How do I define the index within the array?

From a hardware design perspective, how does one optimize histogram operation (array index accumulation)?

• The histogram operation is defined as: Input array = N integers (ranged 0 ... 2**K - 1) Initialize histogram array = (2 ** K) integers, all initialized to zero. For each integer V in input array, increment histogram[V] by one Current architectures (CPU and GPU) can be used as starting point for the discussion, but the intention is to bring the discussion further than that.

• Answer:

  This is counting sort. See the wiki entry http://en.wikipedia.org/wiki/Counting_sort. You could probably parallelize it by having multiple threads and using one of the concurrent containers from Intel Thread Building Blocks.