153 lines
4.5 KiB
C++
153 lines
4.5 KiB
C++
/*
|
|
*
|
|
* @APPLE_LICENSE_HEADER_START@
|
|
*
|
|
* Copyright (c) 1999-2008 Apple Inc. All Rights Reserved.
|
|
*
|
|
* This file contains Original Code and/or Modifications of Original Code
|
|
* as defined in and that are subject to the Apple Public Source License
|
|
* Version 2.0 (the 'License'). You may not use this file except in
|
|
* compliance with the License. Please obtain a copy of the License at
|
|
* http://www.opensource.apple.com/apsl/ and read it before using this
|
|
* file.
|
|
*
|
|
* The Original Code and all software distributed under the License are
|
|
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
|
|
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
|
|
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
|
|
* Please see the License for the specific language governing rights and
|
|
* limitations under the License.
|
|
*
|
|
* @APPLE_LICENSE_HEADER_END@
|
|
*
|
|
*/
|
|
/*
|
|
File: SequenceNumberMap.cpp
|
|
|
|
Contains: Implements object defined in SequenceNumberMap.h.
|
|
|
|
|
|
|
|
|
|
*/
|
|
|
|
#include <string.h>
|
|
#include "MyAssert.h"
|
|
#include "OSMemory.h"
|
|
|
|
#include "SequenceNumberMap.h"
|
|
|
|
SequenceNumberMap::SequenceNumberMap(UInt32 inSlidingWindowSize)
|
|
: fSlidingWindow(NULL),
|
|
fWindowSize( (SInt32) inSlidingWindowSize),
|
|
fNegativeWindowSize( (SInt32) inSlidingWindowSize - (SInt32) (2 * inSlidingWindowSize)),
|
|
fHighestSeqIndex(0),
|
|
fHighestSeqNumber(0)
|
|
{
|
|
Assert(fNegativeWindowSize < 0);
|
|
Assert(fWindowSize < 32768);//AddSequenceNumber makes this assumption
|
|
|
|
}
|
|
|
|
Bool16 SequenceNumberMap::AddSequenceNumber(UInt16 inSeqNumber)
|
|
{
|
|
// Returns whether sequence number has already been added.
|
|
|
|
//Check to see if object has been initialized
|
|
if (fSlidingWindow == NULL)
|
|
{
|
|
fSlidingWindow = NEW Bool16[fWindowSize + 1];
|
|
::memset(fSlidingWindow, 0, fWindowSize * sizeof(Bool16));
|
|
fHighestSeqIndex = 0;
|
|
fHighestSeqNumber = inSeqNumber;
|
|
}
|
|
|
|
// First check to see if this sequence number is so far below the highest sequence number
|
|
// we can't even put it in the sliding window.
|
|
|
|
SInt16 theWindowOffset = inSeqNumber - fHighestSeqNumber;
|
|
|
|
if (theWindowOffset < fNegativeWindowSize)
|
|
return false;//We don't know, but for safety, assume we haven't seen it.
|
|
|
|
// If this seq # is higher thn the highest previous, set the highest to be this
|
|
// new sequence number, and zero out our sliding window as we go.
|
|
|
|
while (theWindowOffset > 0)
|
|
{
|
|
fHighestSeqNumber++;
|
|
|
|
fHighestSeqIndex++;
|
|
if (fHighestSeqIndex == fWindowSize)
|
|
fHighestSeqIndex = 0;
|
|
fSlidingWindow[fHighestSeqIndex] = false;
|
|
|
|
theWindowOffset--;
|
|
}
|
|
|
|
// Find the right entry in the sliding window for this sequence number, taking
|
|
// into account that we may need to wrap.
|
|
|
|
SInt32 theWindowIndex = fHighestSeqIndex + theWindowOffset;
|
|
if (theWindowIndex < 0)
|
|
theWindowIndex += fWindowSize;
|
|
|
|
Assert(theWindowIndex >= 0);
|
|
Assert(theWindowIndex < fWindowSize);
|
|
|
|
// Turn this index on, return whether it was already turned on.
|
|
Bool16 alreadyAdded = fSlidingWindow[theWindowIndex];
|
|
fSlidingWindow[theWindowIndex] = true;
|
|
#if SEQUENCENUMBERMAPTESTING
|
|
//if (alreadyAdded)
|
|
// qtss_printf("Found a duplicate seq num. Num = %d\n", inSeqNumber);
|
|
#endif
|
|
return alreadyAdded;
|
|
}
|
|
|
|
#if SEQUENCENUMBERMAPTESTING
|
|
void SequenceNumberMap::Test()
|
|
{
|
|
SequenceNumberMap theMap1;
|
|
Bool16 retval = theMap1.AddSequenceNumber(64674);
|
|
Assert(retval == false);
|
|
|
|
retval = theMap1.AddSequenceNumber(64582);
|
|
Assert(retval == false);
|
|
|
|
retval = theMap1.AddSequenceNumber(64777);
|
|
Assert(retval == false);
|
|
|
|
retval = theMap1.AddSequenceNumber(64582);
|
|
Assert(retval == TRUE);
|
|
|
|
retval = theMap1.AddSequenceNumber(64674);
|
|
Assert(retval == TRUE);
|
|
|
|
retval = theMap1.AddSequenceNumber(1);
|
|
Assert(retval == FALSE);
|
|
|
|
retval = theMap1.AddSequenceNumber(65500);
|
|
Assert(retval == FALSE);
|
|
|
|
retval = theMap1.AddSequenceNumber(65500);
|
|
Assert(retval == FALSE);
|
|
|
|
retval = theMap1.AddSequenceNumber(32768);
|
|
Assert(retval == FALSE);
|
|
|
|
retval = theMap1.AddSequenceNumber(1024);
|
|
Assert(retval == FALSE);
|
|
|
|
retval = theMap1.AddSequenceNumber(32757);
|
|
Assert(retval == FALSE);
|
|
|
|
retval = theMap1.AddSequenceNumber(32799);
|
|
Assert(retval == FALSE);
|
|
|
|
retval = theMap1.AddSequenceNumber(32768);
|
|
Assert(retval == FALSE);
|
|
|
|
}
|
|
#endif
|