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/*
* Copyright (C) 2015 The Android Open Source Project
*
* 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.
*/
package com.android.apkzlib.zip.utils;
import com.google.common.base.Verify;
import java.util.Calendar;
import java.util.Date;
/**
* Yes. This actually refers to MS-DOS in 2015. That's all I have to say about legacy stuff.
*/
public class MsDosDateTimeUtils {
/**
* Utility class: no constructor.
*/
private MsDosDateTimeUtils() {
}
/**
* Packs java time value into an MS-DOS time value.
*
* @param time the time value
* @return the MS-DOS packed time
*/
public static int packTime(long time) {
Calendar c = Calendar.getInstance();
c.setTime(new Date(time));
int seconds = c.get(Calendar.SECOND);
int minutes = c.get(Calendar.MINUTE);
int hours = c.get(Calendar.HOUR_OF_DAY);
/*
* Here is how MS-DOS packs a time value:
* 0-4: seconds (divided by 2 because we only have 5 bits = 32 different numbers)
* 5-10: minutes (6 bits = 64 possible values)
* 11-15: hours (5 bits = 32 possible values)
*
* source: https://msdn.microsoft.com/en-us/library/windows/desktop/ms724247(v=vs.85).aspx
*/
return (hours << 11) | (minutes << 5) | (seconds / 2);
}
/**
* Packs the current time value into an MS-DOS time value.
*
* @return the MS-DOS packed time
*/
public static int packCurrentTime() {
return packTime(new Date().getTime());
}
/**
* Packs java time value into an MS-DOS date value.
*
* @param time the time value
* @return the MS-DOS packed date
*/
public static int packDate(long time) {
Calendar c = Calendar.getInstance();
c.setTime(new Date(time));
/*
* Even MS-DOS used 1 for January. Someone wasn't really thinking when they decided on Java
* it would start at 0...
*/
int day = c.get(Calendar.DAY_OF_MONTH);
int month = c.get(Calendar.MONTH) + 1;
/*
* MS-DOS counts years starting from 1980. Since its launch date was in 81, it was obviously
* not necessary to talk about dates earlier than that.
*/
int year = c.get(Calendar.YEAR) - 1980;
Verify.verify(year >= 0 && year < 128);
/*
* Here is how MS-DOS packs a date value:
* 0-4: day (5 bits = 32 values)
* 5-8: month (4 bits = 16 values)
* 9-15: year (7 bits = 128 values)
*
* source: https://msdn.microsoft.com/en-us/library/windows/desktop/ms724247(v=vs.85).aspx
*/
return (year << 9) | (month << 5) | day;
}
/**
* Packs the current time value into an MS-DOS date value.
*
* @return the MS-DOS packed date
*/
public static int packCurrentDate() {
return packDate(new Date().getTime());
}
}
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