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/*
* SIP Communicator, the OpenSource Java VoIP and Instant Messaging client.
*
* Distributable under LGPL license.
* See terms of license at gnu.org.
*/
package net.java.sip.communicator.impl.neomedia.audiolevel;
/**
* The class implements a basic mapping utility that allows binding
* <tt>long</tt> CSRC ID-s to <tt>int</tt> audio levels. The class does not
* implement any synchronization for neither read nor write operations but it
* is still intended to handle concurrent access in a manner that can be
* considered graceful for the audio level use case. The class uses a
* bi-dimensional <tt>long[][]</tt> matrix that is recreated every time a
* new CSRC is added or an existing one is removed. Iterating through the
* matrix is only possible after obtaining a direct reference to it. It is
* possible for this reference to become invalid shortly after someone has
* obtained it (e.g. because someone added a new CSRC) but this should not
* cause problems for the CSRC audio level delivery case.
*
* @author Emil Ivov
*/
public class AudioLevelMap
{
/**
* The matrix containing a CSRC-to-level mappings.
*/
private long[][] levels = null;
/**
* If this map already contains <tt>csrc</tt> this method updates its level,
* otherwise we add a new entry mapping <tt>csrc</tt> to <tt>level</tt>.
*
* @param csrc the CSRC key that we'd like to add/update.
* @param level the new audio level for the specified <tt>csrc</tt>.
*/
public void putLevel(long csrc, int level)
{
//copy the levels matrix so that no one pulls it from under our feet.
long[][] levelsRef = levels;
int csrcIndex = findCSRC(levelsRef, csrc);
if ( csrcIndex == -1)
{
//we don't have the csrc in there yet so we need a new row.
levels = appendCSRCToMatrix(levelsRef, csrc, level);
}
else
{
levelsRef[csrcIndex][1] = level;
}
}
/**
* Removes <tt>csrc</tt> and it's mapped level from this map.
*
* @param csrc the CSRC ID that we'd like to remove from this map.
*
* @return <tt>true</tt> if <tt>csrc</tt> was present in the <tt>Map</tt>
* and <tt>false</tt> otherwise.
*/
public boolean removeLevel(long csrc)
{
//copy the levels matrix so that no one pulls it from under our feet.
long[][] levelsRef = levels;
int index = findCSRC(levelsRef, csrc);
if ( index == -1)
return false;
if( levelsRef.length == 1)
{
levels = null;
return true;
}
//copy levelsRef into newLevels ref making sure we skip the entry
//containing the CSRC ID that we are trying to remove;
long[][] newLevelsRef = new long[levelsRef.length - 1][2];
for( int j=0, i = 0; i < levelsRef.length; i++ )
{
if(levelsRef[i][0] == csrc)
continue;
newLevelsRef[j][0] = levelsRef[i][0];
newLevelsRef[j][1] = levelsRef[i][1];
}
levels = newLevelsRef;
return true;
}
/**
* Returns the audio level of the specified <tt>csrc</tt> id or <tt>-1</tt>
* if <tt>csrc</tt> is not currently registered in this map.
*
* @param csrc the CSRC ID whose level we'd like to obtain.
*
* @return the audio level of the specified <tt>csrc</tt> id or <tt>-1</tt>
* if <tt>csrc</tt> is not currently registered in this map.
*/
public int getLevel(long csrc)
{
long[][] levelsRef = levels;
int index = findCSRC(levelsRef, csrc);
if( index == -1)
return -1;
return (int)levelsRef[index][1];
}
/**
* Returns a reference to the bi-directional array encapsulated by this map.
* Note that the actual array used by this map may change as soon as this
* method returns and its contents and order may hence no longer correspond
* to those in the returned array.
*
* @return a reference to the bi-directional array encapsulated by this map
* or <tt>null</tt> if the map is still empty.
*/
public long[][] getReference()
{
return levels;
}
/**
* Returns the index of the specified <tt>csrc</tt> level in the
* <tt>levels</tt> matrix or <tt>-1</tt> if <tt>levels</tt> is <tt>null</tt>
* or does not contain <tt>csrc</tt>.
*
* @param levels the bi-dimensional array that we'd like to search for
* the specified <tt>csrc</tt>.
* @param csrc the CSRC identifier that we are looking for.
*
* @return the the index of the specified <tt>csrc</tt> level in the
* <tt>levels</tt> matrix or <tt>-1</tt> if <tt>levels</tt> is <tt>null</tt>
* or does not contain <tt>csrc</tt>.
*/
private int findCSRC(long[][] levels, long csrc)
{
if( levels == null )
return -1;
for (int i = 0; i < levels.length; i++)
{
if (levels [i][0] == csrc)
return i;
}
return -1;
}
/**
* Creates a new bi-dimensional array containing all entries (if any) from
* the <tt>levels</tt> matrix and an extra entry for the specified
* <tt>csrc</tt> and <tt>level</tt>.
*
* @param levels the bi-dimensional levels array that we'd like to add a
* mapping to.
* @param csrc the CSRC identifier that we'd like to add to the
* <tt>levels</tt> bi-dimensional array.
* @param level the level corresponding to the <tt>csrc</tt> identifier.
*
* @return a new matrix containing all entries from levels and a new one
* mapping <tt>csrc</tt> to <tt>level</tt>
*/
private long[][] appendCSRCToMatrix(long[][] levels, long csrc, int level)
{
int newLength = 1;
if( levels != null && levels.length > 0)
{
newLength = levels.length + 1;
}
long[][] newLevels = new long[newLength][2];
//put the new level.
newLevels[0][0] = csrc;
newLevels[0][1] = level;
if( newLength == 1)
return newLevels;
for (int i = 0; i < levels.length; i ++)
{
//csrc
newLevels[i+1][0] = levels [i][0];
//level
newLevels[i+1][1] = levels [i][1];
}
return newLevels;
}
}
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