timegm.c File Reference

#include <time.h>
#include <stdlib.h>

Go to the source code of this file.

Macros
#define	_DAYS_IN_MONTH(x)   ((x == 1) ? days_in_feb : DAYS_IN_MONTH[x])
#define	_DAYS_IN_YEAR(year)   (_ISLEAP (year) ? 366 : 365)
#define	_ISLEAP(y)    (((y) % 4) == 0 && (((y) % 100) != 0 || (((y) + 1900) % 400) == 0))
#define	_SEC_IN_DAY   86400L
#define	_SEC_IN_HOUR   3600L
#define	_SEC_IN_MINUTE   60L

Functions
time_t	timegm (struct tm *tim_p)
static void	validate_structure (struct tm *tim_p)

Variables
static const int	_DAYS_BEFORE_MONTH [12] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 }
static const int	DAYS_IN_MONTH [12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }

Macro Definition Documentation

_DAYS_IN_MONTH

#define _DAYS_IN_MONTH

(

x

)

((x == 1) ? days_in_feb : DAYS_IN_MONTH[x])

Definition at line 41 of file timegm.c.

_DAYS_IN_YEAR

#define _DAYS_IN_YEAR

(

year

)

(_ISLEAP (year) ? 366 : 365)

Definition at line 54 of file timegm.c.

_ISLEAP

#define _ISLEAP

(

y

)

(((y) % 4) == 0 && (((y) % 100) != 0 || (((y) + 1900) % 400) == 0))

Definition at line 52 of file timegm.c.

_SEC_IN_DAY

#define _SEC_IN_DAY   86400L

Definition at line 31 of file timegm.c.

_SEC_IN_HOUR

#define _SEC_IN_HOUR   3600L

Definition at line 30 of file timegm.c.

_SEC_IN_MINUTE

#define _SEC_IN_MINUTE   60L

As there is no timegm() function neither in newlib nor in POSIX, we add one here (based on a simplified newlib mktime()).

It is used in Chan FatFS to convert dates fields.

Definition at line 29 of file timegm.c.

Function Documentation

timegm()

time_t timegm

(

struct tm *

tim_p

)

Definition at line 67 of file timegm.c.

{
  time_t tim = 0;
  long days = 0;
  int year;
 
  /* validate structure */
  validate_structure (tim_p);
 
  /* compute hours, minutes, seconds */
  tim += tim_p->tm_sec + (tim_p->tm_min * _SEC_IN_MINUTE)
         + (tim_p->tm_hour * _SEC_IN_HOUR);
 
  /* compute days in year */
  days += tim_p->tm_mday - 1;
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wunsafe-buffer-usage"
#endif
  days += _DAYS_BEFORE_MONTH[tim_p->tm_mon];
#pragma GCC diagnostic pop
  if (tim_p->tm_mon > 1 && _DAYS_IN_YEAR (tim_p->tm_year) == 366)
    days++;
 
  /* compute day of the year */
  tim_p->tm_yday = (int)days;
 
  if (tim_p->tm_year > 10000 || tim_p->tm_year < -10000)
    return (time_t)-1;
 
  /* compute days in other years */
  if ((year = tim_p->tm_year) > 70)
    {
      for (year = 70; year < tim_p->tm_year; year++)
        days += _DAYS_IN_YEAR (year);
    }
  else if (year < 70)
    {
      for (year = 69; year > tim_p->tm_year; year--)
        days -= _DAYS_IN_YEAR (year);
      days -= _DAYS_IN_YEAR (year);
    }
 
  /* compute total seconds */
  tim += (days * _SEC_IN_DAY);
 
  /* compute day of the week */
  if ((tim_p->tm_wday = (int)((days + 4) % 7)) < 0)
    tim_p->tm_wday += 7;
 
  return tim;
}

References _DAYS_BEFORE_MONTH, _DAYS_IN_YEAR, _SEC_IN_DAY, _SEC_IN_HOUR, _SEC_IN_MINUTE, and validate_structure().

validate_structure()

static void validate_structure ( struct tm *  tim_p )

static

Definition at line 125 of file timegm.c.

{
  div_t res;
  int days_in_feb = 28;
 
#pragma GCC diagnostic push
#if defined(__clang__)
#elif defined(__GNUC__)
// For div()
#pragma GCC diagnostic ignored "-Waggregate-return"
#endif
  /* calculate time & date to account for out of range values */
  if (tim_p->tm_sec < 0 || tim_p->tm_sec > 59)
    {
      res = div (tim_p->tm_sec, 60);
      tim_p->tm_min += res.quot;
      if ((tim_p->tm_sec = res.rem) < 0)
        {
          tim_p->tm_sec += 60;
          --tim_p->tm_min;
        }
    }
 
  if (tim_p->tm_min < 0 || tim_p->tm_min > 59)
    {
      res = div (tim_p->tm_min, 60);
      tim_p->tm_hour += res.quot;
      if ((tim_p->tm_min = res.rem) < 0)
        {
          tim_p->tm_min += 60;
          --tim_p->tm_hour;
        }
    }
 
  if (tim_p->tm_hour < 0 || tim_p->tm_hour > 23)
    {
      res = div (tim_p->tm_hour, 24);
      tim_p->tm_mday += res.quot;
      if ((tim_p->tm_hour = res.rem) < 0)
        {
          tim_p->tm_hour += 24;
          --tim_p->tm_mday;
        }
    }
 
  if (tim_p->tm_mon < 0 || tim_p->tm_mon > 11)
    {
      res = div (tim_p->tm_mon, 12);
      tim_p->tm_year += res.quot;
      if ((tim_p->tm_mon = res.rem) < 0)
        {
          tim_p->tm_mon += 12;
          --tim_p->tm_year;
        }
    }
#pragma GCC diagnostic pop
 
  if (_DAYS_IN_YEAR (tim_p->tm_year) == 366)
    days_in_feb = 29;
 
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wunsafe-buffer-usage"
#endif
  if (tim_p->tm_mday <= 0)
    {
      while (tim_p->tm_mday <= 0)
        {
          if (--tim_p->tm_mon == -1)
            {
              tim_p->tm_year--;
              tim_p->tm_mon = 11;
              days_in_feb
                  = ((_DAYS_IN_YEAR (tim_p->tm_year) == 366) ? 29 : 28);
            }
          tim_p->tm_mday += _DAYS_IN_MONTH (tim_p->tm_mon);
        }
    }
  else
    {
      while (tim_p->tm_mday > _DAYS_IN_MONTH (tim_p->tm_mon))
        {
          tim_p->tm_mday -= _DAYS_IN_MONTH (tim_p->tm_mon);
          if (++tim_p->tm_mon == 12)
            {
              tim_p->tm_year++;
              tim_p->tm_mon = 0;
              days_in_feb
                  = ((_DAYS_IN_YEAR (tim_p->tm_year) == 366) ? 29 : 28);
            }
        }
    }
#pragma GCC diagnostic pop
}

References _DAYS_IN_MONTH, and _DAYS_IN_YEAR.

Referenced by timegm().

Variable Documentation

_DAYS_BEFORE_MONTH

const int _DAYS_BEFORE_MONTH[12] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 }

static

Definition at line 48 of file timegm.c.

Referenced by timegm().

DAYS_IN_MONTH

const int DAYS_IN_MONTH[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }

static

Definition at line 37 of file timegm.c.