; RDRAND on CLOCK · HW free × TSC · local · never eaten
; LINEAR BGS->BGF->SDF · atoms EZZIE PHI THERMO on BGF · free rides · no duo
        rdtsc
        mov     r8d, eax
        rdrand  eax
        jnc     .r
.m:     xor     eax, r8d
        or      eax, 1
        ret
.r:     rdrand  eax
        jmp     .m