public vm()
{
//Initialize devices;
cpu = new CPU(this); // Initializes the cpu
ram = new Memory(PAGE_DIRECTORY_SIZE * Frame.FRAME_SIZE); //Allocates enough ram to fit number of page tables allowed
hdi = new HDI("disk0"); //Maps a folder to the hard disk interface
disk0 = new VirtualDataDisk("vhd.nvmd"); // Virtual data disk
devices = new VMDevice[] {
cpu, // Processer, device 0
ram, // RAM, device 1
hdi, // Hard drive Interface, device 3
disk0, // Virtual Data Disk, device 4
};
callstack = new CallStack(this,ram);
pager = new Pager(ram, PAGE_DIRECTORY_SIZE);
//setup premade page for callstack and bios
BPG = pager.CreatePageEntry(Pager.PAGE_KERNEL_MODE);
CSP = pager.getVAT(1024,pager.getEntry(BPG)); //bios will be loaded at 0 to 1023
CBP = CSP;
CR3I = BPG;
CR3 = pager.getEntry(CR3I);
}
public Pager(Memory RAM, int PDSize)
{
//machine = Machine;
ram = RAM;
PageDirectory = new PageDirectoryEntry[PDSize];
for (int i = 0; i < PDSize; i++) {
PageDirectory[i] = new PageDirectoryEntry() { PTAddress = 0, AccessLevel = false, InUse = false };
}
}
public void AddPage(PageDirectoryEntry entry)
{
//Find free frame
Frame freeFrame = ram.findFreeFrame();
freeFrame.IsFree = false;
for(int i = 0; i < PageDirectory.Length; i++) {
if(PageDirectory[i].PTAddress == entry.PTAddress) {
freeFrame.PageTable = i;
break;
}
}
//Add frame to PT
for (int i = 0; i < Pager.PAGE_TABLE_SIZE / 4; i++) {
if (ram.ReadUInt((uint)(entry.PTAddress + i * 4)) == 0) {
ram.Write((uint)(entry.PTAddress + i * 4),freeFrame.Address);
break;
}
}
}
public string ReadString(uint address, PageDirectoryEntry entry)
{
int len = ReadInt(address, entry);
address += 4;
char[] chr = new char[len];
for (int i = 0; i < len; i++) {
chr[i] = (char)Read ((uint)(address + i), entry);
}
return new String(chr);
}
public uint ReadUInt(uint address, PageDirectoryEntry entry)
{
return ram.ReadUInt(getVAT(address,entry));
}
public void SwitchPage(int newpage)
{
CR3I = newpage;
CR3 = pager.getEntry(CR3I);
SP = CR3.stack_pointer;
HP = CR3.heap_pointer;
BP = CR3.base_pointer;
}
public void FreePageTable(PageDirectoryEntry entry)
{
uint addr = entry.PTAddress;
//Read pages
for (int i = 0; i < PAGE_TABLE_SIZE / 4; i++) {
uint frameAddr = ram.ReadUInt((uint)(addr + (i*4)));
int frameindex = (int)(frameAddr / Frame.FRAME_SIZE);
Frame frame = ram.getFrame(frameindex);
frame.IsFree = true; // Set frame to free, clears the frame
}
}
public void WritePageTable(PageDirectoryEntry entry)
{
//Write page table
uint addr = entry.PTAddress; // Get page table address
// Write: Page addresses
for (int i = 0; i < PAGE_TABLE_SIZE / 4; i++) {
ram.Write((uint)(addr + (i*4)), 0u);
}
//Write first page address start
ram.Write(addr,addr + PAGE_TABLE_SIZE + 4);
}
///<summary>
///Check if the address will overflow to the next page with the given size
///</summary>
///<returns>
///False if the address overflows
///</returns>
public bool checkVAT(uint address, uint size, PageDirectoryEntry entry)
{
uint addr1 = getVAT(address,entry);
uint addr2 = getVAT(address + size,entry);
return (addr2 - addr1 == size);
}
/// <summary>
/// Setup the heap memory allocation for the page table
/// </summary>
/// <param name='entry'>
/// Page table to setup
/// </param>
public void SetupMemoryAllocation(PageDirectoryEntry entry)
{
entry.free_pointer = entry.heap_pointer; //set free-list pointer to start of heap
ram.Write(getVAT(entry.heap_pointer,entry),0); // write 0 because there is no next block
ram.Write(getVAT(entry.heap_pointer,entry) + 4,(uint)(GetPageDirectoryEntrySize(entry) - entry.heap_pointer)); //Write size of free block (total size of heap)
}
public void LoadProgram(byte[] data, PageDirectoryEntry entry)
{
uint origin = getVAT (0u, entry);
if (checkVAT (0u, (uint)data.Length, entry)) { //does the program fit in the first page?
for (int i = 0; i < data.Length; i++) {
ram.Write ((uint)(origin + i), data[i]); //this should be safe
}
} else { //oooh boy
//get length of program
uint length = (uint)data.Length;
uint writtenbytes = 0;
//loop through pages
for (int i = 0; i < GetPageDirectoryEntrySize(entry); i++) {
//get page start
uint origio = getVAT(writtenbytes,entry);
//get length of current page
uint curlen = (uint)(i == 0 ? Frame.FRAME_SIZE - PAGE_TABLE_SIZE : Frame.FRAME_SIZE);
//write through each page
for (int j = 0; j < curlen; j++) {
ram.Write((uint)(origio + j), data[writtenbytes]);
writtenbytes++;
}
}
}
}
public uint GetPageDirectoryEntrySize(PageDirectoryEntry entry)
{
uint addr = entry.PTAddress;
uint count = 0;
for(int i = 0; i < PAGE_TABLE_SIZE / 4; i++) {
uint a = ram.ReadUInt((uint)(addr + i*4));
if(a != 0) {
count++;
}
}
return count * Frame.FRAME_SIZE;
}
public string PopString(PageDirectoryEntry entry)
{
uint size = ram.ReadUInt(getVAT(entry.stack_pointer,entry));
if (entry.stack_pointer + size + 4 >= entry.heap_pointer) {
throw new Exception("No more items in stack!");
}
string val = "";
if(checkVAT(entry.stack_pointer,size,entry)) { //check for page overflow
val = ram.ReadString(getVAT(entry.stack_pointer,entry));
} else {
val = ReadString(entry.stack_pointer,entry); //use method for safe writing under page overflow
}
entry.stack_pointer += size + 4;
return val;
}
public byte PopByte(PageDirectoryEntry entry)
{
if (entry.stack_pointer + 1 >= entry.heap_pointer) {
throw new Exception("No more items in stack!");
}
byte val = ram.Read(getVAT(entry.stack_pointer,entry));
entry.stack_pointer++;
return val;
}
public void MergeFreeBlocks(PageDirectoryEntry entry)
{
uint pdsize = GetPageDirectoryEntrySize(entry);
for (uint addr = entry.free_pointer; addr < pdsize;) {
uint nextblock = ram.ReadUInt(getVAT(addr, entry)); //read address of next free block
if(nextblock == 0) {
break; //end of list
}
uint blocksize = ram.ReadUInt(getVAT(addr + 4, entry)); //read size of current free block
if(addr + blocksize >= nextblock) {
uint nextsize = ram.ReadUInt(getVAT(nextblock + 4, entry)); //read size of next block
uint newsize = blocksize + nextsize;
uint nextpointer = ram.ReadUInt(getVAT(nextblock, entry));
ram.Write(getVAT(addr,entry),nextpointer);
ram.Write(getVAT(addr + 4,entry),newsize);
}
addr = nextblock;
}
}
/// <summary>
/// Allocate a new block of memory in the page table with the specified size
/// </summary>
/// <param name='size'>
/// Size of memory to allocate
/// </param>
/// <param name='entry'>
/// Page table to use
/// </param>
/// <returns>
/// The address of the allocated block
/// </returns>
public uint Malloc(uint size,PageDirectoryEntry entry)
{
uint lastaddr = entry.free_pointer; //last free block pointer
bool isfirst = true;
//loop through freelist , check for large enough chunk
uint pdsize = GetPageDirectoryEntrySize(entry);
for (uint addr = entry.free_pointer; addr < pdsize; ) {
uint nextblock = ram.ReadUInt(getVAT(addr, entry)); //read address of next free block
uint blocksize = ram.ReadUInt(getVAT(addr + 4, entry)); //read size of current free block
if (blocksize >= size) {
uint newsize = blocksize - size; //get new size of free block
uint newaddr = addr + size; //get new address of free block
if (newsize >= 8) { //if size < 8, block is gone cause we can't store the next block pointer
ram.Write(getVAT(newaddr,entry),nextblock); // set next block pointer
ram.Write(getVAT(newaddr + 4,entry),newsize); //write new size of new freeblock
ram.Write(getVAT(lastaddr,entry),getVAT(newaddr,entry)); //set pointer of last block to point to this new one
if (isfirst) {
entry.free_pointer = newaddr; //update first freepointer
}
}
else //set pointer to skip unexisting block
{
ram.Write(getVAT(lastaddr,entry),getVAT(nextblock,entry));
}
return addr; //return address of allocated space
}
if (nextblock == 0) { // there is no next block, break from loop
break;
}
addr = nextblock;
isfirst = false;
}
throw new OutOfMemoryException(String.Format("No more free blocks to allocate memory in page table: {0}",entry.PTAddress));
}
/// <summary>
/// Setup the heap and stack for the page table
/// </summary>
/// <param name='entry'>
/// Page directory entry
/// </param>
/// <param name='stack_pointer'>
/// New stack_pointer, relative address.
/// </param>
/// <param name='heap_pointer'>
/// New heap_pointer, relative address
/// </param>
public void SetupMemory(PageDirectoryEntry entry, uint stack_start, uint heap_start)
{
entry.stack_pointer = heap_start - 1;
entry.base_pointer = stack_start;
entry.heap_pointer = heap_start;
}
public void Write(uint address, float value, PageDirectoryEntry entry)
{
byte[] convertedValues = BitConverter.GetBytes(value);
ram.Write(getVAT(address + 0,entry),convertedValues[0]);
ram.Write(getVAT(address + 1,entry),convertedValues[1]);
ram.Write(getVAT(address + 2,entry),convertedValues[2]);
ram.Write(getVAT(address + 3,entry),convertedValues[3]);
}
public uint PopUInt(PageDirectoryEntry entry)
{
if (entry.stack_pointer + 4 >= entry.heap_pointer) {
throw new Exception("No more items in stack!");
}
uint val = ram.ReadUInt(getVAT(entry.stack_pointer,entry));
entry.stack_pointer += 4;
return val;
}
///<summary>
///Translates the page relative address to a 'physical' one
///</summary>
public uint getVAT(uint address, PageDirectoryEntry entry)
{
// Get address
uint ptaddr = entry.PTAddress;
//The 4 and 5 is for keeping space for integers stored to keep stuff from overflowing to different pages, strings need their own logic to do this.
if(address < Frame.FRAME_SIZE - PAGE_TABLE_SIZE - 4) { //address is in the first frame
return ptaddr + PAGE_TABLE_SIZE + address;
} else { //address is after first frame
int page = (int)(address / Frame.FRAME_SIZE);
int offset = (int)(address - page * Frame.FRAME_SIZE + PAGE_TABLE_SIZE);
if(offset > Frame.FRAME_SIZE - 5) { //fix for addresses over framesize - 512
page++;
offset -= Frame.FRAME_SIZE;
}
uint pageaddr = ram.ReadUInt((uint)(ptaddr + (page * 4)));
return (uint)(pageaddr + offset);
}
/*
// Get Page id
int page = (int)(address / Frame.FRAME_SIZE);
int offset = (int)(address - page * Frame.FRAME_SIZE);
// Get page table entry address
uint pageaddr = ram.ReadUInt((uint)(ptaddr + (page * 4)));
// Get address
return (uint)(pageaddr + offset);
*/
}
// ------- CUSTOM OVERLOADS FOR RAM METHODS USING VAT (WARNING SLOW!)-------
//Write methods
public void Write(uint address, byte value, PageDirectoryEntry entry)
{
ram.Write(getVAT(address,entry),value);
}
public void Push(float data,PageDirectoryEntry entry)
{
if (entry.stack_pointer - 4 < entry.base_pointer) {
throw new Exception("No more space in stack!");
}
entry.stack_pointer -= 4;
ram.Write(getVAT(entry.stack_pointer,entry),data);
}
public void Write(uint address, string value, PageDirectoryEntry entry)
{
Write((uint)(address), (uint)value.Length, entry);
address += 4;
for (int i = 0; i < value.Length; i++)
{
Write((uint)(address + i), ((byte)value[i]), entry);
}
}
public void Push(string data,PageDirectoryEntry entry)
{
if (entry.stack_pointer - (data.Length + 4) < entry.base_pointer) {
throw new Exception("No more space in stack!");
}
entry.stack_pointer -= (uint)(data.Length + 4);
if(checkVAT(entry.stack_pointer,(uint)(data.Length + 4),entry)) { //check for overflow to next page
ram.Write(getVAT(entry.stack_pointer,entry),data);
} else {
Write(entry.stack_pointer,data,entry); //use paging method to write, slower
}
}
internal ushort ReadUInt16(uint address, PageDirectoryEntry entry)
{
return ram.ReadUInt16(getVAT(address,entry));
}
public byte Read(uint address, PageDirectoryEntry entry)
{
return ram.Read(getVAT(address,entry));
}
public int CreatePageEntry(bool mode)
{
//Declare stuff
int index = 0;
//Find free entry in page directory
PageDirectoryEntry entry = new PageDirectoryEntry();
for (int i = 0; i < PageDirectory.Length; i++) {
if (!PageDirectory[i].InUse) {
entry = PageDirectory[i];
index = i;
break;
}
}
//Find a free ram frame for the first page
Frame mainFrame = ram.findFreeFrame();
mainFrame.IsFree = false;
mainFrame.PageTable = index;
entry.PTAddress = mainFrame.Address;
entry.AccessLevel = mode;
entry.InUse = true;
//Write page table to ram for entry
WritePageTable(entry);
PageDirectory[index] = entry;
return index;
}
public float ReadFloat(uint address, PageDirectoryEntry entry)
{
return ram.ReadFloat(getVAT(address,entry));
}
public uint[] ReadPageTable(PageDirectoryEntry entry)
{
uint[] array = new uint[PAGE_TABLE_SIZE / 4];
for (int i = 0; i < PAGE_TABLE_SIZE / 4; i++) {
uint addr = ram.ReadUInt((uint)(entry.PTAddress + i * 4));
array[i] = addr;
}
return array;
}
public void FreePageEntry(PageDirectoryEntry entry)
{
FreePageTable(entry);
entry.InUse = false;
}