CSLA is used in many computational systems to alleviate the problem of carry propagation delay by independently generating multiple carries and then select a carry to generate the sum . However, the CSLA is not area efficient because it uses multiple pairs of Ripple Carry Adders (RCA) to generate partial sum and carry by considering carry input Cin=0 and cin=1, then the final sum and carry are selected by the multiplexers (mux). The sum for each bit position in an elementary adder is generated sequentially only after the previous bit position has been summed and a carry propagated into the next position.
Ravikumar, N.; Vishwanath, M.; and Reddy, B.Durga Malleswara
"An Area Efficient 32-bit Carry-select Adder for Low Power Applications,"
International Journal of Computer and Communication Technology: Vol. 7
, Article 8.
Available at: https://www.interscience.in/ijcct/vol7/iss2/8