📲STX per stSTX Calculation

How the ratio of STX per stSTX is enforced in Clarity

Each cycle, the amount of STX backing a single stSTX token should go up, unless the amount of withdrawals have been greater than deposits (i.e. a net outflow). Nonetheless, each stacker using the protocol will get their pro-rata share of the yield each stacking cycle.

Let's take a look at the code that calculates the ratio:

(define-public (get-stx-per-ststx (reserve-trait <sticky-reserve-trait>))
  (let (
    (stx-amount (unwrap-panic (contract-call? reserve-trait get-total-stx)))
  )
    (try! (contract-call? .sticky-dao check-is-protocol (contract-of reserve-trait)))
    (ok (get-stx-per-ststx-helper stx-amount))
  )
)

(define-read-only (get-stx-per-ststx-helper (stx-amount uint))
  (let (
    (ststx-supply (unwrap-panic (contract-call? .ststx-token get-total-supply)))
  )
    (if (is-eq ststx-supply u0)
      u1000000
      (/ (* stx-amount u1000000) ststx-supply)
    )
  )
)

In the above calculation, we simply take the ratio of total deposits against PoX rewards that have been earned in STX.