#include <errno.h>#include <stdlib.h>#include <sys/intr.h>#include <sys/time.h>#include <sys/timer.h>#define TIMER_NAME_LEN	32#define TIMERS		16typedef struct timer {    char name[TIMER_NAME_LEN];    struct timeval tv;    struct timeval period;    timer_func_t f;    void *arg;    struct timer *next;} *timer_t;static struct timer timertab[TIMERS];static timer_t timers = NULL;static voidtimer_clear(timer_t timer){    timerclear(&(timer->tv));    timerclear(&(timer->period));    timer->f = NULL;    timer->next = NULL;}static voidtimer_insert(timer_t timer){    timer_t t;    if (timers == NULL) {	timers = timer;	return;    }    /* Insert new timer at head of list */    if (timercmp(&(timer->tv), &(timers->tv), <)) {	timer->next = timers;	timers = timer;	return;    }    /* Insert new timer somewhere after the head of the list */    for (t = timers; t->next != NULL; t = t->next)	if (timercmp(&(timer->tv), &(t->next->tv), <))	    break;    timer->next = t->next;    t->next = timer;}/* * This interrupt service routine is called by the clock isr.  Assume * interrupts are disabled and cannot be reenabled. */voidtimer_isr(){        struct timeval now;    timer_t t;        utime(&(now.tv_sec), &(now.tv_usec));        for (; timers != NULL;)     {	   if (timercmp(&now, &(timers->tv), <))break;		   (*(timers->f)) ();	   t = timers;	   timers = timers->next;	   if (timerisset(&(t->period)))  //2002年10月15日修改	   { 	       timeradd(&(t->tv), &(t->period), &(t->tv));	       timer_insert(t);	   } 	   else 	   {	       timer_clear(t);	   }    }    }voidtimer_init(){    int i;    for (i = 0; i < TIMERS; i++)	timer_clear(&(timertab[i]));}static timer_ttimer_alloc(){    int i;    for (i = 0; i < TIMERS; i++)	if (timertab[i].f == NULL)	    break;    if (i == TIMERS)	return NULL;    return &(timertab[i]);}inttimer_start(char *name, timeval_t dur, timer_func_t f, void *arg){    struct timeval now;    timer_t t;    if (dur->tv_sec == 0 && dur->tv_usec == 0)	return EINVAL;    disable;    t = timer_alloc();    if (t == NULL) {	enable;	return EAGAIN;    }    t->f = f;    t->arg = arg;    /* Compute expiration time of new timer */    utime(&(now.tv_sec), &(now.tv_usec));    timeradd(&now, dur, &(t->tv));    timer_insert(t);    enable;    return 0;}inttimer_loop(char *name, timeval_t period, timer_func_t f, void *arg){    struct timeval now;    timer_t t;    if (period->tv_sec == 0 && period->tv_usec == 0)	return EINVAL;    disable;    t = timer_alloc();    if (t == NULL) {	enable;	return EAGAIN;    }    t->f = f;    t->arg = arg;    t->period.tv_sec = period->tv_sec;    t->period.tv_usec = period->tv_usec;    /* Compute expiration time of new timer */    utime(&(now.tv_sec), &(now.tv_usec));    timeradd(&now, period, &(t->tv));    timer_insert(t);    enable;    return 0;}