wiring_time.h

/*
  Copyright (c) 2011 Arduino.  All right reserved.
  Copyright (c) 2013 by Paul Stoffregen <paul@pjrc.com> (delayMicroseconds)
 
  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.
 
  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  See the GNU Lesser General Public License for more details.
 
  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#ifndef _WIRING_TIME_H_
#define _WIRING_TIME_H_
 
#include "clock.h"
#include "dwt.h"
#include <sys/time.h> // for struct timeval
 
#ifdef __cplusplus
extern "C" {
#endif
extern uint32_t millis(void) ;

extern uint32_t micros(void) ;

extern void delay(uint32_t ms) ;

static inline void delayMicroseconds(uint32_t) __attribute__((always_inline, unused));
static inline void delayMicroseconds(uint32_t us)
{
#if defined(DWT_BASE) && !defined(DWT_DELAY_DISABLED)
  int32_t start  = dwt_getCycles();
  int32_t cycles = us * (SystemCoreClock / 1000000);
 
  while ((int32_t)dwt_getCycles() - start < cycles);
#else
  __IO uint32_t currentTicks = SysTick->VAL;
  /* Number of ticks per millisecond */
  const uint32_t tickPerMs = SysTick->LOAD + 1;
  /* Number of ticks to count */
  const uint32_t nbTicks = ((us - ((us > 0) ? 1 : 0)) * tickPerMs) / 1000;
  /* Number of elapsed ticks */
  uint32_t elapsedTicks = 0;
  __IO uint32_t oldTicks = currentTicks;
  do {
    currentTicks = SysTick->VAL;
    elapsedTicks += (oldTicks < currentTicks) ? tickPerMs + oldTicks - currentTicks :
                    oldTicks - currentTicks;
    oldTicks = currentTicks;
  } while (nbTicks > elapsedTicks);
#endif
}

int __attribute__((weak)) _gettimeofday(struct timeval *tv, void *tz)
{
  (void)tz;
  tv->tv_sec = getCurrentMillis() / 1000;
  tv->tv_usec = getCurrentMicros() - (tv->tv_sec * 1000000);  // get remaining microseconds
  return 0;
}
 
#ifdef __cplusplus
}
#endif
 
#endif /* _WIRING_TIME_H_ */