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px4-firmware/nuttx/lib/time/lib_gmtimer.c

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/****************************************************************************
* lib/time/lib_gmtimer.c
*
* Copyright (C) 2007, 2009, 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdbool.h>
#include <time.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/time.h>
/****************************************************************************
* Definitions
****************************************************************************/
#define SEC_PER_MIN ((time_t)60)
#define SEC_PER_HOUR ((time_t)60 * SEC_PER_MIN)
#define SEC_PER_DAY ((time_t)24 * SEC_PER_HOUR)
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* Calendar/UTC conversion routines */
static void clock_utc2calendar(time_t utc, int *year, int *month, int *day);
#ifdef CONFIG_GREGORIAN_TIME
static void clock_utc2gregorian (time_t jdn, int *year, int *month, int *day);
#ifdef CONFIG_JULIAN_TIME
static void clock_utc2julian(time_t jdn, int *year, int *month, int *day);
#endif /* CONFIG_JULIAN_TIME */
#endif /* CONFIG_GREGORIAN_TIME */
/**************************************************************************
* Public Constant Data
**************************************************************************/
/****************************************************************************
* Public Variables
****************************************************************************/
/**************************************************************************
* Private Variables
**************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Function: clock_calendar2utc, clock_gregorian2utc,
* and clock_julian2utc
*
* Description:
* Calendar to UTC conversion routines. These conversions
* are based on algorithms from p. 604 of Seidelman, P. K.
* 1992. Explanatory Supplement to the Astronomical
* Almanac. University Science Books, Mill Valley.
*
****************************************************************************/
#ifdef CONFIG_GREGORIAN_TIME
static void clock_utc2calendar(time_t utc, int *year, int *month, int *day)
{
#ifdef CONFIG_JULIAN_TIME
if (utc >= GREG_DUTC)
{
clock_utc2gregorian(utc + JD_OF_EPOCH, year, month, day);
}
else
{
clock_utc2julian (utc + JD_OF_EPOCH, year, month, day);
}
#else /* CONFIG_JULIAN_TIME */
clock_utc2gregorian(utc + JD_OF_EPOCH, year, month, day);
#endif /* CONFIG_JULIAN_TIME */
}
static void clock_utc2gregorian(time_t jd, int *year, int *month, int *day)
{
long l, n, i, j, d, m, y;
l = jd + 68569;
n = (4*l) / 146097;
l = l - (146097*n + 3)/4;
i = (4000*(l+1))/1461001;
l = l - (1461*i)/4 + 31;
j = (80*l)/2447;
d = l - (2447*j)/80;
l = j/11;
m = j + 2 - 12*l;
y = 100*(n-49) + i + l;
*year = y;
*month = m;
*day = d;
}
#ifdef CONFIG_JULIAN_TIME
static void clock_utc2julian(time_t jd, int *year, int *month, int *day)
{
long j, k, l, n, d, i, m, y;
j = jd + 1402;
k = (j-1)/1461;
l = j - 1461*k;
n = (l-1)/365 - l/1461;
i = l - 365*n + 30;
j = (80*i)/2447;
d = i - (2447*j)/80;
i = j/11;
m = j + 2 - 12*i;
y = 4*k + n + i - 4716;
*year = y;
*month = m;
*day = d;
}
#endif /* CONFIG_JULIAN_TIME */
#else/* CONFIG_GREGORIAN_TIME */
/* Only handles dates since Jan 1, 1970 */
static void clock_utc2calendar(time_t days, int *year, int *month, int *day)
{
int value;
int min;
int max;
int tmp;
bool leapyear;
/* There is one leap year every four years, so we can get close with the
* following:
*/
value = days / (4*365 + 1); /* Number of 4-years periods since the epoch*/
days -= value * (4*365 + 1); /* Remaining days */
value <<= 2; /* Years since the epoch */
/* Then we will brute force the next 0-3 years */
for (;;)
{
/* Is this year a leap year (we'll need this later too) */
leapyear = clock_isleapyear(value + 1970);
/* Get the number of days in the year */
tmp = (leapyear ? 366 : 365);
/* Do we have that many days? */
if (days >= tmp)
{
/* Yes.. bump up the year */
value++;
days -= tmp;
}
else
{
/* Nope... then go handle months */
break;
}
}
/* At this point, value has the year and days has number days into this year */
*year = 1970 + value;
/* Handle the month (zero based) */
min = 0;
max = 11;
do
{
/* Get the midpoint */
value = (min + max) >> 1;
/* Get the number of days that occurred before the beginning of the month
* following the midpoint.
*/
tmp = clock_daysbeforemonth(value + 1, leapyear);
/* Does the number of days before this month that equal or exceed the
* number of days we have remaining?
*/
if (tmp > days)
{
/* Yes.. then the month we want is somewhere from 'min' and to the
* midpoint, 'value'. Could it be the midpoint?
*/
tmp = clock_daysbeforemonth(value, leapyear);
if (tmp > days)
{
/* No... The one we want is somewhere between min and value-1 */
max = value - 1;
}
else
{
/* Yes.. 'value' contains the month that we want */
break;
}
}
else
{
/* No... The one we want is somwhere between value+1 and max */
min = value + 1;
}
/* If we break out of the loop because min == max, then we want value
* to be equal to min == max.
*/
value = min;
}
while (min < max);
/* The selected month number is in value. Subtract the number of days in the
* selected month
*/
days -= clock_daysbeforemonth(value, leapyear);
/* At this point, value has the month into this year (zero based) and days has
* number of days into this month (zero based)
*/
*month = value + 1; /* 1-based */
*day = days + 1; /* 1-based */
}
#endif /* CONFIG_GREGORIAN_TIME */
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Function: gmtime_r
*
* Description:
* Time conversion (based on the POSIX API)
*
****************************************************************************/
FAR struct tm *gmtime_r(FAR const time_t *timer, FAR struct tm *result)
{
time_t epoch;
time_t jdn;
int year;
int month;
int day;
int hour;
int min;
int sec;
/* Get the seconds since the EPOCH */
epoch = *timer;
sdbg("timer=%d\n", (int)epoch);
/* Convert to days, hours, minutes, and seconds since the EPOCH */
jdn = epoch / SEC_PER_DAY;
epoch -= SEC_PER_DAY * jdn;
hour = epoch / SEC_PER_HOUR;
epoch -= SEC_PER_HOUR * hour;
min = epoch / SEC_PER_MIN;
epoch -= SEC_PER_MIN * min;
sec = epoch;
sdbg("hour=%d min=%d sec=%d\n",
(int)hour, (int)min, (int)sec);
/* Convert the days since the EPOCH to calendar day */
clock_utc2calendar(jdn, &year, &month, &day);
sdbg("jdn=%d year=%d month=%d day=%d\n",
(int)jdn, (int)year, (int)month, (int)day);
/* Then return the struct tm contents */
result->tm_year = (int)year - 1900; /* Relative to 1900 */
result->tm_mon = (int)month - 1; /* zero-based */
result->tm_mday = (int)day; /* one-based */
result->tm_hour = (int)hour;
result->tm_min = (int)min;
result->tm_sec = (int)sec;
return result;
}
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