Detailed Description

This CStream derived class allow using a memory buffer as a CStream.

This class is useful for storing any required set of variables or objects, and then read them to other objects, or storing them to a file, for example.

See also:: CStream

#include <mrpt/utils/CMemoryStream.h>

Inheritance diagram for mrpt::utils::CMemoryStream:

[legend]

List of all members.

Public Types

enum TSeekOrigin { sFromBeginning = 0, sFromCurrent = 1, sFromEnd = 2 }

Used in CStream::Seek. More...

Public Member Functions

CMemoryStream ()

Default constructor.

CMemoryStream (const void *data, const uint64_t nBytesInData)

Constructor to initilize the data in the stream from a block of memory (which is copied), and sets the current stream position at the beginning of the data.

void assignMemoryNotOwn (const void *data, const uint64_t nBytesInData)

Initilize the data in the stream from a block of memory which is NEITHER OWNED NOR COPIED by the object, so it must exist during the whole live of the object.

virtual ~CMemoryStream ()

Destructor.

void Clear ()

Clears the memory buffer.

void changeSize (uint64_t newSize)

Change size.

uint64_t Seek (long Offset, CStream::TSeekOrigin Origin=sFromBeginning)

Method for moving to a specified position in the streamed resource.

uint64_t getTotalBytesCount ()

Returns the total size of the internal buffer.

uint64_t getPosition ()

Method for getting the current cursor position, where 0 is the first byte and TotalBytesCount-1 the last one.

void * getRawBufferData ()

Method for getting a pointer to the raw stored data.

bool saveBufferToFile (const std::string &file_name)

Saves the entire buffer to a file.

bool loadBufferFromFile (const std::string &file_name)

Loads the entire buffer from a file.

void setAllocBlockSize (uint64_t alloc_block_size)

Change the size of the additional memory block that is reserved whenever the current block runs too short (default=0x10000 bytes)

size_t ReadBuffer (void *Buffer, size_t Count)

Reads a block of bytes from the stream into Buffer

Exceptions:

std::exception On any error, or if ZERO bytes are read.

template<typename T >

size_t ReadBufferFixEndianness (T *ptr, size_t ElementCount)

Reads a sequence of elemental datatypes, taking care of reordering their bytes from the MRPT stream standard (little endianness) to the format of the running architecture.

virtual size_t ReadBufferImmediate (void *Buffer, size_t Count)

Reads a block of bytes from the stream into Buffer, and returns the amound of bytes actually read, without waiting for more extra bytes to arrive (just those already enqued in the stream).

void WriteBuffer (const void *Buffer, size_t Count)

Writes a block of bytes to the stream from Buffer.

template<typename T >

void WriteBufferFixEndianness (const T *ptr, size_t ElementCount)

Writes a sequence of elemental datatypes, taking care of reordering their bytes from the running architecture to MRPT stream standard (little endianness).

size_t CopyFrom (CStream *Source, size_t Count)

Copies a specified number of bytes from one stream to another.

void WriteObject (const CSerializable *o)

Writes an object to the stream.

CSerializablePtr ReadObject ()

Reads an object from stream, its class determined at runtime, and returns a smart pointer to the object.

void ReadObject (CSerializable *existingObj)

Reads an object from stream, where its class must be the same as the supplied object, where the loaded object will be stored in.

CStream & operator<< (const CSerializablePtr &pObj)

Write an object to a stream in the binary MRPT format.

CStream & operator<< (const CSerializable &obj)

Write an object to a stream in the binary MRPT format.

CStream & operator>> (CSerializablePtr &pObj)

CStream & operator>> (CSerializable &obj)

virtual int printf (const char *fmt,...) MRPT_printf_format_check(2

Writes a string to the stream in a textual form.

template<typename T >

virtual int void printf_vector (const char *fmt, const std::vector< T > &V)

Prints a vector in the format [A,B,C,...] using CStream::printf, and the fmt string for each vector element.

void sendMessage (const utils::CMessage &msg)

Send a message to the device.

bool receiveMessage (utils::CMessage &msg)

Tries to receive a message from the device.

bool getline (std::string &out_str)

Reads from the stream until a '
' character is found ('' characters are ignored).

Protected Member Functions

size_t Read (void *Buffer, size_t Count)

Method responsible for reading from the stream.

size_t Write (const void *Buffer, size_t Count)

Method responsible for writing to the stream.

void resize (uint64_t newSize)

Resizes the internal buffer size.

Protected Attributes

void_ptr_noncopy

m_memory

Internal data.

uint64_t m_size

uint64_t m_position

uint64_t m_bytesWritten

uint64_t m_alloc_block_size

bool m_read_only

If the memory block does not belong to the object.

Member Enumeration Documentation

enum mrpt::utils::CStream::TSeekOrigin [inherited]

Used in CStream::Seek.

Enumerator:

sFromBeginning
sFromCurrent
sFromEnd

Definition at line 60 of file CStream.h.

Constructor & Destructor Documentation

mrpt::utils::CMemoryStream::CMemoryStream ( )

Default constructor.

mrpt::utils::CMemoryStream::CMemoryStream	(	const void *	data,
		const uint64_t	nBytesInData
	)

Constructor to initilize the data in the stream from a block of memory (which is copied), and sets the current stream position at the beginning of the data.

See also:: assignMemoryNotOwn

virtual mrpt::utils::CMemoryStream::~CMemoryStream ( ) [virtual]

Destructor.

Member Function Documentation

void mrpt::utils::CMemoryStream::assignMemoryNotOwn	(	const void *	data,
		const uint64_t	nBytesInData
	)

Initilize the data in the stream from a block of memory which is NEITHER OWNED NOR COPIED by the object, so it must exist during the whole live of the object.

After assigning a block of data with this method, the object becomes "read-only", so further attempts to change the size of the buffer will raise an exception. This method resets the write and read positions to the beginning.

void mrpt::utils::CMemoryStream::changeSize ( uint64_t newSize )

Change size.

This would be rarely used. Use ">>" operators for writing to stream.

See also:: Stream

void mrpt::utils::CMemoryStream::Clear ( )

Clears the memory buffer.

size_t mrpt::utils::CStream::CopyFrom	(	CStream *	Source,
		size_t	Count
	)		`[inherited]`

Copies a specified number of bytes from one stream to another.

bool mrpt::utils::CStream::getline ( std::string & out_str ) [inherited]

Reads from the stream until a '
' character is found ('' characters are ignored).

Returns:: false on EOF or any other read error.

uint64_t mrpt::utils::CMemoryStream::getPosition ( ) [virtual]

Method for getting the current cursor position, where 0 is the first byte and TotalBytesCount-1 the last one.

Implements mrpt::utils::CStream.

void* mrpt::utils::CMemoryStream::getRawBufferData ( )

Method for getting a pointer to the raw stored data.

The lenght in bytes is given by getTotalBytesCount

uint64_t mrpt::utils::CMemoryStream::getTotalBytesCount ( ) [virtual]

Returns the total size of the internal buffer.

Implements mrpt::utils::CStream.

bool mrpt::utils::CMemoryStream::loadBufferFromFile ( const std::string & file_name )

Loads the entire buffer from a file.

Returns:: true on success, false on error

CStream& mrpt::utils::CStream::operator<< ( const CSerializablePtr & pObj ) [inherited]

Write an object to a stream in the binary MRPT format.

CStream& mrpt::utils::CStream::operator<< ( const CSerializable & obj ) [inherited]

Write an object to a stream in the binary MRPT format.

CStream& mrpt::utils::CStream::operator>> ( CSerializablePtr & pObj ) [inherited]

CStream& mrpt::utils::CStream::operator>> ( CSerializable & obj ) [inherited]

virtual int mrpt::utils::CStream::printf	(	const char *	fmt,
			...
	)		`[virtual, inherited]`

Writes a string to the stream in a textual form.

See also:: CStdOutStream

template<typename T >

virtual int void mrpt::utils::CStream::printf_vector	(	const char *	fmt,
		const std::vector< T > &	V
	)		`[inline, inherited]`

Prints a vector in the format [A,B,C,...] using CStream::printf, and the fmt string for each vector element.

Definition at line 219 of file CStream.h.

size_t mrpt::utils::CMemoryStream::Read	(	void *	Buffer,
		size_t	Count
	)		`[protected, virtual]`

Method responsible for reading from the stream.

Implements mrpt::utils::CStream.

size_t mrpt::utils::CStream::ReadBuffer	(	void *	Buffer,
		size_t	Count
	)		`[inherited]`

Reads a block of bytes from the stream into Buffer

Exceptions:

std::exception On any error, or if ZERO bytes are read.

Returns:: The amound of bytes actually read.

Note:: This method is endianness-dependent.

See also:: ReadBufferImmediate ; Important, see: ReadBufferFixEndianness,

template<typename T >

size_t mrpt::utils::CStream::ReadBufferFixEndianness	(	T *	ptr,
		size_t	ElementCount
	)		`[inline, inherited]`

Reads a sequence of elemental datatypes, taking care of reordering their bytes from the MRPT stream standard (little endianness) to the format of the running architecture.

Parameters:

ElementCount	The number of elements (not bytes) to read.
ptr	A pointer to the first output element in an array (or std::vector<>, etc...).

Returns:

The amound of *bytes* (not elements) actually read (under error situations, the last element may be invalid if the data stream abruptly ends). Example of usage:

   uint32_t  N;
   s >> N;
   vector<float>  vec(N);
   if (N) 
     s.ReadBufferFixEndianness<float>(&vec[0],N);

Exceptions:

std::exception On any error, or if ZERO bytes are read.

See also:: ReadBufferFixEndianness, ReadBuffer

Definition at line 109 of file CStream.h.

References mrpt::utils::reverseBytesInPlace().

Referenced by mrpt::math::operator>>().

virtual size_t mrpt::utils::CStream::ReadBufferImmediate	(	void *	Buffer,
		size_t	Count
	)		`[inline, virtual, inherited]`

Reads a block of bytes from the stream into Buffer, and returns the amound of bytes actually read, without waiting for more extra bytes to arrive (just those already enqued in the stream).

Note that this method will fallback to ReadBuffer() in most CStream classes but in some hardware-related classes.

Exceptions:

std::exception On any error, or if ZERO bytes are read.

Reimplemented in mrpt::hwdrivers::CInterfaceFTDI.

Definition at line 127 of file CStream.h.

CSerializablePtr mrpt::utils::CStream::ReadObject ( ) [inherited]

Reads an object from stream, its class determined at runtime, and returns a smart pointer to the object.

Exceptions:

std::exception	On I/O error or undefined class.
mrpt::utils::CExceptionEOF	On an End-Of-File condition found at a correct place: an EOF that abruptly finishes in the middle of one object raises a plain std::exception instead.

Referenced by mrpt::math::operator>>().

void mrpt::utils::CStream::ReadObject ( CSerializable * existingObj ) [inherited]

Reads an object from stream, where its class must be the same as the supplied object, where the loaded object will be stored in.

Exceptions:

std::exception	On I/O error or different class found.
mrpt::utils::CExceptionEOF	On an End-Of-File condition found at a correct place: an EOF that abruptly finishes in the middle of one object raises a plain std::exception instead.

bool mrpt::utils::CStream::receiveMessage ( utils::CMessage & msg ) [inherited]

Tries to receive a message from the device.

Exceptions:

std::exception On communication errors

Returns:: True if successful, false if there is no new data from the device (but communications seem to work fine)

See also:: The frame format is described in sendMessage()

void mrpt::utils::CMemoryStream::resize ( uint64_t newSize ) [protected]

Resizes the internal buffer size.

bool mrpt::utils::CMemoryStream::saveBufferToFile ( const std::string & file_name )

Saves the entire buffer to a file.

Returns:: true on success, false on error

uint64_t mrpt::utils::CMemoryStream::Seek	(	long	Offset,
		CStream::TSeekOrigin	Origin = `sFromBeginning`
	)		`[virtual]`

Method for moving to a specified position in the streamed resource.

See also:: CStream::Seek

Implements mrpt::utils::CStream.

void mrpt::utils::CStream::sendMessage ( const utils::CMessage & msg ) [inherited]

Send a message to the device.

Note that only the low byte from the "type" field will be used.

For frames of size < 255 the frame format is an array of bytes in this order:

  <START_FLAG> <HEADER> <LENGTH> <BODY> <END_FLAG>
        <START_FLAG>    = 0x69
        <HEADER>                = A header byte
        <LENGHT>                = Number of bytes of BODY
        <BODY>                  = N x bytes
        <END_FLAG>              = 0X96
  Total length  =       <LENGTH> + 4

For frames of size > 255 the frame format is an array of bytes in this order:

  <START_FLAG> <HEADER> <HIBYTE(LENGTH)> <LOBYTE(LENGTH)> <BODY> <END_FLAG>
        <START_FLAG>    = 0x79
        <HEADER>                = A header byte
        <LENGHT>                = Number of bytes of BODY
        <BODY>                  = N x bytes
        <END_FLAG>              = 0X96
  Total length  =       <LENGTH> + 5

Exceptions:

std::exception On communication errors

void mrpt::utils::CMemoryStream::setAllocBlockSize ( uint64_t alloc_block_size ) [inline]

Change the size of the additional memory block that is reserved whenever the current block runs too short (default=0x10000 bytes)

Definition at line 129 of file CMemoryStream.h.

References ASSERT_.

size_t mrpt::utils::CMemoryStream::Write	(	const void *	Buffer,
		size_t	Count
	)		`[protected, virtual]`

Method responsible for writing to the stream.

Write attempts to write up to Count bytes to Buffer, and returns the number of bytes actually written.

Implements mrpt::utils::CStream.

void mrpt::utils::CStream::WriteBuffer	(	const void *	Buffer,
		size_t	Count
	)		`[inherited]`

Writes a block of bytes to the stream from Buffer.

Exceptions:

std::exception On any error

See also:: Important, see: WriteBufferFixEndianness

Note:: This method is endianness-dependent.

template<typename T >

void mrpt::utils::CStream::WriteBufferFixEndianness	(	const T *	ptr,
		size_t	ElementCount
	)		`[inline, inherited]`

Writes a sequence of elemental datatypes, taking care of reordering their bytes from the running architecture to MRPT stream standard (little endianness).

Parameters:

ElementCount	The number of elements (not bytes) to write.
ptr	A pointer to the first input element in an array (or std::vector<>, etc...). Example of usage: vector<float> vec = ... uint32_t N = vec.size(); s << N if (N) s.WriteBufferFixEndianness<float>(&vec[0],N);

Exceptions:

std::exception On any error