busywait.c

开放源码的编译器open watcom 1.6.0版的源代码

/****************************************************************************
*
*                            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:  Busy wait serial port stuff.
*
****************************************************************************/


#include "serial.h"

extern  int             GetByte( void );
extern  unsigned        WaitCount( void );
extern  void            NothingToDo( void );

int WaitByte( unsigned timer_ticks )
{
    unsigned wait_time;      /* timer variable for testing time-out */
    int      data;           /* storing data from receive buffer */

    wait_time = WaitCount() + timer_ticks;
    for( ;; ) {
        data = GetByte();
        if( data != NO_DATA ) break;    /* character received */
        if( WaitCount() >= wait_time ) break;
        NothingToDo();
    }
    return( data );
}


void Wait( unsigned timer_ticks )
{
    unsigned wait_time;

    wait_time = WaitCount() + timer_ticks;
    while( WaitCount() < wait_time );
}