3.3.4.7 PASUB and SUB Inputs

The PASUB signal controls the mode of pre-adder (subtraction or addition). The SUB signal controls whether the multiplier product is to be subtracted or added.

Table 3-4. Truth Table for Computation of Result P and CDOUT
SIMDDOTPSUBPASUBResult P and CDOUT
0000CARRYIN + C[47:0] + E[47:0] + { (B[17:0] + D[17:0]) x A[17:0] }
0001CARRYIN + C[47:0] + E[47:0] + { (B[17:0] - D[17:0]) x A[17:0] }
0010CARRYIN + C[47:0] + E[47:0] - { (B[17:0] + D[17:0]) x A[17:0] }
0011CARRYIN + C[47:0] + E[47:0] - { (B[17:0] - D[17:0]) x A[17:0] }
0100CARRYIN + C[47:0] + E[47:0] +

{ (B[8:0] + D[8:0]) x A[17:9] + (B[17:9] + D[17:9]) x A[8:0] } x 29

0101CARRYIN + C[47:0] + E[47:0] +

{ (B[8:0] - D[8:0]) x A[17:9] + (B[17:9] - D[17:9]) x A[8:0] } x 29

0110CARRYIN + C[47:0] + E[47:0] +

{ (B[8:0] + D[8:0]) x A[17:9] - (B[17:9] + D[17:9]) x A[8:0] } x 29

0111CARRYIN + C[47:0] + E[47:0] +

{ (B[8:0] - D[8:0]) x A[17:9] - (B[17:9] - D[17:9]) x A[8:0] } x 29

1000P[17:0] = CARRYIN + { B[8:0] x A[8:0] }

P[47:18] = C[47:18] + E[47:18] + { (B[17:9] + D[17:9]) x A[17:9] }

1001P[17:0] = CARRYIN + { B[8:0] x A[8:0] }

P[47:18] = C[47:18] + E[47:18] + { (B[17:9] - D[17:9]) x A[17:9] }

1010P[17:0] = CARRYIN + { B[8:0] x A[8:0] }

P[47:18] = C[47:18] + E[47:18] - { (B[17:9] + D[17:9]) x A[17:9] }

1011P[17:0] = CARRYIN + { B[8:0] x A[8:0] }

P[47:18] = C[47:18] + E[47:18] - { (B[17:9] - D[17:9]) x A[17:9] }