The "4 machine cycles" refers to how this works on PowerPC, namely the
"time base" register is incremented at the bus clock rate, which is usually
1/4 the cpu tick rate. On the Intel platform it does RDTSC and pushes the
64 bit result. I believe RDTSC is at the CPU clock rate.
You definitely need to do "long" arithmetic on the result, since the low 32
bits do tick over once in a while. Beyond that, I have no specific
-- Eliot Moss