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https://github.com/TomHarte/CLK.git
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299 lines
9.6 KiB
C++
299 lines
9.6 KiB
C++
//
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// Storage.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 10/07/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#ifndef Storage_hpp
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#define Storage_hpp
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#include <cmath>
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#include <cstdint>
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#include <limits>
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#include <numeric>
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namespace Storage {
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/*!
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Contains either an absolute time or a time interval, described as a quotient, in terms of a
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clock rate to which the time is relative and its length in cycles based on that clock rate.
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*/
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struct Time {
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unsigned int length, clock_rate;
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constexpr Time() : length(0), clock_rate(1) {}
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constexpr Time(unsigned int unsigned_int_value) : length(unsigned_int_value), clock_rate(1) {}
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constexpr Time(int int_value) : Time(unsigned(int_value)) {}
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constexpr Time(unsigned int length, unsigned int clock_rate) : length(length), clock_rate(clock_rate) {}
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constexpr Time(int length, int clock_rate) : Time(unsigned(length), unsigned(clock_rate)) {}
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Time(uint64_t length, uint64_t clock_rate) {
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install_result(length, clock_rate);
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}
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Time(float value) {
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install_float(value);
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}
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static constexpr Time simplified(unsigned int _length, unsigned int _clock_rate) {
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const auto gcd = std::gcd(_length, _clock_rate);
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return Time(_length / gcd, _clock_rate / gcd);
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}
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/*!
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Reduces this @c Time to its simplest form; eliminates all common factors from @c length
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and @c clock_rate.
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*/
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void simplify() {
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unsigned int common_divisor = std::gcd(length, clock_rate);
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length /= common_divisor;
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clock_rate /= common_divisor;
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}
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/*!
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@returns the floating point conversion of this @c Time. This will often be less precise.
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*/
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template <typename T> T get() const {
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return T(length) / T(clock_rate);
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}
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inline bool operator < (const Time &other) const {
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return uint64_t(other.clock_rate) * uint64_t(length) < uint64_t(clock_rate) * uint64_t(other.length);
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}
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inline bool operator <= (const Time &other) const {
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return uint64_t(other.clock_rate) * uint64_t(length) <= uint64_t(clock_rate) * uint64_t(other.length);
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}
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inline bool operator > (const Time &other) const {
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return uint64_t(other.clock_rate) * uint64_t(length) > uint64_t(clock_rate) * uint64_t(other.length);
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}
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inline bool operator >= (const Time &other) const {
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return uint64_t(other.clock_rate) * uint64_t(length) >= uint64_t(clock_rate) * uint64_t(other.length);
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}
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inline bool operator == (const Time &other) const {
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return uint64_t(other.clock_rate) * uint64_t(length) == uint64_t(clock_rate) * uint64_t(other.length);
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}
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inline Time operator + (const Time &other) const {
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if(!other.length) return *this;
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uint64_t result_length;
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uint64_t result_clock_rate;
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if(clock_rate == other.clock_rate) {
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result_length = uint64_t(length) + uint64_t(other.length);
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result_clock_rate = clock_rate;
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} else {
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result_length = uint64_t(length) * uint64_t(other.clock_rate) + uint64_t(other.length) * uint64_t(clock_rate);
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result_clock_rate = uint64_t(clock_rate) * uint64_t(other.clock_rate);
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}
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return Time(result_length, result_clock_rate);
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}
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inline Time &operator += (const Time &other) {
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if(!other.length) return *this;
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if(!length) {
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*this = other;
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return *this;
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}
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uint64_t result_length;
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uint64_t result_clock_rate;
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if(clock_rate == other.clock_rate) {
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result_length = uint64_t(length) + uint64_t(other.length);
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result_clock_rate = uint64_t(clock_rate);
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} else {
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result_length = uint64_t(length) * uint64_t(other.clock_rate) + uint64_t(other.length) * uint64_t(clock_rate);
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result_clock_rate = uint64_t(clock_rate) * uint64_t(other.clock_rate);
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}
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install_result(result_length, result_clock_rate);
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return *this;
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}
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inline Time operator - (const Time &other) const {
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if(!other.length) return *this;
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uint64_t result_length;
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uint64_t result_clock_rate;
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if(clock_rate == other.clock_rate) {
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result_length = uint64_t(length) - uint64_t(other.length);
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result_clock_rate = clock_rate;
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} else {
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result_length = uint64_t(length) * uint64_t(other.clock_rate) - uint64_t(other.length) * uint64_t(clock_rate);
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result_clock_rate = uint64_t(clock_rate) * uint64_t(other.clock_rate);
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}
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return Time(result_length, result_clock_rate);
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}
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inline Time operator -= (const Time &other) {
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if(!other.length) return *this;
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uint64_t result_length;
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uint64_t result_clock_rate;
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if(clock_rate == other.clock_rate) {
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result_length = uint64_t(length) - uint64_t(other.length);
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result_clock_rate = uint64_t(clock_rate);
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} else {
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result_length = uint64_t(length) * uint64_t(other.clock_rate) - uint64_t(other.length) * uint64_t(clock_rate);
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result_clock_rate = uint64_t(clock_rate) * uint64_t(other.clock_rate);
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}
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install_result(result_length, result_clock_rate);
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return *this;
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}
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inline Time operator * (const Time &other) const {
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uint64_t result_length = uint64_t(length) * uint64_t(other.length);
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uint64_t result_clock_rate = uint64_t(clock_rate) * uint64_t(other.clock_rate);
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return Time(result_length, result_clock_rate);
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}
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inline Time &operator *= (const Time &other) {
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uint64_t result_length = uint64_t(length) * uint64_t(other.length);
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uint64_t result_clock_rate = uint64_t(clock_rate) * uint64_t(other.clock_rate);
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install_result(result_length, result_clock_rate);
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return *this;
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}
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inline Time operator * (unsigned int multiplier) const {
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uint64_t result_length = uint64_t(length) * uint64_t(multiplier);
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uint64_t result_clock_rate = uint64_t(clock_rate);
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return Time(result_length, result_clock_rate);
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}
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inline Time &operator *= (unsigned int multiplier) {
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uint64_t result_length = uint64_t(length) * uint64_t(multiplier);
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uint64_t result_clock_rate = uint64_t(clock_rate);
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install_result(result_length, result_clock_rate);
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return *this;
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}
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inline Time operator / (const Time &other) const {
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uint64_t result_length = uint64_t(length) * uint64_t(other.clock_rate);
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uint64_t result_clock_rate = uint64_t(clock_rate) * uint64_t(other.length);
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return Time(result_length, result_clock_rate);
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}
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inline Time &operator /= (const Time &other) {
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uint64_t result_length = uint64_t(length) * uint64_t(other.clock_rate);
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uint64_t result_clock_rate = uint64_t(clock_rate) * uint64_t(other.length);
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install_result(result_length, result_clock_rate);
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return *this;
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}
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inline Time operator / (unsigned int divisor) const {
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uint64_t result_length = uint64_t(length);
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uint64_t result_clock_rate = uint64_t(clock_rate) * uint64_t(divisor);
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return Time(result_length, result_clock_rate);
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}
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inline Time &operator /= (unsigned int divisor) {
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uint64_t result_length = uint64_t(length);
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uint64_t result_clock_rate = uint64_t(clock_rate) * uint64_t(divisor);
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install_result(result_length, result_clock_rate);
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return *this;
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}
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inline void set_zero() {
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length = 0;
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clock_rate = 1;
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}
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inline void set_one() {
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length = 1;
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clock_rate = 1;
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}
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static Time max() {
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return Time(std::numeric_limits<unsigned int>::max());
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}
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private:
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inline void install_result(uint64_t long_length, uint64_t long_clock_rate) {
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if(long_length <= std::numeric_limits<unsigned int>::max() && long_clock_rate <= std::numeric_limits<unsigned int>::max()) {
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length = unsigned(long_length);
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clock_rate = unsigned(long_clock_rate);
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return;
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}
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// TODO: switch to appropriate values if the result is too large or small to fit, even with trimmed accuracy.
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if(!long_length) {
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length = 0;
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clock_rate = 1;
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return;
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}
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while(!(long_length&0xf) && !(long_clock_rate&0xf)) {
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long_length >>= 4;
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long_clock_rate >>= 4;
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}
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while(!(long_length&1) && !(long_clock_rate&1)) {
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long_length >>= 1;
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long_clock_rate >>= 1;
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}
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if(long_length > std::numeric_limits<unsigned int>::max() || long_clock_rate > std::numeric_limits<unsigned int>::max()) {
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uint64_t common_divisor = std::gcd(long_length, long_clock_rate);
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long_length /= common_divisor;
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long_clock_rate /= common_divisor;
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// Okay, in desperation accept a loss of accuracy.
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while(
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(long_length > std::numeric_limits<unsigned int>::max() || long_clock_rate > std::numeric_limits<unsigned int>::max()) &&
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(long_clock_rate > 1)) {
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long_length >>= 1;
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long_clock_rate >>= 1;
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}
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}
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if(long_length <= std::numeric_limits<unsigned int>::max() && long_clock_rate <= std::numeric_limits<unsigned int>::max()) {
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length = unsigned(long_length);
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clock_rate = unsigned(long_clock_rate);
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} else {
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length = std::numeric_limits<unsigned int>::max();
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clock_rate = 1u;
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}
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}
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inline void install_float(float value) {
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// Grab the float's native mantissa and exponent.
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int exponent;
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const float mantissa = frexpf(value, &exponent);
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// Turn the mantissa into an int, and adjust the exponent
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// appropriately.
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const uint64_t loaded_mantissa = uint64_t(ldexpf(mantissa, 24));
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const auto relative_exponent = exponent - 24;
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// If the mantissa is negative and its absolute value fits within a 64-bit integer,
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// just load up.
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if(relative_exponent <= 0 && relative_exponent > -64) {
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install_result(loaded_mantissa, uint64_t(1) << -relative_exponent);
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return;
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}
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// If the exponent is positive but doesn't cause loaded_mantissa to overflow,
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// install with the natural encoding.
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if(relative_exponent > 0 && relative_exponent < (64 - 24)) {
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install_result(loaded_mantissa << relative_exponent, 1);
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return;
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}
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// Otherwise, if this number is too large to store, store the maximum value.
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if(relative_exponent > 0) {
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install_result(std::numeric_limits<uint64_t>::max(), 1);
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return;
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}
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// If the number is too small to store accurately, store 0.
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if(relative_exponent < 0) {
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install_result(0, 1);
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return;
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}
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}
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};
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}
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#endif /* Storage_h */
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