190 lines
4.3 KiB
C++
190 lines
4.3 KiB
C++
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/*++
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Copyright (c) 1997 Microsoft Corporation
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Module Name:
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buffer.h
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Abstract:
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Definition of BUFFER class.
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Author:
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Vlad Sadovsky (vlads) 26-Jan-1997
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Revision History:
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26-Jan-1997 VladS created
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--*/
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#ifndef _INC_BUFFER
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#define _INC_BUFFER
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extern "C"
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{
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# include <windows.h>
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};
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/*************************************************************************
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NAME: BUFFER (buf)
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SYNOPSIS: A resizable object which lives in the application heap.
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Upon construction, the buffer takes a requested size in
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bytes; it allocates storage sufficient to hold that size.
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The client can later change this size with Resize, Trim,
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and FillOut. QuerySize returns the current size of
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the buffer; QueryPtr returns a pointer to its storage.
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Note that a buffer may have size 0, in which case it
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keeps no allocated storage.
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INTERFACE: BUFFER() - Constructor, naming initial size in bytes
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QuerySize() - return size in bytes
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QueryPtr() - return pointer to data buffer
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Resize() - resize the object to the given number
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of bytes. Returns TRUE if the resize was
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successful; otherwise returns FALSE (use
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GetLastError for error code)
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Trim() - force block to occupy no more storage
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than the client has requested.
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PARENT:
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**************************************************************************/
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class BUFFER
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{
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private:
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BYTE * _pb; // pointer to storage
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UINT _cb; // size of storage, as requested by client
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inline VOID VerifyState() const;
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UINT QueryActualSize();
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dllexp BOOL GetNewStorage( UINT cbRequested );
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BOOL ReallocStorage( UINT cbNewlyRequested );
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public:
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dllexp BUFFER( UINT cbRequested = 0 )
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{
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_pb = NULL;
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_cb = 0;
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if ( cbRequested != 0 )
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{
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GetNewStorage(cbRequested);
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}
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}
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dllexp ~BUFFER()
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{
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if ( _pb )
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{
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::LocalFree( (HANDLE) _pb );
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}
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}
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dllexp VOID * QueryPtr() const
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{ return _pb; }
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dllexp UINT QuerySize() const
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{ return _cb; }
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//
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// If a resize is needed, added cbSlop to it
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//
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dllexp BOOL Resize( UINT cbNewReqestedSize,
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UINT cbSlop = 0);
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// The following method deals with the difference between the
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// actual memory size and the requested size. These methods are
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// intended to be used when optimization is key.
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// Trim reallocates the buffer so that the actual space allocated is
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// minimally more than the size requested
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//
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dllexp VOID Trim();
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};
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//
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// This class is a single item in a chain of buffers
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//
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class BUFFER_CHAIN_ITEM : public BUFFER
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{
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friend class BUFFER_CHAIN;
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public:
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dllexp BUFFER_CHAIN_ITEM( UINT cbReq = 0 )
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: BUFFER( cbReq ),
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_cbUsed( 0 )
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{ _ListEntry.Flink = NULL; }
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dllexp ~BUFFER_CHAIN_ITEM()
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{ if ( _ListEntry.Flink )
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RemoveEntryList( &_ListEntry );
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}
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dllexp DWORD QueryUsed( VOID ) const
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{ return _cbUsed; }
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dllexp VOID SetUsed( DWORD cbUsed )
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{ _cbUsed = cbUsed; }
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private:
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LIST_ENTRY _ListEntry;
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DWORD _cbUsed; // Bytes of valid data in this buffer
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};
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class BUFFER_CHAIN
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{
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public:
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dllexp BUFFER_CHAIN()
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{ InitializeListHead( &_ListHead ); }
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dllexp ~BUFFER_CHAIN()
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{ DeleteChain(); }
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dllexp BOOL AppendBuffer( BUFFER_CHAIN_ITEM * pBCI );
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//
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// Returns total number of bytes freed by deleting all of the buffer
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// chain items
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//
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dllexp DWORD DeleteChain();
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//
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// Enums buffer chain. Pass pBCI as NULL on first call, pass return
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// value till NULL on subsequent calls
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//
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dllexp BUFFER_CHAIN_ITEM * NextBuffer( BUFFER_CHAIN_ITEM * pBCI );
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//
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// Gives back total number of bytes allocated by chain (includes unused
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// bytes)
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//
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dllexp DWORD CalcTotalSize( BOOL fUsed = FALSE ) const;
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private:
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LIST_ENTRY _ListHead;
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};
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#endif /* _INC_BUFFER */
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