clock.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 114 行

/****************************************************************************
*
*                            Open Watcom Project
*
*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
*  ========================================================================
*
*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
*    Public License version 1.0 (the 'License'). You may not use this file
*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
*    ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
*    provided with the Original Code and Modifications, and is also
*    available at www.sybase.com/developer/opensource.
*
*    The Original Code and all software distributed under the License are
*    distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
*    EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
*    ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF
*    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR
*    NON-INFRINGEMENT. Please see the License for the specific language
*    governing rights and limitations under the License.
*
*  ========================================================================
*
* Description:  Implementation of the ANSI/ISO clock() function.
*
****************************************************************************/

#include "variety.h"
#include <time.h>
#if defined( __QNX__ )
#include <sys/types.h>
#include <sys/timers.h>
#elif defined( __LINUX__ )
#include <sys/times.h>
#include <errno.h>
#endif
#include <rtinit.h>
#include "timedata.h"

#ifdef __LINUX__

_WCRTLINK clock_t clock( void )
{
    struct tms  buf;
    int         save_errno = errno;
    clock_t     clk = times( &buf );
    errno = save_errno;
    return clk;
}

#else

#define MAX_CLOCK_T   ~( ( clock_t ) 0 )
#define MAX_SECONDS   ( ( time_t ) ( MAX_CLOCK_T / CLOCKS_PER_SEC ) - 1 )

static clock_t init_milliseconds;
static time_t  init_seconds;

static void get_clock_time( time_t *secs, clock_t *milliseconds )
{
#if defined( __QNX__ )
    struct timespec     timer;

    getclock( TIMEOFDAY, &timer );
    *secs = ( time_t ) timer.tv_sec;
    *milliseconds = ( clock_t ) ( timer.tv_nsec / ( 1000000000 / CLOCKS_PER_SEC ) );
#else
    struct tm t;

    *milliseconds = ( clock_t ) __getctime( &t );
    *secs = __local_mktime( &t, NULL, NULL );
#endif
} /* get_clock_time() */

_WCRTLINK clock_t clock( void )
{
    time_t      new_seconds;
    clock_t     ticks;

    /*
     * Get the change in seconds and milliseconds of seconds since startup.
     */
    get_clock_time( &new_seconds, &ticks );
    ticks -= init_milliseconds;
    new_seconds -= init_seconds;

    /*
     * Make sure we won't overflow.
     */
    if( new_seconds > MAX_SECONDS )
        return( ( clock_t ) -1 );

    /*
     * `ticks' right now contains the number of milliseconds of seconds since
     * startup.  We still need to account for the number of full seconds that
     * may have passed.
     */
    ticks += ( clock_t ) ( new_seconds * CLOCKS_PER_SEC );

    return( ticks );
}

static void __clock_init( void )
{
    get_clock_time( &init_seconds, &init_milliseconds );
}

AXI( __clock_init, INIT_PRIORITY_LIBRARY )

#endif