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PORead file into ByteArrays of 4 bytes
 

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    <p>I would like to know how I could read a file into ByteArrays that are 4 bytes long. These arrays will be manipulated and then have to be converted back to a single array ready to be written to a file.</p> <p><strong>EDIT:</strong> Code snippet.</p> <pre><code> var arrays = new List&lt;byte[]&gt;(); using (var f = new FileStream("file.cfg.dec", FileMode.Open)) { for (int i = 0; i &lt; f.Length; i += 4) { var b = new byte[4]; var bytesRead = f.Read(b, i, 4); if (bytesRead &lt; 4) { var b2 = new byte[bytesRead]; Array.Copy(b, b2, bytesRead); arrays.Add(b2); } else if (bytesRead &gt; 0) arrays.Add(b); } } foreach (var b in arrays) { BitArray source = new BitArray(b); BitArray target = new BitArray(source.Length); target[26] = source[0]; target[31] = source[1]; target[17] = source[2]; target[10] = source[3]; target[30] = source[4]; target[16] = source[5]; target[24] = source[6]; target[2] = source[7]; target[29] = source[8]; target[8] = source[9]; target[20] = source[10]; target[15] = source[11]; target[28] = source[12]; target[11] = source[13]; target[13] = source[14]; target[4] = source[15]; target[19] = source[16]; target[23] = source[17]; target[0] = source[18]; target[12] = source[19]; target[14] = source[20]; target[27] = source[21]; target[6] = source[22]; target[18] = source[23]; target[21] = source[24]; target[3] = source[25]; target[9] = source[26]; target[7] = source[27]; target[22] = source[28]; target[1] = source[29]; target[25] = source[30]; target[5] = source[31]; var back2byte = BitArrayToByteArray(target); arrays.Clear(); arrays.Add(back2byte); } using (var f = new FileStream("file.cfg.enc", FileMode.Open)) { foreach (var b in arrays) f.Write(b, 0, b.Length); } </code></pre> <hr> <p><strong>EDIT 2:</strong> Here is the Ugly Betty-looking code that accomplishes what I wanted. Now I must refine it for performance...</p> <pre><code>var arrays_ = new List&lt;byte[]&gt;(); var arrays_save = new List&lt;byte[]&gt;(); var arrays = new List&lt;byte[]&gt;(); using (var f = new FileStream("file.cfg.dec", FileMode.Open)) { for (int i = 0; i &lt; f.Length; i += 4) { var b = new byte[4]; var bytesRead = f.Read(b, 0, b.Length); if (bytesRead &lt; 4) { var b2 = new byte[bytesRead]; Array.Copy(b, b2, bytesRead); arrays.Add(b2); } else if (bytesRead &gt; 0) arrays.Add(b); } } foreach (var b in arrays) { arrays_.Add(b); } foreach (var b in arrays_) { BitArray source = new BitArray(b); BitArray target = new BitArray(source.Length); target[26] = source[0]; target[31] = source[1]; target[17] = source[2]; target[10] = source[3]; target[30] = source[4]; target[16] = source[5]; target[24] = source[6]; target[2] = source[7]; target[29] = source[8]; target[8] = source[9]; target[20] = source[10]; target[15] = source[11]; target[28] = source[12]; target[11] = source[13]; target[13] = source[14]; target[4] = source[15]; target[19] = source[16]; target[23] = source[17]; target[0] = source[18]; target[12] = source[19]; target[14] = source[20]; target[27] = source[21]; target[6] = source[22]; target[18] = source[23]; target[21] = source[24]; target[3] = source[25]; target[9] = source[26]; target[7] = source[27]; target[22] = source[28]; target[1] = source[29]; target[25] = source[30]; target[5] = source[31]; var back2byte = BitArrayToByteArray(target); arrays_save.Add(back2byte); } using (var f = new FileStream("file.cfg.enc", FileMode.Open)) { foreach (var b in arrays_save) f.Write(b, 0, b.Length); } </code></pre> <p><strong>EDIT 3:</strong> Loading a big file into byte arrays of 4 bytes wasn't the smartest idea... I have over 68 million arrays being processed and manipulated. I really wonder if its possible to load it into a single array and still have the bit manipulation work. :/</p>
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    1. USAlan Alvarez
    1. USAlan Alvarez
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    1. COany reason you don't want to load the file into a single byte-array (size identical to filesize) ?
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      1. PORead file into ByteArrays of 4 bytes
      1. USYahia
    2. COthe byte array is converted to bit array and the bits shifted based on a table that is 32 bits long. If I load a byte array higher than 4 bytes long, the bit manipulation doesnt work properly and returns "00" for the exceeding bytes.
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      1. PORead file into ByteArrays of 4 bytes
      1. USAlan Alvarez
    3. COFrom my POV you are solving the wrong problem at the expense of rather bad performance... from your description I assume the code that does the bit shifting is buggy - please show that code...
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      1. PORead file into ByteArrays of 4 bytes
      1. USYahia
 

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