[ds1820tousb.git] / time.c

/* $Id: time.c,v 1.2 2009/03/16 20:32:23 simimeie Exp $
 * USB interface for ds1820
 * This file provides time functions.
 * (C) Michael "Fox" Meier 2009
 */

#include <avr/interrupt.h>
#include "time.h"

static volatile uint32_t curts[2] = { 0, 0 };
static volatile uint8_t actts = 0;

void time_init(void) {
  /* Set timer0 to run with CLK/1024. That gives 57.2 Overflow interrupts
   * per second at 15 MHz. */
  TCCR0B |= _BV(2) | _BV(0);
  /* Enable timer interrupts */
  TIMSK |= _BV(1);
}

/* ISR(TIM1_OVF_vect, ISR_NOBLOCK)  doesn't work in the goddamn stoneage ubuntu version */
ISR(TIM0_OVF_vect)
{
  sei(); /* Workaround, should use ISR_NOBLOCK instead */
  {
    uint8_t nextts = (~actts) & 0x01;
    curts[nextts]++;
    actts = nextts;
  }
}

uint32_t gettime(void)
{
  return curts[actts];
}
Commit	Line	Data
93ac315e MPM	1	/* $Id: time.c,v 1.2 2009/03/16 20:32:23 simimeie Exp $
	2	* USB interface for ds1820
	3	* This file provides time functions.
	4	* (C) Michael "Fox" Meier 2009
	5	*/
	6
	7	#include <avr/interrupt.h>
	8	#include "time.h"
	9
	10	static volatile uint32_t curts[2] = { 0, 0 };
	11	static volatile uint8_t actts = 0;
	12
	13	void time_init(void) {
	14	/* Set timer0 to run with CLK/1024. That gives 57.2 Overflow interrupts
	15	* per second at 15 MHz. */
	16	TCCR0B \|= _BV(2) \| _BV(0);
	17	/* Enable timer interrupts */
	18	TIMSK \|= _BV(1);
	19	}
	20
	21	/* ISR(TIM1_OVF_vect, ISR_NOBLOCK) doesn't work in the goddamn stoneage ubuntu version */
	22	ISR(TIM0_OVF_vect)
	23	{
	24	sei(); /* Workaround, should use ISR_NOBLOCK instead */
	25	{
	26	uint8_t nextts = (~actts) & 0x01;
	27	curts[nextts]++;
	28	actts = nextts;
	29	}
	30	}
	31
	32	uint32_t gettime(void)
	33	{
	34	return curts[actts];
	35	}