aboutsummaryrefslogtreecommitdiff
path: root/NorthstarDedicatedTest/include/protobuf/stubs/int128.cc
blob: bc7e855409b9efd2cfba024974d9881f5bed7987 (plain)
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
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include <stubs/int128.h>

#include <iomanip>
#include <ostream>  // NOLINT(readability/streams)
#include <sstream>

#include <stubs/logging.h>

#include <port_def.inc>

namespace google {
namespace protobuf {

const uint128_pod kuint128max = {uint64_t{0xFFFFFFFFFFFFFFFFu},
                                 uint64_t{0xFFFFFFFFFFFFFFFFu}};

// Returns the 0-based position of the last set bit (i.e., most significant bit)
// in the given uint64. The argument may not be 0.
//
// For example:
//   Given: 5 (decimal) == 101 (binary)
//   Returns: 2
#define STEP(T, n, pos, sh)                   \
  do {                                        \
    if ((n) >= (static_cast<T>(1) << (sh))) { \
      (n) = (n) >> (sh);                      \
      (pos) |= (sh);                          \
    }                                         \
  } while (0)
static inline int Fls64(uint64 n) {
  GOOGLE_DCHECK_NE(0, n);
  int pos = 0;
  STEP(uint64, n, pos, 0x20);
  uint32 n32 = n;
  STEP(uint32, n32, pos, 0x10);
  STEP(uint32, n32, pos, 0x08);
  STEP(uint32, n32, pos, 0x04);
  return pos + ((uint64_t{0x3333333322221100u} >> (n32 << 2)) & 0x3);
}
#undef STEP

// Like Fls64() above, but returns the 0-based position of the last set bit
// (i.e., most significant bit) in the given uint128. The argument may not be 0.
static inline int Fls128(uint128 n) {
  if (uint64 hi = Uint128High64(n)) {
    return Fls64(hi) + 64;
  }
  return Fls64(Uint128Low64(n));
}

void uint128::DivModImpl(uint128 dividend, uint128 divisor,
                         uint128* quotient_ret, uint128* remainder_ret) {
  if (divisor == 0) {
    GOOGLE_LOG(FATAL) << "Division or mod by zero: dividend.hi=" << dividend.hi_
                      << ", lo=" << dividend.lo_;
  } else if (dividend < divisor) {
    *quotient_ret = 0;
    *remainder_ret = dividend;
    return;
  } else {
    int dividend_bit_length = Fls128(dividend);
    int divisor_bit_length = Fls128(divisor);
    int difference = dividend_bit_length - divisor_bit_length;
    uint128 quotient = 0;
    while (difference >= 0) {
      quotient <<= 1;
      uint128 shifted_divisor = divisor << difference;
      if (shifted_divisor <= dividend) {
        dividend -= shifted_divisor;
        quotient += 1;
      }
      difference -= 1;
    }
    //record the final quotient and remainder
    *quotient_ret = quotient;
    *remainder_ret = dividend;
  }
}


uint128& uint128::operator/=(const uint128& divisor) {
  uint128 quotient = 0;
  uint128 remainder = 0;
  DivModImpl(*this, divisor, &quotient, &remainder);
  *this = quotient;
  return *this;
}
uint128& uint128::operator%=(const uint128& divisor) {
  uint128 quotient = 0;
  uint128 remainder = 0;
  DivModImpl(*this, divisor, &quotient, &remainder);
  *this = remainder;
  return *this;
}

std::ostream& operator<<(std::ostream& o, const uint128& b) {
  std::ios_base::fmtflags flags = o.flags();

  // Select a divisor which is the largest power of the base < 2^64.
  uint128 div;
  std::streamsize div_base_log;
  switch (flags & std::ios::basefield) {
    case std::ios::hex:
      div =
          static_cast<uint64>(uint64_t{0x1000000000000000u});  // 16^15
      div_base_log = 15;
      break;
    case std::ios::oct:
      div = static_cast<uint64>(
          uint64_t{01000000000000000000000u});  // 8^21
      div_base_log = 21;
      break;
    default:  // std::ios::dec
      div = static_cast<uint64>(
          uint64_t{10000000000000000000u});  // 10^19
      div_base_log = 19;
      break;
  }

  // Now piece together the uint128 representation from three chunks of
  // the original value, each less than "div" and therefore representable
  // as a uint64.
  std::ostringstream os;
  std::ios_base::fmtflags copy_mask =
      std::ios::basefield | std::ios::showbase | std::ios::uppercase;
  os.setf(flags & copy_mask, copy_mask);
  uint128 high = b;
  uint128 low;
  uint128::DivModImpl(high, div, &high, &low);
  uint128 mid;
  uint128::DivModImpl(high, div, &high, &mid);
  if (high.lo_ != 0) {
    os << high.lo_;
    os << std::noshowbase << std::setfill('0') << std::setw(div_base_log);
    os << mid.lo_;
    os << std::setw(div_base_log);
  } else if (mid.lo_ != 0) {
    os << mid.lo_;
    os << std::noshowbase << std::setfill('0') << std::setw(div_base_log);
  }
  os << low.lo_;
  std::string rep = os.str();

  // Add the requisite padding.
  std::streamsize width = o.width(0);
  if (width > rep.size()) {
    if ((flags & std::ios::adjustfield) == std::ios::left) {
      rep.append(width - rep.size(), o.fill());
    } else {
      rep.insert(static_cast<std::string::size_type>(0),
                 width - rep.size(), o.fill());
    }
  }

  // Stream the final representation in a single "<<" call.
  return o << rep;
}

}  // namespace protobuf
}  // namespace google

#include <port_undef.inc>  // NOLINT