Digital arrangement for error checking in binary adder including block carry look-ahead units.

摘要

A binary adder is comprised of a plurality of block carry look-ahead units. Each of the units includes a block carry-in generator (38), an adding section (40), a block carry-out generator (102) and a carry coincidence checker (110). The block carry-in generator (38) is arranged to receive a plurality of carry generate variables and a plurality of carry propagate variables from the other units, generating a carry-in using carry look-ahead scheme. The adding section (40) is coupled to receive the carry-in from said block carry-in generator (38) and further receives two operand data to be added and generates a resultant sum of the two operand data. The block carry-out generator (102) receives the two operand data and also receives the carry-in from the block carry-in generator (38). The block carry-out generator (102) produces a carry-out of the unit to be applied to a lower order block carry look-ahead unit. The carry coincidence checker (110) is arranged to receive the carry-in from the carry-in generator (38) and also receives a carry from another block carry look-ahead unit. The carry, which is applied from another unit, corresponds to the carry-out. The checker (110) performs a coincidence check between the carry-in and the carry applied from another unit.