C# Tips：位运算相关
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// -----------------------------------------------------------------------
// <copyright file="UInt64MaskHelper.cs" author="Yaping Xin">
//
//
// File Name : UInt64MaskHelper.cs
// Description : Helper class to support UInt64 bit mask.
// Project Title : UInt64MaskHelper
// Author(s) : Yaping Xin
// Code Review Done :
// Modification History: Created at Aug 10, 2012
//
// </copyright>
// -----------------------------------------------------------------------
namespace BitsHelper
{
/// <summary>
/// Helper class to support UInt64 bit mask.
/// </summary>
public static class UInt64MaskHelper
{
#region Constant definition
/// <summary>
/// Constant definition of max avaiable bytes length.
/// </summary>
public const int MaxBytesLength = 8;
/// <summary>
/// Constant definition bits count within a byte
/// </summary>
public const int ByteBitsCount = 8;
#endregion Constant definition
#region Useful Bytes/Bits static readonly array definition
/// <summary>
/// Array of UInt64 byte mask values.
/// </summary>
private static readonly ulong[] U64ByteMaskValues = new ulong[]
{
0x00000000000000FF,
0x000000000000FF00,
0x0000000000FF0000,
0x00000000FF000000,
0x000000FF00000000,
0x0000FF0000000000,
0x00FF000000000000,
0xFF00000000000000
};
/// <summary>
/// Array of max values storaged in different amount of bytes within UInt64 scope.
/// </summary>
private static readonly ulong[] U64BytesMaxValues = new ulong[]
{
0x00000000000000FF,
0x000000000000FFFF,
0x0000000000FFFFFF,
0x00000000FFFFFFFF,
0x000000FFFFFFFFFF,
0x0000FFFFFFFFFFFF,
0x00FFFFFFFFFFFFFF,
0xFFFFFFFFFFFFFFFF
};
/// <summary>
/// Array of shift values to specific byte lowest bit position.
/// </summary>
private static readonly byte[] BytePositionShiftValues = new byte[]
{
0, 8, 16, 24, 32, 40, 48, 56
};
/// <summary>
/// Array of byte bit mask values.
/// </summary>
private static readonly byte[] ByteBitMaskValues = new byte[]
{
0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80
};
/// <summary>
/// Array of byte bit mask values.
/// </summary>
private static readonly byte[] ByteBitOffMaskValues = new byte[]
{
0xFE, 0xFD, 0xFB, 0xF7, 0xEF, 0xDF, 0xBF, 0x7F
};
#endregion Useful Bytes/Bits static readonly array definition
#region Enumeration definition
/// <summary>
/// Enumeration definition of the error code
/// </summary>
public enum ErrorCode : uint
{
/// <summary>No error occurs</summary>
OK = 0,
/// <summary>Argument is Null</summary>
ArgumentIsNull = 1,
/// <summary>Argument is out of range</summary>
ArgumentOutOfRange = 2,
}
#endregion Enumeration definition
#region Encoding methods (numeric value to bytes/bits)
/// <summary>
/// Gets the bytes array to storage the specific UInt64 value.
/// </summary>
/// <param name="value">The specific UInt64 value.</param>
/// <returns>The bytes array.</returns>
public static byte[] GetBytes(ulong value)
{
byte[] result = new byte[MaxBytesLength];
ulong maskResult = value & U64ByteMaskValues[0];
result[0] = (byte)maskResult;
for (int i = 1; i < MaxBytesLength; i++)
{
maskResult = value & U64ByteMaskValues[i];
result[i] = (byte)(maskResult >> BytePositionShiftValues[i]);
}
return result;
}
/// <summary>
/// Gets the byte at specific position from the UInt64 value.
/// Notes: this function will not return detailed error code while error occurs.
/// </summary>
/// <param name="value">The UInt64 value.</param>
/// <param name="bytePosition">The byte position.</param>
/// <param name="result">The byte to get.</param>
/// <returns>
/// <c>true</c> indicates no error occurs during calculating;
/// <c>fasle</c> indicates error occurs.
/// </returns>
public static bool GetByte(ulong value, int bytePosition, out byte result)
{
ErrorCode errorCode;
return UInt64MaskHelper.GetByte(value, bytePosition, out result, out errorCode);
}
/// <summary>
/// Gets the byte at specific position from the UInt64 value.
/// </summary>
/// <param name="value">The UInt64 value.</param>
/// <param name="bytePosition">The byte position.</param>
/// <param name="result">The byte to get.</param>
/// <param name="errorCode">The error code.
/// Will be set to ErrorCode.OK if no error occurs.</param>
/// <returns>
/// <c>true</c> indicates no error occurs during calculating;
/// <c>fasle</c> indicates error occurs, and detailed error is wrote in errorCode output parameter.
/// </returns>
public static bool GetByte(
ulong value,
int bytePosition,
out byte result,
out ErrorCode errorCode)
{
if (bytePosition < 0 || bytePosition >= MaxBytesLength)
{
result = 0;
errorCode = ErrorCode.ArgumentOutOfRange;
return false;
}
ulong maskResult;
if (bytePosition == 0)
{
maskResult = value & U64ByteMaskValues[0];
goto EXIT_PASS;
}
maskResult = value & U64ByteMaskValues[bytePosition];
maskResult >>= BytePositionShiftValues[bytePosition];
EXIT_PASS:
result = (byte)maskResult;
errorCode = ErrorCode.OK;
return true;
}
/// <summary>
/// Gets the bit at specific position from the byte value.
/// Notes: this function will not return detailed error code while error occurs.
/// </summary>
/// <param name="value">The byte value.</param>
/// <param name="bitPosition">The bit position.</param>
/// <param name="result">The bit (0 or 1) to get.</param>
/// <returns>
/// <c>true</c> indicates no error occurs during calculating;
/// <c>fasle</c> indicates error occurs.
/// </returns>
public static bool GetBit(byte value, int bitPosition, out byte result)
{
ErrorCode errorCode;
return UInt64MaskHelper.GetBit(value, bitPosition, out result, out errorCode);
}
/// <summary>
/// Gets the bit at specific position from the byte value.
/// </summary>
/// <param name="value">The byte value.</param>
/// <param name="bitPosition">The bit position.</param>
/// <param name="result">The bit (0 or 1) to get.</param>
/// <param name="errorCode">The error code.
/// Will be set to ErrorCode.OK if no error occurs.</param>
/// <returns>
/// <c>true</c> indicates no error occurs during calculating;
/// <c>fasle</c> indicates error occurs, and detailed error is wrote in errorCode output parameter.
/// </returns>
public static bool GetBit(
byte value,
int bitPosition,
out byte result,
out ErrorCode errorCode)
{
if (bitPosition < 0 || bitPosition >= ByteBitsCount)
{
result = 0;
errorCode = ErrorCode.ArgumentOutOfRange;
return false;
}
if (bitPosition == 0)
{
result = (byte)(value & ByteBitMaskValues[0]);
errorCode = ErrorCode.OK;
return true;
}
byte maskResult = (byte)(value & ByteBitMaskValues[bitPosition]);
result = maskResult >>= bitPosition;
errorCode = ErrorCode.OK;
return true;
}
#endregion Encoding methods (numeric value to bytes/bits)
#region Decoding methods (bytes/bits to numeric value)
/// <summary>
/// Gets the UInt64 value from bytes array.
/// Notes: this function will not return detailed error code while error occurs.
/// </summary>
/// <param name="bytes">The bytes array.</param>
/// <param name="value">The UInt64 value.</param>
/// <returns>
/// <c>true</c> indicates no error occurs during calculating;
/// <c>fasle</c> indicates error occurs.
/// </returns>
public static bool GetUInt64(byte[] bytes, out ulong value)
{
ErrorCode errorCode;
return UInt64MaskHelper.GetUInt64(bytes, out value, out errorCode);
}
/// <summary>
/// Gets the UInt64 value from bytes array.
/// </summary>
/// <param name="bytes">The bytes array.</param>
/// <param name="value">The UInt64 value.</param>
/// <param name="errorCode">The error code.
/// Will be set to ErrorCode.OK if no error occurs.</param>
/// <returns>
/// <c>true</c> indicates no error occurs during calculating;
/// <c>fasle</c> indicates error occurs, and detailed error is wrote in errorCode output parameter.
/// </returns>
public static bool GetUInt64(byte[] bytes, out ulong value, out ErrorCode errorCode)
{
if (bytes == null || bytes.Length == 0)
{
errorCode = ErrorCode.ArgumentIsNull;
value = 0;
return false;
}
if (bytes.Length > MaxBytesLength)
{
errorCode = ErrorCode.ArgumentOutOfRange;
value = 0;
return false;
}
ulong result = bytes[0];
ulong byteValue;
if (bytes.Length > 1)
{
for (int i = 1; i < bytes.Length; i++)
{
byteValue = bytes[i];
byteValue <<= BytePositionShiftValues[i];
result += byteValue;
}
}
value = result;
errorCode = ErrorCode.OK;
return true;
}
#endregion Decoding methods (bytes/bits to numeric value)
#region Set bit value
/// <summary>
/// Sets bit value at specific bit position within the raw byte.
/// Notes: this function will not return detailed error code while error occurs.
/// </summary>
/// <param name="rawByte">The raw byte.</param>
/// <param name="bitPosition">The bit position.</param>
/// <param name="bitValue">if set to <c>true</c> [bit value].</param>
/// <returns>
/// <c>true</c> indicates no error occurs during calculating;
/// <c>fasle</c> indicates error occurs.
/// </returns>
public static bool SetBit(ref byte rawByte, int bitPosition, bool bitValue)
{
ErrorCode errorCode;
return UInt64MaskHelper.SetBit(ref rawByte, bitPosition, bitValue, out errorCode);
}
/// <summary>
/// Sets bit value at specific bit position within the raw byte.
/// </summary>
/// <param name="rawByte">The raw byte.</param>
/// <param name="bitPosition">The bit position.</param>
/// <param name="bitValue"><c>true</c> indicates set bit value to 1;
/// otherwise set bit value to 0.</param>
/// <param name="errorCode">The error code.
/// Will be set to ErrorCode.OK if no error occurs.</param>
/// <returns>
/// <c>true</c> indicates no error occurs during calculating;
/// <c>fasle</c> indicates error occurs, and detailed error is wrote in errorCode output parameter.
/// </returns>
public static bool SetBit(ref byte rawByte, int bitPosition, bool bitValue, out ErrorCode errorCode)
{
if (bitPosition < 0 || bitPosition >= ByteBitsCount)
{
errorCode = ErrorCode.ArgumentOutOfRange;
return false;
}
if (bitValue)
{
rawByte |= ByteBitMaskValues[bitPosition];
}
else
{
rawByte &= ByteBitOffMaskValues[bitPosition];
}
errorCode = ErrorCode.OK;
return true;
}
#endregion Set bit value
}
}