56 lines
2.7 KiB
C
56 lines
2.7 KiB
C
/*
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* Copyright (c) 2007, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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* Author: Oliver Schmidt <ol.sc@web.de>
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*
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* $Id: clock.c,v 1.1 2007/12/15 00:14:19 oliverschmidt Exp $
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*/
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#include <time.h>
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#include "contiki.h"
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/*-----------------------------------------------------------------------------------*/
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clock_time_t
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clock_time(void)
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{
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/* Contiki contains quite some calculations based on clock_time_t so we want
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* to avoid defining clock_time_t to be 32 bit because that would mean a lot
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* of overhead for cc65 targets.
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* On the other hand we want to avoid wrapping around frequently so the idea
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* is to reduce the clock resolution to the bare minimum. This is defined by
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* the TCP/IP stack using a 1/2 second periodic timer. So CLOCK_CONF_SECOND
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* needs to be defined at least as 2.
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* The value 2 works out especially nicely as it allows us to implement the
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* clock frequency devider below purely in (32 bit) integer arithmetic based
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* on the educated guess of CLK_TCK being an even value. */
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return clock() / (CLK_TCK / CLOCK_CONF_SECOND);
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}
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/*-----------------------------------------------------------------------------------*/
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