C# Class SharpOS.Kernel.Memory.PageAllocator

The PageAllocator class handles physical memory page allocation and provides the OS an interface for memory paging/mapping. The PageAllocator class is portable, making use of the SharpOS.ADC.Pager class to implement platform- specific paging mechanisms.

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Public Methods

Method	Description
Alloc ( ) : void*	Allocates a page of memory. This function returns null when out of memory.
Dealloc ( void page ) : void	Deallocates the memory page pointed to by page.
Dump ( int count ) : void
DumpInfo ( ) : void
DumpStack ( uint stack, uint stackptr, int count ) : void
GetPageAttributes ( void page, uint granularity, PageAllocator ret_err ) : PageAttributes
IsPageFree ( void page ) : bool	Checks if a given page is allocated. If the page is allocated, the method returns true. This function starts from the current stack pointer and goes backward.
IsPageReserved ( void page ) : bool	Returns true if the given page is reserved (that is, not available for allocation).
MapPage ( void page, void physPage, uint granularity, PageAttributes attr ) : PageAllocator.Errors	Modifies the virtual memory mapping of the given super-page to point to the given physical super page. Both pointers must be aligned along the platform's native super-page boundaries. This function is only available on platforms which can provide super-page mapping. The Intel 386 and later processors support this using the 'page directory', which maps large 4MB sections of memory at a time (via redirection to page tables which contain 4KB blocks).
ReservePage ( void page ) : bool	Reserves a memory page so that it cannot be allocated using M:Alloc() or M:RangeAlloc(uint count).
ReservePageRange ( void firstPage, uint pages, string name ) : bool	Reserves a range of memory pages so that they cannot be allocated using M:Alloc() or M:RangeAlloc(uint count).
SetPageAttributes ( void page, uint granularity, PageAttributes attr ) : Errors
Setup ( byte kernelOffset, uint _kernelSize, uint totalKbMem ) : void	Initializes page management and paging. Using Alloc and related management functions before calling this function results in a kernel panic. After this function is called, the ReservePage and ReservePageRange functions can be used to reserve memory that should not be allocated. You should ensure that no memory allocations have happened between calling this function and reserving memory.

Private Methods

Method	Description
DumpReservedStack ( ReservedPages pageStack, uint stackPtr, int count ) : void
GetReservedPage ( ) : ReservedPages*
PopFreePage ( ) : void*	Pops the free page from the free page stack
PrintError ( Errors error ) : void
PtrToPage ( void ptr ) : void*	Gets the page address of a given pointer.
PushFreePage ( void page ) : void	Pushes the free page to the free page stack

Method Details

Alloc() public static method

Allocates a page of memory. This function returns null when out of memory.

public static Alloc ( ) : void*
return	void*

Dealloc() public static method

Deallocates the memory page pointed to by page.

public static Dealloc ( void page ) : void
page	void	/// A pointer which is aligned along the platform's native page boundaries. ///
return	void

Dump() public static method

public static Dump ( int count ) : void
count	int
return	void

DumpInfo() public static method

public static DumpInfo ( ) : void
return	void

DumpStack() public static method

public static DumpStack ( uint stack, uint stackptr, int count ) : void
stack	uint
stackptr	uint
count	int
return	void

GetPageAttributes() public static method

public static GetPageAttributes ( void page, uint granularity, PageAllocator ret_err ) : PageAttributes
page	void
granularity	uint
ret_err	PageAllocator
return	PageAttributes

IsPageFree() public static method

Checks if a given page is allocated. If the page is allocated, the method returns true. This function starts from the current stack pointer and goes backward.

public static IsPageFree ( void page ) : bool
page	void
return	bool

IsPageReserved() public static method

Returns true if the given page is reserved (that is, not available for allocation).

public static IsPageReserved ( void page ) : bool
page	void
return	bool

MapPage() public static method

Modifies the virtual memory mapping of the given super-page to point to the given physical super page. Both pointers must be aligned along the platform's native super-page boundaries.

This function is only available on platforms which can provide super-page mapping. The Intel 386 and later processors support this using the 'page directory', which maps large 4MB sections of memory at a time (via redirection to page tables which contain 4KB blocks).

public static MapPage ( void page, void physPage, uint granularity, PageAttributes attr ) : PageAllocator.Errors
page	void
physPage	void
granularity	uint
attr	PageAttributes	/// The attributes to apply to the paging table entry for this super-page. If /// one or more flags given in this parameter are not supported by the current /// platform, the call will fail, returning false. ///
return	PageAllocator.Errors

ReservePage() public static method

Reserves a memory page so that it cannot be allocated using M:Alloc() or M:RangeAlloc(uint count).

public static ReservePage ( void page ) : bool
page	void	/// A pointer which is aligned along the platform's native page boundaries. ///
return	bool

ReservePageRange() public static method

Reserves a range of memory pages so that they cannot be allocated using M:Alloc() or M:RangeAlloc(uint count).

public static ReservePageRange ( void firstPage, uint pages, string name ) : bool
firstPage	void
pages	uint	/// The amount of pages to reserve. ///
name	string
return	bool

SetPageAttributes() public static method

public static SetPageAttributes ( void page, uint granularity, PageAttributes attr ) : Errors
page	void
granularity	uint
attr	PageAttributes
return	Errors

Setup() public static method

Initializes page management and paging. Using Alloc and related management functions before calling this function results in a kernel panic. After this function is called, the ReservePage and ReservePageRange functions can be used to reserve memory that should not be allocated. You should ensure that no memory allocations have happened between calling this function and reserving memory.

public static Setup ( byte kernelOffset, uint _kernelSize, uint totalKbMem ) : void
kernelOffset	byte
_kernelSize	uint
totalKbMem	uint
return	void