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- using System;
- using System.Collections.Generic;
- using System.Text;
- namespace Wayne.Lib
- {
- /// <summary>
- /// Binary Encoder/Decoder with the custom 5-bit-per-byte format that
- /// is especially good for screen viewing, since the characters that
- /// may be confused has been eliminated (I/1/l/O/0). The purpose is
- /// to encode binary data into a string representation.
- /// </summary>
- public class BinaryConvert5Bit
- {
- /// <summary>
- /// Vadildates if a given set of characters are valid.
- /// </summary>
- /// <param name="s"></param>
- /// <returns></returns>
- public bool Valid5BitString(IEnumerable<char> s)
- {
- const string allowedChars = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
- foreach (char character in s)
- {
- if (allowedChars.IndexOf(character) < 0)
- return false;
- }
- return true;
- }
- /// <summary>
- /// Returns the string representation of the bytes
- /// </summary>
- /// <param name="bytes"></param>
- /// <returns></returns>
- public string ToString(byte[] bytes)
- {
- byte[] fivebitBytes = EncodeFiveBitPerBytesArray(bytes);
- string encodedString = ConvertToString(fivebitBytes);
- return encodedString;
- }
- private string ConvertToString(byte[] bytes)
- {
- StringBuilder sb = new StringBuilder();
- foreach (var b in bytes)
- {
- sb.Append(ConvertByte(b));
- }
- return sb.ToString();
- }
- private char ConvertByte(byte b)
- {
- switch (b)
- {
- case 0: return '2';
- case 1: return '3';
- case 2: return '4';
- case 3: return '5';
- case 4: return '6';
- case 5: return '7';
- case 6: return '8';
- case 7: return '9';
- case 8: return 'A';
- case 9: return 'B';
- case 10: return 'C';
- case 11: return 'D';
- case 12: return 'E';
- case 13: return 'F';
- case 14: return 'G';
- case 15: return 'H';
- case 16: return 'J';
- case 17: return 'K';
- case 18: return 'L';
- case 19: return 'M';
- case 20: return 'N';
- case 21: return 'P';
- case 22: return 'Q';
- case 23: return 'R';
- case 24: return 'S';
- case 25: return 'T';
- case 26: return 'U';
- case 27: return 'V';
- case 28: return 'W';
- case 29: return 'X';
- case 30: return 'Y';
- case 31: return 'Z';
- }
- throw new ArgumentException(string.Format("Invalid byte {0} it contains more than 5 bits.", b));
- }
- private byte ConvertChar(char c)
- {
- switch (c)
- {
- case '2': return 0;
- case '3': return 1;
- case '4': return 2;
- case '5': return 3;
- case '6': return 4;
- case '7': return 5;
- case '8': return 6;
- case '9': return 7;
- case 'A': return 8;
- case 'B': return 9;
- case 'C': return 10;
- case 'D': return 11;
- case 'E': return 12;
- case 'F': return 13;
- case 'G': return 14;
- case 'H': return 15;
- case 'J': return 16;
- case 'K': return 17;
- case 'L': return 18;
- case 'M': return 19;
- case 'N': return 20;
- case 'P': return 21;
- case 'Q': return 22;
- case 'R': return 23;
- case 'S': return 24;
- case 'T': return 25;
- case 'U': return 26;
- case 'V': return 27;
- case 'W': return 28;
- case 'X': return 29;
- case 'Y': return 30;
- case 'Z': return 31;
- }
- throw new ArgumentException(string.Format("Invalid char {0}.", c));
- }
- private byte[] EncodeFiveBitPerBytesArray(byte[] bytes)
- {
- byte[] inputBytes = (byte[])bytes.Clone();
- //Calculate resulting number of bytes
- int inputBitCount = inputBytes.Length * 8;
- int resultingBytesCount = inputBitCount / 5;
- if (inputBitCount % 5 > 0)
- resultingBytesCount++;
- byte[] resultBytes = new byte[resultingBytesCount];
- for (int resultByteIndex = resultingBytesCount - 1; resultByteIndex >= 0; resultByteIndex--)
- {
- // Console.WriteLine(ByteListToStringBinary(inputBytes));
- //Get the last five bits of the last byte in the byte array.
- byte fiveBits = (byte)(inputBytes[inputBytes.Length - 1] & 0x1f);
- resultBytes[resultByteIndex] = fiveBits;
- //Shift all the bits five places to the right
- for (int inputByteIndex = inputBytes.Length - 1; inputByteIndex >= 0; inputByteIndex--)
- {
- inputBytes[inputByteIndex] = (byte)(inputBytes[inputByteIndex] >> 5);//Shift the remaining 3 bits to the right
- if (inputByteIndex > 0)//If we are at the leftmost byte, there is nothing to take from left.
- inputBytes[inputByteIndex] = (byte)(inputBytes[inputByteIndex] + ((inputBytes[inputByteIndex - 1] & 0x1f) << 3)); //Take last 5 bits of next byte and shift to the left.
- }
- }
- return resultBytes;
- }
- private string ByteListToStringBinary(byte[] inputBytes)
- {
- var bitStream = ConvertBytesToBitStream(inputBytes);
- return BitStreamToString(bitStream);
- }
- private string BitStreamToString(bool[] bitStream)
- {
- var chars = new char[bitStream.Length];
- for (int i = 0; i < bitStream.Length; i++)
- {
- chars[i] = bitStream[i] ? '1' : '0';
- }
- return new string(chars);
- }
- private bool[] ConvertBytesToBitStream(byte[] inputBytes)
- {
- List<bool> bitStream = new List<bool>();
- foreach (var inputByte in inputBytes)
- {
- for (int i = 7; i >= 0; i--)
- {
- bitStream.Add((inputByte & (1 << i)) != 0);
- }
- }
- return bitStream.ToArray();
- }
- /// <summary>
- /// Returns the decoded bytes that was represented by the inputString.
- /// </summary>
- /// <param name="inputString"></param>
- /// <returns></returns>
- public byte[] ToBytes(string inputString)
- {
- byte[] inputBytes = Convert5BitStringToBytes(inputString);
- int numberOfResultingBytes = inputBytes.Length * 5 / 8;
- bool[] inputBitStream = new bool[inputBytes.Length * 5];
- for (int byteIndex = 0; byteIndex < inputBytes.Length; byteIndex++)
- {
- for (int bitIndex = 5; bitIndex >= 1; bitIndex--)
- inputBitStream[byteIndex * 5 + 5 - bitIndex] = IsBitSet(inputBytes[byteIndex], bitIndex);
- }
- //Console.WriteLine("BitStream 1: " + ByteListToStringBinary(inputBitStream));
- //Trim the bitstream to only contain the result bits.
- inputBitStream = TrimBitStream(inputBitStream, numberOfResultingBytes * 8);
- //Console.WriteLine("BitStream 2: " + ByteListToStringBinary(inputBitStream));
- byte[] outputBytes = new byte[numberOfResultingBytes];
- for (int byteIndex = 0; byteIndex < inputBitStream.Length / 8; byteIndex++) //Iterate the bytes within the bit array.
- {
- for (int bitIndex = 0; bitIndex < 8; bitIndex++) //Iterate through the bits within each byte.
- {
- bool b = inputBitStream[byteIndex * 8 + bitIndex];
- if (b)
- {
- outputBytes[byteIndex] = (byte)(outputBytes[byteIndex] | (1 << (7 - bitIndex)));
- }
- }
- }
- //Console.WriteLine("Output bytes: " + ByteListToStringBinary(outputBytes.ToArray()));
- return outputBytes;
- }
- private byte[] Convert5BitStringToBytes(string inputString)
- {
- byte[] result = new byte[inputString.Length];
- for (int i = 0; i < inputString.Length; i++)
- result[i] = ConvertChar(inputString[i]);
- return result;
- }
- private bool[] TrimBitStream(bool[] inputBitStream, int countToKeep)
- {
- bool[] newBitStream = new bool[countToKeep];
- Array.Copy(inputBitStream, inputBitStream.Length - countToKeep, newBitStream, 0, countToKeep);
- return newBitStream;
- }
- private bool IsBitSet(byte b, int byteNumber)
- {
- return (b & (1 << (byteNumber - 1))) != 0;
- }
- }
- }
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