lsst.sphgeom ge0fe5cd092+ac198e9f13
BigInteger.h
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1/*
2 * LSST Data Management System
3 * Copyright 2014-2015 AURA/LSST.
4 *
5 * This product includes software developed by the
6 * LSST Project (http://www.lsst.org/).
7 *
8 * This program is free software: you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation, either version 3 of the License, or
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14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
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21 */
22
23#ifndef LSST_SPHGEOM_BIGINTEGER_H_
24#define LSST_SPHGEOM_BIGINTEGER_H_
25
28
29#include <stdint.h>
30#include <cstring>
31#include <stdexcept>
32
33
34namespace lsst {
35namespace sphgeom {
36
46public:
49 BigInteger(uint32_t * digits, unsigned capacity) :
50 _digits(digits),
51 _capacity(capacity),
52 _size(0),
53 _sign(0)
54 {}
55
56 BigInteger & operator=(BigInteger const & b) {
57 if (this != &b) {
58 _checkCapacity(b._size);
59 _sign = b._sign;
60 _size = b._size;
61 std::memcpy(_digits, b._digits, sizeof(uint32_t) * b._size);
62 }
63 return *this;
64 }
65
68 int getSign() const { return _sign; }
69
71 unsigned getSize() const { return _size; }
72
75 unsigned getCapacity() const { return _capacity; }
76
78 uint32_t const * getDigits() const { return _digits; }
79
81 void setToZero() { _sign = 0; _size = 0; }
82
84 void setTo(int64_t x) {
85 if (x < 0) {
86 setTo(static_cast<uint64_t>(-x));
87 _sign = -1;
88 } else {
89 setTo(static_cast<uint64_t>(x));
90 }
91 }
92
94 void setTo(uint64_t x) {
95 _checkCapacity(2);
96 _digits[0] = static_cast<uint32_t>(x);
97 _digits[1] = static_cast<uint32_t>(x >> 32);
98 _size = (_digits[1] == 0) ? (_digits[0] != 0) : 2;
99 _sign = (_size != 0);
100 }
101
103 void negate() { _sign = -_sign; }
104
106 BigInteger & add(BigInteger const & b);
107
109 BigInteger & subtract(BigInteger const & b);
110
112 BigInteger & multiplyPow2(unsigned n);
113
115 BigInteger & multiply(BigInteger const & b);
116
117private:
118
119 void _checkCapacity(unsigned n) const {
120 if (_capacity < n) {
121 throw std::runtime_error("BigInteger capacity is too small");
122 }
123 }
124
125 uint32_t * _digits; // Unowned
126 unsigned _capacity;
127 unsigned _size;
128 int _sign;
129};
130
131}} // namespace lsst::sphgeom
132
133#endif // LSST_SPHGEOM_BIGINTEGER_H_
Definition: BigInteger.h:45
BigInteger & subtract(BigInteger const &b)
subtract subtracts b from this integer.
Definition: BigInteger.cc:201
BigInteger & multiply(BigInteger const &b)
multiply multiplies this integer by b.
Definition: BigInteger.cc:249
BigInteger & multiplyPow2(unsigned n)
multiplyPow2 multiplies this integer by 2ⁿ.
Definition: BigInteger.cc:214
void setToZero()
setToZero sets this integer to zero.
Definition: BigInteger.h:81
BigInteger(uint32_t *digits, unsigned capacity)
Definition: BigInteger.h:49
int getSign() const
Definition: BigInteger.h:68
void negate()
negate multiplies this integer by -1.
Definition: BigInteger.h:103
BigInteger & add(BigInteger const &b)
add adds b to this integer.
Definition: BigInteger.cc:156
unsigned getCapacity() const
Definition: BigInteger.h:75
void setTo(uint64_t x)
setTo sets this integer to the given unsigned 64 bit integer value.
Definition: BigInteger.h:94
unsigned getSize() const
getSize returns the number of digits in the value of this integer.
Definition: BigInteger.h:71
void setTo(int64_t x)
setTo sets this integer to the given signed 64 bit integer value.
Definition: BigInteger.h:84
uint32_t const * getDigits() const
getDigits returns the underlying digit array.
Definition: BigInteger.h:78