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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 <stdint.h>
37#include <cstring>
38#include <stdexcept>
39
40
41namespace lsst {
42namespace sphgeom {
43
53public:
56 BigInteger(uint32_t * digits, unsigned capacity) :
57 _digits(digits),
58 _capacity(capacity),
59 _size(0),
60 _sign(0)
61 {}
62
64 if (this != &b) {
65 _checkCapacity(b._size);
66 _sign = b._sign;
67 _size = b._size;
68 std::memcpy(_digits, b._digits, sizeof(uint32_t) * b._size);
69 }
70 return *this;
71 }
72
75 int getSign() const { return _sign; }
76
78 unsigned getSize() const { return _size; }
79
82 unsigned getCapacity() const { return _capacity; }
83
85 uint32_t const * getDigits() const { return _digits; }
86
88 void setToZero() { _sign = 0; _size = 0; }
89
91 void setTo(int64_t x) {
92 if (x < 0) {
93 setTo(static_cast<uint64_t>(-x));
94 _sign = -1;
95 } else {
96 setTo(static_cast<uint64_t>(x));
97 }
98 }
99
101 void setTo(uint64_t x) {
102 _checkCapacity(2);
103 _digits[0] = static_cast<uint32_t>(x);
104 _digits[1] = static_cast<uint32_t>(x >> 32);
105 _size = (_digits[1] == 0) ? (_digits[0] != 0) : 2;
106 _sign = (_size != 0);
107 }
108
110 void negate() { _sign = -_sign; }
111
113 BigInteger & add(BigInteger const & b);
114
116 BigInteger & subtract(BigInteger const & b);
117
119 BigInteger & multiplyPow2(unsigned n);
120
122 BigInteger & multiply(BigInteger const & b);
123
124private:
125
126 void _checkCapacity(unsigned n) const {
127 if (_capacity < n) {
128 throw std::runtime_error("BigInteger capacity is too small");
129 }
130 }
131
132 uint32_t * _digits; // Unowned
133 unsigned _capacity;
134 unsigned _size;
135 int _sign;
136};
137
138}} // namespace lsst::sphgeom
139
140#endif // LSST_SPHGEOM_BIGINTEGER_H_
table::Key< int > b
BigInteger is an arbitrary precision signed integer class.
Definition BigInteger.h:52
BigInteger & subtract(BigInteger const &b)
subtract subtracts b from this integer.
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:88
BigInteger(uint32_t *digits, unsigned capacity)
This constructor creates a zero-valued integer with the given digit array.
Definition BigInteger.h:56
int getSign() const
getSign returns -1, 0 or 1 if this integer is negative, zero or positive.
Definition BigInteger.h:75
void negate()
negate multiplies this integer by -1.
Definition BigInteger.h:110
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:82
void setTo(uint64_t x)
setTo sets this integer to the given unsigned 64 bit integer value.
Definition BigInteger.h:101
unsigned getSize() const
getSize returns the number of digits in the value of this integer.
Definition BigInteger.h:78
void setTo(int64_t x)
setTo sets this integer to the given signed 64 bit integer value.
Definition BigInteger.h:91
BigInteger & operator=(BigInteger const &b)
Definition BigInteger.h:63
uint32_t const * getDigits() const
getDigits returns the underlying digit array.
Definition BigInteger.h:85
T memcpy(T... args)