os_kernel_lab/labcodes_answer/lab8_result/user/libs/lock.h

#ifndef __USER_LIBS_LOCK_H__
#define __USER_LIBS_LOCK_H__

#include <defs.h>
#include <atomic.h>
#include <ulib.h>

#define INIT_LOCK           {0}

typedef volatile bool lock_t;

static inline void
lock_init(lock_t *l) {
    *l = 0;
}

static inline bool
try_lock(lock_t *l) {
    return test_and_set_bit(0, l);
}

static inline void
lock(lock_t *l) {
    if (try_lock(l)) {
        int step = 0;
        do {
            yield();
            if (++ step == 100) {
                step = 0;
                sleep(10);
            }
        } while (try_lock(l));
    }
}

static inline void
unlock(lock_t *l) {
    test_and_clear_bit(0, l);
}

#endif /* !__USER_LIBS_LOCK_H__ */