| 1 | // QPC_Check.cpp : Defines the entry point for the console application.
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| 2 | //
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| 3 | #include "stdafx.h"
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| 4 | #include <stdio.h>
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| 5 | #include <conio.h> // _kbhit()
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| 6 | #include <windows.h> // Sleep()
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| 7 |
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| 8 | // This constant is used to check for forward jumps of the performance counter
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| 9 | // It is dependent upon the frequency of the counter (determined via
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| 10 | // QueryPerformanceFrequency() -- not used in this test app for brevity).
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| 11 | #define FWD_LIMIT (0x1000000)
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| 12 |
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| 13 | int _tmain(int argc, _TCHAR* argv[])
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| 14 | {
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| 15 | BOOL bDone = FALSE ;
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| 16 | char cUserInput ;
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| 17 | LARGE_INTEGER liLastCount, liNewCount ;
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| 18 | int nBackEventTally = 0 ;
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| 19 | int nFwdEventTally = 0 ;
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| 20 |
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| 21 | (void)printf("QPC Check - v1.0 Hit 'c' to display current count, 'x' to exit\n") ;
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| 22 |
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| 23 | // Read counter to prime the LastCount value
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| 24 | if (TRUE != QueryPerformanceCounter ( &liLastCount ))
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| 25 | {
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| 26 | printf("QPC read error\n") ;
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| 27 | bDone = TRUE ;
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| 28 | }
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| 29 |
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| 30 | while (FALSE == bDone)
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| 31 | {
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| 32 | // Respond to user input, if any
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| 33 | if (0 != _kbhit()) // _kbhit() returns 0 or "non-zero"
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| 34 | {
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| 35 | // Get the key
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| 36 | cUserInput = _getch() ;
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| 37 |
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| 38 | if (('x' == cUserInput) || ('X' == cUserInput))
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| 39 | {
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| 40 | printf("Exiting QPC_Check\n") ;
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| 41 | bDone = TRUE ;
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| 42 | }
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| 43 | // Print status and last count
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| 44 | else if (('c' == cUserInput) || ('C' == cUserInput))
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| 45 | {
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| 46 | printf("Backward events: %d Forward events: %d", nBackEventTally, nFwdEventTally ) ;
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| 47 | printf(" Last Count = 0x%08x:%08x\n", liLastCount.u.HighPart, liLastCount.u.LowPart ) ;
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| 48 | }
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| 49 | else if ('b' == cUserInput)
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| 50 | {
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| 51 | printf("Testing backward event...\n") ;
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| 52 | liLastCount.QuadPart += FWD_LIMIT ;
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| 53 | }
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| 54 | else if ('f' == cUserInput)
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| 55 | {
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| 56 | printf("Testing forward event...\n") ;
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| 57 | liLastCount.QuadPart -= (FWD_LIMIT + 1);
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| 58 | }
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| 59 | }
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| 60 |
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| 61 | // Read & check counter
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| 62 | if (TRUE == QueryPerformanceCounter ( &liNewCount ))
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| 63 | {
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| 64 | // Check for new < last
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| 65 | if (liNewCount.QuadPart < liLastCount.QuadPart)
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| 66 | {
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| 67 | nBackEventTally++ ;
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| 68 | printf("Jump backward event: Last = 0x%08x:%08x, New = 0x%08x:%08x\n",
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| 69 | liLastCount.u.HighPart, liLastCount.u.LowPart,
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| 70 | liNewCount.u.HighPart, liNewCount.u.LowPart ) ;
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| 71 | }
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| 72 |
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| 73 | // Check for new >> last
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| 74 | if (liNewCount.QuadPart > (liLastCount.QuadPart + FWD_LIMIT))
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| 75 | {
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| 76 | nFwdEventTally++ ;
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| 77 | printf("Jump forward event: Last = 0x%08x:%08x, New = 0x%08x:%08x\n",
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| 78 | liLastCount.u.HighPart, liLastCount.u.LowPart,
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| 79 | liNewCount.u.HighPart, liNewCount.u.LowPart ) ;
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| 80 | }
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| 81 |
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| 82 | // Update LastCount with new value
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| 83 | liLastCount.QuadPart = liNewCount.QuadPart ;
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| 84 | }
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| 85 | else
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| 86 | {
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| 87 | printf("QPC read error\n" ) ;
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| 88 | bDone = TRUE ;
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| 89 | }
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| 90 | Sleep( 50 ) ; // wait 50 millisecs then check counter again
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| 91 | }
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| 92 |
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| 93 | return 0;
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| 94 | }
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| 95 |
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