// nos-z  nut operating system in Rz
//  model after nos2 in ecse\src    22 Aug 2011
//  run two process (showTwoCount)  23 Aug 2011
//  new Rz syntax                   28 Aug 2011
//  add message passing             31 Aug 2011

syscall()   // anchor for compiler
  a = 0

new(n)      // alloc n
  syscall(14,n)
ei()
  syscall(20)
di()
  syscall(21)
getevent()
  syscall(22)
blockp()
  syscall(23)
bootnos()
  syscall(24)

// global

activep      // current active process
psw          // switchp
sseg         // stack segment
pid          // unique process id

// event
TIMEOUT, STOP, BLOCK

// process descriptor

// 0 next, 1 prev
// 2 id,   3 value
// 4 fp,   5 sp,  6 pc, 7 -
// 8 inbox, 9 awaitbox, 10 msg


// process state
READY, RUNNING, WAIT, DEAD, SEND, RECEIVE

init()
  TIMEOUT = 10
  STOP = 13
  BLOCK = 11
  READY = 1
  RUNNING = 2
  WAIT = 3
  DEAD = 4
  SEND = 5
  RECEIVE = 6
  pid = 1
  sseg = 1000
  activep = 0


//  process descriptor access function

getNext(a)
  return a[0]
getPrev(a)
  return a[1]
setNext(a,v)
  a[0] = v
setPrev(a,v)
  a[1] = v

getId(p)
  return p[2]
getValue(p)
  return p[3]
setId(p,id)
  p[2] = id
setValue(p, v)
  p[3] = v

// ---- process list functions --------

// append a2 to the end of a1
appendDL(a1,a2)
  if(a1 == 0)
    setNext(a2,a2)  // only one item
    setPrev(a2,a2)
    return a2
  else
    b = getPrev(a1)
    setNext(a2,a1)
    setPrev(a1,a2)
    setNext(b,a2)
    setPrev(a2,b)
    return a1

deleteDL(b)
  c = getNext(b)
  if(c == 0 || c == b)
    return 0         // delete singleton
  else
    a = getPrev(b)
    setNext(a,c)
    setPrev(c,a)
    setNext(b,0)    // make b singleton
    return c

showp(a)            // show pid,sseg,ip
  p = a
  while(p != 0)
    print(p[2]," ",p[4]," ",p[6],"\n")
    p = getNext(p)
    if(p == a) p = 0
  print("\n")

newp()              // new process
  p = new(11)       // new pdes
  setNext(p,0)
  setPrev(p,0)
  setValue(p,READY)
  p[4] = sseg
  p[5] = sseg + 1
  p[6] = 0
  sseg = sseg + 1000
  p[7] = 0
  p[8] = 0
  return p

// -------nos functions --------

run(ads)   // return p
  p = newp()
  setId(p,pid)
  pid = pid + 1
  p[6] = ads
  activep = appendDL(activep, p)
  return p

switchp()   // previlege process
  di()
  event = getevent()
  if(event == STOP)
    setValue(activep,DEAD)
    activep = deleteDL(activep)
  else
    setValue(activep,READY)
    activep = getNext(activep) // switch next
  ei()

// ------- semaphore ------

// field: svalue(value) slist(wait-list)
// semaphore access functions

getsval(s)
  return s[0]
getslist(s)
  return s[1]
setsval(s,v)
  s[0] = v
setslist(s,v)
  s[1] = v

initsem(v)
  s = new(2)
  setsval(s,v)
  setslist(s,0)  // wait-list null
  return s

wakeup(p)
  setValue(p,READY)
  activep = appendDL(activep,p)

signal(s)
  di()
  p = getslist(s)
  if(p != 0)
    setslist(s,deleteDL(p))
    wakeup(p)
  else
    setsval(s,getsval(s)+1)
  ei()

wait(s)
  di()
  v = getsval(s)
  if( v <= 0 )        // block activep
    p = activep
    activep = deleteDL(activep)
    setValue(p,WAIT)  // to wait-list
    setslist(s,appendDL(getslist(s),p))
    blockp()
  else
    setsval(s,v-1)
  ei()

// --------- message passing --------

getMbox(p)
  return p[8]
getAwait(p)
  return p[9]
getMsg(p)
  return p[10]
setMbox(p,m)
  p[8] = m
setAwait(p,m)
  p[9] = m
setMsg(p,m)
  p[10] = m

// search mail p in the box
// return mail if found else 0
findmail(p,box)
  y = 0				// return value
  x = box
  while( x != 0 )
    if( x == p )
      y = x
      x = 0			// exit
    else
      x = getNext(x)
      if( x == box )
        x = 0		// not found
  return y

// p is pointer to process
send(p,mess)
  di()
  box = getAwait(activep)
  m = findmail(p,box)
  if( m == 0 )
    m = activep		// self
    setMsg(m,mess)
    activep = deleteDL(activep)
    setMbox(p,appendDL(getMbox(p),m))
    setValue(m,SEND)
    blockp()
  else              // p is waiting
    setMsg(p,mess)
    m = deleteDL(p)
    if( box == p )
      setAwait(activep,m)
    wakeup(p)
  ei()

receive(p)
  di()
  box = getMbox(activep)
  m = findmail(p,box)
  if( m == 0 )		// put to await p
    m = activep		// self
    activep = deleteDL(activep)
    setAwait(p,appendDL(getAwait(p),m))
    setValue(m,RECEIVE)
    blockp()
    getMsg(m)		// retrieve from self
  else				// already in mbox
    m = deleteDL(p)
    if( box == p )
      setMbox(activep,m)
    getMsg(p)		// retrieve mbox
    wakeup(p)
  ei()

// -------- user program ------

p1, p2             // user process

count1()
  i = 10
  while(i < 100)
    print(i," ")
    i = i + 2

count2()
  i = 3
  while(i < 100)
    print(i," ")
    i = i + 2

showTwoCount()
  p1 = run(count1())
  p2 = run(count2())

// ----- process synchronisation using two semaphores

semx, semy    // semaphore

prox()
  i = 0
  while( i < 10 )
    wait(semy)
    signal(semx)
    print(" x:",i)
    i = i + 1

proy()
  i = 0
  while( i < 10 )
    wait(semx)
    signal(semy)
    print(" y:",i)
    i = i + 1

showSync()
  semx = initsem(0)
  semy = initsem(1)
  p1 = run(prox())
  p2 = run(proy())

// --- producer, consumer ----


// send 2..n to p2 ended with -1
produce()
  n = 10
  i = 2
  while( i < n )
    send(p2,i)
    i = i + 1
  send(p2,-1)

// receive 2..n from p1 ended with -1
consume()
  m = 1
  while( m > 0 )
    m = receive(p1)
    print(m," ")

showProduce()
  p1 = run(produce())
  p2 = run(consume())

// ------  sum array -------

ax, sem1, sem2

initax()
  ax = new(50)
  i = 0
  while( i < 20 )
    ax[i] = i
    i = i + 1
//  print(ax[19])

sumodd()
  i = 1
  sum = 0
  while( i < 20 )
    sum = sum + ax[i]
    i = i + 2
  ax[1] = sum
  wait(sem1)
  signal(sem2)
  print("sum ", ax[0] + ax[1])

sumeven()
  i = 0
  sum = 0
  while( i < 20 )
    sum = sum + ax[i]
    i = i + 2
  ax[0] = sum
  wait(sem2)
  signal(sem1)
//  print("sum even ", ax[0])

showSum()
  sem1 = initsem(0)
  sem2 = initsem(1)
  p1 = run(sumodd())
  p2 = run(sumeven())

// -----------------

main()
  init()
  psw = run(switchp())
  activep = 0
  // start user process
//  showTwoCount()
//  showSync()
//  showProduce()
  initax()
  showSum()
  bootnos()

// end