![]() TIMER.C: These functions allow one to obtain user and system timings for arbitrary blocks of code. Obtain user and system timings for blocks of code. Timer.c File ReferenceObtain user and system timings for blocks of code. An additional time conversion, isotime() and its re-entrant version, uses far less storage than either ctime() or asctime().Īlong with the usual smattering of utility functions, such as is_leap_year(), this library includes a set of functions related the sun and moon, as well as sidereal time File Reference Main Page Modules Data Structures File List Globals In addition to C standard functions, re-entrant versions of ctime(), asctime(), gmtime() and localtime() are provided which, in addition to being re-entrant, have the property of claiming less permanent storage in RAM. All calculations are made according to the currently configured time zone and daylight saving 'rule'. Therefore no attempt is made to account for time zone, daylight saving, or leap seconds in past dates. Unlike desktop counterparts, it is impractical to implement or maintain the 'zoneinfo' database. The macros UNIX_OFFSET and NTP_OFFSET are defined to assist in converting to and from Unix and NTP time stamps. The use of this 'epoch' helps to simplify the conversion functions, while the 32 bit value allows time to be properly represented until Tue Feb 7 06:28:15 2136 UTC. This implementation uses an unsigned 32 bit integer offset from Midnight Jan 1 2000. ![]() Though not specified in the standard, it is often expected that time_t is a signed integer representing an offset in seconds from Midnight Jan 1 1970. Once initialized, system time is maintained by calling the function system_tick() at one second intervals. The functions set_zone(), set_dst(), and set_system_time() are provided for initialization. Therefore the application must initialize the time system with this information. There is no 'platform standard' method to obtain the current time, time zone, or daylight savings 'rules' in the AVR environment. In addition to the above departures from the standard, there are some behaviors which are different from what is often expected, though allowed under the standard. ![]() The 'Z' conversion is also ignored, due to the lack of time zone name. Section 7.23.3.5 strftime() Only the 'C' locale is supported, therefore the modifiers 'E' and 'O' are ignored. This implementation further specifies that, when positive, the value of tm_isdst represents the amount time is advanced during Daylight Saving time. Section 7.23.1.4 struct tm Per the standard, struct tm->tm_isdst is greater than zero when Daylight Saving time is in effect. In most cases this change will be invisible to the user, handled automatically by the compiler. Section 7.23.2.2, difftime() Due to the lack of a 64 bit double, the function difftime() returns a long integer. Since the application must initialize the time system, this functionality is not implemented. Section 7.23.2.4 time() The standard specifies that time() should return (time_t) -1, if the time is not available. This implementation always returns a 'best effort' representation. Section 7.23.2.3 mktime() The standard specifies that mktime() should return (time_t) -1, if the time cannot be represented. We consider these items belong to operating system code, or to application code when no operating system is present. Section 7.23.2.1 clock() The type clock_t, the macro CLOCKS_PER_SEC, and the function clock() are not implemented. However, due to limitations of the target processor and the nature of its development environment, a practical implementation must of necessity deviate from the standard. The implementation aspires to conform with ISO/IEC 9899 (C90). This file declares the time functions implemented in avr-libc. ![]() #include Introduction to the Time functions Set_position ( int32_t latitude, int32_t longitude) Iso_week_date_r (int year, int yday, struct week_date *) Week_of_month (const struct tm *timeptr, uint8_t start) Week_of_year (const struct tm *timeptr, uint8_t start) Month_length ( int16_t year, uint8_t month) Strftime (char *s, size_t maxsize, const char *format, const struct tm *timeptr) Localtime_r (const time_t *timer, struct tm *timeptr)Īsctime_r (const struct tm *timeptr, char *buf) ![]() Gmtime_r (const time_t *timer, struct tm *timeptr) ![]()
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