This is a low level CPU tick count timer. What it returns is the value heald within the processor time stamp counter. This counter is incremented every CPU cycle.
When bench marking with this crate you want to assure your CPU is set to fixed multipler. This mean Intel Turbo Boost must be OFF. You can do this in the bios.
This create requires Rust Nightly (as it uses asm! macro)
rust
fn tick() -> u64;
This returns the number of CPU cycles that have passed since the last time the CPU counter has rolled over. OR Power one.
This function step by step:
```nasm
ldfence #cheapest fence on x86 #this prevents instruction re-ordering #ensures all loads are complete #on x64 this is done for you by the memory model #so this fence is free #this fence is here to prevent speculative #execution of rdtsc.
rdtsc #puts timestamp counter values into the low #32bits of rdx and rax.
shl rdx, $32 #move the high section, into the high 32bits of #its register
or rax, rdx #combine bits
retq #leave function ```
Consider this crate licensed under the MIT.
This crate does implement 32bit x86 support, but it is untested.