// nos4  nut operating system in Rz
//  model after nos2 in ecse\src    22 Aug 2011
//  for s23 embed sys demo          20 Jan 2013
//  mailbox                         10 Feb 2013

//  s23 trap for nos

//  20  enable interrupt
//  21  disable interrupt
//  22  block
//  23  get event
//  24  stop simulation

asm(x)	    // dummy for compiler use

new(n)      // alloc n
  asm("trap r1 #14")
blockp()
  asm("trap r0 #22")
wakeup()
  asm("trap r0 #25")
getEvent()
  asm("trap r0 #23")
ei()
  asm("trap r0 #20")
di()
  asm("trap r0 #21")

// global

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

// process descriptor

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

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

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

newp()              // new process
  p = new(11)       // new pdes
  setNext(p,0)
  setPrev(p,0)
  p[4] = sseg
  p[5] = sseg + 500
  p[6] = 0
  sseg = sseg + 1000
  p[7] = 0
  p[8] = 0
  return p

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

init()
  pid = 1
  sseg = 4000
  activep = 0

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

bootnos()
  //  setup interrupt
  asm("mov r1 #interrupt")
  asm("st r1 1000")
  asm("mov r1 #10")
  asm("trap r1 #10 ; set timer1 = 10")
  asm("mov r1 #100")
  asm("trap r1 #11  ; set div = 100")
  asm("trap r0 #20 ; enable int")
  // boot nos
  // restore fp,sp,pc from activep
  asm("ld r1 activep")
  asm("ld fp @4 r1")
  asm("ld sp @5 r1")
  asm("ld r2 @6 r1")
  asm("ret r2")

interrupt()
// switchp()
  asm("trap r0 #21")				// di
  asm("ld r21 activep")				// save activep
  asm("st fp @4 r21")
  asm("st sp @5 r21")
  asm("st r31 @6 r21")
  print("*")

  event = getEvent()
  if(event == 11 || event == 13)	// 11 TIMEOUT, 13 WAKEUP
    activep = getNext(activep) 		// switch next
  else 								// 10 STOP, 12 BLOCK
    activep = deleteDL(activep)

  if(activep == 0)
    asm("trap r0 #24")          	// stop simulation

  asm("ld r21 activep")
  asm("ld fp @4 r21")
  asm("ld sp @5 r21")
  asm("ld r31 @6 r21")
  asm("trap r0 #20")				// ei

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

getMbox(p)
  return p[7]
getAwait(p)
  return p[8]
getMsg(p)
  return p[9]
setMbox(p,m)
  p[7] = m
setAwait(p,m)
  p[8] = m
setMsg(p,m)
  p[9] = 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)
  s = findmail(p,box)
  if( s == 0 )
    s = activep						// self
    setMsg(s,mess)
    activep = deleteDL(activep)
    setMbox(p,appendDL(getMbox(p),s))
    blockp()
  else              				// p is waiting
    setMsg(p,mess)
    s = deleteDL(p)
    if( box == p )
      setAwait(activep,s)
    wakeup(p)
  ei()

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


// --- 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," ")

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

p1, p2			// user process

main()
  init()
  p1 = run(produce())
  p2 = run(consume())
  bootnos()

// end