// nos-z  nut operating system in Rz
//  model after nos2 in ecse\src    22 Aug 2011
//  for s23 embed sys demo          20 Jan 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

// ----- singly linked circular list --------

// pool of singly circular list
numcell, freecell, freelist

initH()
  freecell = new(100)
  numcell = 100
  freelist = 0

newH()
  if( freelist )
    a = freelist
    freelist = a[1]
  else
    a = freecell
    freecell = freecell + 2
    numcell = numcell - 2
    if( numcell <= 0 )
      print("out of cell")
  a[0] = 0
  a[1] = 0
  return a

// function prototypes
getslist(s)
setslist(s,a)

freeH(a)
  a[1] = freelist
  freelist = a

deleteH(s)
  a = getslist(s)
  if( a )
    b = a[1]
    info = b[0]
    if( b == a ) 	// singleton
      setslist(s,0)
    else
      a[1] = b[1]	// delete b
    freeH(b)
  else
    info = 0
  return info

appendH(s,info)
  b = newH()
  b[0] = info
  a = getslist(s)
  if( a )
    b[1] = a[1]
    a[1] = b		// append b
  else
    b[1] = b		// singleton
  setslist(s,b)

// -------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("*")
//  print(" * save",activep)

  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

//  print(" res",activep)			// restore activep
  asm("ld r21 activep")
  asm("ld fp @4 r21")
  asm("ld sp @5 r21")
  asm("ld r31 @6 r21")
  asm("trap r0 #20")		// 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()
  s = new(2)
  setsval(s,1)
  setslist(s,0)  // wait-list null
  return s

signal(s)
  di()
  v = getsval(s)+1
  setsval(s,v)
//  print("%",s,v)
  if(v <= 0)
    p = deleteH(s)
    activep = appendDL(activep,p)
    wakeup()
  ei()

wait(s)
  di()
  v = getsval(s)-1
  setsval(s,v)
//  print("@",s,v)
  if( v < 0 )        // block activep
    appendH(s,activep)
    blockp()
  ei()

// --- use semaphore to protect share resource ------

empty, full, mutex   // semaphores
shareVar

writer()
  i = 0
  while( i < 3 )
    wait(empty)
    wait(mutex)
    shareVar = shareVar + 1
    signal(mutex)
    signal(full)
    i = i + 1

reader()
  i = 0
  while( i < 3 )
    wait(full)
    wait(mutex)
    print("+",shareVar)
    signal(mutex)
    signal(empty)
    i = i + 1

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

p1, p2			// user process

main()
  initH()
  init()
  shareVar = 0
  empty = initsem()
  full = initsem()
  mutex = initsem()
  p1 = run(writer())
  p2 = run(reader())
  bootnos()

// end