interrupts.c

讲述LPC2468在无操作系统条件下使用YAFFS文件系统是如何实现的以及完整的测试代码,代码部分详见lpc2468_yaffs2.rar

#include "config.h"
#include "project.h"

#define TIMER_LOAD_VAL 0xffff
#define READ_TIMER (0xFFFFFFFF - T0TC)

static unsigned int timestamp = 0;
static unsigned int lastdec;

unsigned int  get_timer_masked (void);

void reset_timer (void)
{
	reset_timer_masked ();
}

unsigned int  get_timer (unsigned int  base)
{
	return get_timer_masked() - base;
}

void set_timer (unsigned int  t)
{
	timestamp = t;
}

void udelay (unsigned long usec)
{
//	printf("udelay = %d, T0TC = %d\n", usec, T0TC);
//#if 0
  unsigned int  tmo;
//#if defined (CONFIG_LPC2292) || defined(CONFIG_LPC2468)
#if defined(CONFIG_LPC2468)
  tmo = (usec * CFG_HZ) / 1000000;
#else
	tmo = usec / 1000;
	tmo *= CFG_HZ;
	tmo /= 1000;
#endif
//	printf("udelay = %d, tmo = %d\n", usec, tmo);
	tmo += get_timer (0);
//	printf("udelay = %d, tmo = %d\n", usec, tmo);

	while (get_timer_masked () < tmo)
	{
		printf("T0TC = %d\n", T0TC);
		__asm__ __volatile__(" nop"); // /*NOP*/;
	}
//#endif
}

void reset_timer_masked (void)
{
	/* reset time */
	lastdec = READ_TIMER;
	timestamp = 0;
}

unsigned int  get_timer_masked (void)
{
	unsigned int  now = READ_TIMER;

	if (lastdec >= now) {
		/* normal mode */
		timestamp += lastdec - now;
	} else {
		/* we have an overflow ... */
		timestamp += lastdec + TIMER_LOAD_VAL - now;
	}
	lastdec = now;

	return timestamp;
}

void udelay_masked (unsigned long usec)
{
	unsigned int  tmo;
	unsigned int  endtime;
	signed long diff;

	if (usec >= 1000) {
		tmo = usec / 1000;
		tmo *= CFG_HZ;
		tmo /= 1000;
	} else {
		tmo = usec * CFG_HZ;
		tmo /= (1000*1000);
	}

	endtime = get_timer_masked () + tmo;

	do {
		unsigned int  now = get_timer_masked ();
		diff = endtime - now;
	} while (diff >= 0);
}

void ndelay(unsigned long nsec)
{
  unsigned int  loops = nsec / 600;
  while (loops-- > 0)
  {
    __asm__ __volatile__ (" nop");
  }
}