--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/symport/e32/include/e32shbufcmn.h	Thu Jun 25 15:59:54 2009 +0100
@@ -0,0 +1,176 @@
+// Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).
+// All rights reserved.
+// This component and the accompanying materials are made available
+// under the terms of the License "Symbian Foundation License v1.0"
+// which accompanies this distribution, and is available
+// at the URL "http://www.symbianfoundation.org/legal/sfl-v10.html".
+//
+// Initial Contributors:
+// Nokia Corporation - initial contribution.
+//
+// Contributors:
+//
+// Description:
+// e32/include/e32shbufcmn.h
+// Shareable Data Buffers
+
+/**
+	@file
+	@publishedPartner
+	@prototype
+*/
+
+#ifndef E32SHBUFCMN_H
+#define E32SHBUFCMN_H
+
+#include <e32shbuf_priv.h>
+#include <e32def.h>
+
+/**
+	Defines values used to modify client behaviour when opening a pool or buffer in a new process.
+
+	@publishedPartner
+	@prototype
+*/
+enum TShPoolHandleFlags
+	{
+	/**
+	The buffers will be writeable in the process where this handle is used.
+	If not set, the buffers will be read-only.
+	*/
+	EShPoolWriteable		= 0x0001,
+
+	/**
+	The process will be able to allocate buffers from this pool.
+	If not set, the process will not be able to allocate buffers from this pool.
+	*/
+	EShPoolAllocate			= 0x0002,
+	};
+
+
+/**
+	Defines flags for RShBuf::Alloc() and DShPool::Alloc().
+
+	@see RShBuf::Alloc()
+	@see DShPool::Alloc()
+
+	@publishedPartner
+	@prototype
+*/
+enum TShPoolAllocFlags
+	{
+	/**
+	The thread is willing to wait for a pool grow if no buffer is immediately available.
+	If this is not set, the Alloc() will return immediately if no free buffer is available,
+	but the pool might be able to grow to create new buffers.
+	*/
+	EShPoolAllocCanWait = 0x0001,
+
+	/**
+	Do not automatically map the newly-allocated buffer into this process, if the pool is page-aligned.
+	(RShBuf::Alloc() only.)
+	*/
+	EShPoolAllocNoMap = 0x0002,
+	};
+
+
+/**
+	Defines the attributes of a pool.
+
+	@publishedPartner
+	@prototype
+*/
+class TShPoolInfo
+	{
+public:
+	IMPORT_C TShPoolInfo();
+
+	/**
+	Specifies the size of each buffer in the pool.
+	*/
+	TUint iBufSize;
+
+	/**
+	Specifies the initial number of buffers to be allocated to the pool.
+	*/
+	TUint iInitialBufs;
+
+	/**
+	Specifies the maximum number of buffers the pool can grow to.
+	*/
+	TUint iMaxBufs;
+
+	/**
+	This specifies when the pool grows.  If zero, the pool will not grow or shrink
+	automatically.
+  
+	This is the proportion of free buffers left in the pool at which it should be grown.
+	For example, if the ratio is 0.1, the pool will be grown when the number of free
+	buffers drops to 10%.
+
+	This value is expressed as a 32-bit fixed-point number, where the binary
+	point is defined to be between bits 7 and 8 (where the least-significant
+	bit is defined as bit 0).  (This format is also known as a Q8, or fx24.8
+	number, or alternatively as the value * 256.)  For the example given of 10%,
+	use the value 26.  It represents a value < 1 (i.e. must be < 256).  Calculations
+	are rounded down towards zero, but if calculating how many buffers to trigger
+	on gives 0, the grow will be triggered when 1 buffer is free.
+	*/
+	TUint iGrowTriggerRatio;
+
+	/**
+	This specifies the proportion by which to grow the pool each time it is grown.
+	If zero, the pool will not grow or shrink automatically.
+
+	It is expressed as a 32-bit fx24.8 fixed-point number, in the same way as
+	iGrowTriggerRatio.  Calculations are rounded down towards zero, but if calculating
+	how many buffers to grow by yields 0, then the pool will be grown by 1 buffer.
+	*/
+	TUint iGrowByRatio;
+
+	/**
+	The hysteresis value to ensure that the pool does not automatically shrink
+	immediately after is grows.
+
+	Automatic shrinking will only happen when there are (iGrowTriggerRatio +
+	iGrowByRatio) * iShrinkHysteresisRatio * (total buffers in the pool) free
+	buffers left in the pool.
+
+	The amount by which the pool is shrunk depends on iGrowByRatio: it is the operational
+	inverse, such that the pool would shrink down to the same number of buffers if shrunk
+	immediately after growing (although hysteresis normally prevents this).
+
+	For example, if iGrowByRatio is 10%, a pool of 100 buffers would grow to 110 buffers.
+	To shrink back to 100, a shrink ratio of 10/110 = 9% is required.  That is, if the
+	grow-by ration is G, the shrink-by ratio S is calculated as S = 1 - 1 / (1 + G).
+
+	iShrinkHysteresisRatio is a 32-bit fx24.8 fixed-point number in the same way as
+	iGrowTriggerRatio and iGrowByRatio.  It represents a value > 1 (i.e. must be > 256).
+
+	@see iGrowByRatio
+	*/
+	TUint iShrinkHysteresisRatio;
+
+	/**
+	Specifies the alignment for each buffer, as a shift count (log2 bytes).
+
+	For example, 9 means that each buffer is aligned on a 512-byte boundary.
+	*/
+	TUint iAlignment;
+
+	/**
+	Specifies flags for the pool, as bit values from TShPoolCreateFlags or-ed together.
+
+	@see TShPoolCreateFlags
+	*/
+	TUint iFlags;
+private:
+	TInt iSpare1;			// Reserved for future use
+	TInt iSpare2;
+	TInt iSpare3;
+	TInt iSpare4;
+	};
+
+
+#endif	// E32SHBUF_H
+