//*CMZ : 2.00/12 02/10/98 22.48.06 by Rene Brun
//*CMZ : 1.03/09 07/12/97 12.52.14 by Fons Rademakers
//*-- Author : Rene Brun 28/12/94
//*KEEP,CopyRight,T=C.
/*************************************************************************
* Copyright(c) 1995-1999, The ROOT System, All rights reserved. *
* Authors: Rene Brun, Fons Rademakers. *
* For list of contributors see $ROOTSYS/AA_CREDITS. *
* *
* Permission to use, copy, modify and distribute this software and its *
* documentation for non-commercial purposes is hereby granted without *
* fee, provided that the above copyright notice appears in all copies *
* and that both the copyright notice and this permission notice appear *
* in the supporting documentation. The authors make no claims about the *
* suitability of this software for any purpose. It is provided "as is" *
* without express or implied warranty. *
*************************************************************************/
//*KEND.
//*KEEP,TFree.
#include "TFree.h"
//*KEEP,TFile.
#include "TFile.h"
//*KEEP,Bytes.
#include "Bytes.h"
//*KEND.
ClassImp(TFree)
//______________________________________________________________________________
//
// Service class for TFile.
// Each file has a linked list of free segments. Each free segment
// is described by its firts and last address.
// When an object is written to a file via TObject::Write, a new Key (see TKey)
// is created. The first free segment big enough to accomodate the object
// is used.
// If the object size has a length corresponding to the size of the free segment,
// the free segment is deleted from the list of free segments.
// When an object is deleted from a file, a new TFree object is generated.
// If the deleted object is contiguous to an already deleted object, the free
// segments are merged in one single segment.
//
//______________________________________________________________________________
TFree::TFree()
{
//*-*-*-*-*-*-*-*-*-*-*TFree default constructor*-*-*-*-*-*-*-*-*-*-*-*-*
//*-* =========================
}
//______________________________________________________________________________
TFree::TFree(Seek_t first, Seek_t last)
{
//*-*-*-*-*-*-*-*-*-*-*Constructor for a FREE segment*-*-*-*-*-*-*-*-*-*-*-*-*
//*-* ==============================
fFirst = first;
fLast = last;
gFile->GetListOfFree()->Add(this);
}
//______________________________________________________________________________
TFree *TFree::AddFree(Seek_t first, Seek_t last)
{
//*-*-*-*-*-*-*-*-*-*Add a new free segment to the list of free segments*-*-*
//*-* ===================================================
// If last just preceedes an existing free segment, then first becomes
// the new starting location of the free segment.
// if first just follows an existing free segment, then last becomes
// the new ending location of the free segment.
// if first just follows an existing free segment AND last just preceedes
// an existing free segment, these two segments are merged into
// one single segment.
//
TFree *idcur = this;
while (idcur) {
Seek_t curfirst = idcur->GetFirst();
Seek_t curlast = idcur->GetLast();
if (curlast == first-1) {
idcur->SetLast(last);
TFree *idnext = (TFree*)gFile->GetListOfFree()->After(idcur);
if (idnext == 0) return idcur;
if (idnext->GetFirst() > last+1) return idcur;
idcur->SetLast( idnext->GetLast() );
gFile->GetListOfFree()->Remove(idnext);
return idcur;
}
if (curfirst == last+1) {
idcur->SetFirst(first);
return idcur;
}
if (first < curfirst) {
TFree * newfree = new TFree();
newfree->SetFirst(first);
newfree->SetLast(last);
gFile->GetListOfFree()->AddBefore(idcur, newfree);
return newfree;
}
idcur = (TFree*)gFile->GetListOfFree()->After(idcur);
}
return 0;
}
//______________________________________________________________________________
TFree::~TFree()
{
//*-*-*-*-*-*-*-*-*-*-*-*TFree Destructor*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
//*-* ================
}
//______________________________________________________________________________
void TFree::FillBuffer(char *&buffer)
{
//*-*-*-*-*-*-*-*-*-*-*Encode FREE structure into output buffer*-*-*-*-*-*-*
//*-* ========================================
Version_t version = TFree::Class_Version();
tobuf(buffer, version);
tobuf(buffer, fFirst);
tobuf(buffer, fLast);
}
//______________________________________________________________________________
TFree *TFree::GetBestFree(Int_t nbytes)
{
//*-*-*-*-*-*-*-*-*-*Return the best free segment where to store nbytes*-*-*-*
//*-* ==================================================
TFree *idcur = this;
if (idcur == 0) return 0;
TFree *idcur1 = 0;
do {
Int_t nleft = Int_t(idcur->fLast - idcur->fFirst +1);
if (nleft == nbytes) return idcur; //*-* found an exact match
if(nleft > nbytes+3) if (idcur1 == 0) idcur1=idcur;
idcur = (TFree*)gFile->GetListOfFree()->After(idcur);
} while (idcur !=0);
return idcur1; //*-* return first segment >nbytes
}
//______________________________________________________________________________
void TFree::ReadBuffer(char *&buffer)
{
//*-*-*-*-*-*-*-*-*-*-*-*Decode one FREE structure from input buffer*-*-*-*-*
//*-* ===========================================
Version_t version;
frombuf(buffer, &version);
frombuf(buffer, &fFirst);
frombuf(buffer, &fLast);
gFile->GetListOfFree()->Add(this);
}
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