static void do_adjust_special_weekday(timelib_time* time)
{
timelib_sll current_dow, count;
count = time->relative.special.amount;
current_dow = timelib_day_of_week(time->y, time->m, time->d);
if (count == 0) {
/* skip over saturday and sunday */
if (current_dow == 6) {
time->d += 2;
}
/* skip over sunday */
if (current_dow == 0) {
time->d += 1;
}
} else if (count > 0) {
/* skip over saturday and sunday */
if (current_dow == 5) {
time->d += 2;
}
/* skip over sunday */
if (current_dow == 6) {
time->d += 1;
}
/* add increments of 5 weekdays as a week */
time->d += (count / 5) * 7;
/* if current DOW plus the remainder > 5, add two days */
current_dow = timelib_day_of_week(time->y, time->m, time->d);
time->d += (count % 5);
if ((count % 5) + current_dow > 5) {
time->d += 2;
}
} else if (count < 0) {
/* skip over sunday and saturday */
if (current_dow == 1) {
time->d -= 2;
}
/* skip over satruday */
if (current_dow == 0 ) {
time->d -= 1;
}
/* subtract increments of 5 weekdays as a week */
time->d += (count / 5) * 7;
/* if current DOW minus the remainder < 0, subtract two days */
current_dow = timelib_day_of_week(time->y, time->m, time->d);
time->d += (count % 5);
if ((count % 5) + current_dow < 1) {
time->d -= 2;
}
}
}
static void do_adjust_for_weekday(timelib_time* time)
{
timelib_sll current_dow, difference;
current_dow = timelib_day_of_week(time->y, time->m, time->d);
if (time->relative.weekday_behavior == 2)
{
if (time->relative.weekday == 0) {
time->relative.weekday = 7;
}
time->d -= current_dow;
time->d += time->relative.weekday;
return;
}
difference = time->relative.weekday - current_dow;
if ((time->relative.d < 0 && difference < 0) || (time->relative.d >= 0 && difference <= -time->relative.weekday_behavior)) {
difference += 7;
}
if (time->relative.weekday >= 0) {
time->d += difference;
} else {
time->d -= (7 - (abs(time->relative.weekday) - current_dow));
}
time->relative.have_weekday_relative = 0;
}
static void do_adjust_for_weekday(timelib_time* time)
{
timelib_sll current_dow, difference;
current_dow = timelib_day_of_week(time->y, time->m, time->d);
if (time->relative.weekday_behavior == 2)
{
/* To make "this week" work, where the current DOW is a "sunday" */
if (current_dow == 0 && time->relative.weekday != 0) {
time->relative.weekday = -6;
}
/* To make "sunday this week" work, where the current DOW is not a
* "sunday" */
if (time->relative.weekday == 0 && current_dow != 0) {
time->relative.weekday = 7;
}
time->d -= current_dow;
time->d += time->relative.weekday;
return;
}
difference = time->relative.weekday - current_dow;
if ((time->relative.d < 0 && difference < 0) || (time->relative.d >= 0 && difference <= -time->relative.weekday_behavior)) {
difference += 7;
}
if (time->relative.weekday >= 0) {
time->d += difference;
} else {
time->d -= (7 - (abs(time->relative.weekday) - current_dow));
}
time->relative.have_weekday_relative = 0;
}
void timelib_isoweek_from_date(timelib_sll y, timelib_sll m, timelib_sll d, timelib_sll *iw, timelib_sll *iy)
{
int y_leap, prev_y_leap, doy, jan1weekday, weekday;
y_leap = timelib_is_leap(y);
prev_y_leap = timelib_is_leap(y-1);
doy = timelib_day_of_year(y, m, d) + 1;
if (y_leap && m > 2) {
doy++;
}
jan1weekday = timelib_day_of_week(y, 1, 1);
weekday = timelib_day_of_week(y, m, d);
if (weekday == 0) weekday = 7;
if (jan1weekday == 0) jan1weekday = 7;
/* Find if Y M D falls in YearNumber Y-1, WeekNumber 52 or 53 */
if (doy <= (8 - jan1weekday) && jan1weekday > 4) {
*iy = y - 1;
if (jan1weekday == 5 || (jan1weekday == 6 && prev_y_leap)) {
*iw = 53;
} else {
*iw = 52;
}
} else {
*iy = y;
}
/* 8. Find if Y M D falls in YearNumber Y+1, WeekNumber 1 */
if (*iy == y) {
int i;
i = y_leap ? 366 : 365;
if ((i - (doy - y_leap)) < (4 - weekday)) {
*iy = y + 1;
*iw = 1;
return;
}
}
/* 9. Find if Y M D falls in YearNumber Y, WeekNumber 1 through 53 */
if (*iy == y) {
int j;
j = doy + (7 - weekday) + (jan1weekday - 1);
*iw = j / 7;
if (jan1weekday > 4) {
*iw -= 1;
}
}
}
timelib_sll timelib_daynr_from_weeknr(timelib_sll y, timelib_sll w, timelib_sll d)
{
timelib_sll dow, day;
/* Figure out the dayofweek for y-1-1 */
dow = timelib_day_of_week(y, 1, 1);
/* then use that to figure out the offset for day 1 of week 1 */
day = 0 - (dow > 4 ? dow - 7 : dow);
/* Add weeks and days */
return day + ((w - 1) * 7) + d;
}
static void do_adjust_special_weekday(timelib_time* time)
{
timelib_sll count, dow, rem;
count = time->relative.special.amount;
dow = timelib_day_of_week(time->y, time->m, time->d);
/* Add increments of 5 weekdays as a week, leaving the DOW unchanged. */
time->d += (count / 5) * 7;
/* Deal with the remainder. */
rem = (count % 5);
if (count > 0) {
if (rem == 0) {
/* Head back to Friday if we stop on the weekend. */
if (dow == 0) {
time->d -= 2;
} else if (dow == 6) {
time->d -= 1;
}
} else if (dow == 6) {
/* We ended up on Saturday, but there's still work to do, so move
* to Sunday and continue from there. */
time->d += 1;
} else if (dow + rem > 5) {
/* We're on a weekday, but we're going past Friday, so skip right
* over the weekend. */
time->d += 2;
}
} else {
/* Completely mirror the forward direction. This also covers the 0
* case, since if we start on the weekend, we want to move forward as
* if we stopped there while going backwards. */
if (rem == 0) {
if (dow == 6) {
time->d += 2;
} else if (dow == 0) {
time->d += 1;
}
} else if (dow == 0) {
time->d -= 1;
} else if (dow + rem < 1) {
time->d -= 2;
}
}
time->d += rem;
}
int main(void)
{
printf("dow = %d\n", timelib_day_of_week(1978, 12, 22)); /* 5 */
printf("dow = %d\n", timelib_day_of_week(2005, 2, 19)); /* 6 */
}
