prime_modulus.hpp File Reference

#include "../config.hpp"
#include <cstdint>

Namespaces
namespace	quickcpplib
	The QuickCppLib namespace.
namespace	quickcpplib::_xxx
	Per commit unique namespace to prevent different git submodule versions clashing.
namespace	quickcpplib::_xxx::algorithm
namespace	quickcpplib::_xxx::algorithm::prime_modulus
namespace	quickcpplib::_xxx::algorithm::prime_modulus::detail

Functions
constexpr uint64_t	quickcpplib::_xxx::algorithm::prime_modulus::twos_power_prime (size_t power) noexcept
	Returns a constexpr prime just under a twos power e.g. for 8, you get 251, which is the prime just below (1<<8) = 256. Very handy for hash tables.
template<uint32_t power, class T >
constexpr T	quickcpplib::_xxx::algorithm::prime_modulus::detail::mod (T v)
template<class T >
constexpr T	quickcpplib::_xxx::algorithm::prime_modulus::prime_modulus (T v, uint32_t power)
	Return the modulus of a number by the prime just below a twos power. Implemented as a fixed jump table, so the compiler can avoid the CPU division opcode, which still costs 40-90 CPU cycles, and excludes all CPU level parallelism.