
  14 #include <bit>
  15 #include <algorithm>
  16
  17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  18 #pragma GCC system_header
  19 #endif
  20
  21 _LIBCPP_PUSH_MACROS
  22 #include <__undef_macros>
  23
  24
  25 _LIBCPP_BEGIN_NAMESPACE_STD
  26
  27 template <class _Cp, bool _IsConst, typename _Cp::__storage_type = 0> class __bit_iterator;
  28 template <class _Cp> class __bit_const_reference;
  29
  30 template <class _Tp>
  31 struct __has_storage_type
  32 {
  33     static const bool value = false;
  34 };
  35
  36 template <class _Cp, bool = __has_storage_type<_Cp>::value>
  37 class __bit_reference
  38 {
  39     typedef typename _Cp::__storage_type    __storage_type;
  40     typedef typename _Cp::__storage_pointer __storage_pointer;
  41
  42     __storage_pointer __seg_;
  43     __storage_type    __mask_;
  44
  45     friend typename _Cp::__self;
  46
  47     friend class __bit_const_reference<_Cp>;
  48     friend class __bit_iterator<_Cp, false>;
  49 public:
  50     _LIBCPP_INLINE_VISIBILITY
  51     __bit_reference(const __bit_reference&) = default;
  52
  53     _LIBCPP_INLINE_VISIBILITY operator bool() const _NOEXCEPT
  54         {return static_cast<bool>(*__seg_ & __mask_);}
  55     _LIBCPP_INLINE_VISIBILITY bool operator ~() const _NOEXCEPT
  56         {return !static_cast<bool>(*this);}
  57
  58     _LIBCPP_INLINE_VISIBILITY
  59     __bit_reference& operator=(bool __x) _NOEXCEPT
  60     {
  61         if (__x)
  62             *__seg_ |= __mask_;
  63         else
  64             *__seg_ &= ~__mask_;
  65         return *this;
  66     }
  67
  68     _LIBCPP_INLINE_VISIBILITY
  69     __bit_reference& operator=(const __bit_reference& __x) _NOEXCEPT
  70         {return operator=(static_cast<bool>(__x));}
  71
  72     _LIBCPP_INLINE_VISIBILITY void flip() _NOEXCEPT {*__seg_ ^= __mask_;}
  73     _LIBCPP_INLINE_VISIBILITY __bit_iterator<_Cp, false> operator&() const _NOEXCEPT
  74         {return __bit_iterator<_Cp, false>(__seg_, static_cast<unsigned>(__libcpp_ctz(__mask_)));}
  75 private:
  76     _LIBCPP_INLINE_VISIBILITY
  77     __bit_reference(__storage_pointer __s, __storage_type __m) _NOEXCEPT
  78         : __seg_(__s), __mask_(__m) {}
  79 };
  80
  81 template <class _Cp>
  82 class __bit_reference<_Cp, false>
  83 {
  84 };
  85
  86 template <class _Cp>
  87 inline _LIBCPP_INLINE_VISIBILITY
  88 void
  89 swap(__bit_reference<_Cp> __x, __bit_reference<_Cp> __y) _NOEXCEPT
  90 {
  91     bool __t = __x;
  92     __x = __y;
  93     __y = __t;
  94 }
  95
  96 template <class _Cp, class _Dp>
  97 inline _LIBCPP_INLINE_VISIBILITY
  98 void
  99 swap(__bit_reference<_Cp> __x, __bit_reference<_Dp> __y) _NOEXCEPT
 100 {
 101     bool __t = __x;
 102     __x = __y;
 103     __y = __t;
 104 }
 105
 106 template <class _Cp>
 107 inline _LIBCPP_INLINE_VISIBILITY
 108 void
 109 swap(__bit_reference<_Cp> __x, bool& __y) _NOEXCEPT
 110 {
 111     bool __t = __x;
 112     __x = __y;
 113     __y = __t;
 114 }
 115
 116 template <class _Cp>
 117 inline _LIBCPP_INLINE_VISIBILITY
 118 void
 119 swap(bool& __x, __bit_reference<_Cp> __y) _NOEXCEPT
 120 {
 121     bool __t = __x;
 122     __x = __y;
 123     __y = __t;
 124 }
 125
 126 template <class _Cp>
 127 class __bit_const_reference
 128 {
 129     typedef typename _Cp::__storage_type          __storage_type;
 130     typedef typename _Cp::__const_storage_pointer __storage_pointer;
 131
 132     __storage_pointer        __seg_;
 133     __storage_type __mask_;
 134
 135     friend typename _Cp::__self;
 136     friend class __bit_iterator<_Cp, true>;
 137 public:
 138     _LIBCPP_INLINE_VISIBILITY
 139     __bit_const_reference(const __bit_const_reference&) = default;
 140
 141     _LIBCPP_INLINE_VISIBILITY
 142     __bit_const_reference(const __bit_reference<_Cp>& __x) _NOEXCEPT
 143         : __seg_(__x.__seg_), __mask_(__x.__mask_) {}
 144
 145     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR operator bool() const _NOEXCEPT
 146         {return static_cast<bool>(*__seg_ & __mask_);}
 147
 148     _LIBCPP_INLINE_VISIBILITY __bit_iterator<_Cp, true> operator&() const _NOEXCEPT
 149         {return __bit_iterator<_Cp, true>(__seg_, static_cast<unsigned>(__libcpp_ctz(__mask_)));}
 150 private:
 151     _LIBCPP_INLINE_VISIBILITY
 152     _LIBCPP_CONSTEXPR
 153     __bit_const_reference(__storage_pointer __s, __storage_type __m) _NOEXCEPT
 154         : __seg_(__s), __mask_(__m) {}
 155
 156     __bit_const_reference& operator=(const __bit_const_reference&) = delete;
 157 };
 158
 159 // find
 160
 161 template <class _Cp, bool _IsConst>
 162 __bit_iterator<_Cp, _IsConst>
 163 __find_bool_true(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
 164 {
 165     typedef __bit_iterator<_Cp, _IsConst> _It;
 166     typedef typename _It::__storage_type __storage_type;
 167     static const int __bits_per_word = _It::__bits_per_word;
 168     // do first partial word
 169     if (__first.__ctz_ != 0)
 170     {
 171         __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 172         __storage_type __dn = _VSTD::min(__clz_f, __n);
 173         __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 174         __storage_type __b = *__first.__seg_ & __m;
 175         if (__b)
 176             return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(__b)));
 177         if (__n == __dn)
 178             return __first + __n;
 179         __n -= __dn;
 180         ++__first.__seg_;
 181     }
 182     // do middle whole words
 183     for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
 184         if (*__first.__seg_)
 185             return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(*__first.__seg_)));
 186     // do last partial word
 187     if (__n > 0)
 188     {
 189         __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 190         __storage_type __b = *__first.__seg_ & __m;
 191         if (__b)
 192             return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(__b)));
 193     }
 194     return _It(__first.__seg_, static_cast<unsigned>(__n));
 195 }
 196
 197 template <class _Cp, bool _IsConst>
 198 __bit_iterator<_Cp, _IsConst>
 199 __find_bool_false(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
 200 {
 201     typedef __bit_iterator<_Cp, _IsConst> _It;
 202     typedef typename _It::__storage_type __storage_type;
 203     const int __bits_per_word = _It::__bits_per_word;
 204     // do first partial word
 205     if (__first.__ctz_ != 0)
 206     {
 207         __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 208         __storage_type __dn = _VSTD::min(__clz_f, __n);
 209         __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 210         __storage_type __b = ~*__first.__seg_ & __m;
 211         if (__b)
 212             return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(__b)));
 213         if (__n == __dn)
 214             return __first + __n;
 215         __n -= __dn;
 216         ++__first.__seg_;
 217     }
 218     // do middle whole words
 219     for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
 220     {
 221         __storage_type __b = ~*__first.__seg_;
 222         if (__b)
 223             return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(__b)));
 224     }
 225     // do last partial word
 226     if (__n > 0)
 227     {
 228         __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 229         __storage_type __b = ~*__first.__seg_ & __m;
 230         if (__b)
 231             return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(__b)));
 232     }
 233     return _It(__first.__seg_, static_cast<unsigned>(__n));
 234 }
 235
 236 template <class _Cp, bool _IsConst, class _Tp>
 237 inline _LIBCPP_INLINE_VISIBILITY
 238 __bit_iterator<_Cp, _IsConst>
 239 find(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value_)
 240 {
 241     if (static_cast<bool>(__value_))
 242         return __find_bool_true(__first, static_cast<typename _Cp::size_type>(__last - __first));
 243     return __find_bool_false(__first, static_cast<typename _Cp::size_type>(__last - __first));
 244 }
 245
 246 // count
 247
 248 template <class _Cp, bool _IsConst>
 249 typename __bit_iterator<_Cp, _IsConst>::difference_type
 250 __count_bool_true(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
 251 {
 252     typedef __bit_iterator<_Cp, _IsConst> _It;
 253     typedef typename _It::__storage_type __storage_type;
 254     typedef typename _It::difference_type difference_type;
 255     const int __bits_per_word = _It::__bits_per_word;
 256     difference_type __r = 0;
 257     // do first partial word
 258     if (__first.__ctz_ != 0)
 259     {
 260         __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 261         __storage_type __dn = _VSTD::min(__clz_f, __n);
 262         __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 263         __r = _VSTD::__libcpp_popcount(*__first.__seg_ & __m);
 264         __n -= __dn;
 265         ++__first.__seg_;
 266     }
 267     // do middle whole words
 268     for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
 269         __r += _VSTD::__libcpp_popcount(*__first.__seg_);
 270     // do last partial word
 271     if (__n > 0)
 272     {
 273         __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 274         __r += _VSTD::__libcpp_popcount(*__first.__seg_ & __m);
 275     }
 276     return __r;
 277 }
 278
 279 template <class _Cp, bool _IsConst>
 280 typename __bit_iterator<_Cp, _IsConst>::difference_type
 281 __count_bool_false(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
 282 {
 283     typedef __bit_iterator<_Cp, _IsConst> _It;
 284     typedef typename _It::__storage_type __storage_type;
 285     typedef typename _It::difference_type difference_type;
 286     const int __bits_per_word = _It::__bits_per_word;
 287     difference_type __r = 0;
 288     // do first partial word
 289     if (__first.__ctz_ != 0)
 290     {
 291         __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 292         __storage_type __dn = _VSTD::min(__clz_f, __n);
 293         __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 294         __r = _VSTD::__libcpp_popcount(~*__first.__seg_ & __m);
 295         __n -= __dn;
 296         ++__first.__seg_;
 297     }
 298     // do middle whole words
 299     for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
 300         __r += _VSTD::__libcpp_popcount(~*__first.__seg_);
 301     // do last partial word
 302     if (__n > 0)
 303     {
 304         __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 305         __r += _VSTD::__libcpp_popcount(~*__first.__seg_ & __m);
 306     }
 307     return __r;
 308 }
 309
 310 template <class _Cp, bool _IsConst, class _Tp>
 311 inline _LIBCPP_INLINE_VISIBILITY
 312 typename __bit_iterator<_Cp, _IsConst>::difference_type
 313 count(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value_)
 314 {
 315     if (static_cast<bool>(__value_))
 316         return __count_bool_true(__first, static_cast<typename _Cp::size_type>(__last - __first));
 317     return __count_bool_false(__first, static_cast<typename _Cp::size_type>(__last - __first));
 318 }
 319
 320 // fill_n
 321
 322 template <class _Cp>
 323 void
 324 __fill_n_false(__bit_iterator<_Cp, false> __first, typename _Cp::size_type __n)
 325 {
 326     typedef __bit_iterator<_Cp, false> _It;
 327     typedef typename _It::__storage_type __storage_type;
 328     const int __bits_per_word = _It::__bits_per_word;
 329     // do first partial word
 330     if (__first.__ctz_ != 0)
 331     {
 332         __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 333         __storage_type __dn = _VSTD::min(__clz_f, __n);
 334         __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 335         *__first.__seg_ &= ~__m;
 336         __n -= __dn;
 337         ++__first.__seg_;
 338     }
 339     // do middle whole words
 340     __storage_type __nw = __n / __bits_per_word;
 341     _VSTD::memset(_VSTD::__to_address(__first.__seg_), 0, __nw * sizeof(__storage_type));
 342     __n -= __nw * __bits_per_word;
 343     // do last partial word
 344     if (__n > 0)
 345     {
 346         __first.__seg_ += __nw;
 347         __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 348         *__first.__seg_ &= ~__m;
 349     }
 350 }
 351
 352 template <class _Cp>
 353 void
 354 __fill_n_true(__bit_iterator<_Cp, false> __first, typename _Cp::size_type __n)
 355 {
 356     typedef __bit_iterator<_Cp, false> _It;
 357     typedef typename _It::__storage_type __storage_type;
 358     const int __bits_per_word = _It::__bits_per_word;
 359     // do first partial word
 360     if (__first.__ctz_ != 0)
 361     {
 362         __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 363         __storage_type __dn = _VSTD::min(__clz_f, __n);
 364         __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 365         *__first.__seg_ |= __m;
 366         __n -= __dn;
 367         ++__first.__seg_;
 368     }
 369     // do middle whole words
 370     __storage_type __nw = __n / __bits_per_word;
 371     _VSTD::memset(_VSTD::__to_address(__first.__seg_), -1, __nw * sizeof(__storage_type));
 372     __n -= __nw * __bits_per_word;
 373     // do last partial word
 374     if (__n > 0)
 375     {
 376         __first.__seg_ += __nw;
 377         __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 378         *__first.__seg_ |= __m;
 379     }
 380 }
 381
 382 template <class _Cp>
 383 inline _LIBCPP_INLINE_VISIBILITY
 384 void
 385 fill_n(__bit_iterator<_Cp, false> __first, typename _Cp::size_type __n, bool __value_)
 386 {
 387     if (__n > 0)
 388     {
 389         if (__value_)
 390             __fill_n_true(__first, __n);
 391         else
 392             __fill_n_false(__first, __n);
 393     }
 394 }
 395
 396 // fill
 397
 398 template <class _Cp>
 399 inline _LIBCPP_INLINE_VISIBILITY
 400 void
 401 fill(__bit_iterator<_Cp, false> __first, __bit_iterator<_Cp, false> __last, bool __value_)
 402 {
 403     _VSTD::fill_n(__first, static_cast<typename _Cp::size_type>(__last - __first), __value_);
 404 }
 405
 406 // copy
 407
 408 template <class _Cp, bool _IsConst>
 409 __bit_iterator<_Cp, false>
 410 __copy_aligned(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last,
 411                                                      __bit_iterator<_Cp, false> __result)
 412 {
 413     typedef __bit_iterator<_Cp, _IsConst> _In;
 414     typedef  typename _In::difference_type difference_type;
 415     typedef typename _In::__storage_type __storage_type;
 416     const int __bits_per_word = _In::__bits_per_word;
 417     difference_type __n = __last - __first;
 418     if (__n > 0)
 419     {
 420         // do first word
 421         if (__first.__ctz_ != 0)
 422         {
 423             unsigned __clz = __bits_per_word - __first.__ctz_;
 424             difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz), __n);
 425             __n -= __dn;
 426             __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz - __dn));
 427             __storage_type __b = *__first.__seg_ & __m;
 428             *__result.__seg_ &= ~__m;
 429             *__result.__seg_ |= __b;
 430             __result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
 431             __result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_)  % __bits_per_word);
 432             ++__first.__seg_;
 433             // __first.__ctz_ = 0;
 434         }
 435         // __first.__ctz_ == 0;
 436         // do middle words
 437         __storage_type __nw = __n / __bits_per_word;
 438         _VSTD::memmove(_VSTD::__to_address(__result.__seg_),
 439                        _VSTD::__to_address(__first.__seg_),
 440                        __nw * sizeof(__storage_type));
 441         __n -= __nw * __bits_per_word;
 442         __result.__seg_ += __nw;
 443         // do last word
 444         if (__n > 0)
 445         {
 446             __first.__seg_ += __nw;
 447             __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 448             __storage_type __b = *__first.__seg_ & __m;
 449             *__result.__seg_ &= ~__m;
 450             *__result.__seg_ |= __b;
 451             __result.__ctz_ = static_cast<unsigned>(__n);
 452         }
 453     }
 454     return __result;
 455 }
 456
 457 template <class _Cp, bool _IsConst>
 458 __bit_iterator<_Cp, false>
 459 __copy_unaligned(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last,
 460                                                        __bit_iterator<_Cp, false> __result)
 461 {
 462     typedef __bit_iterator<_Cp, _IsConst> _In;
 463     typedef  typename _In::difference_type difference_type;
 464     typedef typename _In::__storage_type __storage_type;
 465     static const int __bits_per_word = _In::__bits_per_word;
 466     difference_type __n = __last - __first;
 467     if (__n > 0)
 468     {
 469         // do first word
 470         if (__first.__ctz_ != 0)
 471         {
 472             unsigned __clz_f = __bits_per_word - __first.__ctz_;
 473             difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz_f), __n);
 474             __n -= __dn;
 475             __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 476             __storage_type __b = *__first.__seg_ & __m;
 477             unsigned __clz_r = __bits_per_word - __result.__ctz_;
 478             __storage_type __ddn = _VSTD::min<__storage_type>(__dn, __clz_r);
 479             __m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __ddn));
 480             *__result.__seg_ &= ~__m;
 481             if (__result.__ctz_ > __first.__ctz_)
 482                 *__result.__seg_ |= __b << (__result.__ctz_ - __first.__ctz_);
 483             else
 484                 *__result.__seg_ |= __b >> (__first.__ctz_ - __result.__ctz_);
 485             __result.__seg_ += (__ddn + __result.__ctz_) / __bits_per_word;
 486             __result.__ctz_ = static_cast<unsigned>((__ddn + __result.__ctz_)  % __bits_per_word);
 487             __dn -= __ddn;
 488             if (__dn > 0)
 489             {
 490                 __m = ~__storage_type(0) >> (__bits_per_word - __dn);
 491                 *__result.__seg_ &= ~__m;
 492                 *__result.__seg_ |= __b >> (__first.__ctz_ + __ddn);
 493                 __result.__ctz_ = static_cast<unsigned>(__dn);
 494             }
 495             ++__first.__seg_;
 496             // __first.__ctz_ = 0;
 497         }
 498         // __first.__ctz_ == 0;
 499         // do middle words
 500         unsigned __clz_r = __bits_per_word - __result.__ctz_;
 501         __storage_type __m = ~__storage_type(0) << __result.__ctz_;
 502         for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first.__seg_)
 503         {
 504             __storage_type __b = *__first.__seg_;
 505             *__result.__seg_ &= ~__m;
 506             *__result.__seg_ |= __b << __result.__ctz_;
 507             ++__result.__seg_;
 508             *__result.__seg_ &= __m;
 509             *__result.__seg_ |= __b >> __clz_r;
 510         }
 511         // do last word
 512         if (__n > 0)
 513         {
 514             __m = ~__storage_type(0) >> (__bits_per_word - __n);
 515             __storage_type __b = *__first.__seg_ & __m;
 516             __storage_type __dn = _VSTD::min(__n, static_cast<difference_type>(__clz_r));
 517             __m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __dn));
 518             *__result.__seg_ &= ~__m;
 519             *__result.__seg_ |= __b << __result.__ctz_;
 520             __result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
 521             __result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_)  % __bits_per_word);
 522             __n -= __dn;
 523             if (__n > 0)
 524             {
 525                 __m = ~__storage_type(0) >> (__bits_per_word - __n);
 526                 *__result.__seg_ &= ~__m;
 527                 *__result.__seg_ |= __b >> __dn;
 528                 __result.__ctz_ = static_cast<unsigned>(__n);
 529             }
 530         }
 531     }
 532     return __result;
 533 }
 534
 535 template <class _Cp, bool _IsConst>
 536 inline _LIBCPP_INLINE_VISIBILITY
 537 __bit_iterator<_Cp, false>
 538 copy(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, __bit_iterator<_Cp, false> __result)
 539 {
 540     if (__first.__ctz_ == __result.__ctz_)
 541         return __copy_aligned(__first, __last, __result);
 542     return __copy_unaligned(__first, __last, __result);
 543 }
 544
 545 // copy_backward
 546
 547 template <class _Cp, bool _IsConst>
 548 __bit_iterator<_Cp, false>
 549 __copy_backward_aligned(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last,
 550                                                      __bit_iterator<_Cp, false> __result)
 551 {
 552     typedef __bit_iterator<_Cp, _IsConst> _In;
 553     typedef  typename _In::difference_type difference_type;
 554     typedef typename _In::__storage_type __storage_type;
 555     const int __bits_per_word = _In::__bits_per_word;
 556     difference_type __n = __last - __first;
 557     if (__n > 0)
 558     {
 559         // do first word
 560         if (__last.__ctz_ != 0)
 561         {
 562             difference_type __dn = _VSTD::min(static_cast<difference_type>(__last.__ctz_), __n);
 563             __n -= __dn;
 564             unsigned __clz = __bits_per_word - __last.__ctz_;
 565             __storage_type __m = (~__storage_type(0) << (__last.__ctz_ - __dn)) & (~__storage_type(0) >> __clz);
 566             __storage_type __b = *__last.__seg_ & __m;
 567             *__result.__seg_ &= ~__m;
 568             *__result.__seg_ |= __b;
 569             __result.__ctz_ = static_cast<unsigned>(((-__dn & (__bits_per_word - 1)) +
 570                                                        __result.__ctz_)  % __bits_per_word);
 571             // __last.__ctz_ = 0
 572          }
 573         // __last.__ctz_ == 0 || __n == 0
 574         // __result.__ctz_ == 0 || __n == 0
 575         // do middle words
 576         __storage_type __nw = __n / __bits_per_word;
 577         __result.__seg_ -= __nw;
 578         __last.__seg_ -= __nw;
 579         _VSTD::memmove(_VSTD::__to_address(__result.__seg_),
 580                        _VSTD::__to_address(__last.__seg_),
 581                        __nw * sizeof(__storage_type));
 582         __n -= __nw * __bits_per_word;
 583         // do last word
 584         if (__n > 0)
 585         {
 586             __storage_type __m = ~__storage_type(0) << (__bits_per_word - __n);
 587             __storage_type __b = *--__last.__seg_ & __m;
 588             *--__result.__seg_ &= ~__m;
 589             *__result.__seg_ |= __b;
 590             __result.__ctz_ = static_cast<unsigned>(-__n & (__bits_per_word - 1));
 591         }
 592     }
 593     return __result;
 594 }
 595
 596 template <class _Cp, bool _IsConst>
 597 __bit_iterator<_Cp, false>
 598 __copy_backward_unaligned(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last,
 599                                                        __bit_iterator<_Cp, false> __result)
 600 {
 601     typedef __bit_iterator<_Cp, _IsConst> _In;
 602     typedef  typename _In::difference_type difference_type;
 603     typedef typename _In::__storage_type __storage_type;
 604     const int __bits_per_word = _In::__bits_per_word;
 605     difference_type __n = __last - __first;
 606     if (__n > 0)
 607     {
 608         // do first word
 609         if (__last.__ctz_ != 0)
 610         {
 611             difference_type __dn = _VSTD::min(static_cast<difference_type>(__last.__ctz_), __n);
 612             __n -= __dn;
 613             unsigned __clz_l = __bits_per_word - __last.__ctz_;
 614             __storage_type __m = (~__storage_type(0) << (__last.__ctz_ - __dn)) & (~__storage_type(0) >> __clz_l);
 615             __storage_type __b = *__last.__seg_ & __m;
 616             unsigned __clz_r = __bits_per_word - __result.__ctz_;
 617             __storage_type __ddn = _VSTD::min(__dn, static_cast<difference_type>(__result.__ctz_));
 618             if (__ddn > 0)
 619             {
 620                 __m = (~__storage_type(0) << (__result.__ctz_ - __ddn)) & (~__storage_type(0) >> __clz_r);
 621                 *__result.__seg_ &= ~__m;
 622                 if (__result.__ctz_ > __last.__ctz_)
 623                     *__result.__seg_ |= __b << (__result.__ctz_ - __last.__ctz_);
 624                 else
 625                     *__result.__seg_ |= __b >> (__last.__ctz_ - __result.__ctz_);
 626                 __result.__ctz_ = static_cast<unsigned>(((-__ddn & (__bits_per_word - 1)) +
 627                                                          __result.__ctz_)  % __bits_per_word);
 628                 __dn -= __ddn;
 629             }
 630             if (__dn > 0)
 631             {
 632                 // __result.__ctz_ == 0
 633                 --__result.__seg_;
 634                 __result.__ctz_ = static_cast<unsigned>(-__dn & (__bits_per_word - 1));
 635                 __m = ~__storage_type(0) << __result.__ctz_;
 636                 *__result.__seg_ &= ~__m;
 637                 __last.__ctz_ -= __dn + __ddn;
 638                 *__result.__seg_ |= __b << (__result.__ctz_ - __last.__ctz_);
 639             }
 640             // __last.__ctz_ = 0
 641          }
 642         // __last.__ctz_ == 0 || __n == 0
 643         // __result.__ctz_ != 0 || __n == 0
 644         // do middle words
 645         unsigned __clz_r = __bits_per_word - __result.__ctz_;
 646         __storage_type __m = ~__storage_type(0) >> __clz_r;
 647         for (; __n >= __bits_per_word; __n -= __bits_per_word)
 648         {
 649             __storage_type __b = *--__last.__seg_;
 650             *__result.__seg_ &= ~__m;
 651             *__result.__seg_ |= __b >> __clz_r;
 652             *--__result.__seg_ &= __m;
 653             *__result.__seg_ |= __b << __result.__ctz_;
 654         }
 655         // do last word
 656         if (__n > 0)
 657         {
 658             __m = ~__storage_type(0) << (__bits_per_word - __n);
 659             __storage_type __b = *--__last.__seg_ & __m;
 660             __clz_r = __bits_per_word - __result.__ctz_;
 661             __storage_type __dn = _VSTD::min(__n, static_cast<difference_type>(__result.__ctz_));
 662             __m = (~__storage_type(0) << (__result.__ctz_ - __dn)) & (~__storage_type(0) >> __clz_r);
 663             *__result.__seg_ &= ~__m;
 664             *__result.__seg_ |= __b >> (__bits_per_word - __result.__ctz_);
 665             __result.__ctz_ = static_cast<unsigned>(((-__dn & (__bits_per_word - 1)) +
 666                                                      __result.__ctz_)  % __bits_per_word);
 667             __n -= __dn;
 668             if (__n > 0)
 669             {
 670                 // __result.__ctz_ == 0
 671                 --__result.__seg_;
 672                 __result.__ctz_ = static_cast<unsigned>(-__n & (__bits_per_word - 1));
 673                 __m = ~__storage_type(0) << __result.__ctz_;
 674                 *__result.__seg_ &= ~__m;
 675                 *__result.__seg_ |= __b << (__result.__ctz_ - (__bits_per_word - __n - __dn));
 676             }
 677         }
 678     }
 679     return __result;
 680 }
 681
 682 template <class _Cp, bool _IsConst>
 683 inline _LIBCPP_INLINE_VISIBILITY
 684 __bit_iterator<_Cp, false>
 685 copy_backward(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, __bit_iterator<_Cp, false> __result)
 686 {
 687     if (__last.__ctz_ == __result.__ctz_)
 688         return __copy_backward_aligned(__first, __last, __result);
 689     return __copy_backward_unaligned(__first, __last, __result);
 690 }
 691
 692 // move
 693
 694 template <class _Cp, bool _IsConst>
 695 inline _LIBCPP_INLINE_VISIBILITY
 696 __bit_iterator<_Cp, false>
 697 move(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, __bit_iterator<_Cp, false> __result)
 698 {
 699     return _VSTD::copy(__first, __last, __result);
 700 }
 701
 702 // move_backward
 703
 704 template <class _Cp, bool _IsConst>
 705 inline _LIBCPP_INLINE_VISIBILITY
 706 __bit_iterator<_Cp, false>
 707 move_backward(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, __bit_iterator<_Cp, false> __result)
 708 {
 709     return _VSTD::copy_backward(__first, __last, __result);
 710 }
 711
 712 // swap_ranges
 713
 714 template <class __C1, class __C2>
 715 __bit_iterator<__C2, false>
 716 __swap_ranges_aligned(__bit_iterator<__C1, false> __first, __bit_iterator<__C1, false> __last,
 717                       __bit_iterator<__C2, false> __result)
 718 {
 719     typedef __bit_iterator<__C1, false> _I1;
 720     typedef  typename _I1::difference_type difference_type;
 721     typedef typename _I1::__storage_type __storage_type;
 722     const int __bits_per_word = _I1::__bits_per_word;
 723     difference_type __n = __last - __first;
 724     if (__n > 0)
 725     {
 726         // do first word
 727         if (__first.__ctz_ != 0)
 728         {
 729             unsigned __clz = __bits_per_word - __first.__ctz_;
 730             difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz), __n);
 731             __n -= __dn;
 732             __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz - __dn));
 733             __storage_type __b1 = *__first.__seg_ & __m;
 734             *__first.__seg_ &= ~__m;
 735             __storage_type __b2 = *__result.__seg_ & __m;
 736             *__result.__seg_ &= ~__m;
 737             *__result.__seg_ |= __b1;
 738             *__first.__seg_  |= __b2;
 739             __result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
 740             __result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_)  % __bits_per_word);
 741             ++__first.__seg_;
 742             // __first.__ctz_ = 0;
 743         }
 744         // __first.__ctz_ == 0;
 745         // do middle words
 746         for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first.__seg_, ++__result.__seg_)
 747             swap(*__first.__seg_, *__result.__seg_);
 748         // do last word
 749         if (__n > 0)
 750         {
 751             __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 752             __storage_type __b1 = *__first.__seg_ & __m;
 753             *__first.__seg_ &= ~__m;
 754             __storage_type __b2 = *__result.__seg_ & __m;
 755             *__result.__seg_ &= ~__m;
 756             *__result.__seg_ |= __b1;
 757             *__first.__seg_  |= __b2;
 758             __result.__ctz_ = static_cast<unsigned>(__n);
 759         }
 760     }
 761     return __result;
 762 }
 763
 764 template <class __C1, class __C2>
 765 __bit_iterator<__C2, false>
 766 __swap_ranges_unaligned(__bit_iterator<__C1, false> __first, __bit_iterator<__C1, false> __last,
 767                         __bit_iterator<__C2, false> __result)
 768 {
 769     typedef __bit_iterator<__C1, false> _I1;
 770     typedef  typename _I1::difference_type difference_type;
 771     typedef typename _I1::__storage_type __storage_type;
 772     const int __bits_per_word = _I1::__bits_per_word;
 773     difference_type __n = __last - __first;
 774     if (__n > 0)
 775     {
 776         // do first word
 777         if (__first.__ctz_ != 0)
 778         {
 779             unsigned __clz_f = __bits_per_word - __first.__ctz_;
 780             difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz_f), __n);
 781             __n -= __dn;
 782             __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 783             __storage_type __b1 = *__first.__seg_ & __m;
 784             *__first.__seg_ &= ~__m;
 785             unsigned __clz_r = __bits_per_word - __result.__ctz_;
 786             __storage_type __ddn = _VSTD::min<__storage_type>(__dn, __clz_r);
 787             __m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __ddn));
 788             __storage_type __b2 = *__result.__seg_ & __m;
 789             *__result.__seg_ &= ~__m;
 790             if (__result.__ctz_ > __first.__ctz_)
 791             {
 792                 unsigned __s = __result.__ctz_ - __first.__ctz_;
 793                 *__result.__seg_ |= __b1 << __s;
 794                 *__first.__seg_  |= __b2 >> __s;
 795             }
 796             else
 797             {
 798                 unsigned __s = __first.__ctz_ - __result.__ctz_;
 799                 *__result.__seg_ |= __b1 >> __s;
 800                 *__first.__seg_  |= __b2 << __s;
 801             }
 802             __result.__seg_ += (__ddn + __result.__ctz_) / __bits_per_word;
 803             __result.__ctz_ = static_cast<unsigned>((__ddn + __result.__ctz_)  % __bits_per_word);
 804             __dn -= __ddn;
 805             if (__dn > 0)
 806             {
 807                 __m = ~__storage_type(0) >> (__bits_per_word - __dn);
 808                 __b2 = *__result.__seg_ & __m;
 809                 *__result.__seg_ &= ~__m;
 810                 unsigned __s = __first.__ctz_ + __ddn;
 811                 *__result.__seg_ |= __b1 >> __s;
 812                 *__first.__seg_  |= __b2 << __s;
 813                 __result.__ctz_ = static_cast<unsigned>(__dn);
 814             }
 815             ++__first.__seg_;
 816             // __first.__ctz_ = 0;
 817         }
 818         // __first.__ctz_ == 0;
 819         // do middle words
 820         __storage_type __m = ~__storage_type(0) << __result.__ctz_;
 821         unsigned __clz_r = __bits_per_word - __result.__ctz_;
 822         for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first.__seg_)
 823         {
 824             __storage_type __b1 = *__first.__seg_;
 825             __storage_type __b2 = *__result.__seg_ & __m;
 826             *__result.__seg_ &= ~__m;
 827             *__result.__seg_ |= __b1 << __result.__ctz_;
 828             *__first.__seg_  = __b2 >> __result.__ctz_;
 829             ++__result.__seg_;
 830             __b2 = *__result.__seg_ & ~__m;
 831             *__result.__seg_ &= __m;
 832             *__result.__seg_ |= __b1 >> __clz_r;
 833             *__first.__seg_  |= __b2 << __clz_r;
 834         }
 835         // do last word
 836         if (__n > 0)
 837         {
 838             __m = ~__storage_type(0) >> (__bits_per_word - __n);
 839             __storage_type __b1 = *__first.__seg_ & __m;
 840             *__first.__seg_ &= ~__m;
 841             __storage_type __dn = _VSTD::min<__storage_type>(__n, __clz_r);
 842             __m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __dn));
 843             __storage_type __b2 = *__result.__seg_ & __m;
 844             *__result.__seg_ &= ~__m;
 845             *__result.__seg_ |= __b1 << __result.__ctz_;
 846             *__first.__seg_  |= __b2 >> __result.__ctz_;
 847             __result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
 848             __result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_)  % __bits_per_word);
 849             __n -= __dn;
 850             if (__n > 0)
 851             {
 852                 __m = ~__storage_type(0) >> (__bits_per_word - __n);
 853                 __b2 = *__result.__seg_ & __m;
 854                 *__result.__seg_ &= ~__m;
 855                 *__result.__seg_ |= __b1 >> __dn;
 856                 *__first.__seg_  |= __b2 << __dn;
 857                 __result.__ctz_ = static_cast<unsigned>(__n);
 858             }
 859         }
 860     }
 861     return __result;
 862 }
 863
 864 template <class __C1, class __C2>
 865 inline _LIBCPP_INLINE_VISIBILITY
 866 __bit_iterator<__C2, false>
 867 swap_ranges(__bit_iterator<__C1, false> __first1, __bit_iterator<__C1, false> __last1,
 868             __bit_iterator<__C2, false> __first2)
 869 {
 870     if (__first1.__ctz_ == __first2.__ctz_)
 871         return __swap_ranges_aligned(__first1, __last1, __first2);
 872     return __swap_ranges_unaligned(__first1, __last1, __first2);
 873 }
 874
 875 // rotate
 876
 877 template <class _Cp>
 878 struct __bit_array
 879 {
 880     typedef typename _Cp::difference_type difference_type;
 881     typedef typename _Cp::__storage_type  __storage_type;
 882     typedef typename _Cp::__storage_pointer __storage_pointer;
 883     typedef typename _Cp::iterator        iterator;
 884     static const unsigned __bits_per_word = _Cp::__bits_per_word;
 885     static const unsigned _Np = 4;
 886
 887     difference_type __size_;
 888     __storage_type __word_[_Np];
 889
 890     _LIBCPP_INLINE_VISIBILITY static difference_type capacity()
 891         {return static_cast<difference_type>(_Np * __bits_per_word);}
 892     _LIBCPP_INLINE_VISIBILITY explicit __bit_array(difference_type __s) : __size_(__s) {}
 893     _LIBCPP_INLINE_VISIBILITY iterator begin()
 894     {
 895         return iterator(pointer_traits<__storage_pointer>::pointer_to(__word_[0]), 0);
 896     }
 897     _LIBCPP_INLINE_VISIBILITY iterator end()
 898     {
 899         return iterator(pointer_traits<__storage_pointer>::pointer_to(__word_[0]) + __size_ / __bits_per_word,
 900                                                   static_cast<unsigned>(__size_ % __bits_per_word));
 901     }
 902 };
 903
 904 template <class _Cp>
 905 __bit_iterator<_Cp, false>
 906 rotate(__bit_iterator<_Cp, false> __first, __bit_iterator<_Cp, false> __middle, __bit_iterator<_Cp, false> __last)
 907 {
 908     typedef __bit_iterator<_Cp, false> _I1;
 909     typedef  typename _I1::difference_type difference_type;
 910     difference_type __d1 = __middle - __first;
 911     difference_type __d2 = __last - __middle;
 912     _I1 __r = __first + __d2;
 913     while (__d1 != 0 && __d2 != 0)
 914     {
 915         if (__d1 <= __d2)
 916         {
 917             if (__d1 <= __bit_array<_Cp>::capacity())
 918             {
 919                 __bit_array<_Cp> __b(__d1);
 920                 _VSTD::copy(__first, __middle, __b.begin());
 921                 _VSTD::copy(__b.begin(), __b.end(), _VSTD::copy(__middle, __last, __first));
 922                 break;
 923             }
 924             else
 925             {
 926                 __bit_iterator<_Cp, false> __mp = _VSTD::swap_ranges(__first, __middle, __middle);
 927                 __first = __middle;
 928                 __middle = __mp;
 929                 __d2 -= __d1;
 930             }
 931         }
 932         else
 933         {
 934             if (__d2 <= __bit_array<_Cp>::capacity())
 935             {
 936                 __bit_array<_Cp> __b(__d2);
 937                 _VSTD::copy(__middle, __last, __b.begin());
 938                 _VSTD::copy_backward(__b.begin(), __b.end(), _VSTD::copy_backward(__first, __middle, __last));
 939                 break;
 940             }
 941             else
 942             {
 943                 __bit_iterator<_Cp, false> __mp = __first + __d2;
 944                 _VSTD::swap_ranges(__first, __mp, __middle);
 945                 __first = __mp;
 946                 __d1 -= __d2;
 947             }
 948         }
 949     }
 950     return __r;
 951 }
 952
 953 // equal
 954
 955 template <class _Cp, bool _IC1, bool _IC2>
 956 bool
 957 __equal_unaligned(__bit_iterator<_Cp, _IC1> __first1, __bit_iterator<_Cp, _IC1> __last1,
 958                   __bit_iterator<_Cp, _IC2> __first2)
 959 {
 960     typedef __bit_iterator<_Cp, _IC1> _It;
 961     typedef  typename _It::difference_type difference_type;
 962     typedef typename _It::__storage_type __storage_type;
 963     static const int __bits_per_word = _It::__bits_per_word;
 964     difference_type __n = __last1 - __first1;
 965     if (__n > 0)
 966     {
 967         // do first word
 968         if (__first1.__ctz_ != 0)
 969         {
 970             unsigned __clz_f = __bits_per_word - __first1.__ctz_;
 971             difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz_f), __n);
 972             __n -= __dn;
 973             __storage_type __m = (~__storage_type(0) << __first1.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 974             __storage_type __b = *__first1.__seg_ & __m;
 975             unsigned __clz_r = __bits_per_word - __first2.__ctz_;
 976             __storage_type __ddn = _VSTD::min<__storage_type>(__dn, __clz_r);
 977             __m = (~__storage_type(0) << __first2.__ctz_) & (~__storage_type(0) >> (__clz_r - __ddn));
 978             if (__first2.__ctz_ > __first1.__ctz_)
 979             {
 980                 if ((*__first2.__seg_ & __m) != (__b << (__first2.__ctz_ - __first1.__ctz_)))
 981                     return false;
 982             }
 983             else
 984             {
 985                 if ((*__first2.__seg_ & __m) != (__b >> (__first1.__ctz_ - __first2.__ctz_)))
 986                     return false;
 987             }
 988             __first2.__seg_ += (__ddn + __first2.__ctz_) / __bits_per_word;
 989             __first2.__ctz_ = static_cast<unsigned>((__ddn + __first2.__ctz_)  % __bits_per_word);
 990             __dn -= __ddn;
 991             if (__dn > 0)
 992             {
 993                 __m = ~__storage_type(0) >> (__bits_per_word - __dn);
 994                 if ((*__first2.__seg_ & __m) != (__b >> (__first1.__ctz_ + __ddn)))
 995                     return false;
 996                 __first2.__ctz_ = static_cast<unsigned>(__dn);
 997             }
 998             ++__first1.__seg_;
 999             // __first1.__ctz_ = 0;
1000         }
1001         // __first1.__ctz_ == 0;
1002         // do middle words
1003         unsigned __clz_r = __bits_per_word - __first2.__ctz_;
1004         __storage_type __m = ~__storage_type(0) << __first2.__ctz_;
1005         for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first1.__seg_)
1006         {
1007             __storage_type __b = *__first1.__seg_;
1008             if ((*__first2.__seg_ & __m) != (__b << __first2.__ctz_))
1009                 return false;
1010             ++__first2.__seg_;
1011             if ((*__first2.__seg_ & ~__m) != (__b >> __clz_r))
1012                 return false;
1013         }
1014         // do last word
1015         if (__n > 0)
1016         {
1017             __m = ~__storage_type(0) >> (__bits_per_word - __n);
1018             __storage_type __b = *__first1.__seg_ & __m;
1019             __storage_type __dn = _VSTD::min(__n, static_cast<difference_type>(__clz_r));
1020             __m = (~__storage_type(0) << __first2.__ctz_) & (~__storage_type(0) >> (__clz_r - __dn));
1021             if ((*__first2.__seg_ & __m) != (__b << __first2.__ctz_))
1022                 return false;
1023             __first2.__seg_ += (__dn + __first2.__ctz_) / __bits_per_word;
1024             __first2.__ctz_ = static_cast<unsigned>((__dn + __first2.__ctz_)  % __bits_per_word);
1025             __n -= __dn;
1026             if (__n > 0)
1027             {
1028                 __m = ~__storage_type(0) >> (__bits_per_word - __n);
1029                 if ((*__first2.__seg_ & __m) != (__b >> __dn))
1030                     return false;
1031             }
1032         }
1033     }
1034     return true;
1035 }
1036
1037 template <class _Cp, bool _IC1, bool _IC2>
1038 bool
1039 __equal_aligned(__bit_iterator<_Cp, _IC1> __first1, __bit_iterator<_Cp, _IC1> __last1,
1040                 __bit_iterator<_Cp, _IC2> __first2)
1041 {
1042     typedef __bit_iterator<_Cp, _IC1> _It;
1043     typedef  typename _It::difference_type difference_type;
1044     typedef typename _It::__storage_type __storage_type;
1045     static const int __bits_per_word = _It::__bits_per_word;
1046     difference_type __n = __last1 - __first1;
1047     if (__n > 0)
1048     {
1049         // do first word
1050         if (__first1.__ctz_ != 0)
1051         {
1052             unsigned __clz = __bits_per_word - __first1.__ctz_;
1053             difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz), __n);
1054             __n -= __dn;
1055             __storage_type __m = (~__storage_type(0) << __first1.__ctz_) & (~__storage_type(0) >> (__clz - __dn));
1056             if ((*__first2.__seg_ & __m) != (*__first1.__seg_ & __m))
1057                 return false;
1058             ++__first2.__seg_;
1059             ++__first1.__seg_;
1060             // __first1.__ctz_ = 0;
1061             // __first2.__ctz_ = 0;
1062         }
1063         // __first1.__ctz_ == 0;
1064         // __first2.__ctz_ == 0;
1065         // do middle words
1066         for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first1.__seg_, ++__first2.__seg_)
1067             if (*__first2.__seg_ != *__first1.__seg_)
1068                 return false;
1069         // do last word
1070         if (__n > 0)
1071         {
1072             __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
1073             if ((*__first2.__seg_ & __m) != (*__first1.__seg_ & __m))
1074                 return false;
1075         }
1076     }
1077     return true;
1078 }
1079
1080 template <class _Cp, bool _IC1, bool _IC2>
1081 inline _LIBCPP_INLINE_VISIBILITY
1082 bool
1083 equal(__bit_iterator<_Cp, _IC1> __first1, __bit_iterator<_Cp, _IC1> __last1, __bit_iterator<_Cp, _IC2> __first2)
1084 {
1085     if (__first1.__ctz_ == __first2.__ctz_)
1086         return __equal_aligned(__first1, __last1, __first2);
1087     return __equal_unaligned(__first1, __last1, __first2);
1088 }
1089
1090 template <class _Cp, bool _IsConst,
1091           typename _Cp::__storage_type>
1092 class __bit_iterator
1093 {
1094 public:
1095     typedef typename _Cp::difference_type                                                          difference_type;
1096     typedef bool                                                                                  value_type;
1097     typedef __bit_iterator                                                                        pointer;
1098     typedef typename conditional<_IsConst, __bit_const_reference<_Cp>, __bit_reference<_Cp> >::type reference;
1099     typedef random_access_iterator_tag                                                            iterator_category;
1100
1101 private:
1102     typedef typename _Cp::__storage_type                                           __storage_type;
1103     typedef typename conditional<_IsConst, typename _Cp::__const_storage_pointer,
1104                                            typename _Cp::__storage_pointer>::type  __storage_pointer;
1105     static const unsigned __bits_per_word = _Cp::__bits_per_word;
1106
1107     __storage_pointer __seg_;
1108     unsigned          __ctz_;
1109
1110 public:
1111     _LIBCPP_INLINE_VISIBILITY __bit_iterator() _NOEXCEPT
1112 #if _LIBCPP_STD_VER > 11
1113     : __seg_(nullptr), __ctz_(0)
1114 #endif
1115     {}
1116
1117     // avoid re-declaring a copy constructor for the non-const version.
1118     using __type_for_copy_to_const =
1119       _If<_IsConst, __bit_iterator<_Cp, false>, struct __private_nat>;
1120
1121     _LIBCPP_INLINE_VISIBILITY
1122     __bit_iterator(const __type_for_copy_to_const& __it) _NOEXCEPT
1123         : __seg_(__it.__seg_), __ctz_(__it.__ctz_) {}
1124
1125     _LIBCPP_INLINE_VISIBILITY reference operator*() const _NOEXCEPT
1126         {return reference(__seg_, __storage_type(1) << __ctz_);}
1127
1128     _LIBCPP_INLINE_VISIBILITY __bit_iterator& operator++()
1129     {
1130         if (__ctz_ != __bits_per_word-1)
1131             ++__ctz_;
1132         else
1133         {
1134             __ctz_ = 0;
1135             ++__seg_;
1136         }
1137         return *this;
1138     }
1139
1140     _LIBCPP_INLINE_VISIBILITY __bit_iterator operator++(int)
1141     {
1142         __bit_iterator __tmp = *this;
1143         ++(*this);
1144         return __tmp;
1145     }
1146
1147     _LIBCPP_INLINE_VISIBILITY __bit_iterator& operator--()
1148     {
1149         if (__ctz_ != 0)
1150             --__ctz_;
1151         else
1152         {
1153             __ctz_ = __bits_per_word - 1;
1154             --__seg_;
1155         }
1156         return *this;
1157     }
1158
1159     _LIBCPP_INLINE_VISIBILITY __bit_iterator operator--(int)
1160     {
1161         __bit_iterator __tmp = *this;
1162         --(*this);
1163         return __tmp;
1164     }
1165
1166     _LIBCPP_INLINE_VISIBILITY __bit_iterator& operator+=(difference_type __n)
1167     {
1168         if (__n >= 0)
1169             __seg_ += (__n + __ctz_) / __bits_per_word;
1170         else
1171             __seg_ += static_cast<difference_type>(__n - __bits_per_word + __ctz_ + 1)
1172                     / static_cast<difference_type>(__bits_per_word);
1173         __n &= (__bits_per_word - 1);
1174         __ctz_ = static_cast<unsigned>((__n + __ctz_)  % __bits_per_word);
1175         return *this;
1176     }
1177
1178     _LIBCPP_INLINE_VISIBILITY __bit_iterator& operator-=(difference_type __n)
1179     {
1180         return *this += -__n;
1181     }
1182
1183     _LIBCPP_INLINE_VISIBILITY __bit_iterator operator+(difference_type __n) const
1184     {
1185         __bit_iterator __t(*this);
1186         __t += __n;
1187         return __t;
1188     }
1189
1190     _LIBCPP_INLINE_VISIBILITY __bit_iterator operator-(difference_type __n) const
1191     {
1192         __bit_iterator __t(*this);
1193         __t -= __n;
1194         return __t;
1195     }
1196
1197     _LIBCPP_INLINE_VISIBILITY
1198     friend __bit_iterator operator+(difference_type __n, const __bit_iterator& __it) {return __it + __n;}
1199
1200     _LIBCPP_INLINE_VISIBILITY
1201     friend difference_type operator-(const __bit_iterator& __x, const __bit_iterator& __y)
1202         {return (__x.__seg_ - __y.__seg_) * __bits_per_word + __x.__ctz_ - __y.__ctz_;}
1203
1204     _LIBCPP_INLINE_VISIBILITY reference operator[](difference_type __n) const {return *(*this + __n);}
1205
1206     _LIBCPP_INLINE_VISIBILITY friend bool operator==(const __bit_iterator& __x, const __bit_iterator& __y)
1207         {return __x.__seg_ == __y.__seg_ && __x.__ctz_ == __y.__ctz_;}
1208
1209     _LIBCPP_INLINE_VISIBILITY friend bool operator!=(const __bit_iterator& __x, const __bit_iterator& __y)
1210         {return !(__x == __y);}
1211
1212     _LIBCPP_INLINE_VISIBILITY friend bool operator<(const __bit_iterator& __x, const __bit_iterator& __y)
1213         {return __x.__seg_ < __y.__seg_ || (__x.__seg_ == __y.__seg_ && __x.__ctz_ < __y.__ctz_);}
1214
1215     _LIBCPP_INLINE_VISIBILITY friend bool operator>(const __bit_iterator& __x, const __bit_iterator& __y)
1216         {return __y < __x;}
1217
1218     _LIBCPP_INLINE_VISIBILITY friend bool operator<=(const __bit_iterator& __x, const __bit_iterator& __y)
1219         {return !(__y < __x);}
1220
1221     _LIBCPP_INLINE_VISIBILITY friend bool operator>=(const __bit_iterator& __x, const __bit_iterator& __y)
1222         {return !(__x < __y);}
1223
1224 private:
1225     _LIBCPP_INLINE_VISIBILITY
1226     __bit_iterator(__storage_pointer __s, unsigned __ctz) _NOEXCEPT
1227         : __seg_(__s), __ctz_(__ctz) {}
1228
1229     friend typename _Cp::__self;
1230
1231     friend class __bit_reference<_Cp>;
1232     friend class __bit_const_reference<_Cp>;
1233     friend class __bit_iterator<_Cp, true>;
1234     template <class _Dp> friend struct __bit_array;
1235     template <class _Dp> friend void __fill_n_false(__bit_iterator<_Dp, false> __first, typename _Dp::size_type __n);
1236     template <class _Dp> friend void __fill_n_true(__bit_iterator<_Dp, false> __first, typename _Dp::size_type __n);
1237     template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> __copy_aligned(__bit_iterator<_Dp, _IC> __first,
1238                                                                                   __bit_iterator<_Dp, _IC> __last,
1239                                                                                   __bit_iterator<_Dp, false> __result);
1240     template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> __copy_unaligned(__bit_iterator<_Dp, _IC> __first,
1241                                                                                     __bit_iterator<_Dp, _IC> __last,
1242                                                                                     __bit_iterator<_Dp, false> __result);
1243     template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> copy(__bit_iterator<_Dp, _IC> __first,
1244                                                                         __bit_iterator<_Dp, _IC> __last,
1245                                                                         __bit_iterator<_Dp, false> __result);
1246     template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> __copy_backward_aligned(__bit_iterator<_Dp, _IC> __first,
1247                                                                                            __bit_iterator<_Dp, _IC> __last,
1248                                                                                            __bit_iterator<_Dp, false> __result);
1249     template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> __copy_backward_unaligned(__bit_iterator<_Dp, _IC> __first,
1250                                                                                              __bit_iterator<_Dp, _IC> __last,
1251                                                                                              __bit_iterator<_Dp, false> __result);
1252     template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> copy_backward(__bit_iterator<_Dp, _IC> __first,
1253                                                                                  __bit_iterator<_Dp, _IC> __last,
1254                                                                                  __bit_iterator<_Dp, false> __result);
1255     template <class __C1, class __C2>friend __bit_iterator<__C2, false> __swap_ranges_aligned(__bit_iterator<__C1, false>,
1256                                                                                            __bit_iterator<__C1, false>,
1257                                                                                            __bit_iterator<__C2, false>);
1258     template <class __C1, class __C2>friend __bit_iterator<__C2, false> __swap_ranges_unaligned(__bit_iterator<__C1, false>,
1259                                                                                              __bit_iterator<__C1, false>,
1260                                                                                              __bit_iterator<__C2, false>);
1261     template <class __C1, class __C2>friend __bit_iterator<__C2, false> swap_ranges(__bit_iterator<__C1, false>,
1262                                                                                  __bit_iterator<__C1, false>,
1263                                                                                  __bit_iterator<__C2, false>);
1264     template <class _Dp> friend __bit_iterator<_Dp, false> rotate(__bit_iterator<_Dp, false>,
1265                                                                 __bit_iterator<_Dp, false>,
1266                                                                 __bit_iterator<_Dp, false>);
1267     template <class _Dp, bool _IC1, bool _IC2> friend bool __equal_aligned(__bit_iterator<_Dp, _IC1>,
1268                                                     __bit_iterator<_Dp, _IC1>,
1269                                                     __bit_iterator<_Dp, _IC2>);
1270     template <class _Dp, bool _IC1, bool _IC2> friend bool __equal_unaligned(__bit_iterator<_Dp, _IC1>,
1271                                                       __bit_iterator<_Dp, _IC1>,
1272                                                       __bit_iterator<_Dp, _IC2>);
1273     template <class _Dp, bool _IC1, bool _IC2> friend bool equal(__bit_iterator<_Dp, _IC1>,
1274                                                                 __bit_iterator<_Dp, _IC1>,
1275                                                                 __bit_iterator<_Dp, _IC2>);
1276     template <class _Dp, bool _IC> friend __bit_iterator<_Dp, _IC> __find_bool_true(__bit_iterator<_Dp, _IC>,
1277                                                                           typename _Dp::size_type);
1278     template <class _Dp, bool _IC> friend __bit_iterator<_Dp, _IC> __find_bool_false(__bit_iterator<_Dp, _IC>,
1279                                                                            typename _Dp::size_type);
1280     template <class _Dp, bool _IC> friend typename __bit_iterator<_Dp, _IC>::difference_type
1281                    __count_bool_true(__bit_iterator<_Dp, _IC>, typename _Dp::size_type);
1282     template <class _Dp, bool _IC> friend typename __bit_iterator<_Dp, _IC>::difference_type
1283                    __count_bool_false(__bit_iterator<_Dp, _IC>, typename _Dp::size_type);
1284 };
1285
1286 _LIBCPP_END_NAMESPACE_STD
1287
1288 _LIBCPP_POP_MACROS
1289
1290 #endif  // _LIBCPP___BIT_REFERENCE