158 lines
3.2 KiB
C
158 lines
3.2 KiB
C
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/**************************************************************************************************
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FILENAME: Alloc.h
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COPYRIGHT<EFBFBD> 2001 Microsoft Corporation and Executive Software International, Inc.
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**************************************************************************************************/
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#ifndef _ALLOC_H_
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#define _ALLOC_H_
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//Allocates or reallocates a memory block automatically handling locking of the pointer etc.
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BOOL
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AllocateMemory(
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IN DWORD SizeInBytes,
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IN OUT PHANDLE phMemory,
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IN OUT PVOID* ppMemory
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);
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struct _SA_CONTEXT;
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struct _SLAB_HEADER;
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struct _PACKET_HEADER;
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//
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// This is the general slab allocator context.
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//
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typedef struct _SA_CONTEXT {
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//
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// Doubly linked list of allocated slabs
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//
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struct _SLAB_HEADER *pAllocatedSlabs;
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//
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// We keep up to two freed slabs lying around
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//
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struct _SLAB_HEADER *pFreeSlabs;
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//
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// Size of a packet in bytes
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//
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DWORD dwPacketSize;
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//
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// Size of a slab in bytes, usually a multiple of the page size.
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//
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DWORD dwSlabSize;
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//
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// Packets per slab
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//
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DWORD dwPacketsPerSlab;
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} SA_CONTEXT, *PSA_CONTEXT;
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//
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// Small header at the top of the page, which contains the slab flink/blink,
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// and a pointer to the free packets in the slab
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//
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typedef struct _SLAB_HEADER {
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//
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// Doubly linked list flink blinks.
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//
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struct _SLAB_HEADER *pNext;
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struct _SLAB_HEADER *pPrev;
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//
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// List of freed packets in this slab. Note that this is the list of
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// packets that were allocated and freed. Packets that have never
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// been allocated so far are not on this list.
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//
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struct _PACKET_HEADER *pFree;
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//
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// Number of unallocated/freed packets in this slab. 0 if slab is full.
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//
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DWORD dwFreeCount;
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} SLAB_HEADER, *PSLAB_HEADER;
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//
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// Header at the top of a packet
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//
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typedef struct _PACKET_HEADER {
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union {
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//
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// In "brand new" packets (ie packets that have never been allocated),
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// the packet header contains garbage.
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//
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//
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// In allocated packets, the packet header contains a pointer back
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// to the slab header
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//
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struct _SLAB_HEADER *pSlab;
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//
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// In packets that have been allocated and freed, the packet header
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// contains a pointer to the next freed pointer. (Packets are put
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// on a singly linked list when they are freed.)
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//
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struct _PACKET_HEADER *pNext;
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};
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} PACKET_HEADER, *PPACKET_HEADER;
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//
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// Returns a packet of size SIZE_OF_PACKET bytes. May return NULL if the
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// system is out of free memory.
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//
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PVOID
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SaAllocatePacket(
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IN OUT PSA_CONTEXT pSaContext
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);
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//
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// Frees a packet allocated by SaAllocatePacket.
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//
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VOID
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SaFreePacket(
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IN PSA_CONTEXT pSaContext,
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IN PVOID pMemory
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);
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//
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// Frees all slabs currently in use
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//
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VOID
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SaFreeAllPackets(
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IN OUT PSA_CONTEXT pSaContext
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);
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//
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// Initialises a slab-allocator context.
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//
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BOOL
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SaInitialiseContext(
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IN OUT PSA_CONTEXT pSaContext,
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IN CONST DWORD dwPacketSize,
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IN CONST DWORD dwSlabSize
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);
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//
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// Frees all memory associated with a context, and resets the context
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//
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VOID
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SaFreeContext(
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IN OUT PSA_CONTEXT pSaContext
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);
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#endif
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