Enrico Fraccaroli (Galfurian)
125 lines
4.7 KiB
C
125 lines
4.7 KiB
C
/// @file time.h
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/// @brief Time-related functions.
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/// @copyright (c) 2014-2024 This file is distributed under the MIT License.
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/// See LICENSE.md for details.
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#pragma once
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#include "stddef.h"
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/// @brief This timer counts down in real (i.e., wall clock) time. At each
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/// expiration, a SIGALRM signal is generated.
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#define ITIMER_REAL 0
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/// @brief This timer counts down against the user-mode CPU time consumed by the
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/// process. At each expiration, a SIGVTALRM signal is generated.
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#define ITIMER_VIRTUAL 1
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/// @brief This timer counts down against the total (i.e., both user and system)
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/// CPU time consumed by the process. At each expiration, a SIGPROF signal is
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/// generated.
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#define ITIMER_PROF 2
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/// Used to store time values.
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typedef unsigned int time_t;
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/// Used to get information about the current time.
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typedef struct tm_t {
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/// Seconds [0 to 59]
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int tm_sec;
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/// Minutes [0 to 59]
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int tm_min;
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/// Hours [0 to 23]
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int tm_hour;
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/// Day of the month [1 to 31]
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int tm_mday;
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/// Month [0 to 11]
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int tm_mon;
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/// Year [since 1900]
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int tm_year;
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/// Day of the week [0 to 6]
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int tm_wday;
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/// Day in the year [0 to 365]
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int tm_yday;
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/// Is Daylight Saving Time.
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int tm_isdst;
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} tm_t;
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/// Rappresents time.
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typedef struct _timeval {
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time_t tv_sec; ///< Seconds.
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time_t tv_usec; ///< Microseconds.
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} timeval;
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/// Rappresents a time interval.
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typedef struct _itimerval {
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timeval it_interval; ///< Next value.
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timeval it_value; ///< Current value.
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} itimerval;
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/// @brief Specify intervals of time with nanosecond precision.
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typedef struct timespec {
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time_t tv_sec; ///< Seconds.
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long tv_nsec; ///< Nanoseconds.
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} timespec;
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/// @brief Returns the current time.
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/// @param t Where the time should be stored.
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/// @return The current time.
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time_t time(time_t *t);
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/// @brief Return the difference between the two time values.
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/// @param time1 The first time value.
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/// @param time2 The second time value.
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/// @return The difference in terms of seconds.
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time_t difftime(time_t time1, time_t time2);
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/// @brief The current time broken down into a tm_t structure.
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/// @param timep A pointer to a variable holding the current time.
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/// @return The time broken down.
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tm_t *localtime(const time_t *timep);
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/// @brief Formats the time tm according to the format specification format
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/// and places the result in the character array s of size max.
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/// @param s The destination buffer.
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/// @param max The maximum length of the buffer.
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/// @param format The buffer used to generate the time.
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/// @param tm The broken-down time.
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/// @return The number of bytes (excluding the terminating null) placed in s.
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size_t strftime(char *s, size_t max, const char *format, const tm_t *tm);
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/// @brief Suspends the execution of the calling thread.
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/// @param req The amount of time we want to sleep.
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/// @param rem The remaining time we did not sleep.
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/// @return If the call is interrupted by a signal handler, nanosleep()
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/// returns -1, sets errno to EINTR, and writes the remaining time
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/// into the structure pointed to by rem unless rem is NULL.
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/// @details
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/// The execution is suspended until either at least the time specified
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/// in *req has elapsed, or the delivery of a signal that triggers the
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/// invocation of a handler in the calling thread or that terminates
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/// the process.
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int nanosleep(const timespec *req, timespec *rem);
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/// @brief Causes the calling thread to sleep either until the number of
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/// real-time seconds specified in seconds have elapsed or
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/// until a signal arrives which is not ignored.
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/// @param seconds The number of seconds we want to sleep.
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/// @return Zero if the requested time has elapsed, or the number of seconds
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/// left to sleep, if the call was interrupted by a signal handler.
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unsigned int sleep(unsigned int seconds);
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/// @brief Fills the structure pointed to by curr_value with the current setting
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/// for the timer specified by which.
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/// @param which which timer.
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/// @param curr_value where we place the timer value.
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/// @return 0 on success, -1 on failure and errno is set to indicate the error.
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int getitimer(int which, itimerval *curr_value);
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/// @brief The system provides each process with three interval timers, each
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/// decrementing in a distinct time domain. When any timer expires, a signal is
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/// sent to the process, and the timer (potentially) restarts.
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/// @param which which timer.
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/// @param new_value the new value for the timer.
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/// @param old_value output variable where the function places the previous value.
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/// @return 0 on success, -1 on failure and errno is set to indicate the error.
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int setitimer(int which, const itimerval *new_value, itimerval *old_value);
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