我已经实现了用户级别的线程系统。我需要一些帮助来实现计数信号量,使用二进制信号量实现(上下函数如下所述)。 这里是我的执行二进制信号的接口:使用Binary-Semaphore实现计数信号量
typedef enum BinSemStatus{
locked,
unlocked
} BinSemStatus;
struct semaphore {
BinSemStatus status;
int bid;
};
int bsem_alloc();//allocate a new binary semaphore,return its descriptor
void bsem_free(int id);
void bsem_down(int id);
void bsem_up(int id);
这里是计数信号接口的接口:
struct counting_semaphore* counting_alloc(uint value);
counting_free(struct counting_semaphore* sem);
// If the value representing the count of
// the semaphore variable is not negative, decrement it by 1. If the
// semaphore variable is now
// negative, the thread executing acquire is blocked until the value is
// greater or equal to 1.
// Otherwise, the thread continues execution.
void up(struct counting_semaphore* sem);
// Increments the value of semaphore
// variable by 1.
void down(struct counting_semaphore* sem);
我所试图做的是无效了(结构counting_semaphore * sem) 来锁定value.But正如你可以看到,这是不够的。我已经在有问题的情况下添加了一条评论。
struct counting_semaphore {
int binary_descriptor;
int value;
};
void down(struct counting_semaphore *sem){
bsem_down(sem->binary_descriptor);
if (sem->value > 0){
sem->value--;
}
else{
//not sure what to do here, maybe use anather semaphore in some way?
}
bsem_up(sem->binary_descriptor);
}
void up(struct counting_semaphore *sem){
bsem_down(sem->binary_descriptor);
sem->value++;
bsem_up(sem->binary_descriptor);
}
'counting_free(结构counting_semaphore * SEM);' - >'无效counting_free(结构counting_semaphore * SEM);' – 4386427
你有没有试过编写任何代码了吗? – 4386427
问题是什么? –