ibitstream Class Reference

Input bit stream. More...

Inheritance diagram for ibitstream:

Public Member Functions
	ibitstream (FILE *file, int buffersize=DEFAULT_IOBUFFER_SIZE)
	Start ibitstream using a FILE ptr to an open file.
	ibitstream (const char *filename, int buffersize=DEFAULT_IOBUFFER_SIZE)
	Start inputbitstream by filename.
	ibitstream (int fd, int buffersize=DEFAULT_IOBUFFER_SIZE)
	Start inputbitstream by file descriptor.
	~ibitstream ()
	Destructor only uses base class destructor.
virtual void	close ()
	Close the IO file.
virtual bool	is_open () const
	Is the IO file closed?
void	setupstream ()
	Allocate a buffer and set up all pointers, then fill buffer.
void	windup ()
	Put the current word to the buffer with upper 0 bits as needed.
virtual void	print () const
	Print buffer contents.
virtual int	get_bytes_used ()
	Return the number of bytes used so far in this stream.
Word_t	readbits (int nbits)
	Read data from the buffer as unsigned ints.
int32_t	readbits_int (int nbits)
	Read data from the buffer as (signed) ints.
Word_t	read_unary ()
	Read a single unary-coded value.
int	readstring (char *s, int count=-1)
	Read a null-terminated string of 8-bit characters from the bit stream.
Public Member Functions inherited from bitstream
	bitstream ()
	Dummy default constructor.
	bitstream (const char *filename, int buffersize=DEFAULT_IOBUFFER_SIZE)
	Start bitstream by filename.
virtual	~bitstream ()
	Destructor deletes output buffer, closes file.
int	get_bitptr ()
	Get the position of the bitptr.

Protected Attributes
FILE *	fp
Protected Attributes inherited from bitstream
size_t	bufsize
	Size of I/O buffer (bytes).
size_t	buf_used
Byte_t *	buffer_base
	Pointer to the buffer.
Byte_t *	beyondbuffer
	Pointer just beyond buffer (convenience).
union {
Byte_t *   Bptr
	Pointer to the current word (as Byte_t *).
Word_t *   Dptr
	Pointer to the current word (as Word_t *).
}	buffptr
	Pointer to the current word.
int	bitptr
	Pointer to the current bits.

Private Member Functions
void	next_word ()
	Move to next word in buffer, refilling it if needed.
int	fill ()
	Fill the read buffer and reset for more data.

Private Attributes
Word_t	partial_word
int	partial_word_bitptr

Additional Inherited Members
Public Types inherited from bitstream
enum	{ DEFAULT_IOBUFFER_SIZE =1024*1024 }
	Make *Dptr always point to same place as Bptr. More...
enum	{ MAX_BITSTREAM_BUFSIZE =16*1024*1024 }
Static Protected Attributes inherited from bitstream
static const int	Bits_per_word = 8*sizeof(Word_t)
	Bits per buffer word.

Detailed Description

Input bit stream.

Allows you to read data N bits at a time with buffered reading.

Member Function Documentation

close()

void ibitstream::close ( )

virtual

Close the IO file.

Implements bitstream.

Referenced by ~ibitstream().

fill()

int ibitstream::fill ( )

private

Fill the read buffer and reset for more data.

Returns

Bytes read from disk.

References bitstream::beyondbuffer, bitstream::bitptr, bitstream::buf_used, bitstream::buffer_base, bitstream::buffptr, and bitstream::bufsize.

Referenced by next_word(), and setupstream().

get_bytes_used()

int ibitstream::get_bytes_used ( )

virtual

Return the number of bytes used so far in this stream.

Reimplemented from bitstream.

References bitstream::beyondbuffer, bitstream::bitptr, bitstream::buf_used, and bitstream::buffptr.

is_open()

bool ibitstream::is_open ( ) const

virtual

Is the IO file closed?

Implements bitstream.

print()

void ibitstream::print ( ) const

virtual

Print buffer contents.

Implements bitstream.

References bitstream::bitptr, bitstream::buffer_base, and bitstream::buffptr.

read_unary()

Word_t ibitstream::read_unary

(

)

Read a single unary-coded value.

Returns

The unary-coded value from the stream.

References readbits().

Referenced by mexp_golomb_read_u32().

readbits()

Word_t ibitstream::readbits

(

int

n_bits

)

Read data from the buffer as unsigned ints.

Parameters

n_bits

Number of bits to use

Returns

Data read (in the lowest n_bits bits).

References bitstream::bitptr, bitstream::Bits_per_word, bitstream::buffptr, and next_word().

Referenced by mexp_golomb_read_u32(), read_unary(), readbits_int(), readstring(), and windup().

readbits_int()

int ibitstream::readbits_int

(

int

n_bits

)

Read data from the buffer as (signed) ints.

Parameters

n_bits

Number of bits to read.

Returns

The data read from the stream.

References readbits().

readstring()

int ibitstream::readstring	(	char *	s,
		int	count = -1 )

Read a null-terminated string of 8-bit characters from the bit stream.

Parameters

s	Pointer to the string (must be available memory).
count	Maximum size of the string.

Returns

Number of chars read (including null).

References readbits().

setupstream()

void ibitstream::setupstream ( )

virtual

Allocate a buffer and set up all pointers, then fill buffer.

Reimplemented from bitstream.

References bitstream::bufsize, fill(), and bitstream::setupstream().

Referenced by ibitstream(), ibitstream(), and ibitstream().

windup()

void ibitstream::windup ( )

virtual

Put the current word to the buffer with upper 0 bits as needed.

Implements bitstream.

References bitstream::bitptr, and readbits().

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The documentation for this class was generated from the following files:

• /builddir/build/BUILD/slimdata-2.7.1-build/slim_v2_7_1/src/bitstream.h
• /builddir/build/BUILD/slimdata-2.7.1-build/slim_v2_7_1/src/bitstream.cpp