text: #include "types.h"
  #include "defs.h"
  #include "param.h"
  #include "memlayout.h"
  #include "mmu.h"
  #include "x86.h"
  #include "proc.h"
  #include "rand.h" // cs202
  #include "spinlock.h"
  
  struct {
    struct spinlock lock;
    struct proc proc[NPROC];
  } ptable;
  
  int totalTickets; // cs202
  const int stride1 = 10000; // cs202
  int isStride = 0; // cs202
  
  static struct proc *initproc;
  
  int nextpid = 1;
  extern void forkret(void);
  extern void trapret(void);
  
  static void wakeup1(void *chan);
  
  // cs202 ----->
  int
  info(int type, int val)
  {
  	if(type == 1)
  		cprintf("\n There are %d processes in the system.\n\n", val);
  	else if(type == 2)
  		cprintf("\n There are total %d system calls that a process has done so far.\n\n", val);
  	else if(type == 3)
  		cprintf("\n There are %d memory pages used by the current process.\n\n", val);
  
  	return 0;	
  }
  
  int
  getProcCount(void)
  {
  	struct proc *p;
  	int count = 0;
  	
  	acquire(&ptable.lock);
  	
  	for(p = ptable.proc; p < &ptable.proc[NPROC]; p++)
  	{
  		if(p->state != UNUSED) ++count;
  	}
  	
  	release(&ptable.lock);
    
  	return count;	
  }
  
  int
  getSysCallCount(void)
  {
  	struct proc *curproc = myproc();
  	
  	acquire(&ptable.lock);
  	
  	int count = count = curproc->sysCallCount;
  	
  	release(&ptable.lock);
    
  	return count;	
  }
  
  int
  getPageSize(void)
  {
  	struct proc *curproc = myproc();
  	
  	int count = 0;
  
  	uint i;
  	acquire(&ptable.lock);
  
  	for(i = 0; i < curproc->sz; i+= sizeof(pte_t))
  	{
  		if((char *)curproc->pgdir[i] == curproc->kstack)
  			break;
  		
  		if(curproc->pgdir[i] & PTE_P)
  			++count;
  	}
  
  	release(&ptable.lock);
    
  	return count;	
  }
  
  void
  setTickets(struct proc* p, int val)
  {
  	p->tickets = val;
  	client_init(p);
  }
  
  void
  showProcesses(void)
  {
  	struct proc* p;
  	struct pstate pStates;
  	
  	acquire(&ptable.lock);
  	for(p = ptable.proc; p != &(ptable.proc[NPROC]); p++)
  	{
  		const int index = p - ptable.proc;
  		if(p->state != UNUSED)
  		{
  			pStates.pid[index] = p->pid;
  			pStates.runTimes[index] = p->runTimes;
  			pStates.waitingTimes[index] = p->waitingTimes;
  			pStates.tickets[index] = p->tickets;
  			pStates.isRun[index] = p->isRun;
  			pStates.state[index] = p->state;
  			pStates.name[index] = p->name;
  			pStates.stride[index] = p->stride;
  			pStates.pass[index] = p->pass;
  		}
  	}	
  	pStates.totalTickets = totalTickets;
  
  	cprintf("\f");
  	if(!isStride)
  	{
  		cprintf("Using Lottery Scheduling:\n");
  	}
  	else
  	{
  		cprintf("Using Stride Scheduling:\n");
  	}
  	
  	for(p = ptable.proc; p != &(ptable.proc[NPROC]); p++)
  	{
  		const int index = p - ptable.proc;
  		if(pStates.pid[index] != 0 && pStates.name[index] == p->name && pStates.state[index] != SLEEPING && pStates.state[index] != ZOMBIE)
  		{
  			if(!isStride)
  			{
  				cprintf("Pid:%d (%s)\t tickets:%d\t executedTimes:%d\t state:%d\t running:%d\t waitingTimes:%d \n",
  				pStates.pid[index], pStates.name[index], pStates.tickets[index], pStates.runTimes[index], pStates.state[index], pStates.isRun[index], pStates.waitingTimes[index]);
  			}
  			else
  			{			
  				cprintf("Pid:%d (%s)\t tickets:%d\t executedTimes:%d\t state:%d\t running: %d\t waitingTimes:%d\t stride:%d\t pass:%d \n",
  				pStates.pid[index], pStates.name[index], pStates.tickets[index], pStates.runTimes[index], pStates.state[index], pStates.isRun[index], pStates.waitingTimes[index], pStates.stride[index], pStates.pass[index]);
  			}
  		}
  	}
  	
  	release(&ptable.lock);
  }
  
  void
  client_init(struct proc* p)
  {
  	if(p->tickets == 0)
  	{
  		p->stride = 0;
  		p->pass = -1;
  	}
  	else
  	{
  		p->stride = stride1/p->tickets;
  		p->pass = p->stride;
  	}
  }
  
  void
  client_update(struct proc* p)
  {
          p->pass += p->stride;
  }
  
  void
  setStride(int val)
  {
  	acquire(&ptable.lock);
  	isStride = val;
  	release(&ptable.lock);
  	
  	if(val)
  	{
  		cprintf("Set scheduler to \"Stride\"!\n");
  	}
  	else
  	{
  		cprintf("Set scheduler to \"Lottery\"!\n");
  	}
  }
  
  void
  updatestatistics()
  {
    struct proc *p;
  
    for(p = ptable.proc; p < &ptable.proc[NPROC]; p++)
    {
      switch(p->state)
  	{
        case RUNNABLE:
          ++p->waitingTimes;
          break;
        case RUNNING:
          ++p->runTimes;
          break;
        default:
          ;
      }
    }
  }
  // cs202 <-----
  
  void
  pinit(void)
  {
    initlock(&ptable.lock, "ptable");
  }
  
  // Must be called with interrupts disabled
  int
  cpuid() {
    return mycpu()-cpus;
  }
  
  // Must be called with interrupts disabled to avoid the caller being
  // rescheduled between reading lapicid and running through the loop.
  struct cpu*
  mycpu(void)
  {
    int apicid, i;
    
    if(readeflags()&FL_IF)
      panic("mycpu called with interrupts enabled\n");
    
    apicid = lapicid();
    // APIC IDs are not guaranteed to be contiguous. Maybe we should have
    // a reverse map, or reserve a register to store &cpus[i].
    for (i = 0; i < ncpu; ++i) {
      if (cpus[i].apicid == apicid)
        return &cpus[i];
    }
    panic("unknown apicid\n");
  }
  
  // Disable interrupts so that we are not rescheduled
  // while reading proc from the cpu structure
  struct proc*
  myproc(void) {
    struct cpu *c;
    struct proc *p;
    pushcli();
    c = mycpu();
    p = c->proc;
    popcli();
    return p;
  }
  
  //PAGEBREAK: 32
  // Look in the process table for an UNUSED proc.
  // If found, change state to EMBRYO and initialize
  // state required to run in the kernel.
  // Otherwise return 0.
  static struct proc*
  allocproc(void)
  {
    struct proc *p;
    char *sp;
  
    acquire(&ptable.lock);
  
    for(p = ptable.proc; p < &ptable.proc[NPROC]; p++)
      if(p->state == UNUSED)
        goto found;
  
    release(&ptable.lock);
    return 0;
  
  found:
    p->state = EMBRYO;
    p->pid = nextpid++;
  
    release(&ptable.lock);
  
    // Allocate kernel stack.
    if((p->kstack = kalloc()) == 0){
      p->state = UNUSED;
      return 0;
    }
    sp = p->kstack + KSTACKSIZE;
  
    // Leave room for trap frame.
    sp -= sizeof *p->tf;
    p->tf = (struct trapframe*)sp;
  
    // Set up new context to start executing at forkret,
    // which returns to trapret.
    sp -= 4;
    *(uint*)sp = (uint)trapret;
  
    sp -= sizeof *p->context;
    p->context = (struct context*)sp;
    memset(p->context, 0, sizeof *p->context);
    p->context->eip = (uint)forkret;
  
    return p;
  }
  
  //PAGEBREAK: 32
  // Set up first user process.
  void
  userinit(void)
  {
    struct proc *p;
    extern char _binary_initcode_start[], _binary_initcode_size[];
  
    p = allocproc();
    
    initproc = p;
    if((p->pgdir = setupkvm()) == 0)
      panic("userinit: out of memory?");
    inituvm(p->pgdir, _binary_initcode_start, (int)_binary_initcode_size);
    p->sz = PGSIZE;
    memset(p->tf, 0, sizeof(*p->tf));
    p->tf->cs = (SEG_UCODE << 3) | DPL_USER;
    p->tf->ds = (SEG_UDATA << 3) | DPL_USER;
    p->tf->es = p->tf->ds;
    p->tf->ss = p->tf->ds;
    p->tf->eflags = FL_IF;
    p->tf->esp = PGSIZE;
    p->tf->eip = 0;  // beginning of initcode.S
  
    safestrcpy(p->name, "initcode", sizeof(p->name));
    p->cwd = namei("/");
  
    // this assignment to p->state lets other cores
    // run this process. the acquire forces the above
    // writes to be visible, and the lock is also needed
    // because the assignment might not be atomic.
    acquire(&ptable.lock);
  
    p->state = RUNNABLE;
  
    release(&ptable.lock);
  }
  
  // Grow current process's memory by n bytes.
  // Return 0 on success, -1 on failure.
  int
  growproc(int n)
  {
    uint sz;
    struct proc *curproc = myproc();
  
    sz = curproc->sz;
    if(n > 0){
      if((sz = allocuvm(curproc->pgdir, sz, sz + n)) == 0)
        return -1;
    } else if(n < 0){
      if((sz = deallocuvm(curproc->pgdir, sz, sz + n)) == 0)
        return -1;
    }
    curproc->sz = sz;
    switchuvm(curproc);
    return 0;
  }
  
  // Create a new process copying p as the parent.
  // Sets up stack to return as if from system call.
  // Caller must set state of returned proc to RUNNABLE.
  int
  fork(void)
  {
    int i, pid;
    struct proc *np;
    struct proc *curproc = myproc();
  
    // Allocate process.
    if((np = allocproc()) == 0){
      return -1;
    }
  
    // Copy process state from proc.
    if((np->pgdir = copyuvm(curproc->pgdir, curproc->sz)) == 0){
      kfree(np->kstack);
      np->kstack = 0;
      np->state = UNUSED;
      return -1;
    }
    np->sz = curproc->sz;
    np->parent = curproc;
    *np->tf = *curproc->tf;
       
    // cs202 ----->
    np->sysCallCount = 0;
    setTickets(np, 10);
    np->runTimes = 0; 
    np->waitingTimes = 0;
    np->isRun = 0;
    // cs202 <-----
   
    // Clear %eax so that fork returns 0 in the child.
    np->tf->eax = 0;
  
    for(i = 0; i < NOFILE; i++)
      if(curproc->ofile[i])
        np->ofile[i] = filedup(curproc->ofile[i]);
    np->cwd = idup(curproc->cwd);
  
    safestrcpy(np->name, curproc->name, sizeof(curproc->name));
  
    pid = np->pid;
  
    acquire(&ptable.lock);
  
    np->state = RUNNABLE;
  
    release(&ptable.lock);
    
    return pid;
  }
  
  // Exit the current process.  Does not return.
  // An exited process remains in the zombie state
  // until its parent calls wait() to find out it exited.
  void
  exit(void)
  {
    struct proc *curproc = myproc();
    struct proc *p;
    int fd;
  
    if(curproc == initproc)
      panic("init exiting");
  
    // Close all open files.
    for(fd = 0; fd < NOFILE; fd++){
      if(curproc->ofile[fd]){
        fileclose(curproc->ofile[fd]);
        curproc->ofile[fd] = 0;
      }
    }
  
    begin_op();
    iput(curproc->cwd);
    end_op();
    curproc->cwd = 0;
  
    acquire(&ptable.lock);
  
    // Parent might be sleeping in wait().
    wakeup1(curproc->parent);
  
    // Pass abandoned children to init.
    for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
      if(p->parent == curproc){
        p->parent = initproc;
        if(p->state == ZOMBIE)
          wakeup1(initproc);
      }
    }
    
    setTickets(curproc, 0); // cs202
    
    // Jump into the scheduler, never to return.
    curproc->state = ZOMBIE;
    sched();
    panic("zombie exit");
  }
  
  // Wait for a child process to exit and return its pid.
  // Return -1 if this process has no children.
  int
  wait(void)
  {
    struct proc *p;
    int havekids, pid;
    struct proc *curproc = myproc();
    
    acquire(&ptable.lock);
    for(;;){
      // Scan through table looking for exited children.
      havekids = 0;
      for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
        if(p->parent != curproc)
          continue;
        havekids = 1;
        if(p->state == ZOMBIE){
          // Found one.
          pid = p->pid;
          kfree(p->kstack);
          p->kstack = 0;
          freevm(p->pgdir);
          p->pid = 0;
          p->parent = 0;
          p->name[0] = 0;
          p->killed = 0;
          p->state = UNUSED;
  		p->sysCallCount = 0; // cs202
  		p->runTimes = 0; // cs202
  		setTickets(p, 0); // cs202
  		p->waitingTimes = 0; // cs202
  		p->isRun = 0; // cs202
          release(&ptable.lock);
          return pid;
        }
      }
  
      // No point waiting if we don't have any children.
      if(!havekids || curproc->killed){
        release(&ptable.lock);
        return -1;
      }
  
      // Wait for children to exit.  (See wakeup1 call in proc_exit.)
      sleep(curproc, &ptable.lock);  //DOC: wait-sleep
    }
  }
  
  //PAGEBREAK: 42
  // Per-CPU process scheduler.
  // Each CPU calls scheduler() after setting itself up.
  // Scheduler never returns.  It loops, doing:
  //  - choose a process to run
  //  - swtch to start running that process
  //  - eventually that process transfers control
  //      via swtch back to the scheduler.
  void
  scheduler(void)
  {
    struct proc *p;
    struct cpu *c = mycpu();
    int min_pass = 2 * stride1; // cs202
    c->proc = 0;
    
    // cs202 ----->
    acquire(&ptable.lock);
    setTickets(ptable.proc, 10);
    release(&ptable.lock);
    // cs202 <-----
    
    for(;;){
      // Enable interrupts on this processor.
      sti();
  	
  	// cs202 ----->
  	acquire(&ptable.lock);
      totalTickets = 0;
      for(p = ptable.proc; p < &ptable.proc[NPROC]; p++)
      {
  		if(p->state == RUNNABLE)
  	    {
  			totalTickets += p->tickets;
  			
  			if(min_pass > p->pass && p->pass > 0)
  				min_pass = p->pass+1;
  	    }
      }
      release(&ptable.lock);
  
  	const int winner = random_at_most(totalTickets);
  	int ticketCount = 0;
  	// cs202 <-----
  
      // Loop over process table looking for process to run.
      acquire(&ptable.lock);
      for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
        if(p->state != RUNNABLE)
          continue;
  	
  	  // cs202 ----->
  	  ticketCount += p->tickets;
  	  if(!isStride) // Using Lottery
  	  {
  		  if(ticketCount < winner)
  			  continue;
  	  }
  	  else // Using Stride
  	  {
  		  if(p->pass > min_pass) 
  			  continue;
  	  }
  	  // cs202 <-----
  
        // Switch to chosen process.  It is the process's job
        // to release ptable.lock and then reacquire it
        // before jumping back to us.
        c->proc = p;
        switchuvm(p);
        p->state = RUNNING;
  
  	  // cs202 ----->
  	  p->isRun = 1;
  	  updatestatistics();
  	  client_update(p);
  	  // cs202 <-----
  	  
        swtch(&(c->scheduler), p->context);
  	  
  	  // cs202 ----->
  	  p->isRun = 0;
  	  // cs202 <-----	
  			
        switchkvm();
  
        // Process is done running for now.
        // It should have changed its p->state before coming back.
        c->proc = 0;
  	  
  	  break; // cs202
      }
  	min_pass += stride1; // cs202
  
      release(&ptable.lock);
    }
  }
  
  // Enter scheduler.  Must hold only ptable.lock
  // and have changed proc->state. Saves and restores
  // intena because intena is a property of this
  // kernel thread, not this CPU. It should
  // be proc->intena and proc->ncli, but that would
  // break in the few places where a lock is held but
  // there's no process.
  void
  sched(void)
  {
    int intena;
    struct proc *p = myproc();
  
    if(!holding(&ptable.lock))
      panic("sched ptable.lock");
    if(mycpu()->ncli != 1)
      panic("sched locks");
    if(p->state == RUNNING)
      panic("sched running");
    if(readeflags()&FL_IF)
      panic("sched interruptible");
    intena = mycpu()->intena;
    swtch(&p->context, mycpu()->scheduler);
    mycpu()->intena = intena;
  }
  
  // Give up the CPU for one scheduling round.
  void
  yield(void)
  {
    acquire(&ptable.lock);  //DOC: yieldlock
    myproc()->state = RUNNABLE;
    sched();
    release(&ptable.lock);
  }
  
  // A fork child's very first scheduling by scheduler()
  // will swtch here.  "Return" to user space.
  void
  forkret(void)
  {
    static int first = 1;
    // Still holding ptable.lock from scheduler.
    release(&ptable.lock);
  
    if (first) {
      // Some initialization functions must be run in the context
      // of a regular process (e.g., they call sleep), and thus cannot
      // be run from main().
      first = 0;
      iinit(ROOTDEV);
      initlog(ROOTDEV);
    }
  
    // Return to "caller", actually trapret (see allocproc).
  }
  
  // Atomically release lock and sleep on chan.
  // Reacquires lock when awakened.
  void
  sleep(void *chan, struct spinlock *lk)
  {
    struct proc *p = myproc();
    
    if(p == 0)
      panic("sleep");
  
    if(lk == 0)
      panic("sleep without lk");
  
    // Must acquire ptable.lock in order to
    // change p->state and then call sched.
    // Once we hold ptable.lock, we can be
    // guaranteed that we won't miss any wakeup
    // (wakeup runs with ptable.lock locked),
    // so it's okay to release lk.
    if(lk != &ptable.lock){  //DOC: sleeplock0
      acquire(&ptable.lock);  //DOC: sleeplock1
      release(lk);
    }
    // Go to sleep.
    p->chan = chan;
    p->state = SLEEPING;
  
    sched();
  
    // Tidy up.
    p->chan = 0;
  
    // Reacquire original lock.
    if(lk != &ptable.lock){  //DOC: sleeplock2
      release(&ptable.lock);
      acquire(lk);
    }
  }
  
  //PAGEBREAK!
  // Wake up all processes sleeping on chan.
  // The ptable lock must be held.
  static void
  wakeup1(void *chan)
  {
    struct proc *p;
  
    for(p = ptable.proc; p < &ptable.proc[NPROC]; p++)
      if(p->state == SLEEPING && p->chan == chan)
        p->state = RUNNABLE;
  }
  
  // Wake up all processes sleeping on chan.
  void
  wakeup(void *chan)
  {
    acquire(&ptable.lock);
    wakeup1(chan);
    release(&ptable.lock);
  }
  
  // Kill the process with the given pid.
  // Process won't exit until it returns
  // to user space (see trap in trap.c).
  int
  kill(int pid)
  {
    struct proc *p;
  
    acquire(&ptable.lock);
    for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
      if(p->pid == pid){
        p->killed = 1;
        // Wake process from sleep if necessary.
        if(p->state == SLEEPING)
          p->state = RUNNABLE;
        release(&ptable.lock);
        return 0;
      }
    }
    release(&ptable.lock);
    return -1;
  }
  
  //PAGEBREAK: 36
  // Print a process listing to console.  For debugging.
  // Runs when user types ^P on console.
  // No lock to avoid wedging a stuck machine further.
  void
  procdump(void)
  {
    static char *states[] = {
    [UNUSED]    "unused",
    [EMBRYO]    "embryo",
    [SLEEPING]  "sleep ",
    [RUNNABLE]  "runble",
    [RUNNING]   "run   ",
    [ZOMBIE]    "zombie"
    };
    int i;
    struct proc *p;
    char *state;
    uint pc[10];
  
    for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
      if(p->state == UNUSED)
        continue;
      if(p->state >= 0 && p->state < NELEM(states) && states[p->state])
        state = states[p->state];
      else
        state = "???";
      cprintf("%d %s %s", p->pid, state, p->name);
      if(p->state == SLEEPING){
        getcallerpcs((uint*)p->context->ebp+2, pc);
        for(i=0; i<10 && pc[i] != 0; i++)
          cprintf(" %p", pc[i]);
      }
      cprintf("\n");
    }
  }