v.c

国内一位牛人自己开发的操作系统

#include"kernel.h"

#define WRONG_THREAD_ID		-1
#define WRONG_SEMAPHORE_ID	-2
#define WRONG_THREAD_STATE	-3
#define WRONG_CAPABILITY	-4

static int v(int semaphore_id,int *steps,struct capability *cap)
{
	struct semaphore *s;
	struct thread *t;
	struct return_stack *rt;
	int i,thread_id,fr_th,ba_th,my_step;

	if((semaphore_id<0)||(semaphore_id>=SEMAPHORE_NUMBER))
		return WRONG_SEMAPHORE_ID;
	s=&(os->semaphore[semaphore_id]);
	if(s->process<0)
		return WRONG_SEMAPHORE_ID;
	if(!KERNEL_COMPARE_CAPABILITY(s->capability,(*cap)))
		return WRONG_CAPABILITY;
	if((my_step=(*steps))==0){
		*steps=s->value;
		return 0;
	};
	for(i=0;;i++){
		thread_id=s->thread_ring;
		if(my_step>0){
			if((thread_id<0)||(i>=my_step)){
				s->value=s->value+my_step-i;
				break;
			}
		}else{
			if(thread_id<0)
				break;
		};
		s->value++;
		t=&(os->thread[thread_id]);
		fr_th=t->sem_front;ba_th=t->sem_back;
		if(fr_th==thread_id)
			s->thread_ring=-1;
		else{
			s->thread_ring=fr_th;
			os->thread[fr_th].sem_back=ba_th;
			os->thread[ba_th].sem_front=fr_th;
		}
		t->sleep_semaphore=(-1);
		if(t->set_v_operation_result_flag){
			rt=&(t->return_stack[t->return_stack_top-1]);
			if(t->return_stack_top<RETURN_BLOCK_NUMBER)
			if(t->return_stack_top>0)
				rt->environment.system_call=i+2;
		}
		insert_into_heap(thread_id);
	}
	*steps=s->value;
	return i;
}
int v_thread(int thread_id)
{
	int value;
	struct thread *t;
	struct semaphore *s;

	if((thread_id<0)||(thread_id>=THREAD_NUMBER))
		return(WRONG_THREAD_ID);
	t=&(os->thread[thread_id]);	
	if(t->state!=SLEEP)
		return(WRONG_THREAD_STATE);
	s=&(os->semaphore[t->sleep_semaphore]);
	if(s->process<0)
		return WRONG_SEMAPHORE_ID;
	s->thread_ring=thread_id;
	value=1;
	return(v(t->sleep_semaphore,&value,&(os->system_capability)));
}

int system_call_v(int semaphore_id,int *steps,struct capability *cap)
{
	if(semaphore_id==0)
		return WRONG_SEMAPHORE_ID;
	else
		return v(semaphore_id,steps,cap);
}