ByteStorage.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Data / System / Data / Common / ByteStorage.cs / 1305376 / ByteStorage.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
// [....]
// [....] 
//----------------------------------------------------------------------------- 

namespace System.Data.Common { 
    using System;
    using System.Xml;
    using System.Data.SqlTypes;
    using System.Collections; 

    internal sealed class ByteStorage : DataStorage { 
 
        private const Byte defaultValue = 0;
 
        private Byte[] values;

        internal ByteStorage(DataColumn column)
        : base(column, typeof(Byte), defaultValue) { 
        }
 
        override public Object Aggregate(int[] records, AggregateType kind) { 
            bool hasData = false;
            try { 
                switch (kind) {
                    case AggregateType.Sum:
                        UInt64 sum = defaultValue;
                        foreach (int record in records) { 
                            if (IsNull(record))
                                continue; 
                            checked { sum += values[record];} 
                            hasData = true;
                        } 
                        if (hasData) {
                            return sum;
                        }
                        return NullValue; 

                    case AggregateType.Mean: 
                        Int64 meanSum = (Int64)defaultValue; 
                        int meanCount = 0;
                        foreach (int record in records) { 
                            if (IsNull(record))
                                continue;
                            checked { meanSum += (Int64)values[record];}
                            meanCount++; 
                            hasData = true;
                        } 
                        if (hasData) { 
                            Byte mean;
                            checked {mean = (Byte)(meanSum / meanCount);} 
                            return mean;
                        }
                        return NullValue;
 
                    case AggregateType.Var:
                    case AggregateType.StDev: 
                        int count = 0; 
                        double var = (double)defaultValue;
                        double prec = (double)defaultValue; 
                        double dsum = (double)defaultValue;
                        double sqrsum = (double)defaultValue;

                        foreach (int record in records) { 
                            if (IsNull(record))
                                continue; 
                            dsum += (double)values[record]; 
                            sqrsum += (double)values[record]*(double)values[record];
                            count++; 
                        }

                        if (count > 1) {
                            var = ((double)count * sqrsum - (dsum * dsum)); 
                            prec = var / (dsum * dsum);
 
                            // we are dealing with the risk of a cancellation error 
                            // double is guaranteed only for 15 digits so a difference
                            // with a result less than 1e-15 should be considered as zero 

                            if ((prec < 1e-15) || (var <0))
                                var = 0;
                            else 
                                var = var / (count * (count -1));
 
                            if (kind == AggregateType.StDev) { 
                                return Math.Sqrt(var);
                            } 
                            return var;
                        }
                        return NullValue;
 
                    case AggregateType.Min:
                        Byte min = Byte.MaxValue; 
                        for (int i = 0; i < records.Length; i++) { 
                            int record = records[i];
                            if (IsNull(record)) 
                                continue;
                            min=Math.Min(values[record], min);
                            hasData = true;
                        } 
                        if (hasData) {
                            return min; 
                        } 
                        return NullValue;
 
                    case AggregateType.Max:
                        Byte max = Byte.MinValue;
                        for (int i = 0; i < records.Length; i++) {
                            int record = records[i]; 
                            if (IsNull(record))
                                continue; 
                            max=Math.Max(values[record], max); 
                            hasData = true;
                        } 
                        if (hasData) {
                            return max;
                        }
                        return NullValue; 

                    case AggregateType.First: 
                        if (records.Length > 0) { 
                            return values[records[0]];
                        } 
                        return null;

                    case AggregateType.Count:
                        return base.Aggregate(records, kind); 

                } 
            } 
            catch (OverflowException) {
                throw ExprException.Overflow(typeof(Byte)); 
            }
            throw ExceptionBuilder.AggregateException(kind, DataType);
        }
 
         override public int Compare(int recordNo1, int recordNo2) {
            Byte valueNo1 = values[recordNo1]; 
            Byte valueNo2 = values[recordNo2]; 

            if (valueNo1 == defaultValue || valueNo2 == defaultValue) { 
                int bitCheck = CompareBits(recordNo1, recordNo2);
                if (0 != bitCheck)
                    return bitCheck;
            } 
            return valueNo1.CompareTo(valueNo2);
            //return(valueNo1 - valueNo2); // copied from Byte.CompareTo(Byte) 
        } 

        public override int CompareValueTo(int recordNo, object value) { 
            System.Diagnostics.Debug.Assert(0 <= recordNo, "Invalid record");
            System.Diagnostics.Debug.Assert(null != value, "null value");

            if (NullValue == value) { 
                if (IsNull(recordNo)) {
                    return 0; 
                } 
                return 1;
            } 

            Byte valueNo1 = values[recordNo];
            if ((defaultValue == valueNo1) && IsNull(recordNo)) {
                return -1; 
            }
            return valueNo1.CompareTo((Byte)value); 
            //return(valueNo1 - valueNo2); // copied from Byte.CompareTo(Byte) 
        }
 
        public override object ConvertValue(object value) {
            if (NullValue != value) {
                if (null != value) {
                    value = ((IConvertible)value).ToByte(FormatProvider); 
                }
                else { 
                    value = NullValue; 
                }
            } 
            return value;
        }

        override public void Copy(int recordNo1, int recordNo2) { 
            CopyBits(recordNo1, recordNo2);
            values[recordNo2] = values[recordNo1]; 
        } 

         override public Object Get(int record) { 
            Byte value = values[record];
            if (value != defaultValue) {
                return value;
            } 
            return GetBits(record);
        } 
 
         override public void Set(int record, Object value) {
            System.Diagnostics.Debug.Assert(null != value, "null value"); 
            if (NullValue == value) {
                values[record] = defaultValue;
                SetNullBit(record, true);
            } 
            else {
                values[record] = ((IConvertible)value).ToByte(FormatProvider); 
                SetNullBit(record, false); 
            }
        } 

         override public void SetCapacity(int capacity) {
            Byte[] newValues = new Byte[capacity];
            if (null != values) { 
                Array.Copy(values, 0, newValues, 0, Math.Min(capacity, values.Length));
            } 
            values = newValues; 
            base.SetCapacity(capacity);
        } 

         override public object ConvertXmlToObject(string s) {
            return XmlConvert.ToByte(s);
        } 

        override public string ConvertObjectToXml(object value) { 
            return XmlConvert.ToString((Byte) value); 
        }
 
        override protected object GetEmptyStorage(int recordCount) {
            return new Byte[recordCount];
        }
 
        override protected void CopyValue(int record, object store, BitArray nullbits, int storeIndex) {
            Byte[] typedStore = (Byte[]) store; 
            typedStore[storeIndex] = values[record]; 
            nullbits.Set(storeIndex, IsNull(record));
        } 

        override protected void SetStorage(object store, BitArray nullbits) {
            values = (Byte[]) store;
            SetNullStorage(nullbits); 
        }
    } 
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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ByteStorage.cs source code in C# .NET

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