#include <stdio.h>
#include <monitor.h>
#include <kmalloc.h>
#include <assert.h>


// Initialize monitor.
void     
monitor_init (monitor_t * mtp, size_t num_cv) {
    int i;
    assert(num_cv>0);
    mtp->next_count = 0;
    mtp->cv = NULL;
    sem_init(&(mtp->mutex), 1); //unlocked
    sem_init(&(mtp->next), 0);
    mtp->cv =(condvar_t *) kmalloc(sizeof(condvar_t)*num_cv);
    assert(mtp->cv!=NULL);
    for(i=0; i<num_cv; i++){
        mtp->cv[i].count=0;
        sem_init(&(mtp->cv[i].sem),0);
        mtp->cv[i].owner=mtp;
    }
}

// Unlock one of threads waiting on the condition variable. 
void 
cond_signal (condvar_t *cvp) {
   //LAB7 EXERCISE1: 2014011330
   cprintf("cond_signal begin: cvp %x, cvp->count %d, cvp->owner->next_count %d\n", cvp, cvp->count, cvp->owner->next_count);  
  /*
   *      cond_signal(cv) {
   *          if(cv.count>0) {
   *             mt.next_count ++;
   *             signal(cv.sem);
   *             wait(mt.next);
   *             mt.next_count--;
   *          }
   *       }
   */
   // cvp->owner->next_count == number of sleeping signaled process.
   if (cvp->count > 0) {
	   // If there are process waiting on this process
	   // <=> Waiting queue of the condition variable is not empty, wake them up.
	   // But first, I should sleep because I signaled. (Hoare monitor)
	   cvp->owner->next_count ++;
	   up(&(cvp->sem));
	   down(&(cvp->owner->next));
	   // After I was resched, number waited --.
	   // Why not number of cv but cv's owner have a count?
	   cvp->owner->next_count --;
   }
   cprintf("cond_signal end: cvp %x, cvp->count %d, cvp->owner->next_count %d\n", cvp, cvp->count, cvp->owner->next_count);
}

// Suspend calling thread on a condition variable waiting for condition Atomically unlocks 
// mutex and suspends calling thread on conditional variable after waking up locks mutex. Notice: mp is mutex semaphore for monitor's procedures
void
cond_wait (condvar_t *cvp) {
    //LAB7 EXERCISE1: 2014011330
    cprintf("cond_wait begin:  cvp %x, cvp->count %d, cvp->owner->next_count %d\n", cvp, cvp->count, cvp->owner->next_count);
   /*
    *         cv.count ++;
    *         if(mt.next_count>0)
    *            signal(mt.next)
    *         else
    *            signal(mt.mutex);
    *         wait(cv.sem);
    *         cv.count --;
    */
    cvp->count ++;
    if (cvp->owner->next_count > 0) {
    	up(&(cvp->owner->next));
    } else {
    	up(&(cvp->owner->mutex));
    }
    down(&(cvp->sem));
    cvp->count --;
    cprintf("cond_wait end:  cvp %x, cvp->count %d, cvp->owner->next_count %d\n", cvp, cvp->count, cvp->owner->next_count);
}