libiso8601/add.c at master · npmccallum/libiso8601 · GitHub

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/* vim: set tabstop=8 shiftwidth=4 softtabstop=4 expandtab smarttab colorcolumn=80: */
/**
 * Copyright: 2013 Red Hat, Inc.
 * Author: Nathaniel McCallum <npmccallum@redhat.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "iso8601.h"
#include "internal.h"

void iso8601_add_years(iso8601_time *time, int years)
{
    time->year += years;
}

void iso8601_add_months(iso8601_time *time, int months)
{
    if (months < 0) {
        int years = months / 12 - 1;
        iso8601_add_years(time, years);
        months -= years * 12;
    }

    months += time->month - 1;
    iso8601_add_years(time, months / 12);
    time->month = months % 12 + 1;
}

void iso8601_add_days(iso8601_time *time, int days)
{
    days += time->day;

    if (days > 0) {
        while (days > length_month_days(time->year, time->month)) {
            days -= length_month_days(time->year, time->month);
            iso8601_add_months(time, 1);
        }
    } else {
        do {
            iso8601_add_months(time, -1);
            days += length_month_days(time->year, time->month);
        } while (days < 1);
    }

    time->day = days;
}

void iso8601_add_hours(iso8601_time *time, int hours)
{
    if (hours < 0) {
        int days = hours / 24 - 1;
        iso8601_add_days(time, days);
        hours -= days * 24;
    }

    hours += time->hour;
    iso8601_add_days(time, hours / 24);
    time->hour = hours % 24;
}

void iso8601_add_minutes(iso8601_time *time, int minutes)
{
    if (minutes < 0) {
        int hours = minutes / 60 - 1;
        iso8601_add_hours(time, hours);
        minutes -= hours * 60;
    }

    minutes += time->minute;
    iso8601_add_hours(time, minutes / 60);
    time->minute = minutes % 60;
}

void iso8601_add_seconds(iso8601_time *time, int seconds)
{
    if (seconds < 0) {
        int minutes = seconds / 60 - 1;
        iso8601_add_minutes(time, minutes);
        seconds -= minutes * 60;
    }

    seconds += time->second;
    iso8601_add_minutes(time, seconds / 60);
    time->second = seconds % 60;
}

void iso8601_add_useconds(iso8601_time *time, int useconds)
{
    if (useconds < 0) {
        int seconds = useconds / 1000000 - 1;
        iso8601_add_seconds(time, seconds);
        time->usecond -= seconds * 1000000;
    }

    useconds += time->usecond;
    iso8601_add_seconds(time, useconds / 1000000);
    time->usecond = useconds % 1000000;
}