diff options
-rw-r--r-- | number.cpp | 52 | ||||
-rw-r--r-- | number.h | 23 |
2 files changed, 75 insertions, 0 deletions
@@ -184,6 +184,42 @@ number::operator<<(std::uint32_t shift) const return result; } +number +number::operator>>(std::uint32_t shift) const +{ + number result(*this); + + /* + * Since, internally, we store 32-bits-wide integers, we can just get rid + * of "shift / 32" first integers. + */ + for (unsigned int i = 0; i < shift / 32; ++i) { + if (result == 0) { + return 0; + } + + result._operands.pop_front(); + } + + shift %= 32; + + std::uint32_t carry = 0; + + for (auto it = result._operands.rbegin(); it != result._operands.rend(); ++it) { + auto &operand = *it; + + std::uint32_t tmp = ((1ull * operand) >> shift) | carry; + + carry = ((1ull * operand) << (32 - shift)); + + operand = tmp; + } + + result.shrink_to_fit(); + + return result; +} + /* }}} */ /* Comparison operators {{{ */ @@ -266,6 +302,14 @@ number::operator<<=(std::uint32_t n) } number & +number::operator>>=(std::uint32_t n) +{ + *this = *this >> n; + + return *this; +} + +number & number::operator++() { *this = *this + 1; @@ -275,6 +319,14 @@ number::operator++() /* }}} */ +void +number::shrink_to_fit() +{ + while (_operands.back() == 0) { + _operands.pop_back(); + } +} + std::ostream & operator<<(std::ostream &os, const number &n) { @@ -63,6 +63,14 @@ public: number operator<<(std::uint32_t n) const; /** + * \brief Return a number equals to this number where n bits have been + * shifted to the right. + * + * \param n Number of bits to shift. + */ + number operator>>(std::uint32_t) const; + + /** * \brief Tell whether the number passed as parameter is strictly less than * this number. * @@ -130,11 +138,26 @@ public: number &operator<<=(std::uint32_t); /** + * \brief Shift the number n bits to the right. + * + * \param n Number of bits to shift. + */ + number &operator>>=(std::uint32_t); + + /** * \brief Increment this number. */ number &operator++(); private: + /** + * \brief Remove unused leading 0 operands. + * + * Call this method after shrinking the number so that leading 0 operands + * are removed. + */ + void shrink_to_fit(); + /* First item is the least significant. */ std::list<std::uint32_t> _operands; }; |