mirror of
https://github.com/plctlab/riscv-operating-system-mooc.git
synced 2025-12-25 00:37:43 +00:00
120 lines
2.2 KiB
C
120 lines
2.2 KiB
C
#include "os.h"
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extern void schedule(void);
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/* interval ~= 1s */
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#define TIMER_INTERVAL CLINT_TIMEBASE_FREQ
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static uint32_t _tick = 0;
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#define MAX_TIMER 10
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static struct timer timer_list[MAX_TIMER];
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/* load timer interval(in ticks) for next timer interrupt.*/
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void timer_load(int interval)
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{
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/* each CPU has a separate source of timer interrupts. */
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int id = r_mhartid();
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*(uint64_t*)CLINT_MTIMECMP(id) = *(uint64_t*)CLINT_MTIME + interval;
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}
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void timer_init()
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{
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struct timer *t = &(timer_list[0]);
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for (int i = 0; i < MAX_TIMER; i++) {
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t->func = NULL; /* use .func to flag if the item is used */
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t->arg = NULL;
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t++;
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}
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/*
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* On reset, mtime is cleared to zero, but the mtimecmp registers
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* are not reset. So we have to init the mtimecmp manually.
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*/
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timer_load(TIMER_INTERVAL);
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/* enable machine-mode timer interrupts. */
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w_mie(r_mie() | MIE_MTIE);
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}
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struct timer *timer_create(void (*handler)(void *arg), void *arg, uint32_t timeout)
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{
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/* TBD: params should be checked more, but now we just simplify this */
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if (NULL == handler || 0 == timeout) {
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return NULL;
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}
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/* use lock to protect the shared timer_list between multiple tasks */
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spin_lock();
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struct timer *t = &(timer_list[0]);
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for (int i = 0; i < MAX_TIMER; i++) {
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if (NULL == t->func) {
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break;
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}
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t++;
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}
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if (NULL != t->func) {
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spin_unlock();
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return NULL;
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}
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t->func = handler;
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t->arg = arg;
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t->timeout_tick = _tick + timeout;
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spin_unlock();
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return t;
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}
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void timer_delete(struct timer *timer)
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{
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spin_lock();
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struct timer *t = &(timer_list[0]);
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for (int i = 0; i < MAX_TIMER; i++) {
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if (t == timer) {
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t->func = NULL;
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t->arg = NULL;
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break;
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}
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t++;
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}
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spin_unlock();
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}
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/* this routine should be called in interrupt context (interrupt is disabled) */
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static inline void timer_check()
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{
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struct timer *t = &(timer_list[0]);
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for (int i = 0; i < MAX_TIMER; i++) {
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if (NULL != t->func) {
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if (_tick >= t->timeout_tick) {
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t->func(t->arg);
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/* once time, just delete it after timeout */
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t->func = NULL;
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t->arg = NULL;
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break;
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}
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}
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t++;
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}
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}
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void timer_handler()
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{
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_tick++;
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printf("tick: %d\n", _tick);
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timer_check();
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timer_load(TIMER_INTERVAL);
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schedule();
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}
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