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copied!<p>This code is cribbed directly from <a href="http://books.google.com/books?id=iBNKMspIlqEC&lpg=SL20-PA11&vq=Transposing%20an%208x8-bit%20matrix&pg=SL20-PA11#v=snippet&q=Transposing%20an%208x8-bit%20matrix&f=false" rel="noreferrer">"Hacker's Delight" - Figure 7-2 Transposing an 8x8-bit matrix</a>, I take no credit for it:</p> <pre><code>void transpose8(unsigned char A[8], int m, int n, unsigned char B[8]) { unsigned x, y, t; // Load the array and pack it into x and y. x = (A[0]<<24) | (A[m]<<16) | (A[2*m]<<8) | A[3*m]; y = (A[4*m]<<24) | (A[5*m]<<16) | (A[6*m]<<8) | A[7*m]; t = (x ^ (x >> 7)) & 0x00AA00AA; x = x ^ t ^ (t << 7); t = (y ^ (y >> 7)) & 0x00AA00AA; y = y ^ t ^ (t << 7); t = (x ^ (x >>14)) & 0x0000CCCC; x = x ^ t ^ (t <<14); t = (y ^ (y >>14)) & 0x0000CCCC; y = y ^ t ^ (t <<14); t = (x & 0xF0F0F0F0) | ((y >> 4) & 0x0F0F0F0F); y = ((x << 4) & 0xF0F0F0F0) | (y & 0x0F0F0F0F); x = t; B[0]=x>>24; B[n]=x>>16; B[2*n]=x>>8; B[3*n]=x; B[4*n]=y>>24; B[5*n]=y>>16; B[6*n]=y>>8; B[7*n]=y; } </code></pre> <p>I didn't check if this rotates in the direction you need, if not you might need to adjust the code.</p> <p>Also, keep in mind datatypes & sizes - <code>int</code> & <code>unsigned (int)</code> might not be 32 bits on your platform.</p> <p>BTW, I suspect the book (Hacker's Delight) is essential for the kind of work you're doing... check it out, lots of great stuff in there.</p>

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