UniqueId.cxx

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/*------------------------------------------------------------------------------
 
    Copyright (c) 2004 Media Development Loan Fund
  
    This file is part of the Campcaster project.
    https://www.campware.org/
    To report bugs, send an e-mail to [email protected]
  
    Campcaster is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
   
    Campcaster is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
  
    You should have received a copy of the GNU General Public License
    along with Campcaster; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  
  
    Author   : $Author: fgerlits $
    Version  : $Revision: 2329 $
    Location : $URL: svn://code.campware.org/campcaster/trunk/campcaster/src/modules/core/src/UniqueId.cxx $
 
------------------------------------------------------------------------------*/

/* ============================================================ include files */

#ifdef HAVE_CONFIG_H
 #include "configure.h"
#endif
 
#include <cstdlib>

#include "LiveSupport/Core/Uuid.h"
#include "LiveSupport/Core/Md5.h"
#include "LiveSupport/Core/UniqueId.h"


using namespace LiveSupport::Core;

/* ===================================================  local data structures */


/* ================================================  local constants & macros */


/* ===============================================  local function prototypes */


/* =============================================================  module code */

/*------------------------------------------------------------------------------
 *  Generate a globally unique id.
 *----------------------------------------------------------------------------*/
Ptr<UniqueId>::Ref
UniqueId :: generateId(void)                        throw ()
{
    Ptr<Uuid>::Ref      uuid = Uuid::generateId();
    // as uuid is 128 bits, but we have only 63 bits, create an md5 hash
    // (which is still 128 bits), and use its values to create a 63 value
    // hopefully this is unique enough
    Md5                 md5((std::string)*uuid);
    uint64_t            idValue;

    idValue  = md5.high64bits();
    idValue += md5.low64bits();
    // make sure it's 63 bits only, so that signed 64 bit containers can
    // also accept it
    idValue &= 0x7fffffffffffffffLL;

    Ptr<UniqueId>::Ref  id(new UniqueId(idValue));

    return id;
}

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