DSP58 users can benefit from the pre-adder in several applications ranging from wireless applications (for example, in algorithms as in the Long-Term Evolution specification), in generic filtering (FIR and IIR), in video processing (for example, alpha blending), and many others. The most common use for the pre-adder is to pre-add corresponding values of a symmetric FIR filter tap delay line.
Refer to Pre-Adder Used as a Multiplexer for information on how the pre-adder can be used as a 2:1 multiplexer to dynamically select between A[26:0] and D[26:0].