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LSST Data Management Base Package
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BigInteger.h
Go to the documentation of this file.
1/*
2 * This file is part of sphgeom.
3 *
4 * Developed for the LSST Data Management System.
5 * This product includes software developed by the LSST Project
6 * (http://www.lsst.org).
7 * See the COPYRIGHT file at the top-level directory of this distribution
8 * for details of code ownership.
9 *
10 * This software is dual licensed under the GNU General Public License and also
11 * under a 3-clause BSD license. Recipients may choose which of these licenses
12 * to use; please see the files gpl-3.0.txt and/or bsd_license.txt,
13 * respectively. If you choose the GPL option then the following text applies
14 * (but note that there is still no warranty even if you opt for BSD instead):
15 *
16 * This program is free software: you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License as published by
18 * the Free Software Foundation, either version 3 of the License, or
19 * (at your option) any later version.
20 *
21 * This program is distributed in the hope that it will be useful,
22 * but WITHOUT ANY WARRANTY; without even the implied warranty of
23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
24 * GNU General Public License for more details.
25 *
26 * You should have received a copy of the GNU General Public License
27 * along with this program. If not, see <http://www.gnu.org/licenses/>.
28 */
29
30#ifndef LSST_SPHGEOM_BIGINTEGER_H_
31#define LSST_SPHGEOM_BIGINTEGER_H_
32
35
36#include <cstring>
37#include <stdexcept>
38#include <cstdint>
39
40namespace lsst {
41namespace sphgeom {
42
52public:
55 BigInteger(std::uint32_t * digits, unsigned capacity) :
56 _digits(digits),
57 _capacity(capacity),
58 _size(0),
59 _sign(0)
60 {}
61
63 if (this != &b) {
64 _checkCapacity(b._size);
65 _sign = b._sign;
66 _size = b._size;
67 std::memcpy(_digits, b._digits, sizeof(std::uint32_t) * b._size);
68 }
69 return *this;
70 }
71
74 int getSign() const { return _sign; }
75
77 unsigned getSize() const { return _size; }
78
81 unsigned getCapacity() const { return _capacity; }
82
84 std::uint32_t const * getDigits() const { return _digits; }
85
87 void setToZero() { _sign = 0; _size = 0; }
88
91 if (x < 0) {
92 setTo(static_cast<std::uint64_t>(-x));
93 _sign = -1;
94 } else {
95 setTo(static_cast<std::uint64_t>(x));
96 }
97 }
98
101 _checkCapacity(2);
102 _digits[0] = static_cast<std::uint32_t>(x);
103 _digits[1] = static_cast<std::uint32_t>(x >> 32);
104 _size = (_digits[1] == 0) ? (_digits[0] != 0) : 2;
105 _sign = (_size != 0);
106 }
107
109 void negate() { _sign = -_sign; }
110
112 BigInteger & add(BigInteger const & b);
113
115 BigInteger & subtract(BigInteger const & b);
116
118 BigInteger & multiplyPow2(unsigned n);
119
121 BigInteger & multiply(BigInteger const & b);
122
123private:
124
125 void _checkCapacity(unsigned n) const {
126 if (_capacity < n) {
127 throw std::runtime_error("BigInteger capacity is too small");
128 }
129 }
130
131 std::uint32_t * _digits; // Unowned
132 unsigned _capacity;
133 unsigned _size;
134 int _sign;
135};
136
137}} // namespace lsst::sphgeom
138
139#endif // LSST_SPHGEOM_BIGINTEGER_H_
BigInteger is an arbitrary precision signed integer class.
Definition BigInteger.h:51
BigInteger & subtract(BigInteger const &b)
subtract subtracts b from this integer.
void setTo(std::int64_t x)
setTo sets this integer to the given signed 64 bit integer value.
Definition BigInteger.h:90
BigInteger & multiply(BigInteger const &b)
multiply multiplies this integer by b.
BigInteger & multiplyPow2(unsigned n)
multiplyPow2 multiplies this integer by 2ⁿ.
void setToZero()
setToZero sets this integer to zero.
Definition BigInteger.h:87
void setTo(std::uint64_t x)
setTo sets this integer to the given unsigned 64 bit integer value.
Definition BigInteger.h:100
int getSign() const
getSign returns -1, 0 or 1 if this integer is negative, zero or positive.
Definition BigInteger.h:74
void negate()
negate multiplies this integer by -1.
Definition BigInteger.h:109
BigInteger & add(BigInteger const &b)
add adds b to this integer.
unsigned getCapacity() const
getCapacity returns the number of digits in the underlying digit array.
Definition BigInteger.h:81
std::uint32_t const * getDigits() const
getDigits returns the underlying digit array.
Definition BigInteger.h:84
BigInteger(std::uint32_t *digits, unsigned capacity)
This constructor creates a zero-valued integer with the given digit array.
Definition BigInteger.h:55
unsigned getSize() const
getSize returns the number of digits in the value of this integer.
Definition BigInteger.h:77
BigInteger & operator=(BigInteger const &b)
Definition BigInteger.h:62
T memcpy(T... args)