reading data from binary file

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Hi All,

I have to read data from a binary file at a specific location 0*FFF0 and store the data into a variable using c# .The binary file is being given as input .

Can anyone help me out ?????

Posted 18-Jul-11 1:05am

Member 7979279

Updated 18-Jul-11 2:12am

Ramalinga Koushik

v2

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lukeer · Answer 1 · 2011-07-18T01:19:00

Solution 1

You could try using a file stream. Seek() to the position you want to start from and then Read() the bytes you need.

Edit: You mentioned to need only one byte. The code is updated for that need.

using (System.IO.FileStream stream = new System.IO.FileStream(filepath, System.IO.FileMode.Open))
{
    int startIndex = 0xFFF0;

    stream.Seek( startIndex);
    byte data = stream.ReadByte();

    stream.Close();
}

Error handling is left to the implementer, of course.

Posted 18-Jul-11 1:19am

lukeer

Updated 19-Jul-11 23:26pm

v2

Comments

Jefis 18-Jul-11 8:50am

You need to seek to reading position.
stream.Seek(offset <...>)
and then Read.

lukeer 19-Jul-11 5:31am

You could, ~~but since FileStream.Read() supports an offset right away, you don't need to~~ and you should do so.

Jefis 19-Jul-11 9:09am

No it doesn't!.
offset: The byte offset in array at which the read bytes will be placed.

lukeer 20-Jul-11 5:19am

Yes, Jefis, you are right.
I thought completely wrong about the index parameter. I will update my answer accordingly.
Thank you for correcting this mistake.

Member 7979279 19-Jul-11 7:32am

Thanks sir , Here actually in detail what i have to do is :I have 1 byte at the address FFF0 and i have to read the byte bits-wise i.e i have to store the first 4 bits in a variable and the other 4 bits in another variable from that fff0 address byte .eg :fff0 : int v1=first 4 bits ,v2 = other 4 bits ;fff0 =00100011 ;v1 =0011(lower bits),v2=0010(upper bits).

lukeer 19-Jul-11 8:04am

Thats two separate tasks. Get the byte you want by using FileStream.Read(). Through the data variable you will have access to a byte array of length 1. You can access the only byte in it with data[0].

The second task is to split the byte into nibbles. Let's use bit-masking for that. AFAIK C# doesn't support a dual number representation in code. But hex is nearly as readable. So the mask for a low nibble is 0x0F, which means 00001111 in dual. A high nibble mask would then be 11110000b or 0xF0.

byte lowNibbleByte = data[0] & 0x0F;
byte highNibbleByte = (data[0] & 0xF0) >> 4;

As you can see, highNibbleByte is shifted right four bits after masking to match your example.