/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ /* ***** BEGIN LICENSE BLOCK ***** * Version: NPL 1.1/GPL 2.0/LGPL 2.1 * * The contents of this file are subject to the Netscape Public License * Version 1.1 (the "License"); you may not use this file except in * compliance with the License. You may obtain a copy of the License at * http://www.mozilla.org/NPL/ * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is mozilla.org code. * * The Initial Developer of the Original Code is * Netscape Communications Corporation. * Portions created by the Initial Developer are Copyright (C) 1998 * the Initial Developer. All Rights Reserved. * * Contributor(s): * * Alternatively, the contents of this file may be used under the terms of * either the GNU General Public License Version 2 or later (the "GPL"), or * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), * in which case the provisions of the GPL or the LGPL are applicable instead * of those above. If you wish to allow use of your version of this file only * under the terms of either the GPL or the LGPL, and not to allow others to * use your version of this file under the terms of the NPL, indicate your * decision by deleting the provisions above and replace them with the notice * and other provisions required by the GPL or the LGPL. If you do not delete * the provisions above, a recipient may use your version of this file under * the terms of any one of the NPL, the GPL or the LGPL. * * ***** END LICENSE BLOCK ***** */ #ifndef nsSegmentedBuffer_h__ #define nsSegmentedBuffer_h__ #include "nsMemory.h" #include "prclist.h" class nsSegmentedBuffer { public: nsSegmentedBuffer() : mSegmentSize(0), mMaxSize(0), mSegAllocator(nsnull), mSegmentArray(nsnull), mSegmentArrayCount(0), mFirstSegmentIndex(0), mLastSegmentIndex(0) {} ~nsSegmentedBuffer() { Empty(); NS_IF_RELEASE(mSegAllocator); } NS_COM nsresult Init(PRUint32 segmentSize, PRUint32 maxSize, nsIMemory* allocator = nsnull); NS_COM char* AppendNewSegment(); // pushes at end // returns true if no more segments remain: PRBool DeleteFirstSegment(); // pops from beginning // returns true if no more segments remain: PRBool DeleteLastSegment(); // pops from beginning // Call Realloc() on last segment. This is used to reduce memory // consumption when data is not an exact multiple of segment size. PRBool ReallocLastSegment(size_t newSize); NS_COM void Empty(); // frees all segments NS_COM PRUint32 GetSegmentCount() { if (mFirstSegmentIndex <= mLastSegmentIndex) return mLastSegmentIndex - mFirstSegmentIndex; else return mSegmentArrayCount + mLastSegmentIndex - mFirstSegmentIndex; } NS_COM PRUint32 GetSegmentSize() { return mSegmentSize; } PRUint32 GetMaxSize() { return mMaxSize; } PRUint32 GetSize() { return GetSegmentCount() * mSegmentSize; } NS_COM char* GetSegment(PRUint32 indx) { NS_ASSERTION(indx < GetSegmentCount(), "index out of bounds"); PRInt32 i = ModSegArraySize(mFirstSegmentIndex + (PRInt32)indx); return mSegmentArray[i]; } protected: PRInt32 ModSegArraySize(PRInt32 n) { PRUint32 result = n & (mSegmentArrayCount - 1); NS_ASSERTION(result == n % mSegmentArrayCount, "non-power-of-2 mSegmentArrayCount"); return result; } PRBool IsFull() { return ModSegArraySize(mLastSegmentIndex + 1) == mFirstSegmentIndex; } protected: PRUint32 mSegmentSize; PRUint32 mMaxSize; nsIMemory* mSegAllocator; char** mSegmentArray; PRUint32 mSegmentArrayCount; PRInt32 mFirstSegmentIndex; PRInt32 mLastSegmentIndex; }; // NS_SEGMENTARRAY_INITIAL_SIZE: This number needs to start out as a // power of 2 given how it gets used. We double the segment array // when we overflow it, and use that fact that it's a power of 2 // to compute a fast modulus operation in IsFull. // // 32 segment array entries can accommodate 128k of data if segments // are 4k in size. That seems like a reasonable amount that will avoid // needing to grow the segment array. #define NS_SEGMENTARRAY_INITIAL_COUNT 32 #endif // nsSegmentedBuffer_h__