mlib::bitstream Class Reference

Read and write bit fields. More...

#include <bitstream.h>

Public Member Functions
	bitstream (std::iostream &str, unsigned int pack)
	Constructor.
bool	read ()
	Read the next bit.
int	read (size_t sz, bool is_signed=false)
	Read a number of bits.
void	write (bool val)
	Write a bit to stream.
void	write (int val, size_t sz)
	Write a number of bits.
void	flush ()
	If there are any leftover bits, encode them in one character and write them out to stream.

Protected Member Functions
virtual char	encode (unsigned char bits)
	Encode bit field in a byte.
virtual unsigned char	decode (char chr)
	Decode bit field from a byte.

Protected Attributes
const unsigned int	packing
	number of used bits per byte
std::iostream &	s
	underlining (byte) stream

Detailed Description

Read and write bit fields.

This class allows reading and writing of bit fields from or to a byte stream.

It allows for different byte encodings using the protected encode/decode functions.

Constructor & Destructor Documentation

bitstream()

mlib::bitstream::bitstream	(	std::iostream &	str,
		unsigned int	pack )

Constructor.

Parameters

str	Underlining iostream
pack	Number of bits per byte

Member Function Documentation

decode()

unsigned char mlib::bitstream::decode ( char chr )

inlineprotectedvirtual

Decode bit field from a byte.

The default implementation unpacks the bit field from the LSB of byte.

Parameters

chr	encoded byte

Returns

resulting bit field

encode()

char mlib::bitstream::encode ( unsigned char bits )

inlineprotectedvirtual

Encode bit field in a byte.

The default implementation packs the bit field in the LSB of byte.

Parameters

bits	bit field to encode

Returns

encoded byte

read() [1/2]

bool mlib::bitstream::read

(

)

Read the next bit.

Read a single bit from stream.

If there are no more bits available in current byte, tries to get a new byte and decodes it using decode() function.

Returns

Bit value

Remarks

All bits read after stream reaches EOF are 0.

read() [2/2]

int mlib::bitstream::read	(	size_t	sz,
		bool	sign = false )

Read a number of bits.

Invokes bit read function repeatedly to read all bits.

Parameters

sz	Width of bit field
sign	true if first bit should be interpreted as a sign value.

Returns

value (0 to 2^sz-1 or -2^sz-1 to 2^sz-1)

write() [1/2]

void mlib::bitstream::write

(

bool

val

)

Write a bit to stream.

If it has accumulated enough bits calls encode() function to encode them and writes a new byte to underlining stream.

Parameters

val	Bit value to write

write() [2/2]

void mlib::bitstream::write	(	int	val,
		size_t	sz )

Write a number of bits.

Invokes bit write function repeatedly to write each bit.

Parameters

val	Value to write (0 to 2sz-1 )
sz	Width of bit field

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

• include/mlib/bitstream.h
• src/bitstream.cpp