Byte array to int16 array

Question

Is there a more efficient way to convert byte array to int16 array ?? or is there a way to use Buffer.BlockCopy to copy evry two byte to int16 array ???

public static int[] BYTarrToINT16arr(string fileName)
{
try
{
int bYte = 2;
byte[] buf = File.ReadAllBytes(fileName); 
int bufPos = 0;
int[] data = new int[buf.Length/2];
byte[] bt = new byte[bYte];
for (int i = 0; i < buf.Length/2; i++)
{
Array.Copy(buf, bufPos, bt, 0, bYte);
bufPos += bYte;
Array.Reverse(bt);
data[i] = BitConverter.ToInt16(bt, 0);
}
return data;
}
catch
{
return null;
}
}

Please don't add things like "C#" to the ends of your titles. That's what the tags are for. — John Saunders
– John Saunders, Commented Mar 26, 2012 at 2:28
Also, I strongly suggest you get rid of that try/catch block. If there's an exception, then you want to know about it. — John Saunders
– John Saunders, Commented Mar 26, 2012 at 2:28
P.S. return type is int[] not Int16[] Apologies for for confusion — Raj
– Raj, Commented Mar 26, 2012 at 5:32

Andrew Cooper · Accepted Answer · 2012-03-26 06:39:16Z

4

Use a FileStream and a BinaryReader. Something like this:

var int16List = List<Int16>();
using (var stream = new FileStream(filename, FileMode.Open))
using (var reader = new BinaryReader(stream))
{
    try
    {
        while (true)
            int16List.Add(reader.ReadInt16());
    }
    catch (EndOfStreamException ex)
    {
        // We've read the whole file
    }
}
return int16List.ToArray();

You can also read the whole file into a byte[], and then use a MemoryStream instead of the FileStream if you want.

If you do this then you'll also be able to size the List approrpriately up front and make it a bit more efficient.

edited Mar 26, 2012 at 6:39

answered Mar 26, 2012 at 2:20

Andrew Cooper

32.7k5 gold badges86 silver badges124 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Andrew Cooper Over a year ago

If you want an int[] (rather than Int16[]) then just use a List<int> to build the array in the first place.

Raj Over a year ago

I want 2-2 byte converted to int[]...if i use List<int>..it will grab 4 bytes and convert to int32...right ??

Sergey Kalinichenko · Accepted Answer · 2012-03-26 02:20:44Z

1

Apart from having an off-by-one possibility in case the number of bytes is odd (you'll miss the last byte) your code is OK. You can optimize it by dropping the bt array altogether, swapping i*2 and i*2+1 bytes before calling BitConverter.ToInt16, and passing i*2 as the starting index to the BitConverter.ToInt16 method.

answered Mar 26, 2012 at 2:20

Sergey Kalinichenko

729k85 gold badges1.2k silver badges1.6k bronze badges

Comments

Martijn Pieters · Accepted Answer · 2012-05-28 07:04:14Z

1

This works if you don't mind using interopservices. I assume it is faster than the other techniques.

using System.Runtime.InteropServices;   

public Int16[] Copy_Byte_Buffer_To_Int16_Buffer(byte[] buffer)

{
    Int16[] result = new Int16[1];
    int size = buffer.Length;
    if ((size % 2) != 0)
    {
        /* Error here */
        return result;
    }
    else
    {
        result = new Int16[size/2];
        IntPtr ptr_src = Marshal.AllocHGlobal (size);
        Marshal.Copy (buffer, 0, ptr_src, size);
        Marshal.Copy (ptr_src, result, 0, result.Length);
        Marshal.FreeHGlobal (ptr_src);
        return result;
    }
}

edited May 28, 2012 at 7:04

Martijn Pieters

1.1m326 gold badges4.2k silver badges3.4k bronze badges

answered May 28, 2012 at 6:31

James Edgar

1,9761 gold badge12 silver badges4 bronze badges

Comments

YoryeNathan · Accepted Answer · 2012-03-26 02:37:38Z

0

var bytes = File.ReadAllBytes(path);

var ints = bytes.TakeWhile((b, i) => i % 2 == 0).Select((b, i) => BitConverter.ToInt16(bytes, i));

if (bytes.Length % 2 == 1)
{
    ints = ints.Union(new[] {BitConverter.ToInt16(new byte[] {bytes[bytes.Length - 1], 0}, 0)});
}

return ints.ToArray();

answered Mar 26, 2012 at 2:37

YoryeNathan

14.6k5 gold badges42 silver badges61 bronze badges

Comments

Keith Nicholas · Accepted Answer · 2012-03-26 03:03:47Z

0

try...

int index = 0;            
var my16s = bytes.GroupBy(x => (index++) / 2)
           .Select(x => BitConverter.ToInt16(x.Reverse().ToArray(),0)).ToList();

edited Mar 26, 2012 at 3:03

answered Mar 26, 2012 at 2:23

Keith Nicholas

44.4k15 gold badges101 silver badges168 bronze badges

Collectives™ on Stack Overflow

Byte array to int16 array

5 Answers 5

2 Comments

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

2 Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related