3.3.4.6 CDIN_FDBK_SEL

For accumulation operations, the Math block output must be fed back to the E input of the adder block. Selection of this input is controlled by combinations of the CDIN_FDBK_SEL and ARSHFT17 inputs. Following is the truth table for operand E.

Table 3-3. Truth Table for Propagating Operand E of the Adder or Accumulator
CDIN_FDBK_SELARSHFT17Operand E
0000
0010
010P[47:0]
011{17{P[47]}, P[47:18]}
110CDIN[47:0]
111{17{CDIN[47]}, CDIN[47:18]}