Atomically increment two integers with CAS

Question

Apparently, it is possible to atomically increment two integers with compare-and-swap instructions. This talk claims that such an algorithm exists but it does not detail wha

Answer 1

Make me think of a sequence lock. Not very accurate (putting this from memory) but something along the lines of:

let x,y and s be 64 bit integers.

To increment:

atomic s++ (I mean atomic increment using 64 bit CAS op)

memory barrier
atomic x++
atomic y++
atomic s++
memory barrier

To read:

do {
    S1 = load s
    X = load x
    Y = load y
    memory barrier
    S2 = load s
} while (S1 != S2)

Also see https://en.wikipedia.org/wiki/Seqlock