LSSTApplications  20.0.0
LSSTDataManagementBasePackage
BigInteger.h
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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 
34 namespace lsst {
35 namespace sphgeom {
36 
45 class BigInteger {
46 public:
49  BigInteger(uint32_t * digits, unsigned capacity) :
50  _digits(digits),
51  _capacity(capacity),
52  _size(0),
53  _sign(0)
54  {}
55 
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 
117 private:
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_
lsst::sphgeom::BigInteger::negate
void negate()
negate multiplies this integer by -1.
Definition: BigInteger.h:103
lsst::utils::n
Definition: Demangle.cc:62
lsst::sphgeom::BigInteger::getDigits
uint32_t const * getDigits() const
getDigits returns the underlying digit array.
Definition: BigInteger.h:78
lsst::sphgeom::BigInteger::setTo
void setTo(uint64_t x)
setTo sets this integer to the given unsigned 64 bit integer value.
Definition: BigInteger.h:94
lsst::sphgeom::BigInteger::subtract
BigInteger & subtract(BigInteger const &b)
subtract subtracts b from this integer.
Definition: BigInteger.cc:201
lsst::sphgeom::BigInteger::multiplyPow2
BigInteger & multiplyPow2(unsigned n)
multiplyPow2 multiplies this integer by 2ⁿ.
Definition: BigInteger.cc:214
lsst::sphgeom::BigInteger::getSize
unsigned getSize() const
getSize returns the number of digits in the value of this integer.
Definition: BigInteger.h:71
lsst::sphgeom::BigInteger::setTo
void setTo(int64_t x)
setTo sets this integer to the given signed 64 bit integer value.
Definition: BigInteger.h:84
lsst::sphgeom::BigInteger::BigInteger
BigInteger(uint32_t *digits, unsigned capacity)
This constructor creates a zero-valued integer with the given digit array.
Definition: BigInteger.h:49
lsst::sphgeom::BigInteger::setToZero
void setToZero()
setToZero sets this integer to zero.
Definition: BigInteger.h:81
lsst::sphgeom::BigInteger::getCapacity
unsigned getCapacity() const
getCapacity returns the number of digits in the underlying digit array.
Definition: BigInteger.h:75
lsst::sphgeom::BigInteger::add
BigInteger & add(BigInteger const &b)
add adds b to this integer.
Definition: BigInteger.cc:156
x
double x
Definition: ChebyshevBoundedField.cc:277
lsst::sphgeom::BigInteger
BigInteger is an arbitrary precision signed integer class.
Definition: BigInteger.h:45
std::runtime_error
STL class.
b
table::Key< int > b
Definition: TransmissionCurve.cc:467
lsst
A base class for image defects.
Definition: imageAlgorithm.dox:1
lsst::sphgeom::BigInteger::getSign
int getSign() const
getSign returns -1, 0 or 1 if this integer is negative, zero or positive.
Definition: BigInteger.h:68
std::memcpy
T memcpy(T... args)
lsst::sphgeom::BigInteger::multiply
BigInteger & multiply(BigInteger const &b)
multiply multiplies this integer by b.
Definition: BigInteger.cc:249
lsst::sphgeom::BigInteger::operator=
BigInteger & operator=(BigInteger const &b)
Definition: BigInteger.h:56