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made unique id 63 bits, so that signed 64 bit containers can hold it

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maroy 2005-04-28 15:01:33 +00:00
parent 0520d5b516
commit df15345907
1 changed files with 12 additions and 4 deletions
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16
livesupport/modules/core/src/UniqueId.cxx
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@ -22,7 +22,7 @@
Author : $Author: maroy $
Version : $Revision: 1.3 $
Version : $Revision: 1.4 $
Location : $Source: /home/paul/cvs2svn-livesupport/newcvsrepo/livesupport/modules/core/src/UniqueId.cxx,v $
------------------------------------------------------------------------------*/
@ -60,11 +60,19 @@ Ptr<UniqueId>::Ref
UniqueId :: generateId(void) throw ()
{
Ptr<Uuid>::Ref uuid = Uuid::generateId();
// as uuid is 128 bits, but we have only 64 bits, create an md5 hash
// (which is still 128 bits), and use its values to create a 64 value
// 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);
Ptr<UniqueId>::Ref id(new UniqueId(md5.high64bits() + md5.low64bits()));
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;
}