I think I figured out those equations myself...
Minimum:
- Single: -3P + R
- Quad: -3P + R + 1
-3P => P is# of 4-input butterfly unit and 3 is maximum# of bits growth per each 4-input butterfly unit
R => for the last stage, either a 4 or a 2 -input butterfly. The 2-input butterfly unit discards one less bit than the 4-input butterfly unit.
1 => I am assuming that this is purely due to implementation differences between Quad and Single.
Also several assumptions are made to derive the maximum outputs:
1) If scaling occurs, each stage (4-input butterfly unit) can scale up to maximum of 4.
2) Assuming that no scaling occurs for the last stage of quad
3) Assuming that no scaling occurs during the first stage.
4) P and R => total# of 4-input and 2-input butterfly units respectively
Given the above assumptions, then the equations for maximum are: (minimum) + (max amount of scaling)
Single : (-3P + R) + ((P-1)*4) = P+R -4
Quad : -(3P + R + 1) + ((P-2)*4) = P+R-7
Seeing how equations work out... my assumptions are probably correct then...
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