#include <xen/lib.h>
#include <xen/sched.h>
#include <xen/time.h>
#include <xen/sched-if.h>
#include <xen/softirq.h>
#include <xen/errno.h>
#include <xen/list.h>
#include <xen/timer.h>

#define MAX 100

struct vcpu *Vcpu[MAX];
int next_vcpu=0;

/* Add a VCPU */
static int simple_vcpu_init(struct vcpu *v){
    int t=0;
    /*find the first position of array available*/
    while(t<MAX){
        if (Vcpu[t]==NULL) {
            Vcpu[t]=v;
            printk("\n\nadd VCPU %d\n\n", t);
        }
        t++;
        break;
    }
    return 0;
}

static void simple_vcpu_destroy(struct vcpu *v)
{
    int t=MAX;
    int max_index=MAX;
    /*find the struct vcpu in Vcpu[] and destroy it*/
    while(t!=0 && v!=Vcpu[t]){
        t--;
    }
    printk("\n\ndestroy VCPU %d\n\n",t);

    while(t!=0 && Vcpu[t]==NULL){
        max_index--;
    }
    Vcpu[t]=Vcpu[max_index];
    Vcpu[max_index]=NULL;
    Vcpu[t]=NULL;
    xfree(v->sched_priv);
}


struct task_slice simple_schedule(s_time_t now){
    struct task_slice ret;
    ret.time = MILLISECS(100); 
    /*if next array position == NULL than restart to 0*/
    if (Vcpu[next_vcpu+1]==NULL){ 
        ret.task = Vcpu[0];
        next_vcpu=0;
    }
    else ret.task = Vcpu[next_vcpu+1];
    
    next_vcpu++;
    return ret;
}

struct scheduler sched_simple_def = {
    .name           = "Very simple Scheduler",
    .opt_name       = "simple",
    .sched_id       = 13,
    .init_vcpu      = simple_vcpu_init,
    .destroy_vcpu   = simple_vcpu_destroy,
    .do_schedule    = simple_schedule,

};