source: trunk/src/corelib/plugin/quuid.cpp@ 104

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#include "quuid.h"

#include "qdatastream.h"

QT_BEGIN_NAMESPACE

/*!
    \class QUuid
    \brief The QUuid class stores a Universally Unique Identifier (UUID).

    \reentrant
    \ingroup misc

    Using \e{U}niversally \e{U}nique \e{ID}entifiers (UUID) is a
    standard way to uniquely identify entities in a distributed
    computing environment. A UUID is a 16-byte (128-bit) number
    generated by some algorithm that is meant to guarantee that the
    UUID will be unique in the distributed computing environment where
    it is used. The acronym GUID is often used instead, \e{G}lobally
    \e{U}nique \e{ID}entifiers, but it refers to the same thing.

    \target Variant field
    Actually, the GUID is one \e{variant} of UUID. Multiple variants
    are in use. Each UUID contains a bit field that specifies which
    type (variant) of UUID it is. Call variant() to discover which
    type of UUID an instance of QUuid contains. It extracts the three
    most signifcant bits of byte 8 of the 16 bytes. In QUuid, byte 8
    is \c{QUuid::data4[0]}. If you create instances of QUuid using the
    constructor that accepts all the numeric values as parameters, use
    the following table to set the three most significant bits of
    parameter \c{b1}, which becomes \c{QUuid::data4[0]} and contains
    the variant field in its three most significant bits. In the
    table, 'x' means \e {don't care}.

    \table
    \header
    \o msb0
    \o msb1
    \o msb2
    \o Variant 

    \row
    \o 0
    \o x
    \o x
    \o NCS (Network Computing System)

    \row
    \o 1
    \o 0
    \o x
    \o DCE (Distributed Computing Environment)

    \row
    \o 1
    \o 1
    \o 0
    \o Microsoft (GUID)

    \row
    \o 1
    \o 1
    \o 1
    \o Reserved for future expansion

    \endtable