Internals of streamReorder

This document describes the structure and execution of streamReorder, implemented as streamReorder function.

The streamReorder adjusts the output order within a fix size group. Suppose the fix size is Wn, each Wn input data are reordered to output following the pattern from input configuration.

For example, Wn = 4, reorder config is 2,1,0,3.

Input order is 1,2,3,4,5,6,7 (1 is first input and 7 is last).

Each group of 4 data elements is reordered: 0 1 2 3 –> 2 1 0 3 and 4 5 6 7 –> 6 5 4 7.

Output is 2,1,0,3,6,5,4,7.

The design of this primitive applies ping-pong arrays to obtain high performance. One is storing the input data while output data from another one.

Caution

Applicable conditions. 1. The length of input stream is a multiple (>=1) of the length of reorder config stream set by the _WindowSize template parameter. 2. The configuration is loaded once in one invocation, and reused until the end. 3. The types of input stream and output stream are same.