//  v1_zad5.cpp
//  prevodjenje iz komandne linije: bcc -ms -Ic:\bc31\include -Lc:\bc31\lib v1_zad5.cpp

#include <stdio.h>
#include <dos.h>

struct PCB{      // pomeraj u odnosu na poc. adresu strukture
   unsigned pc;  // +0
   unsigned sp;  // +2
   unsigned bp;  // +4
   unsigned ax;  // +6
   unsigned bx;  // +8
   unsigned cx;  // +10
   unsigned dx;  // +12  - izraženo u bajtovima
   unsigned* stack;
};

PCB *p[3];
PCB* running; 

int nextThread;

//makro
#define dispatch(x) { \
   nextThread = x; \
   _dispatch(); \
 }

void _dispatch() {
 asm {   
	push bx
	mov bx, running
	mov bx[6], ax	    // ax
	pop WORD PTR [bx+8] // bx
	mov bx[10], cx      // cx
	mov bx[12], dx      // dx
	pop WORD PTR [bx+4] // bp
	pop WORD PTR [bx]   // pc
 	mov bx[2], sp       // sp
 }
 running=p[nextThread];
 asm {
	mov bx, running
	mov sp, bx[2]        // sp
  push WORD PTR [bx]   // pc
	push WORD PTR [bx+4] // bp
	mov ax, [bx+6]       // ax
	push WORD PTR [bx+8]
	mov cx, [bx+10]      // cx
	mov dx, [bx+12]      // dx
	pop bx		     // bx
 } 
}

// funkcija koju izvrsava nit 1
void a() {
  for (int i = 0; i < 3; ++i) printf("U a() %d\n",i);
  
  asm mov ax, 7
  
  dispatch(2);
 
  asm mov i, ax
  
  printf(" u a() ax = %d\n",i);

  for (i = 0; i < 3; ++i) printf("U a() %d\n",i);

  dispatch(2);
}
// funkcija koju izvrsava nit 2
void b() {
  for (int i = 0; i < 3; ++i) printf("U b() %d\n",i);

  asm mov ax, 2

  dispatch(1);

  for (i = 0; i < 3; ++i) printf("U b() %d\n",i);
 
  dispatch(0);
}

void createThread(PCB *newPCB, void (*body)()) {
  unsigned* st = new unsigned[1024];
  
  newPCB->pc = FP_OFF(body);
   
  // stek je sada prazan 
  newPCB->sp = FP_OFF(st+1024);
  newPCB->bp = FP_OFF(st+1024);
  newPCB->stack = st;
}


void delete_all() {
  delete [] p[1]->stack;
  delete [] p[2]->stack;
  delete p[0];
  delete p[1];
  delete p[2];
}
int main() {
  p[1] = new PCB();
  createThread(p[1], a);
  printf("napravio a\n");

  p[2] = new PCB();
  createThread(p[2], b);
  printf("napravio b\n");

  p[0] = new PCB();
  running = p[0];
  dispatch(1);
  
  printf("Kraj.\n");
  delete_all();
  return 0;
}