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From: -Jm- (john-markNOjoSPAM@pattersongray.com.invalid)
Subject: Re: NtQuerySystemInformation API Call
View: Complete Thread (10 articles)
Original Format
Newsgroups: microsoft.public.vb.winapi
Date: 2000/07/11
Your probably right about the variant, but I didn't know how to
translate a PVOID, probably should be LONG.  Anyway, here's the
C++ code for a program that extracts the CPU usage from the
system using this NtQuerySystemInformation API.

#include <windows.h>
#include <conio.h>
#include <stdio.h>

#define SystemBasicInformation       0
#define SystemPerformanceInformation 2
#define SystemTimeInformation        3

#define Li2Double(x) ((double)((x).HighPart) * 4.294967296E9 +
(double)((x).LowPart))

typedef struct
{
    DWORD   dwUnknown1;
    ULONG   uKeMaximumIncrement;
    ULONG   uPageSize;
    ULONG   uMmNumberOfPhysicalPages;
    ULONG   uMmLowestPhysicalPage;
    ULONG   uMmHighestPhysicalPage;
    ULONG   uAllocationGranularity;
    PVOID   pLowestUserAddress;
    PVOID   pMmHighestUserAddress;
    ULONG   uKeActiveProcessors;
    BYTE    bKeNumberProcessors;
    BYTE    bUnknown2;
    WORD    wUnknown3;
} SYSTEM_BASIC_INFORMATION;

typedef struct
{
    LARGE_INTEGER   liIdleTime;
    DWORD           dwSpare[76];
} SYSTEM_PERFORMANCE_INFORMATION;

typedef struct
{
    LARGE_INTEGER liKeBootTime;
    LARGE_INTEGER liKeSystemTime;
    LARGE_INTEGER liExpTimeZoneBias;
    ULONG         uCurrentTimeZoneId;
    DWORD         dwReserved;
} SYSTEM_TIME_INFORMATION;


// ntdll!NtQuerySystemInformation (NT specific!)
//
// The function copies the system information of the
// specified type into a buffer
//
// NTSYSAPI
// NTSTATUS
// NTAPI
// NtQuerySystemInformation(
//    IN UINT SystemInformationClass,    // information type
//    OUT PVOID SystemInformation,       // pointer to buffer
//    IN ULONG SystemInformationLength,  // buffer size in bytes
//    OUT PULONG ReturnLength OPTIONAL   // pointer to a 32-bit
//                                       // variable that
receives
//                                       // the number of bytes
//                                       // written to the
buffer
// );
typedef LONG (WINAPI *PROCNTQSI)(UINT,PVOID,ULONG,PULONG);

PROCNTQSI NtQuerySystemInformation;


void main(void)
{
    SYSTEM_PERFORMANCE_INFORMATION SysPerfInfo;
    SYSTEM_TIME_INFORMATION        SysTimeInfo;
    SYSTEM_BASIC_INFORMATION       SysBaseInfo;
    double                         dbIdleTime;
    double                         dbSystemTime;
    LONG                           status;
    LARGE_INTEGER                  liOldIdleTime = {0,0};
    LARGE_INTEGER                  liOldSystemTime = {0,0};

    NtQuerySystemInformation = (PROCNTQSI)GetProcAddress(
                                          GetModuleHandle
("ntdll"),
                                         "NtQuerySystemInformatio
n"
                                         );

    if (!NtQuerySystemInformation)
        return;

    // get number of processors in the system
    status = NtQuerySystemInformation
(SystemBasicInformation,&SysBaseInfo,sizeof(SysBaseInfo),NULL);
    if (status != NO_ERROR)
        return;

 printf("\nCPU Usage (press any key to exit):    ");
    while(!_kbhit())
    {
        // get new system time
     status = NtQuerySystemInformation
(SystemTimeInformation,&SysTimeInfo,sizeof(SysTimeInfo),0);
        if (status!=NO_ERROR)
            return;

        // get new CPU's idle time
        status = NtQuerySystemInformation
(SystemPerformanceInformation,&SysPerfInfo,sizeof
(SysPerfInfo),NULL);
        if (status != NO_ERROR)
            return;

        // if it's a first call - skip it
       if (liOldIdleTime.QuadPart != 0)
       {
            // CurrentValue = NewValue - OldValue
            dbIdleTime = Li2Double(SysPerfInfo.liIdleTime) -
Li2Double(liOldIdleTime);
            dbSystemTime = Li2Double
(SysTimeInfo.liKeSystemTime) - Li2Double(liOldSystemTime);

            // CurrentCpuIdle = IdleTime / SystemTime
            dbIdleTime = dbIdleTime / dbSystemTime;

            // CurrentCpuUsage% = 100 - (CurrentCpuIdle * 100) /
NumberOfProcessors
            dbIdleTime = 100.0 - dbIdleTime * 100.0 / (double)
SysBaseInfo.bKeNumberProcessors + 0.5;

            printf("\b\b\b\b%3d%%",(UINT)dbIdleTime);
       }

        // store new CPU's idle and system time
        liOldIdleTime = SysPerfInfo.liIdleTime;
        liOldSystemTime = SysTimeInfo.liKeSystemTime;
  
        // wait one second
        Sleep(1000);
    } printf("\n");
}

If someone could help translate just the actual
NtQuerySystemInformation API to VBasic 5.0 I'd be greatly
indebted.  I think the main problem to worry about is that the
NTDLL.DLL isn't available to applications (at least I've
heard).  I think this is why the author of the above code chose
to use the GetProcAddress() function to get the handle of the
DLL for the call.  I don't know how this would translate to VB,
but I do know that just when I think something can't be done in
VB, I figure it out and it works.

Thanks
Jm




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