//******************************************************************************************************//  DateTimeRounding.cs - Gbtc////  Copyright © 2016, Grid Protection Alliance.  All Rights Reserved.////  Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See//  the NOTICE file distributed with this work for additional information regarding copyright ownership.//  The GPA licenses this file to you under the MIT License (MIT), 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.opensource.org/licenses/MIT////  Unless agreed to in writing, the subject software distributed under the License is distributed on an//  "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the//  License for the specific language governing permissions and limitations.////  Code Modification History://  ----------------------------------------------------------------------------------------------------//  11/17/2016 - Steven E. Chisholm//       Generated original version of source code. ////****************************************************************************************************** using System;using System.Collections.Generic; namespace GSF{    /// <summary>    /// Responsible for rounding measurements to their nearest time bucket.    /// For example: a 30 sample per second value of 5.1666766 would round to 5.1666667    /// </summary>    public class DateTimeRounding    {        private readonly int m_ticksPerInterval;        private readonly int m_ticksPerHalfInterval;        private readonly int[] m_distribution;         private DateTimeRounding(int samplesPerSecond)        {            m_distribution = new int[samplesPerSecond + 1];            double ticksPerInterval = (TimeSpan.TicksPerSecond / (double)samplesPerSecond);            for (int i = 0; i < samplesPerSecond; i++)                m_distribution[i] = (int)(Math.Round(i * ticksPerInterval));            m_distribution[samplesPerSecond] = (int)TimeSpan.TicksPerSecond;             m_ticksPerInterval = (int)(ticksPerInterval);            m_ticksPerHalfInterval = m_ticksPerInterval / 2;        }         /// <summary>        /// Rounds the specified timestamp        /// </summary>        /// <param name="time"></param>        /// <returns></returns>        public DateTime Round(DateTime time)        {            long ticks = time.Ticks;            //Time rounded down to nearest second            long ticksTruncatedToSeconds = ticks - ticks % TimeSpan.TicksPerSecond;            //Compute the frame by taking the ticks after a second, adding 1/2 the interval value, then integer rounding            int frame = (int)(ticks - ticksTruncatedToSeconds + m_ticksPerHalfInterval) / m_ticksPerInterval;            return new DateTime(ticksTruncatedToSeconds + m_distribution[frame]);        }         /// <summary>        /// Rounds the specified timestamp        /// </summary>        /// <param name="time"></param>        /// <returns></returns>        public long Round(long time)        {            long baseTicks = time - time % TimeSpan.TicksPerSecond;            int frame = (int)(time - baseTicks + m_ticksPerHalfInterval) / m_ticksPerInterval;            return baseTicks + m_distribution[frame];        }         private static Dictionary<int, DateTimeRounding> s_cache = new Dictionary<int, DateTimeRounding>();         /// <summary>        /// Creates a <see cref="DateTimeRounding"/>        /// </summary>        /// <param name="samplesPerSecond">the samples per second for the rounding algorithm</param>        /// <returns></returns>        public static DateTimeRounding Create(int samplesPerSecond)        {            lock (s_cache)            {                DateTimeRounding rv;                if (!s_cache.TryGetValue(samplesPerSecond, out rv))                {                    rv = new DateTimeRounding(samplesPerSecond);                    s_cache.Add(samplesPerSecond, rv);                }                return rv;            }        }    }}