addrspace nachos

bool
AddrSpace::Load(char *filename) {
    NoffHeader noffH;
    unsigned int i, size;
    OpenFile *executable = kernel->fileSystem->Open(filename);

    if (executable == NULL) {
        DEBUG(dbgFile, "\n Error opening file: " << filename);
        return FALSE;
    }

    // read file header
    executable->ReadAt((char *)&noffH, sizeof(noffH), 0);
    if ((noffH.noffMagic != NOFFMAGIC) &&
        (WordToHost(noffH.noffMagic) == NOFFMAGIC))
        SwapHeader(&noffH);
    ASSERT(noffH.noffMagic == NOFFMAGIC);

    kernel->addrLock->P();

// how big is address space?
#ifdef RDATA
    size = noffH.code.size + noffH.readonlyData.size + noffH.initData.size +
           noffH.uninitData.size + UserStackSize;
    // we need to increase the size
    // to leave room for the stack
#else
    // how big is address space?
    size = noffH.code.size + noffH.initData.size + noffH.uninitData.size + UserStackSize; // we need to increase the size
                                                                                          // to leave room for the stack
#endif
    numPages = divRoundUp(size, PageSize);
    size = numPages * PageSize;

    // Check the available memory enough to load new process
    if (numPages > kernel->gPhysPageBitMap->NumClear())
    {
        printf("\nAddrSpace:Load: not enough memory for new process..!");
        numPages = 0;
        delete executable;
        kernel->addrLock->V();
        return FALSE;
    }

    // set up the translation page
    pageTable = new TranslationEntry[numPages];
    for (i = 0; i < numPages; i++)
    {
        pageTable[i].virtualPage = i;
        pageTable[i].physicalPage = kernel->gPhysPageBitMap->FindAndSet();
        pageTable[i].valid = TRUE;
        pageTable[i].use = FALSE;
        pageTable[i].dirty = FALSE;
        pageTable[i].readOnly = FALSE;
        // init data on main memory
        bzero(&(kernel->machine->mainMemory[pageTable[i].physicalPage * PageSize]), PageSize);
    }

    kernel->addrLock->V();

    // copy code segment into memory
    if (noffH.code.size > 0)
    {
        for (i = 0; i < numPages; i++)
            executable->ReadAt(&(kernel->machine->mainMemory[noffH.code.virtualAddr])
                                    + (pageTable[i].physicalPage * PageSize),
                               PageSize, noffH.code.inFileAddr + (i * PageSize));
    }

    // copy initial data segment into memory
    if (noffH.initData.size > 0)
    {
        for (i = 0; i < numPages; i++)
            executable->ReadAt(&(kernel->machine->mainMemory[noffH.initData.virtualAddr])
                                    + (pageTable[i].physicalPage * PageSize),
                               PageSize, noffH.initData.inFileAddr + (i * PageSize));
    }

    // copy read-only segment into memory
#ifdef RDATA
    if (noffH.readonlyData.size > 0)
    {
        for (i = 0; i < numPages; i++)
            executable->ReadAt(&(kernel->machine->mainMemory[noffH.readonlyData.virtualAddr])
                                    + (pageTable[i].physicalPage * PageSize),
                               PageSize, noffH.readonlyData.inFileAddr + (i * PageSize));
    }
#endif

    delete executable;
    return TRUE;
}