Sleep down to 100 Nano seconds

[monoceres]

My god I was surprised when I found this function, it's frickin' awesome.

It allows you to sleep down to 100 nanoseconds!

UDF:

; #FUNCTION#;===============================================================================
;
; Name...........: _HighPrecisionSleep()
; Description ...: Sleeps down to 0.1 microseconds
; Syntax.........: _HighPrecisionSleep( $iMicroSeconds, $hDll=False)
; Parameters ....:  $iMicroSeconds      - Amount of microseconds to sleep
;                  $hDll  - Can be supplied so the UDF doesn't have to re-open the dll all the time.
; Return values .: None
; Author ........: Andreas Karlsson (monoceres)
; Modified.......:
; Remarks .......: Even though this has high precision you need to take into consideration that it will take some time for autoit to call the function.
; Related .......:
; Link ..........; 
; Example .......; No
;
;;==========================================================================================
Func _HighPrecisionSleep($iMicroSeconds,$hDll=False)
    Local $hStruct, $bLoaded
    If Not $hDll Then
        $hDll=DllOpen("ntdll.dll")
        $bLoaded=True
    EndIf
    $hStruct=DllStructCreate("int64 time;")
    DllStructSetData($hStruct,"time",-1*($iMicroSeconds*10))
    DllCall($hDll,"dword","ZwDelayExecution","int",0,"ptr",DllStructGetPtr($hStruct))
    If $bLoaded Then DllClose($hDll)
EndFunc

No msdn link for this one, since there is none

Note: Even though it supports down to 100 ns sleep don't count on that for being correct in practise because autoit will take some time to call the function (and all the other sutff that are in the UDF). For example on my machine, it took autoit 260 microseconds to call the function.

Edited October 13, 2008 by monoceres

[martin]

My god I was surprised when I found this function, it's frickin' awesome.

It allows you to sleep down to 100 nanoseconds!

UDF:

; #FUNCTION#;===============================================================================
;
; Name...........: _HighPrecisionSleep()
; Description ...: Sleeps down to 0.1 microseconds
; Syntax.........: _HighPrecisionSleep( $iMicroSeconds, $hDll=False)
; Parameters ....:  $iMicroSeconds      - Amount of microseconds to sleep
;                  $hDll  - Can be supplied so the UDF doesn't have to re-open the dll all the time.
; Return values .: None
; Author ........: Andreas Karlsson (monoceres)
; Modified.......:
; Remarks .......: Even though this has high precision you need to take into consideration that it will take some time for autoit to call the function.
; Related .......:
; Link ..........; 
; Example .......; No
;
;;==========================================================================================
Func _HighPrecisionSleep($iMicroSeconds,$hDll=False)
    Local $hStruct, $bLoaded
    If Not $hDll Then
        $hDll=DllOpen("ntdll.dll")
        $bLoaded=True
    EndIf
    $hStruct=DllStructCreate("int64 time;")
    DllStructSetData($hStruct,"time",-1*($iMicroSeconds*10))
    DllCall($hDll,"dword","ZwDelayExecution","int",0,"ptr",DllStructGetPtr($hStruct))
    If $bLoaded Then DllClose($hDll)
EndFunc

No msdn link for this one, since there are none

Note: Even though it supports down to 100 ns sleep don't count on that for being correct in practise because autoit will take some time to call the function (and all the other sutff that are in the UDF). For example on my machine, it took autoit 260 microseconds to call the function.

Very interesting. I'm having a bit of a problem finding a use for this.

Do you understand how to use the ZwDelayExecution function with positive values? (I don't.)

[monoceres]

Very interesting. I'm having a bit of a problem finding a use for this.

Do you understand how to use the ZwDelayExecution function with positive values? (I don't.)

It's not completely useless. Now you can create high precision timers without eating up or the cpu or create very tight loops without getting the CPU up to 100%.

I have no idea how to use positive values. According to this thread (also the thread where I found out about the function) on CodeGuru, positive values are "the absolute time to wake up". I have no idea how to calculate this (maybe nanoseconds since postix or something).

[Szhlopp]

It's not completely useless. Now you can create high precision timers without eating up or the cpu or create very tight loops without getting the CPU up to 100%.

I have no idea how to use positive values. According to this thread (also the thread where I found out about the function) on CodeGuru, positive values are "the absolute time to wake up". I have no idea how to calculate this (maybe nanoseconds since postix or something).

Crazy...

Nanoseconds = ?

Microseconds = ?

I'm a newb...

[monoceres]

Crazy...

Nanoseconds = ?

Microseconds = ?

I'm a newb...

Oh, you need to study the SI prefixes

[JRowe]

Microsecond = 1/1,000,000th of a second (one millionth)

Nanosecond = 1/1,000,000,000th of a second (one billionth)

The ms usually referred to in computer languages is millisecond, or one thousandth of a second.

Nanosecond precision is , well, wow.

[Szhlopp]

Oh, you need to study the SI prefixes

I have a zeptosecond script

Lol... Sorry, I should have thought about just looking those up again....

Since I'm a idiot. How did you measure the time it took for that to process?

Edited August 9, 2008 by Szhlopp

[BrettF]

Just a question, why would you want to pause for a 100 nanoseconds? I can't see a real use for that much precision...

But otherwise this is awesome!

Edited August 9, 2008 by BrettF

[monoceres]

I have a zeptosecond script

Lol... Sorry, I should have thought about just looking those up again....

Since I'm a idiot. How did you measure the time it took for that to process?

Very simple:

$dll=DLlOpen("ntdll.dll")
$timer=TimerInit()
_HighPrecisionSleep(2*1000,$dll); Sleep for 2 milliseconds.
MsgBox(0,"",TimerDiff($timer)); If it says for example 2.35 then 350 microseconds was wasted.

Just a question, why would you want to pause for a 100 nanoseconds? I can't see a real use for that much precision...

But otherwise this is awesome!

Actually, I just tested and 100 nanoseconds of sleep is enough to keep the CPU percentage at 0% on my machine

And, Thanks

Edited October 17, 2008 by monoceres

[monoceres]

Wow that's interesting..this function is so unknown that this thread is already #6 when googling ZwDelayExecution

[UPSman2]

Ntdll.dll is an NT layer DLL file that controls Windows NT system functions.

and the dll is full of functions

[andybiochem]

Hi Monoceres!

This looks really good, I could do with an accurate sleep for a timer I'm working on.

I don't seems to be able to get it to work....am I using it incorrectly?? :

#include <array.au3>

;----- open dll -----
$dll = DllOpen("ntdll.dll")

;----- array of sleeps to test -----
Dim $sleep[6] = [0.1,1,10,50,100,500]

;----- cal HP-sleep for each -----
For $i = 0 to 5
    $t = TimerInit()
    _HighPrecisionSleep($sleep[$i],$dll)
    $sleep[$i] &= " = " & TimerDiff($t)
Next

;----- display array -----
_ArrayDisplay($sleep)


;----- hp sleep by monoceres -----
Func _HighPrecisionSleep($iMicroSeconds,$hDll=False)
    Local $hStruct, $bLoaded
    If Not $hDll Then
        $hDll=DllOpen("ntdll.dll")
        $bLoaded=True
    EndIf
    $hStruct=DllStructCreate("int64 time;")
    DllStructSetData($hStruct,"time",-1*($iMicroSeconds*10))
    DllCall($hDll,"dword","ZwDelayExecution","int",0,"ptr",DllStructGetPtr($hStruct))
    If $bLoaded Then DllClose($hDll)
EndFunc

...I keep getting 15.x ms of sleep back???

[BrettF]

I'm thinking you should have:

_HighPrecisionSleep($sleep[$i]*1000,$dll)

[andybiochem]

Hmmm, maybe I'm not using it correctly???

expandcollapse popup

;=============================================
; Testing 3 different types of SLEEP function
;=============================================

#include <array.au3>

;----- results array -----
Dim $results[1]

;----- array of sleeps to test -----
Dim $sleep[6] = [0.1,1,10,50,100,500]

;----- call HP-sleep -----
_ArrayAdd($results,"_HighPrecisionSleep()")
$dll = DllOpen("ntdll.dll")
For $i = 0 to 5
    $t = TimerInit()
    _HighPrecisionSleep($sleep[$i] * 1000,$dll)
    _ArrayAdd($results,$sleep[$i] & " = " & TimerDiff($t))
Next

;----- call accurate sleep by ludocus -----
_ArrayAdd($results,"")
_ArrayAdd($results,"_AccurateSleep()")
For $i = 0 to 5
    $t = TimerInit()
    _AccurateSleep($sleep[$i])
    _ArrayAdd($results,$sleep[$i] & " = " & TimerDiff($t))
Next

;----- call normal sleep -----
_ArrayAdd($results,"")
_ArrayAdd($results,"AutoIt Sleep()")
For $i = 0 to 5
    $t = TimerInit()
    Sleep($sleep[$i])
    _ArrayAdd($results,$sleep[$i] & " = " & TimerDiff($t))
Next

;----- display array -----
_ArrayDisplay($results)


;##### FUNCTIONS #####

;----- hp sleep by monoceres -----
Func _HighPrecisionSleep($iMicroSeconds,$hDll=False)
    Local $hStruct, $bLoaded
    If Not $hDll Then
        $hDll=DllOpen("ntdll.dll")
        $bLoaded=True
    EndIf
    $hStruct=DllStructCreate("int64 time;")
    DllStructSetData($hStruct,"time",-1*($iMicroSeconds*10))
    DllCall($hDll,"dword","ZwDelayExecution","int",0,"ptr",DllStructGetPtr($hStruct))
    If $bLoaded Then DllClose($hDll)
EndFunc

;----- accurate sleep by ludocus -----
Func _AccurateSleep($sTime)
    $timer=TimerInit()
    Do
        $tmp = TimerDiff($timer)
    Until $tmp >= $sTime
EndFunc

See my results:

[BrettF]

My results:

[DexterMorgan]

This is pretty cool May come in handy somewhere

[TomCat]

Hi have some problems with your _HighPrecisionSleep funktion.

After a time the sleep time is getting longer and longer in a running script any idea why ?

[AdmiralAlkex]

Hi have some problems with your _HighPrecisionSleep funktion.

After a time the sleep time is getting longer and longer in a running script any idea why ?

_HighPrecisionSleep() shouldn't get longer no matter how many times you run it, please make a small (runnable) reproducer that shows the problem and I am sure the problem can be found

[jvanegmond]

Thank you again, monoceres.

Just for convenience I thought I post this:

$hDll=DllOpen("ntdll.dll")

$init = TimerInit()
_HighPrecisionSleepUnsafe(1000000, $hDll)
ConsoleWrite( TimerDiff($init) )

Func _HighPrecisionSleepUnsafe($iMicroSeconds,$hDll)
    _HighPrecisionSleepRawUnsafe( -1*($iMicroSeconds*10), $hDll )
EndFunc

Func _HighPrecisionSleepRawUnsafe($iMicroSecondsRaw, $hDll)
    $hStruct=DllStructCreate("int64 time;")
    DllStructSetData($hStruct,"time",$iMicroSecondsRaw)
    DllCall($hDll,"dword","ZwDelayExecution","int",0,"ptr",DllStructGetPtr($hStruct))
EndFunc

[WolfWorld]

For people who want it to be more accurate try this

Global $hDll=DllOpen("ntdll.dll")

Func _HighPrecisionSleep($iMicroSeconds)

Local $hStruct

$hStruct=DllStructCreate("int64 time;")

DllStructSetData($hStruct,"time",-1*($iMicroSeconds*10))

DllCall($hDll,"dword","ZwDelayExecution","int",0,"ptr",DllStructGetPtr($hStruct))

EndFunc

This will be faster at least on my PC. Remember Autoit is still a scripting language.