/****************************************************************************

** 

**

** Implementation of QDataStream class

**

** Created : 930831

**

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#include "qdatastream.h"

#ifndef QT_NO_DATASTREAM

#include "qbuffer.h"

#include <stdio.h>

#include <ctype.h>

#include <stdlib.h>

// REVISED: warwick

/*!

  \class QDataStream qdatastream.h

  \brief The QDataStream class provides serialization of

  binary data to a QIODevice.

  \ingroup io

  A data stream is a binary stream of encoded information which is 100%

  independent of the host computer operation system, CPU or byte order.	 A

  stream that is written by a PC under DOS/Windows can be read by a

  Sun SPARC running Solaris.

  The QDataStream class implements serialization of primitive types, like

  \c char, \c short, \c int, \c char* etc.  Serialization of more complex

  data is accomplished by breaking up the data into primitive units.

  The programmer can select which byte order to use when serializing data.

  The default setting is big endian (MSB first). Changing it to little

  endian breaks the portability (unless the reader also changes to little

  endian).  We recommend keeping this setting unless you have

  special requirements.

  A data stream cooperates closely with a QIODevice. A QIODevice

  represents an input/output medium one can read data from and write data

  to.  The QFile class is an example of an IO device.

  Example (write data to a stream):

  \code

    QFile f( "file.dta" );

    f.open( IO_WriteOnly );			// open file for writing

    QDataStream s( &f );			// serialize using f

    s << "the answer is";			// serialize string

    s << (Q_INT32)42;				// serialize integer

  \endcode

  Example (read data from a stream):

  \code

    QFile f( "file.dta" );

    f.open( IO_ReadOnly );			// open file for reading

    QDataStream s( &f );			// serialize using f

    char   *str;

    Q_INT32 a;

    s >> str >> a;				// "the answer is" and 42

    delete str;					// delete string

  \endcode

  In the last example, if you read into a QString instead of a \c char*

  you do not have to delete it.

  Normally, each item written to the stream is written in a fixed binary

  format.

  For example, a \c char* is written as a 32-bit integer equal to the

  length of the string including the NUL byte, followed by all the

  characters of the string including the NUL byte. Similarly when

  reading a string, 4 bytes are read to create the 32-bit length value,

  then that many characters for the string including the NUL. For a complete

  description of all Qt types supporting data streaming see \link

  datastreamformat.html Format of the QDataStream operators \endlink .

  If you want a "parsing" input stream, see QTextStream. If you just want the

  data to be human-readable to aid in debugging, you can set the data

  stream into printable data mode with setPrintableData(). The data is

  then written slower, in a human readable bloated form that is sufficient

  for debugging.

  If you are producing a new binary data format, such as a file format

  for documents created by your application, you could use a QDataStream

  to write the data in a portable format. Typically, you would write

  a brief header containing a magic string and a version number to give

  yourself room for future expansion. For example:

  \code

    // Open the file.

    QFile f( "file.xxx" );

    f.open( IO_WriteOnly );

    QDataStream s( &f );

    // Write a header with a "magic number" and a version

    s << 0xa0b0c0d0;

    s << 123;

    // Write the data

    s << [lots of interesting data]

  \endcode

  Then read it in with:

  \code

    // Open the file.

    QFile f( "file.xxx" );

    f.open( IO_ReadOnly );

    QDataStream s( &f );

    // Read and check the header

    Q_UINT32 magic;

    s >> magic;

    if ( magic != 0xa0b0c0d0 )

	return XXX_BAD_FILE_FORMAT;

    // Read the version

    Q_INT32 version;

    s >> version;

    if ( version < 100 )

	return XXX_BAD_FILE_TOO_OLD;

    if ( version > 123 )

	return XXX_BAD_FILE_TOO_NEW;

    if ( version <= 110 )

	s.setVersion(1);

    // Read the data

    s >> [lots of interesting data];

    if ( version > 120 )

	s >> [data new in XXX version 1.2];

    s >> [other interesting data];

  \endcode

  \sa QTextStream QVariant

*/

/*****************************************************************************

  QDataStream member functions

 *****************************************************************************/

#if defined(CHECK_STATE)

#undef  CHECK_STREAM_PRECOND

#define CHECK_STREAM_PRECOND  if ( !dev ) {				\

				qWarning( "QDataStream: No device" );	\

				return *this; }

#else

#define CHECK_STREAM_PRECOND

#endif

static int  systemWordSize = 0;

static bool systemBigEndian;

static const int DefaultStreamVersion = 3;

// 3 is default in Qt 2.1

// 2 is the Qt 2.0.x format

// 1 is the Qt 1.x format

/*!

  Constructs a data stream that has no IO device.

  \sa setDevice()

*/

QDataStream::QDataStream()

{

    if ( systemWordSize == 0 )			// get system features

	qSysInfo( &systemWordSize, &systemBigEndian );

    dev	      = 0;				// no device set

    owndev    = FALSE;

    byteorder = BigEndian;			// default byte order

    printable = FALSE;

    ver	      = DefaultStreamVersion;

    noswap    = systemBigEndian;

}

/*!

  Constructs a data stream that uses the IO device \a d.

  \sa setDevice(), device()

*/

QDataStream::QDataStream( QIODevice *d )

{

    if ( systemWordSize == 0 )			// get system features

	qSysInfo( &systemWordSize, &systemBigEndian );

    dev	      = d;				// set device

    owndev    = FALSE;

    byteorder = BigEndian;			// default byte order

    printable = FALSE;

    ver	      = DefaultStreamVersion;

    noswap    = systemBigEndian;

}

/*!

  Constructs a data stream that operates on a byte array through an

  internal QBuffer device.

  Example:

  \code

    static char bindata[] = { 231, 1, 44, ... };

    QByteArray	a;

    a.setRawData( bindata, sizeof(bindata) );	// a points to bindata

    QDataStream s( a, IO_ReadOnly );		// open on a's data

    s >> [something];				// read raw bindata

    a.resetRawData( bindata, sizeof(bindata) ); // finished

  \endcode

  The QArray::setRawData() function is not for the inexperienced.

*/

QDataStream::QDataStream( QByteArray a, int mode )

{

    if ( systemWordSize == 0 )			// get system features

	qSysInfo( &systemWordSize, &systemBigEndian );

    dev	      = new QBuffer( a );		// create device

    ((QBuffer *)dev)->open( mode );		// open device

    owndev    = TRUE;

    byteorder = BigEndian;			// default byte order

    printable = FALSE;

    ver	      = DefaultStreamVersion;

    noswap    = systemBigEndian;

}

/*!

  Destructs the data stream.

  The destructor will not affect the current IO device, unless it

  is an internal IO device processing a QByteArray passed in the constructor.

*/

QDataStream::~QDataStream()

{

    if ( owndev )

	delete dev;

}

/*!

  \fn QIODevice *QDataStream::device() const

  Returns the IO device currently set.

  \sa setDevice(), unsetDevice()

*/

/*!

  void QDataStream::setDevice(QIODevice *d )

  Sets the IO device to \a d.

  \sa device(), unsetDevice()

*/

void QDataStream::setDevice(QIODevice *d )

{

    if ( owndev ) {

	delete dev;

	owndev = FALSE;

    }

    dev = d;

}

/*!

  Unsets the IO device.	 This is the same as calling setDevice( 0 ).

  \sa device(), setDevice()

*/

void QDataStream::unsetDevice()

{

    setDevice( 0 );

}

/*!

  \fn bool QDataStream::atEnd() const

  Returns TRUE if the IO device has reached the end position (end of

  stream or file) or if there is no IO device set.

  Returns FALSE if the current position of the read/write head of the IO

  device is somewhere before the end position.

  \sa QIODevice::atEnd()

*/

/*!\fn bool QDataStream::eof() const

  \obsolete

  Returns TRUE if the IO device has reached the end position (end of

  stream or file) or if there is no IO device set.

  Returns FALSE if the current position of the read/write head of the IO

  device is somewhere before the end position.

  \sa QIODevice::atEnd()

*/

/*!

  \fn int QDataStream::byteOrder() const

  Returns the current byte order setting - either \c BigEndian or

  \c LittleEndian.

  \sa setByteOrder()

*/

/*!

  Sets the serialization byte order to \a bo.

  The \a bo parameter can be \c QDataStream::BigEndian or

  \c QDataStream::LittleEndian.

  The default setting is big endian.  We recommend leaving this setting unless

  you have special requirements.

  \sa byteOrder()

*/

void QDataStream::setByteOrder( int bo )

{

    byteorder = bo;

    if ( systemBigEndian )

	noswap = byteorder == BigEndian;

    else

	noswap = byteorder == LittleEndian;

}

/*!

  \fn bool QDataStream::isPrintableData() const

  Returns TRUE if the printable data flag has been set.

  \sa setPrintableData()

*/

/*!

  \fn void QDataStream::setPrintableData( bool enable )

  Sets or clears the printable data flag.

  If this flag is set, the write functions will generate output that

  consists of printable characters (7 bit ASCII).

  We recommend enabling printable data only for debugging purposes

  (it is slower and creates larger output).

*/

/*!

  \fn int QDataStream::version() const

  Returns the version number of the data serialization format.

  In Qt 2.1, this number is by default 3.

  \sa setVersion()

*/

/*!

  \fn void QDataStream::setVersion( int v )

  Sets the version number of the data serialization format.

  In order to accomodate for new functionality, the datastream

  serialization format of some Qt classes has changed in some versions of

  Qt. If you want to read data that was created by an earlier version of

  Qt, or write data that can be read by a program that was compiled with

  an earlier version of Qt, use this function to modify the serialization

  format of QDataStream.

  For Qt 1.x compatibility, use \a v == 1.

  For Qt 2.0.x compatibility, use \a v == 2 (Not required for reading in

  Qt 2.1).

  \sa version()

*/

/*****************************************************************************

  QDataStream read functions

 *****************************************************************************/

static Q_INT32 read_int_ascii( QDataStream *s )

{

    register int n = 0;

    char buf[40];

    while ( TRUE ) {

	buf[n] = s->device()->getch();

	if ( buf[n] == '\n' || n > 38 )		// $-terminator

	    break;

	n++;

    }

    buf[n] = '\0';

    return atol( buf );

}

/*!

  \fn QDataStream &QDataStream::operator>>( Q_UINT8 &i )

  Reads an unsigned byte from the stream and returns a reference to

  the stream.

*/

/*!

  Reads a signed byte from the stream.

*/

QDataStream &QDataStream::operator>>( Q_INT8 &i )

{

    CHECK_STREAM_PRECOND

    if ( printable ) {				// printable data

	i = (Q_INT8)dev->getch();

	if ( i == '\\' ) {			// read octal code

	    char buf[4];

	    dev->readBlock( buf, 3 );

	    i = (buf[2] & 0x07)+((buf[1] & 0x07) << 3)+((buf[0] & 0x07) << 6);

	}

    } else {					// data or text

	i = (Q_INT8)dev->getch();

    }

    return *this;

}

/*!

  \fn QDataStream &QDataStream::operator>>( Q_UINT16 &i )

  Reads an unsigned 16-bit integer from the stream and returns a reference to

  the stream.

*/

/*!

  Reads a signed 16-bit integer from the stream and returns a reference to

  the stream.

*/

QDataStream &QDataStream::operator>>( Q_INT16 &i )

{

    CHECK_STREAM_PRECOND

    if ( printable ) {				// printable data

	i = (Q_INT16)read_int_ascii( this );

    } else if ( noswap ) {			// no conversion needed

	dev->readBlock( (char *)&i, sizeof(Q_INT16) );

    } else {					// swap bytes

	register uchar *p = (uchar *)(&i);

	char b[2];

	dev->readBlock( b, 2 );

	*p++ = b[1];

	*p   = b[0];

    }

    return *this;

}

/*!

  \fn QDataStream &QDataStream::operator>>( Q_UINT32 &i )

  Reads an unsigned 32-bit integer from the stream and returns a reference to

  the stream.

*/

/*!

  Reads a signed 32-bit integer from the stream and returns a reference to

  the stream.

*/

QDataStream &QDataStream::operator>>( Q_INT32 &i )

{

    CHECK_STREAM_PRECOND

    if ( printable ) {				// printable data

	i = read_int_ascii( this );

    } else if ( noswap ) {			// no conversion needed

	dev->readBlock( (char *)&i, sizeof(Q_INT32) );

    } else {					// swap bytes

	register uchar *p = (uchar *)(&i);

	char b[4];

	dev->readBlock( b, 4 );

	*p++ = b[3];

	*p++ = b[2];

	*p++ = b[1];

	*p   = b[0];

    }

    return *this;

}

/*!

  \fn QDataStream &QDataStream::operator>>( Q_UINT64 &i )

  Reads an unsigned 64-bit integer from the stream and returns a reference to

  the stream, or uses the Q_UINT32 operator if 64 bit is not available.

*/

/*!

  Reads a signed 64-bit integer from the stream and returns a reference to

  the stream, or uses the Q_UINT32 operator if 64 bit is not available.

*/

QDataStream &QDataStream::operator>>( Q_INT64 &i )

{

    CHECK_STREAM_PRECOND

    if ( printable ) {				// printable data

	i = read_int_ascii( this );

    } else if ( noswap ) {			// no conversion needed

	dev->readBlock( (char *)&i, sizeof(Q_INT64) );

    } else {					// swap bytes

	register uchar *p = (uchar *)(&i);

	char b[sizeof(Q_INT64)];

	dev->readBlock( b, sizeof(Q_INT64) );

	if ( sizeof(Q_INT64) == 8 ) {

	    *p++ = b[7];

	    *p++ = b[6];