DllCall to CallNtPowerInformation: cannot find function inside DLL

[dcdc]

Hi,

I have little experience using DllCall and I am stuck with this DLL.
I want to extract idle info from CallNtPowerInformation, specifically the SystemPowerInformation structure.
That should give me a more accurate idle time compared to A_TimeIdle, considering that some cbt softwares as Skype, MS Teams and others can prevent the system to idle for example during a video conference, which is not considered inside A_TimeIdle (as it is based on GetLastInputInfo).

For some reasons I get an ErrorLevel -4

I am also not sure how to pass the enumeration parameter InformationLevel, I have tried it either as "Str", "SystemPowerInformation" or as "Uint" 12.

My code is:

Code: Select all

#NoEnv  
SendMode Input 
structSize:=4*3+1
VarSetCapacity(myStruct, structSize, 0)
returnValue:=DllCall("CallNtPowerInformation", "Str", "SystemPowerInformation", "Int", 0, "Uint", 0, "Ptr", &myStruct, "Uint", structSize)
msgbox, %ErrorLevel%
;Reference to DLL: https://docs.microsoft.com/en-us/windows/win32/api/powerbase/nf-powerbase-callntpowerinformation

Any suggestion is appreciated

[HotKeyIt]

You'll need "PowrProf\CallNtPowerInformation".

[dcdc]

That worked!!!

For the enumerator, it was enough using "Uint", 12
Also, I found that the struct size was wrong: it must be 4*4 bytes even though the last member is an Uchar.

Thank you very much

[AHKStudent]

That worked!!!

For the enumerator, it was enough using "Uint", 12
Also, I found that the struct size was wrong: it must be 4*4 bytes even though the last member is an Uchar.

Thank you very much

can u post the final code?
thanks

[dcdc]

Sure
Here it is:

Code: Select all

#NoEnv
SendMode Input
structSize:=4*4
VarSetCapacity(myStruct, structSize, 0)
returnValue:=DllCall("PowrProf\CallNtPowerInformation", "Uint", 12, "Str", "NULL", "Uint", 0, "Ptr", &myStruct, "Uint", structSize)
msgbox % "ErrorLevel: " . ErrorLevel . "`nreturnValue: " . returnValue  . "`nreturnValueHex: " . Format("0x{:X}", returnValue) . "`nMaxIdlenessAllowed: " . NumGet(myStruct, 0, "UInt") . "`nIdleness: " . NumGet(myStruct, 4, "UInt") . "`nTimeRemaining: " . NumGet(myStruct, 8, "UInt") . "`nCoolingMode: " . NumGet(myStruct, 12, "Uchar")
;Reference to DLL: https://docs.microsoft.com/en-us/windows/win32/api/powerbase/nf-powerbase-callntpowerinformation

I still don't understand how to interpret the

Code: Select all

MaxIdlenessAllowed

and

Code: Select all

TimeRemaining

In fact, I get:
MaxIdlenessAllowed = 0 (always)
Idleness = according to the CPU unused %
TimeRemaining = 4294967295 (but a few times I read a lower value)
CoolingMode = 0

I tried on three different Win10 machines, waiting 20 seconds of inactivity or not, before reading, although I cannot get the logic of these parameters.

One of the machines runs an app which resets the idle timer (using SetThreadExecutionState), although also there I cannot notice any difference in the behavior.

Asked on SO as well: https://stackoverflow.com/questions/65371304/understanding-maxidlenessallowed-and-timeremaining-in-system-power-information-s

[just me]

SYSTEM_POWER_INFORMATION ?

[dcdc]

Thank you just me. Although that doesn't explain much more than a couple of words.
A few points that are unclear:
-I understand that TimeRemaining decrements. It doesn't increment, instead. Although that is not written anywhere.
- What does it mean a MaxIdlenessAllowed of zero?
- When does TimeRemaining start decrementing?
- Why doesn't it decrement in my cases?
- Is it updated every second/millisecond/15 seconds?

[just me]

Might be useful.

[dcdc]

Oh yes, that does help, thanks! I'll need to figure out why my readings are consistently like that, with some tests with the sleep parameters.
Also, I didn't realize that, on a machine that is used as a server, is always on and accessible from the internet, sleep must most probably be disabled and therefore this dll wouldn't help to get the idle time.
Ouch.