rebol [ title: "Chrono - High-precision time measurement" file: %windows-chrono.r author: "Maxim Olivier-Adlhoch" version: 1.0.2 license: 'MIT date: 2010-08-25 disclaimer: "Absolutely no guarantees, use at own risk." notes: "Routines & utility functions for VERY precise counters on MS Windows 2000 and up." ] ;===================================================== ; libs ;===================================================== k32-lib: load/library join to-rebol-file get-env "systemroot" %"/system32/Kernel32.dll" ;===================================================== ; structs ;===================================================== ; MSDN docs here: http://msdn.microsoft.com/en-us/library/aa383713%28VS.85%29.aspx i64-struct: make struct! [ low [integer!] hi [integer!] ] [ 0 0] ;===================================================== ; routines ;===================================================== QueryPerformanceCounter: make routine! compose/deep [ ; MSDN docs here: http://msdn.microsoft.com/en-us/library/ms644904%28v=VS.85%29.aspx time-ptr [struct* [(first i64-struct)]] return: [integer!] ] k32-lib "QueryPerformanceCounter" QueryPerformanceFrequency: make routine! compose/deep [ time-ptr [struct* [(first i64-struct)]] return: [integer!] ] k32-lib "QueryPerformanceFrequency" ;===================================================== ; functions ;===================================================== ;----------------- ;- i64-to-float() ;----------------- i64-to-float: func [ i64 [struct!] ][ either negative? i64/low [ (i64/hi * 4294967296.0) + 2147483648.0 + (i64/low AND 2147483647 ) ; {} ][ (i64/hi * 4294967296.0) + (i64/low) ] ] ;----------------- ;- get-tick() ; ; CAUTION! no error checking done for speed reasons. ; ; QueryPerformanceCounter actually returns 0 when an error occurs or non-zero otherwise. ; if there is no performanceCounter, the lib will fail anyways, when GLOBAL_TICK-RESOLUTION is ; set. ; ; so its pretty safe even if we don't do any check on the return value of the routine. ;----------------- get-tick: func [/local s][ s: make struct! first i64-struct [0 0] QueryPerformanceCounter s i64-to-float s ] ;----------------- ;- get-tick-resolution() ;----------------- get-tick-resolution: func [/local s][ s: make struct! first i64-struct [0 0] if 0 = QueryPerformanceFrequency s [ to-error "NO performance counter on this system" ] reduce [ s/hi s/low] ] ;----------------- ;- time-lapse() ; ; note that we do not set the processor/thread affinity and this COULD lead to ; different CPUS returning different counter values ; ; multi-core CPUS use the same clock for all cores, so for the vast ; majority of cases, this simple func is ok. ; ; AFAIK, the BIOS or HAL should synchronise both clocks (or always return the ; clock for the same CPU), but some multi-processor motherboards might have issues. ;----------------- time-lapse: func [ blk [block!] /local start ][ start: get-tick do blk ; return diff in seconds to-time ((get-tick - start) / GLOBAL_TICK-RESOLUTION) ] ;----------------- ;- chrono-time() ;----------------- chrono-time: func [ ][ GLOBAL_CHRONO-TIMED + to-time ((get-tick - GLOBAL_CHRONO-INITIAL-TICK) / GLOBAL_TICK-RESOLUTION) ] ;===================================================== ; GLOBALS ;===================================================== ; used for converting to time GLOBAL_TICK-RESOLUTION: second get-tick-resolution ; used to provide more precise time via chrono-time GLOBAL_CHRONO-TIMED: now/precise GLOBAL_CHRONO-INITIAL-TICK: get-tick ;===================================================== ; TESTS ;===================================================== ; un-comment to test library comment [ probe time-lapse [print "."] probe time-lapse [prin "."] probe time-lapse [sine 45] probe time-lapse [wait 1.75] ; this actually highlights how imprecise the rebol timers really are! probe time-lapse [wait 1.75] ; this actually highlights how imprecise the rebol timers really are! probe time-lapse [wait 1.75] ; this actually highlights how imprecise the rebol timers really are! ask "!" ]