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{
Basic heap handling for windows platforms
This file is part of the Free Pascal run time library.
Copyright (c) 2001-2005 by Free Pascal development team
See the file COPYING.FPC, included in this distribution,
for details about the copyright.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
**********************************************************************}
{*****************************************************************************
OS Memory allocation / deallocation
****************************************************************************}
{ In kernel mode we can either use FPC's build in memory manager or we use a
custom non-chunking manager. The problem with the build in one is that the
driver developer has far less control of the allocated memory blocks. }
{ memory functions }
{$ifdef KMODE}
function ExAllocatePoolWithTag(PoolType: LongInt; NumberOfBytes: PtrUInt; Tag: LongWord): Pointer; stdcall; external ntdll name 'ExAllocatePoolWithTag';
procedure ExFreePoolWithTag(P: Pointer; Tag: LongWord); stdcall; external ntdll name 'ExFreePoolWithTag';
{$else KMODE}
function RtlAllocateHeap(hHeap : THandle; dwFlags : LongWord; Size : Longword): Pointer;
stdcall; external ntdll name 'RtlAllocateHeap';
function RtlFreeHeap(hHeap : THandle; dwFlags : LongWord; MemoryPointer : Pointer): Boolean;
stdcall; external ntdll name 'RtlFreeHeap';
function RtlCreateHeap(Flags: LongWord; Base: Pointer; SizeToReserve: PtrUInt;
SizeToCommit: PtrUInt; Lock: Pointer; Parameters: Pointer): THandle;
stdcall; external ntdll name 'RtlCreateHeap';
var
SysHeap: THandle = 0;
procedure PrepareSysHeap;
begin
if IsLibrary then
// create a new heap (flag is HEAP_GROWABLE)
SysHeap := RtlCreateHeap(2, Nil, 65534, 65534, Nil, Nil)
else
// use the heap passed on startup
SysHeap := THandle(PSimplePEB(CurrentPEB)^.ProcessHeap);
end;
{$endif KMODE}
{$ifndef KMODE}
// default memory manager
function SysOSAlloc(size: ptruint): pointer;
begin
if SysHeap = 0 then
PrepareSysHeap;
SysOSAlloc := RtlAllocateHeap(SysHeap, 0, size);
end;
{$define HAS_SYSOSFREE}
procedure SysOSFree(p: pointer; size: ptruint);
begin
// if heap isn't set, then nothing was allocated
if SysHeap <> 0 then
RtlFreeHeap(SysHeap, 0, p);
end;
{$else KMODE}
// custom non-chunking memory manager for kernel mode
// memory layout:
// <PtrUInt>: Size of reserved chunk
// <Tag>: Tag that was used in ExAllocateFromPoolWithTag (needed in free)
// <...>: Userdata
function SysGetMem(Size: PtrUInt): Pointer;
var
tag: LongWord;
pooltype: LongInt;
begin
if HeapUsePagedPool then
pooltype := 1
else
pooltype := 0;
tag := Ord(HeapPoolTag[1]) + Ord(HeapPoolTag[2]) shl 8 +
Ord(HeapPoolTag[3]) shl 16 + Ord(HeapPoolTag[4]) shl 24;
// the kernel keeps track of our memory, but there's no way to ask it
// so we need to track the size by ourself
SysGetMem := ExAllocatePoolWithTag(pooltype, Size + SizeOf(PtrUInt) + SizeOf(LongWord), tag);
// save the size
PPtrUInt(SysGetMem)^ := Size;
SysGetMem := SysGetMem + SizeOf(PtrUInt);
// save the tag
PLongWord(SysGetMem)^ := tag;
SysGetMem := SysGetMem + SizeOf(LongWord);
end;
function SysFreeMem(p: Pointer): PtrUInt;
var
tag: PLongWord;
begin
tag := p - SizeOf(LongWord);
// we need to pass the tag we used to allocate the memory (else: BSOD)
ExFreePoolWithTag(p - SizeOf(PtrUInt) - SizeOf(LongWord), tag^);
SysFreeMem := 0;
end;
function SysFreeMemSize(p: Pointer; Size: PtrUInt): PtrUInt;
begin
SysFreeMemSize := 0;
if (Size > 0) and (p <> nil) then
Result := SysFreeMem(p);
end;
Function SysAllocMem(Size: PtrUInt): Pointer;
begin
SysAllocMem := SysGetMem(Size);
if SysAllocMem <> nil then
FillChar(SysAllocMem^, Size, 0);
end;
Function SysReAllocMem (var p: pointer; Size: PtrUInt): Pointer;
begin
SysReAllocMem := SysGetMem(Size);
Move(p^, SysReAllocMem^, Size);
p := SysReAllocMem;
end;
function SysTryResizeMem(var p: Pointer; size: PtrUInt): Boolean;
var
res: pointer;
begin
res := SysGetMem(Size);
SysTryResizeMem := (res <> Nil) or (Size = 0);
if SysTryResizeMem then
p := res;
end;
function SysMemSize(P : pointer): PtrUInt;
begin
SysMemSize := PPtrUInt(P - SizeOf(PtrUInt) - SizeOf(LongWord))^;
end;
function SysGetHeapStatus: THeapStatus;
begin
FillChar(SysGetHeapStatus, SizeOf(SysGetHeapStatus), 0);
end;
function SysGetFPCHeapStatus: TFPCHeapStatus;
begin
FillChar(SysGetFPCHeapStatus, SizeOf(SysGetHeapStatus), 0);
end;
{$endif KMODE}
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