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author | 2017-04-05 21:39:00 -0400 | |
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committer | 2017-04-06 11:39:00 +1000 | |
commit | f809f0e08d451c7fa05116c9c7b147f499ea82d7 (patch) | |
tree | 8a97a329d1be1014fb51bd36b400c4dee4d2153f /src/lib/util/timeconv.h | |
parent | ee19701c2cd582c17c8a3b855386cd1b79856560 (diff) |
Introduced an 'util::arbitrary_clock' template class, to represent a clock that "knows" when the epoch starts (#2010)
* Introduced an 'util::arbitrary_clock' template class, to represent a clock that "knows" when the epoch starts
Also:
- Converted the NTFS filetime code to use util::arbitrary_clock
- Converted the Mac datetime code to use util::atribrary_clock
This is in preparation for a bigger change to Imgtool where I eliminate usage of time_t
Diffstat (limited to 'src/lib/util/timeconv.h')
-rw-r--r-- | src/lib/util/timeconv.h | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/src/lib/util/timeconv.h b/src/lib/util/timeconv.h index ab8fd50fdcd..e2f6a987135 100644 --- a/src/lib/util/timeconv.h +++ b/src/lib/util/timeconv.h @@ -14,18 +14,232 @@ #pragma once #include "osdcore.h" +#include "coreutil.h" #include <chrono> namespace util { /*************************************************************************** + GLOBAL VARIABLES +***************************************************************************/ + +extern std::chrono::system_clock::duration system_clock_adjustment; + + +/*************************************************************************** TYPE DEFINITIONS ***************************************************************************/ typedef std::chrono::duration<std::uint64_t, std::ratio<1, 10000000> > ntfs_duration; +//--------------------------------------------------------- +// arbitrary_clock - an std::chrono clock that "knows" the +// date of the epoch's begining +//--------------------------------------------------------- + +template<typename Rep, int Y, int M, int D, int H, int N, int S, typename Ratio> +class arbitrary_clock +{ +public: + typedef Rep rep; + typedef Ratio period; + typedef std::chrono::duration<rep, period> duration; + typedef std::chrono::time_point<arbitrary_clock> time_point; + static constexpr int base_year = Y; + static constexpr int base_month = M; + static constexpr int base_day = D; + static constexpr int base_hour = H; + static constexpr int base_minute = N; + static constexpr int base_second = S; + + //--------------------------------------------------------- + // from_arbitrary_time_point - converts an arbitrary_clock + // with a different scale to this arbitrary_clock's scale + //--------------------------------------------------------- + + template<typename Rep2, int Y2, int M2, int D2, int H2, int N2, int S2, typename Ratio2> + static time_point from_arbitrary_time_point(const std::chrono::time_point<arbitrary_clock<Rep2, Y2, M2, D2, H2, N2, S2, Ratio2> > &tp) + { + const int64_t our_absolute_day = absolute_day(Y, M, D); + const int64_t their_absolute_day = absolute_day(Y2, M2, D2); + + const auto our_fract_day = std::chrono::hours(H) + std::chrono::minutes(N) + std::chrono::seconds(S); + const auto their_fract_day = std::chrono::hours(H2) + std::chrono::minutes(N2) + std::chrono::seconds(S2); + + const std::chrono::duration<Rep, Ratio> adjustment(std::chrono::hours(24) * (their_absolute_day - our_absolute_day) + (their_fract_day - our_fract_day)); + const duration result_duration = std::chrono::duration_cast<duration>(tp.time_since_epoch() + adjustment); + return time_point(result_duration); + } + + + //--------------------------------------------------------- + // to_arbitrary_time_point - converts an arbitrary_clock + // of this scale to one of different scale + //--------------------------------------------------------- + + template<typename Rep2, int Y2, int M2, int D2, int H2, int N2, int S2, typename Ratio2> + static std::chrono::time_point<arbitrary_clock<Rep2, Y2, M2, D2, H2, N2, S2, Ratio2> > to_arbitrary_time_point(const time_point &tp) + { + return arbitrary_clock<Rep2, Y2, M2, D2, H2, N2, S2, Ratio2>::from_arbitrary_time_point(tp); + } + + + //--------------------------------------------------------- + // to_tm - formats a structure of type 'struct tm' + //--------------------------------------------------------- + + static struct tm to_tm(const time_point &tp) + { + std::chrono::time_point<tm_conversion_clock> normalized_tp = to_arbitrary_time_point< + std::int64_t, + tm_conversion_clock::base_year, + tm_conversion_clock::base_month, + tm_conversion_clock::base_day, + tm_conversion_clock::base_hour, + tm_conversion_clock::base_minute, + tm_conversion_clock::base_second, + tm_conversion_clock::period>(tp); + return internal_to_tm(normalized_tp.time_since_epoch()); + } + + + //--------------------------------------------------------- + // to_system_clock - converts to a system_clock time_point + //--------------------------------------------------------- + + static std::chrono::time_point<std::chrono::system_clock> to_system_clock(const time_point &tp) + { + auto normalized_tp = to_arbitrary_time_point< + std::int64_t, + system_conversion_clock::base_year, + system_conversion_clock::base_month, + system_conversion_clock::base_day, + system_conversion_clock::base_hour, + system_conversion_clock::base_minute, + system_conversion_clock::base_second, + system_conversion_clock::period>(tp); + return std::chrono::time_point<std::chrono::system_clock>(normalized_tp.time_since_epoch() + system_clock_adjustment); + } + + //--------------------------------------------------------- + // from_system_clock - converts from a system_clock time_point + //--------------------------------------------------------- + + static time_point from_system_clock(const std::chrono::time_point<std::chrono::system_clock> &tp) + { + std::chrono::time_point<system_conversion_clock> normalized_tp(tp.time_since_epoch() - system_clock_adjustment); + return from_arbitrary_time_point(normalized_tp); + } + +private: + // By positioning the base year at 1601, we can ensure that: + // + // * years with leap years are at the end of every quadyear + // * quadyears without leap years are at the end of every century + // * centuries where the last quadyear has a leap year at the end are at the + // end of every quadcentury + typedef arbitrary_clock<std::int64_t, 1601, 1, 1, 0, 0, 0, std::ratio<1, 1> > tm_conversion_clock; + + //--------------------------------------------------------- + // internal_to_tm - formats a structure of type 'struct tm' + // based on a normalized clock + //--------------------------------------------------------- + + static struct tm internal_to_tm(std::chrono::duration<std::int64_t, std::ratio<1, 1> > duration) + { + constexpr int days_in_year(365); + constexpr int days_in_four_years((days_in_year * 4) + 1); + constexpr int days_in_century((days_in_four_years * 25) - 1); + constexpr int days_in_four_centuries((days_in_century * 4) + 1); + + constexpr tm_conversion_clock::duration day(std::chrono::hours(24)); + constexpr tm_conversion_clock::duration year(day * days_in_year); + constexpr tm_conversion_clock::duration four_years(day * days_in_four_years); + constexpr tm_conversion_clock::duration century(day * days_in_century); + constexpr tm_conversion_clock::duration four_centuries(day * days_in_four_centuries); + + // figure out the day of week (note that 0 is Sunday, but January 1st 1601 is + // a Monday, so we have to adjust by one day) + const int day_of_week = int((duration + std::chrono::hours(24)) / day % 7); + + // figure out the year + const int four_centuries_count = int(duration / four_centuries); + duration -= four_centuries_count * four_centuries; + const int century_count = std::min(int(duration / century), 3); + duration -= century_count * century; + const int four_years_count = std::min(int(duration / four_years), 25); + duration -= four_years_count * four_years; + const int year_count = int(duration / year); + duration -= year_count * year; + const int actual_year = tm_conversion_clock::base_year + four_centuries_count * 400 + century_count * 100 + four_years_count * 4 + year_count; + + // figure out the day in the year + const int day_in_year = int(duration / day); + duration -= day_in_year * day; + + // figure out the month + int month, day_in_month = day_in_year; + for (month = 0; month < 12; month++) + { + int days_in_this_month = gregorian_days_in_month(month + 1, actual_year); + if (day_in_month < days_in_this_month) + break; + day_in_month -= days_in_this_month; + } + if (month >= 12) + throw false; + + // figure out the time + const int hour = int(duration / std::chrono::hours(1)); + duration -= std::chrono::hours(hour); + const int minute = int(duration / std::chrono::minutes(1)); + duration -= std::chrono::minutes(minute); + const int second = int(duration / std::chrono::seconds(1)); + duration -= std::chrono::seconds(second); + + // populate the result and return + struct tm result; + memset(&result, 0, sizeof(result)); + result.tm_year = actual_year - 1900; + result.tm_mon = month; + result.tm_mday = day_in_month + 1; + result.tm_yday = day_in_year; + result.tm_sec = second; + result.tm_min = minute; + result.tm_hour = hour; + result.tm_wday = day_of_week; + return result; + } + + + typedef arbitrary_clock<std::int64_t, 1970, 1, 1, 0, 0, 0, std::chrono::system_clock::period > system_conversion_clock; + + //------------------------------------------------- + // absolute_day - returns the absolute day count + // for the specified year/month/day + //------------------------------------------------- + + static int64_t absolute_day(int year, int month, int day) + { + // first factor the year + int64_t result = (year - 1) * 365; + result += (year - 1) / 4; + result -= (year - 1) / 100; + result += (year - 1) / 400; + + // then the month + for (int i = 1; i < month; i++) + result += gregorian_days_in_month(i, year); + + // then the day + result += day - 1; + return result; + } +}; + + /*************************************************************************** INLINE FUNCTIONS ***************************************************************************/ |