#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 EDOM_INFO(d)   ((struct rrobin_vcpu_info *)((d)->sched_priv))
#define CPU_INFO(cpu)  \
    ((struct rrobin_cpu_info *)per_cpu(schedule_data, cpu).sched_priv)
#define RUNQ(cpu)      (&CPU_INFO(cpu)->runnableq)

struct list_head *vcpu_list_head;
struct list_head *head;
struct list_head *vcpu_list_tail;
/*struct list_head *runq = RUNQ(cpu);*/
struct list_head *runq;

struct rrobin_vcpu_info {
    struct list_head list;
    struct vcpu *vcpu;
};

struct rrobin_cpu_info {
    struct list_head runnableq;
};

/* Add a VCPU */
static int rrobin_vcpu_init(struct vcpu *v){
    struct rrobin_vcpu_info *inf;
    if ( (v->sched_priv = xmalloc(struct rrobin_vcpu_info)) == NULL )
        return 1;
    memset(v->sched_priv, 0, sizeof(struct rrobin_vcpu_info));

    inf = EDOM_INFO(v);
    inf->vcpu = v;


    /* Allocate per-CPU context if this is the first domain to be added. */
    if ( unlikely(per_cpu(schedule_data, v->processor).sched_priv == NULL) )
    {
        per_cpu(schedule_data, v->processor).sched_priv = 
            xmalloc(struct rrobin_cpu_info);
        BUG_ON(per_cpu(schedule_data, v->processor).sched_priv == NULL);
        memset(CPU_INFO(v->processor), 0, sizeof(*CPU_INFO(v->processor)));
        INIT_LIST_HEAD(RUNQ(v->processor));
    }
    INIT_LIST_HEAD(&(inf->list));
    return 0;
}

static void rrobin_vcpu_destroy(struct vcpu *v)
{
    xfree(v->sched_priv);
}

static inline void increment_run_queue(void){
    vcpu_list_head = runq;
    vcpu_list_tail = (vcpu_list_head)->prev;
    head = vcpu_list_head;
    vcpu_list_tail = vcpu_list_head;
    vcpu_list_head = (vcpu_list_tail)->next;
    vcpu_list_tail = head;
}

struct task_slice rrobin_schedule(s_time_t now){
    /*struct list_head temp; 	*/
    int cpu = smp_processor_id();
    /*struct rrobin_vcpu_info *inf = EDOM_INFO(current);*/
    struct rrobin_vcpu_info *runinf;
    struct vcpu *temp;
    struct task_slice ret;
    ret.time = MILLISECS(10); /* Time quantum to scan the VCPU list to find a runnable VCPU */

    runq = RUNQ(cpu);

    if ( !list_empty(runq) ){
        runinf   = list_entry(runq->next,struct rrobin_vcpu_info,list);
        temp = runinf->vcpu;
        ret.task = temp;

    }

increment_run_queue();

return ret;
}

struct scheduler sched_rrobin_def = {
    .name           = "Round robin Scheduler",
    .opt_name       = "rrobin",
    .sched_id       = XEN_SCHEDULER_SEDF,

    .init_vcpu      = rrobin_vcpu_init,
    .destroy_vcpu   = rrobin_vcpu_destroy,

    .do_schedule    = rrobin_schedule,

};