aboutsummaryrefslogtreecommitdiffstats
path: root/include/bit
blob: 8800b22b7bcbce6490742ab9845009bbc7a1e346 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
// -*- C++ -*-
//===------------------------------ bit ----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===---------------------------------------------------------------------===//

#ifndef _LIBCPP_BIT
#define _LIBCPP_BIT

/*
    bit synopsis

namespace std {

  template <class T>
    constexpr bool ispow2(T x) noexcept; // C++20
  template <class T>
    constexpr T ceil2(T x);              // C++20
  template <class T>
    constexpr T floor2(T x) noexcept;    // C++20
  template <class T>
    constexpr T log2p1(T x) noexcept;    // C++20

  // 23.20.2, rotating
  template<class T>
    constexpr T rotl(T x, unsigned int s) noexcept; // C++20
  template<class T>
    constexpr T rotr(T x, unsigned int s) noexcept; // C++20

  // 23.20.3, counting
  template<class T>
    constexpr int countl_zero(T x) noexcept;  // C++20
  template<class T>
    constexpr int countl_one(T x) noexcept;   // C++20
  template<class T>
    constexpr int countr_zero(T x) noexcept;  // C++20
  template<class T>
    constexpr int countr_one(T x) noexcept;   // C++20
  template<class T>
    constexpr int popcount(T x) noexcept;     // C++20

  // 20.15.9, endian 
  enum class endian {
    little = see below,        // C++20
    big = see below,           // C++20
    native = see below         // C++20
};

} // namespace std

*/

#include <__config>
#include <limits>
#include <type_traits>
#include <version>
#include <__debug>

#if defined(__IBMCPP__)
#include "support/ibm/support.h"
#endif
#if defined(_LIBCPP_COMPILER_MSVC)
#include <intrin.h>
#endif

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

#ifndef _LIBCPP_COMPILER_MSVC

inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_ctz(unsigned __x)           _NOEXCEPT { return __builtin_ctz(__x); }

inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_ctz(unsigned long __x)      _NOEXCEPT { return __builtin_ctzl(__x); }

inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); }


inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_clz(unsigned __x)           _NOEXCEPT { return __builtin_clz(__x); }

inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_clz(unsigned long __x)      _NOEXCEPT { return __builtin_clzl(__x); }

inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_clz(unsigned long long __x) _NOEXCEPT { return __builtin_clzll(__x); }


inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_popcount(unsigned __x)           _NOEXCEPT { return __builtin_popcount(__x); }

inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_popcount(unsigned long __x)      _NOEXCEPT { return __builtin_popcountl(__x); }

inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_popcount(unsigned long long __x) _NOEXCEPT { return __builtin_popcountll(__x); }

#else  // _LIBCPP_COMPILER_MSVC

// Precondition:  __x != 0
inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_ctz(unsigned __x) {
  static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
  static_assert(sizeof(unsigned long) == 4, "");
  unsigned long __where;
  if (_BitScanForward(&__where, __x))
    return static_cast<int>(__where);
  return 32;
}

inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_ctz(unsigned long __x) {
    static_assert(sizeof(unsigned long) == sizeof(unsigned), "");
    return __ctz(static_cast<unsigned>(__x));
}

inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_ctz(unsigned long long __x) {
    unsigned long __where;
#if defined(_LIBCPP_HAS_BITSCAN64)
    (defined(_M_AMD64) || defined(__x86_64__))
  if (_BitScanForward64(&__where, __x))
    return static_cast<int>(__where);
#else
  // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
  if (_BitScanForward(&__where, static_cast<unsigned long>(__x)))
    return static_cast<int>(__where);
  if (_BitScanForward(&__where, static_cast<unsigned long>(__x >> 32)))
    return static_cast<int>(__where + 32);
#endif
  return 64;
}

// Precondition:  __x != 0
inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_clz(unsigned __x) {
  static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
  static_assert(sizeof(unsigned long) == 4, "");
  unsigned long __where;
  if (_BitScanReverse(&__where, __x))
    return static_cast<int>(31 - __where);
  return 32; // Undefined Behavior.
}

inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_clz(unsigned long __x) {
    static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
    return __libcpp_clz(static_cast<unsigned>(__x));
}

inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_clz(unsigned long long __x) {
  unsigned long __where;
#if defined(_LIBCPP_HAS_BITSCAN64)
  if (_BitScanReverse64(&__where, __x))
    return static_cast<int>(63 - __where);
#else
  // Win32 doesn't have _BitScanReverse64 so emulate it with two 32 bit calls.
  if (_BitScanReverse(&__where, static_cast<unsigned long>(__x >> 32)))
    return static_cast<int>(63 - (__where + 32));
  if (_BitScanReverse(&__where, static_cast<unsigned long>(__x)))
    return static_cast<int>(63 - __where);
#endif
  return 64; // Undefined Behavior.
}

inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned __x) {
  static_assert(sizeof(unsigned) == 4, "");
  return __popcnt(__x);
}

inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long __x) {
  static_assert(sizeof(unsigned long) == 4, "");
  return __popcnt(__x);
}

inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long long __x) {
  static_assert(sizeof(unsigned long long) == 8, "");
  return __popcnt64(__x);
}

#endif // _LIBCPP_COMPILER_MSVC

template <class _Tp>
using __bitop_unsigned_integer _LIBCPP_NODEBUG_TYPE = integral_constant<bool,
         is_integral<_Tp>::value &&
         is_unsigned<_Tp>::value &&
        _IsNotSame<typename remove_cv<_Tp>::type, bool>::value &&
        _IsNotSame<typename remove_cv<_Tp>::type, signed char>::value &&
        _IsNotSame<typename remove_cv<_Tp>::type, wchar_t>::value &&
        _IsNotSame<typename remove_cv<_Tp>::type, char16_t>::value &&
        _IsNotSame<typename remove_cv<_Tp>::type, char32_t>::value
    >;


template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
_Tp __rotl(_Tp __t, unsigned int __cnt) _NOEXCEPT
{
    static_assert(__bitop_unsigned_integer<_Tp>::value, "__rotl requires unsigned");
    const unsigned int __dig = numeric_limits<_Tp>::digits;
    if ((__cnt % __dig) == 0)
        return __t;
    return (__t << (__cnt % __dig)) | (__t >> (__dig - (__cnt % __dig)));
}


template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
_Tp __rotr(_Tp __t, unsigned int __cnt) _NOEXCEPT
{
    static_assert(__bitop_unsigned_integer<_Tp>::value, "__rotr requires unsigned");
    const unsigned int __dig = numeric_limits<_Tp>::digits;
    if ((__cnt % __dig) == 0)
        return __t;
    return (__t >> (__cnt % __dig)) | (__t << (__dig - (__cnt % __dig)));
}



template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
int __countr_zero(_Tp __t) _NOEXCEPT
{
    static_assert(__bitop_unsigned_integer<_Tp>::value, "__countr_zero requires unsigned");
    if (__t == 0)
        return numeric_limits<_Tp>::digits;

    if      (sizeof(_Tp) <= sizeof(unsigned int))
        return __libcpp_ctz(static_cast<unsigned int>(__t));
    else if (sizeof(_Tp) <= sizeof(unsigned long))
        return __libcpp_ctz(static_cast<unsigned long>(__t));
    else if (sizeof(_Tp) <= sizeof(unsigned long long))
        return __libcpp_ctz(static_cast<unsigned long long>(__t));
    else
    {
        int __ret = 0;
        int __iter = 0;
        const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
        while ((__iter = __libcpp_ctz(static_cast<unsigned long long>(__t))) == __ulldigits)
        {
            __ret += __iter;
            __t >>= __ulldigits;
        }
        return __ret + __iter;
    }
}

template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
int __countl_zero(_Tp __t) _NOEXCEPT
{
    static_assert(__bitop_unsigned_integer<_Tp>::value, "__countl_zero requires unsigned");
    if (__t == 0)
        return numeric_limits<_Tp>::digits;

    if      (sizeof(_Tp) <= sizeof(unsigned int))
        return __libcpp_clz(static_cast<unsigned int>(__t))
              - (numeric_limits<unsigned int>::digits - numeric_limits<_Tp>::digits);
    else if (sizeof(_Tp) <= sizeof(unsigned long))
        return __libcpp_clz(static_cast<unsigned long>(__t))
              - (numeric_limits<unsigned long>::digits - numeric_limits<_Tp>::digits);
    else if (sizeof(_Tp) <= sizeof(unsigned long long))
        return __libcpp_clz(static_cast<unsigned long long>(__t))
              - (numeric_limits<unsigned long long>::digits - numeric_limits<_Tp>::digits);
    else
    {
        int __ret = 0;
        int __iter = 0;
        const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
        while (true) {
            __t = __rotr(__t, __ulldigits);
            if ((__iter = __countl_zero(static_cast<unsigned long long>(__t))) != __ulldigits)
                break;
            __ret += __iter;
            }
        return __ret + __iter;
    }
}

template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
int __countl_one(_Tp __t) _NOEXCEPT
{
    static_assert(__bitop_unsigned_integer<_Tp>::value, "__countl_one requires unsigned");
    return __t != numeric_limits<_Tp>::max()
        ? __countl_zero(static_cast<_Tp>(~__t))
        : numeric_limits<_Tp>::digits;
}


template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
int __countr_one(_Tp __t) _NOEXCEPT
{
    static_assert(__bitop_unsigned_integer<_Tp>::value, "__countr_one requires unsigned");
    return __t != numeric_limits<_Tp>::max()
        ? __countr_zero(static_cast<_Tp>(~__t))
        : numeric_limits<_Tp>::digits;
}


template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
int
__popcount(_Tp __t) _NOEXCEPT
{
    static_assert(__bitop_unsigned_integer<_Tp>::value, "__libcpp_popcount requires unsigned");
    if      (sizeof(_Tp) <= sizeof(unsigned int))
        return __libcpp_popcount(static_cast<unsigned int>(__t));
    else if (sizeof(_Tp) <= sizeof(unsigned long))
        return __libcpp_popcount(static_cast<unsigned long>(__t));
    else if (sizeof(_Tp) <= sizeof(unsigned long long))
        return __libcpp_popcount(static_cast<unsigned long long>(__t));
    else
    {
        int __ret = 0;
        while (__t != 0)
        {
            __ret += __libcpp_popcount(static_cast<unsigned long long>(__t));
            __t >>= numeric_limits<unsigned long long>::digits;
        }
        return __ret;
    }
}


// integral log base 2
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
unsigned __bit_log2(_Tp __t) _NOEXCEPT
{
    static_assert(__bitop_unsigned_integer<_Tp>::value, "__bit_log2 requires unsigned");
    return std::numeric_limits<_Tp>::digits - 1 - __countl_zero(__t);
}

template <class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
bool __ispow2(_Tp __t) _NOEXCEPT
{
    static_assert(__bitop_unsigned_integer<_Tp>::value, "__ispow2 requires unsigned");
	return __t != 0 && (((__t & (__t - 1)) == 0)); 
}


#if _LIBCPP_STD_VER > 17

template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
rotl(_Tp __t, unsigned int __cnt) noexcept
{
    return __rotl(__t, __cnt);
}


// rotr
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
rotr(_Tp __t, unsigned int __cnt) noexcept
{
    return __rotr(__t, __cnt);
}


template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
countl_zero(_Tp __t) noexcept
{
    return __countl_zero(__t);
}


template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
countl_one(_Tp __t) noexcept
{
    return __countl_one(__t);
}


template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
countr_zero(_Tp __t) noexcept
{
	return __countr_zero(__t);
}


template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
countr_one(_Tp __t) noexcept
{
    return __countr_one(__t);
}


template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
popcount(_Tp __t) noexcept
{
    return __popcount(__t);
}


template <class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, bool>
ispow2(_Tp __t) noexcept
{
    return __ispow2(__t);
}

template <class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
floor2(_Tp __t) noexcept
{
    return __t == 0 ? 0 : _Tp{1} << __bit_log2(__t);
}

template <class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
ceil2(_Tp __t) noexcept
{
    if (__t < 2) return 1;
    const unsigned __n = numeric_limits<_Tp>::digits - countl_zero((_Tp)(__t - 1u));
    _LIBCPP_DEBUG_ASSERT(__libcpp_is_constant_evaluated() || __n != numeric_limits<_Tp>::digits, "Bad input to ceil2");

    if constexpr (sizeof(_Tp) >= sizeof(unsigned))
        return _Tp{1} << __n;
    else
    {
        const unsigned __extra = numeric_limits<unsigned>::digits  - numeric_limits<_Tp>::digits;
        const unsigned __retVal = 1u << (__n + __extra);
        return (_Tp) (__retVal >> __extra);
    }
}

template <class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
log2p1(_Tp __t) noexcept
{
    return __t == 0 ? 0 : __bit_log2(__t) + 1;
}


enum class endian
{
    little = 0xDEAD,
    big    = 0xFACE,
#if defined(_LIBCPP_LITTLE_ENDIAN)
    native = little
#elif defined(_LIBCPP_BIG_ENDIAN)
    native = big
#else
    native = 0xCAFE
#endif
};

#endif // _LIBCPP_STD_VER > 17

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP_BIT