Description
There are three separate sets of registers within each Stratix device DSP block.
Two of the register sets are located in the multiplier block. One of these sets includes input registers that feed into the multiplier. The other set (referred to as the pipeline registers) is located at the output of the multiplier.
The final register set is located at the output of the adder/subtractor/accumulator unit.
All three register sets are optional unless you have specified multiply-accumulate mode. In multiply-accumulate mode, the third set is mandatory.