Hi Ali,
the block "chunks to symbols" is a simple look-up table and actually this would have been a better name for it.
Given an array A of size NxD,
you give it an index i \in{ 0,1,...,N-1}
and it gives you back the elements of the array in the i-th position, ie, A[i,0:D-1].
Which part is related to endianess?
best
Achilleas