CODEWITHSUNDEEP
c#.net
Ricky Divjakovski
Ricky Divjakovski

Reputation: 428

Splitting file by hex address

Im facing an difficulty while trying to split a file by hex address to hex address. Its seems as though its splitting fine, but when i check the file, its always copying every byte from the start of the file not the start address.

Please let me know where i am going wrong input string is hex address(string) converted to a long

    private void HexSplit(string inputFile, string outputFile, string startAddress, string endAddress)
    {
        FileStream hexReader = new FileStream(inputFile, FileMode.Open);
        FileStream hexWriter = new FileStream(outputFile, FileMode.Create);

        long StartAddress = Convert.ToInt64(startAddress.ToUpper(), 16);
        long EndAddress = Convert.ToInt64(endAddress.ToUpper(), 16);

        int bytecount = 0;
        while (bytecount != EndAddress)
        {
            if (bytecount >= StartAddress && bytecount <= EndAddress) hexWriter.WriteByte((byte)hexReader.ReadByte());
            bytecount++;
        }

        hexReader.Close();
        hexReader.Dispose();
        hexWriter.Close();
        hexWriter.Dispose();
    }

Upvotes: 1

Views: 388

Answers (1)

Steve
Steve

Reputation: 216302

You should read the input to have the reader positioned on the current starting point

byte b = hexReader.ReadByte();
if (bytecount >= StartAddress && bytecount <= EndAddress) 
    hexWriter.WriteByte(b);

bytecount++;

or you can use the Filestream.Position property to directly set the correct starting point avoiding to read unnecessary parts of the input file

long byteCount = StartAddress;
hexReader.Position = StartAddress;
while (bytecount <= EndAddress)
{
    hexWriter.WriteByte((byte)hexReader.ReadByte());
    bytecount++;
}

Notice that in both cases you should check for the input passed because if the addresses are bigger than the length of the file you will receive an exception

if(hexReader.Length < EndAddress)
   // Error message and return

Upvotes: 1

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