sem_al.c

国内一位牛人自己开发的操作系统

#include"kernel.h"

#define WRONG_PROCESS_NUMBER		-1
#define WRONG_PROCESS_STATE 		-2
#define WRONG_CAPABILITY		-3
#define CREATE_TOO_MANY_SEMAPHORE	-4
#define NO_SEMAPHORE			-5

int allocate_semaphore(int process_id,int value,
	struct capability *process_capability,
	struct capability *semaphore_capability)
{
	int sem_id;
	struct process *p;
	struct semaphore *s;
	struct kernel_time my_time;

	if((process_id<=0)||(process_id>=PROCESS_NUMBER))
		return WRONG_PROCESS_NUMBER;
	p=&(os->process[process_id]);
	if(!KERNEL_COMPARE_CAPABILITY(p->capability,
			(*process_capability)))
		return WRONG_CAPABILITY;
	if(p->semaphore_number>=p->max_semaphore_number)
		return CREATE_TOO_MANY_SEMAPHORE;
	if((sem_id=os->process[0].semaphore_ring)<0)
		return NO_SEMAPHORE;
	s=&(os->semaphore[sem_id]);
	s->value=value;
	s->thread_ring=-1;
	s->thread_id=(-1);
	COPY_CAPABILITY((*semaphore_capability),(s->capability));
	move_semaphore(sem_id,process_id);

	SET_MOST_TIME(my_time);
	SET_MINIMAL_STEP(s->step);
	s->v_value=(-1);
	set_semaphore_time(sem_id,&my_time);

	return sem_id;
}