.ISAE ; ISA Extensions segment
                ALU
                SECP256

;; Computes sum of two Pedersen commitments
;;
;; # Arguments
;; - r512[1], r512[2] - first pair of keys
;; - r512[3], r512[4] - second pair of keys
;;
;; # Returns
;; - t512[5], r512[6] - sum of keys
.ROUTINE sum
                secpadd r512[3], r512[1]
                jif     continue
                fail
continue:       secpadd r512[4], r512[2]
                jif     return
                fail
return:         mov     r512[1], r512[5]
                mov     r512[2], r512[6]
                ret

.ROUTINE verify
                secpneg r512[7], r512[7]
                secpneg r512[8], r512[8]
                eq.n    r512[1], r512[7]
                jif     continue
                fail
continue:       eq.n    r512[2], r512[8]
                jif     return
                fail
return:         nop