title: fast bit-matrix (64x64) transpose algorithm using SIMD (ARM)
body: <p>I am trying to understand, if there is a fast way to do a matrix transpose (64x64 bits) using ARM SIMD instructions.</p>
  <p>I tried to explore the VTRN instruction of ARM SIMD but am not sure of its effective application in this scenario.</p>
  <p>The input matrix is represented as uint64 mat[64], and the output is supposed to be a bitwise transpose.</p>
  <p>For example if the input is:</p>
  <pre><code>0000....
  1111....
  0000....
  1111....
  </code></pre>
  <p>The expected output:</p>
  <pre><code>0101....
  0101....
  0101....
  0101....
  </code></pre>