;;; fake_exponential(factor, numer, denom): integer approximation of
;;; factor * e ** (numer / denom), as specified in EIP-7002.

                           ; [factor, numer, denom]
    dup3                   ; [denom, factor, numer, denom]
    mul                    ; [accum, numer, denom]
    push 1                 ; [i, accum, numer, denom]
    swap1                  ; [accum, i, numer, denom]
    push 0                 ; [output, accum, i, numer, denom]

expo_loop:
    ;; while accum > 0
    push 0                 ; [0, output, accum, i, numer, denom]
    dup3                   ; [accum, 0, output, accum, i, numer, denom]
    gt                     ; [accum > 0, output, accum, i, numer, denom]
    iszero                 ; [!(accum > 0), output, accum, i, numer, denom]
    jumpi @expo_done       ; [output, accum, i, numer, denom]

    ;; output += accum
    dup2                   ; [accum, output, accum, i, numer, denom]
    add                    ; [output, accum, i, numer, denom]

    ;; accum = (accum * numer) // (denom * i)
    swap1                  ; [accum, output, i, numer, denom]
    dup4                   ; [numer, accum, output, i, numer, denom]
    mul                    ; [accum*numer, output, i, numer, denom]
    dup5                   ; [denom, accum*numer, output, i, numer, denom]
    dup4                   ; [i, denom, accum*numer, output, i, numer, denom]
    mul                    ; [i*denom, accum*numer, output, i, numer, denom]
    swap1                  ; [accum*numer, i*denom, output, i, numer, denom]
    div                    ; [accum, output, i, numer, denom]

    ;; i += 1
    swap2                  ; [i, output, accum, numer, denom]
    push 1                 ; [1, i, output, accum, numer, denom]
    add                    ; [i, output, accum, numer, denom]
    swap2                  ; [accum, output, i, numer, denom]
    swap1                  ; [output, accum, i, numer, denom]
    jump @expo_loop

expo_done:
    swap1                  ; [accum, output, i, numer, denom]
    swap4                  ; [denom, output, i, numer, accum]
    swap1                  ; [output, denom, i, numer, accum]
    div                    ; [req_fee, i, numer, accum]
    swap3                  ; [accum, i, numer, req_fee]
    pop                    ; [i, numer, req_fee]
    pop                    ; [numer, req_fee]
    pop                    ; [req_fee]