#ifdef CHANGED
#include "copyright.h"
#include "system.h"
#include "userthread.h"
#include "syscall.h"
#include "addrspace.h"
#include "synch.h"


static void StartUserThread( void * args ){

    DEBUG('x', "Enter StartUserThread function\n");
    // retrieve function and arguments
    // create a ThreadArgs_t struct and cast args content into it
    // because we only have a void in our function definition
    ThreadArgs_t * cpy_args;
    cpy_args = (ThreadArgs_t *) args;

    // init register
    for (int i = 0; i < NumTotalRegs; i++ ) {
        machine->WriteRegister(i, 0);
    }

    // init Program counter and Next Program Counter registers
    machine->WriteRegister(PCReg, cpy_args->f);
    machine->WriteRegister (NextPCReg, machine->ReadRegister(PCReg) + 4);
    DEBUG('x',"PCReg: 0x%x, NextPCReg: 0x%x\n", cpy_args->f, cpy_args->f + 4);

    // init register 4: arguments
    machine->WriteRegister(4, cpy_args->arg);
    DEBUG('x',"Register 4: 0x%x\n", cpy_args->arg);

    // init stack
    machine->WriteRegister(StackReg, cpy_args->stackAddr);
    DEBUG('x',"StackRegister: 0x%x\n", cpy_args->stackAddr);

    // All our registers have values, we can desallocate our cpy_args
    free(cpy_args);
    cpy_args = NULL;

    // run our thread
    machine->Run();
}

int do_ThreadCreate(int f, int arg){

    DEBUG('x',"Enter do_ThreadCreate function\n");

    // Initialize our structure we'll pass to StartUserThread
    ThreadArgs_t * args = (ThreadArgs_t *) malloc(sizeof(ThreadArgs_t));
    args->f = f;
    args->arg = arg;
    
    // Check if we can allocate Stack for our son
    int stackAddr = currentThread->space->AllocateUserStack();
    if ( stackAddr == -1 ) {
        fprintf(stderr, "Segmentation Fault - no space avaible on stack\n");
        Exit(1);
    }
    // create a new Thread and start it
    Thread * newThread = new Thread("new thread");

    // increment number of threads
    currentThread->space->semThreadsCounter->P();
    currentThread->space->threads++;
    currentThread->space->semThreadsCounter->V();
    DEBUG('x', "Increase numbers of Threads:%d\n",currentThread->space->threads);

    newThread->space = currentThread->space;
    newThread->Start(StartUserThread, args);

    return 0;
}

void do_ThreadExit(){
    DEBUG('x', "Enter do_ThreadExit function\n");
    // TODO: what should we do with thread space?
    //       Probalely desallocate it... if no threads remain
    // currentThread->space->Threads--;
    currentThread->space->semThreadsCounter->P();
    currentThread->space->threads--;
    currentThread->space->semThreadsCounter->V();
    int addr = machine->ReadRegister(StackReg);
    currentThread->space->DeAllocateUserStack(addr);
    DEBUG('x', "Decrease numbers of Threads:%d\n",currentThread->space->threads);
    
    if ( currentThread->space->threads == 0 ){
        // No threads remains, desallocate addrspace
        delete currentThread->space;
        interrupt->Powerdown();
    }
    currentThread->Finish();
}
#endif