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Tricks of the Windows Gam…ming Gurus (2nd Edition)
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Disc2.iso
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vc98
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crt
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src
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clock.c
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C/C++ Source or Header
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1998-06-17
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243 lines
/***
*clock.c - Contains the clock runtime
*
* Copyright (c) 1987-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* The clock runtime returns the processor time used by
* the current process.
*
*******************************************************************************/
#ifdef _WIN32
#include <cruntime.h>
#include <windows.h>
#include <stdio.h>
#include <time.h>
#include <internal.h>
#include <sys\timeb.h>
#include <sys\types.h>
void __cdecl __inittime(void);
#ifdef _MSC_VER
#pragma data_seg(".CRT$XIC")
static _PVFV pinit = __inittime;
#pragma data_seg()
#endif /* _MSC_VER */
static unsigned __int64 start_tics;
/***
*clock_t clock() - Return the processor time used by this process.
*
*Purpose:
* This routine calculates how much time the calling process
* has used. At startup time, startup calls __inittime which stores
* the initial time. The clock routine calculates the difference
* between the current time and the initial time.
*
* Clock must reference _cinitime so that _cinitim.asm gets linked in.
* That routine, in turn, puts __inittime in the startup initialization
* routine table.
*
*Entry:
* No parameters.
* itime is a static structure of type timeb.
*
*Exit:
* If successful, clock returns the number of CLK_TCKs (milliseconds)
* that have elapsed. If unsuccessful, clock returns -1.
*
*Exceptions:
* None.
*
*******************************************************************************/
clock_t __cdecl clock (
void
)
{
unsigned __int64 current_tics;
FILETIME ct;
GetSystemTimeAsFileTime( &ct );
current_tics = (unsigned __int64)ct.dwLowDateTime +
(((unsigned __int64)ct.dwHighDateTime) << 32);
/* calculate the elapsed number of 100 nanosecond units */
current_tics -= start_tics;
/* return number of elapsed milliseconds */
return (clock_t)(current_tics / 10000);
}
/***
*void __inittime() - Initialize the time location
*
*Purpose:
* This routine stores the time of the process startup.
* It is only linked in if the user issues a clock runtime call.
*
*Entry:
* No arguments.
*
*Exit:
* No return value.
*
*Exceptions:
* None.
*
*******************************************************************************/
void __cdecl __inittime (
void
)
{
FILETIME st;
GetSystemTimeAsFileTime( &st );
start_tics = (unsigned __int64)st.dwLowDateTime +
(((unsigned __int64)st.dwHighDateTime) << 32);
}
#else /* _WIN32 */
#if defined (_M_MPPC) || defined (_M_M68K)
#include <cruntime.h>
#include <stdio.h>
#include <time.h>
#include <fltintrn.h> /* PFV definition */
#include <sys\timeb.h>
#include <sys\types.h>
#include <internal.h>
/* define the entry in initializer table */
#pragma data_seg(".CRT$XIC")
static PFV __pinittime = _inittime;
#pragma data_seg()
static struct _timeb __itimeb;
/***
*clock_t clock() - Return the processor time used by this process.
*
*Purpose:
* This routine calculates how much time the calling process
* has used. At startup time, startup calls _inittime which stores
* the initial time. The clock routine calculates the difference
* between the current time and the initial time.
*
* Clock must reference _cinitime so that _cinitim.asm gets linked in.
* That routine, in turn, puts _inittime in the startup initialization
* routine table.
*
*Entry:
* No parameters.
* itime is a static structure of type timeb.
*
*Exit:
* If successful, clock returns the number of CLK_TCKs (milliseconds)
* that have elapsed. If unsuccessful, clock returns -1.
*
*Exceptions:
* None.
*
*******************************************************************************/
clock_t __cdecl clock (
void
)
{
struct _timeb now;
clock_t elapsed;
/* Calculate the difference between the initial time and now. */
_ftime(&now);
elapsed = (now.time - __itimeb.time) * CLOCKS_PER_SEC;
elapsed += (int)now.millitm - (int)__itimeb.millitm;
return(elapsed);
}
/***
*void _inittime() - Initialize the time location
*
*Purpose:
* This routine stores the process's time of startup.
* It is only linked in if the user issues a clock runtime
* call.
*
*Entry:
* No arguments.
*
*Exit:
* No return value.
*
*Exceptions:
* None.
*
*******************************************************************************/
void __cdecl _inittime (
void
)
{
_ftime(&__itimeb);
}
/***
*time_t _GetApplicationStartTime() - Initialize the time location
*
*Purpose:
* This routine stores the process's time of startup.
* It is only linked in if the user issues a clock runtime
* call.
*
*Entry:
* No arguments.
*
*Exit:
* initial application start time.
*
*Exceptions:
* None.
*
*******************************************************************************/
time_t __cdecl _GetApplicationStartTime (
void
)
{
/* The reference to _tzset causes _inittime to be executed at startup time.*/
_tzset();
return __itimeb.time ;
}
#endif /* defined (_M_MPPC) || defined (_M_M68K) */
#endif /* _WIN32 */