; FAN SET · esi=target pwm · edi=current · step toward · linear no rebound
; LINEAR BGS->BGF->SDF · atoms EZZIE PHI THERMO on BGF · free rides · no duo
; eax = current + sign(target-cur) clipped · soft step 1 · |1
        mov     eax, edi
        cmp     eax, esi
        je      .live
        jl      .up
        dec     eax
        jmp     .live
.up:    inc     eax
.live:  or      eax, 1
        ret