x86/x86_64 Timer
This is a low level CPU cycle count timer. What it returns is the value held within the processor time stamp counter. This counter is incremented every CPU cycle.
####Considerations
When bench marking with this crate you want to assure your CPU is set to a fixed multipler. This mean Intel Turbo Boost must be OFF. You can do this in via the bios.
This crate requires Rust Nightly (as it uses asm! macro)
####Functions
;
This returns the number of CPU cycles that have passed since the last time the CPU counter has rolled over. OR Power on.
####In Depth Documentation
This function step by step:
#Intel Syntax
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
###License
Consider this crate licensed under the MIT.
###x86 support
This crate does implement 32bit x86 support, but it is untested.