; TX/RX · pair · edi=tx esi=rx
; LINEAR BGS->BGF->SDF · atoms EZZIE PHI THERMO on BGF · free rides · no duo
; out: eax = SDF linear (tx-rx)|1 · r8 = free RNG (tx^rx)|1
; free rides BGF · never folds into field/place
        mov     eax, edi
        mov     r8d, edi
        xor     r8d, esi
        or      r8d, 1
        sub     eax, esi
        or      eax, 1
        ret