nes-proj/cpu/msp430/clock.c

/*
 * Copyright (c) 2005, Swedish Institute of Computer Science
 * All rights reserved. 
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 * 3. Neither the name of the Institute nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
 * SUCH DAMAGE. 
 *
 * This file is part of the Contiki operating system.
 *
 * @(#)$Id: clock.c,v 1.4 2006/08/25 09:40:21 bg- Exp $
 */


#include <io.h>
#include <signal.h>

#include "contiki-conf.h"

#include "sys/clock.h"
#include "sys/etimer.h"

/* 38400 cycles @ 2.4576MHz with divisor 8 ==> 1/8 s */
/* #define INTERVAL (307200ULL / CLOCK_SECOND) */
#define INTERVAL (4096ULL / CLOCK_SECOND)

#define MAX_TICKS (~((clock_time_t)0) / 2)

static volatile clock_time_t count = 0;
/*---------------------------------------------------------------------------*/
interrupt(TIMERA1_VECTOR) timera1 (void) {
  if(TAIV == 2) {
    TACCR1 += INTERVAL;
    ++count;

    if(etimer_pending()
       && (etimer_next_expiration_time() - count - 1) > MAX_TICKS) {
      etimer_request_poll();
      LPM4_EXIT;
    }
  }
}
/*---------------------------------------------------------------------------*/
clock_time_t
clock_time(void)
{
  return count;
}
/*---------------------------------------------------------------------------*/
void
clock_set(clock_time_t clock, clock_time_t fclock)
{  
  TAR = fclock;
  TACCR1 = fclock + INTERVAL;
  count = clock;
}
/*---------------------------------------------------------------------------*/
void
clock_init(void)
{
  dint();

  /* Select SMCLK (2.4576MHz), clear TAR */
/*   TACTL = TASSEL1 | TACLR | ID_3; */
  TACTL = TASSEL0 | TACLR | ID_3;

  /* Initialize ccr1 to create the X ms interval. */
  /* CCR1 interrupt enabled, interrupt occurs when timer equals CCR1. */
  TACCTL1 = CCIE;
  
  /* Interrupt after X ms. */
  TACCR1 = INTERVAL;                    

  /* Start Timer_A in continuous mode. */
  TACTL |= MC1;

  count = 0;
  
  BCSCTL1 &= ~(DIVA1 + DIVA0);   /* remove /8 divisor from ACLK again    */

  /* Enable interrupts. */
  eint();   

}
/*---------------------------------------------------------------------------*/
/**
 * Delay the CPU for a multiple of 2.83 us. 
 */
void
clock_delay(unsigned int i)
{
  asm("add #-1, r15");
  asm("jnz $-2");
  /*
   * This means that delay(i) will delay the CPU for CONST + 3x
   * cycles. On a 2.4756 CPU, this means that each i adds 1.22us of
   * delay.
   *
   * do {
   *   --i;
   * } while(i > 0);
   */
}
/*---------------------------------------------------------------------------*/
/**
 * Wait for a multiple of 10 ms.
 *
 */
void
clock_wait(int i)
{
  clock_time_t start;

  start = clock_time();
  while(clock_time() - start < (clock_time_t)i);
}
/*---------------------------------------------------------------------------*/
void
clock_set_seconds(unsigned long sec)
{

}
unsigned long
clock_seconds(void)
{
  return count / CLOCK_SECOND;
}