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Understanding Modified Baugh-Wooley multiplication algorithm

For Modified Baugh-Wooley multiplication algorithm , why is it !(A0*B5) instead of just (A0*B5) ?

Same questions for !(A1*B5), !(A2*B5), !(A3*B5), !(A4*B5), !(A5*B4), !(A5*3), !(A5*B2), !(A5*B1) and !(A5*B0)

Besides, why there are two extra '1' ?

Modified Baugh-Wooley multiplication algorithm

Solution

  • why two extra '1'?

    See some previous explanation in Matt Timmermans's answer

    Note : '-2' in two complement is 110, and this contributes to the carries, thus two extra '1'

    why flipping the values of some of the partial product bits.

    It is due to signed bit in the MSB (A5 and B5).

    Besides, please see below the Countermeasure for modified baugh-wooley algorithm in the case of A_WIDTH != B_WIDTH with the help of others.

    Countermeasure for modified baugh-wooley algorithm in the case of A_WIDTH != B_WIDTH

    I have written a hardware verilog code for this algorithm Hopefully, this post helps some readers.