wlsb.c File Reference

Window-based Least Significant Bits (W-LSB) encoding. More...

#include "wlsb.h"
#include "interval.h"
#include "rohc_traces.h"
#include "rohc_debug.h"
#include <string.h>
#include <assert.h>

Include dependency graph for wlsb.c:

Data Structures
struct	c_window
	Define a W-LSB window entry. More...
struct	c_wlsb
	Defines a W-LSB encoding object. More...
Functions
struct c_wlsb *	c_create_wlsb (const size_t bits, const size_t window_width, const rohc_lsb_shift_t p)
	Create a new Window-based Least Significant Bits (W-LSB) encoding object.
void	c_destroy_wlsb (struct c_wlsb *const wlsb)
	Destroy a Window-based LSB (W-LSB) encoding object.
void	c_add_wlsb (struct c_wlsb *const wlsb, const uint32_t sn, const uint32_t value)
	Add a value into a W-LSB encoding object.
bool	wlsb_get_k_16bits (const struct c_wlsb *const wlsb, const uint16_t value, size_t *const bits_nr)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
bool	wlsb_get_k_32bits (const struct c_wlsb *const wlsb, const uint32_t value, size_t *const bits_nr)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
void	c_ack_sn_wlsb (struct c_wlsb *s, const uint32_t sn)
	Acknowledge based on the Sequence Number (SN)
int	c_sum_wlsb (struct c_wlsb *s)
	Compute the sum of all the values stored in the W-LSB window.
int	c_mean_wlsb (struct c_wlsb *s)
	Compute the mean of all the values stored in the W-LSB window.

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Detailed Description

Window-based Least Significant Bits (W-LSB) encoding.

Author:

Didier Barvaux <didier.barvaux@toulouse.viveris.com>

David Moreau from TAS

The hackers from ROHC for Linux

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Function Documentation

void c_ack_sn_wlsb	(	struct c_wlsb *	s,
		const uint32_t	sn
	)

Acknowledge based on the Sequence Number (SN)

Removes all entries older than the given SN in the window.

Parameters:

s	The W-LSB object
sn	The SN to acknowledge

References c_wlsb::count, c_wlsb::oldest, c_window::sn, c_wlsb::window, and c_wlsb::window_mask.

Referenced by c_generic_feedback().

void c_add_wlsb	(	struct c_wlsb *const	wlsb,
		const uint32_t	sn,
		const uint32_t	value
	)

Add a value into a W-LSB encoding object.

Parameters:

wlsb	The W-LSB object
sn	The Sequence Number (SN) for the new entry
value	The value to base the LSB coding on

References c_wlsb::count, c_wlsb::next, c_wlsb::oldest, sn, c_window::sn, c_window::value, c_wlsb::window, c_wlsb::window_mask, and c_wlsb::window_width.

Referenced by add_scaled(), rohc_compress(), and rohc_decompress().

struct c_wlsb* c_create_wlsb	(	const size_t	bits,
		const size_t	window_width,
		const rohc_lsb_shift_t	p
	)		[read]

Create a new Window-based Least Significant Bits (W-LSB) encoding object.

Parameters:

bits	The maximal number of bits for representing a value
window_width	The number of entries in the window (power of 2)
p	Shift parameter (see 4.5.2 in the RFC 3095)

Returns:

The newly-created W-LSB encoding object

References c_wlsb::bits, c_wlsb::count, c_wlsb::next, c_wlsb::oldest, c_wlsb::p, rohc_debugf, c_wlsb::window_mask, and c_wlsb::window_width.

Referenced by c_create_sc(), c_generic_create(), c_init_header_info(), and context_create().

void c_destroy_wlsb

(

struct c_wlsb *const

wlsb

)

Destroy a Window-based LSB (W-LSB) encoding object.

Parameters:

wlsb	The W-LSB object to destroy

Referenced by c_destroy_sc(), c_generic_destroy(), context_create(), and context_free().

int c_mean_wlsb

(

struct c_wlsb *

s

)

Compute the mean of all the values stored in the W-LSB window.

This function is used for statistics.

Parameters:

s	The W-LSB object

Returns:

The mean over the W-LSB window

References c_wlsb::count, c_wlsb::oldest, c_window::value, c_wlsb::window, and c_wlsb::window_mask.

Referenced by rohc_c_context(), and rohc_d_context().

int c_sum_wlsb

(

struct c_wlsb *

s

)

Compute the sum of all the values stored in the W-LSB window.

This function is used for statistics.

Parameters:

s	The W-LSB object

Returns:

The sum over the W-LSB window

References c_wlsb::count, c_wlsb::oldest, c_window::value, c_wlsb::window, and c_wlsb::window_mask.

Referenced by rohc_c_context(), and rohc_d_context().

bool wlsb_get_k_16bits	(	const struct c_wlsb *const	wlsb,
		const uint16_t	value,
		size_t *const	bits_nr
	)

Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.

The function is dedicated to 16-bit fields.

Parameters:

wlsb	The W-LSB object
value	The value to encode using the LSB algorithm
bits_nr	OUT: The number of bits required to uniquely recreate the value

Returns:

true in case of success, false if the minimal number of bits can not be found

References c_wlsb::bits, c_wlsb::count, c_wlsb::oldest, c_wlsb::p, c_window::value, c_wlsb::window, and c_wlsb::window_mask.

bool wlsb_get_k_32bits	(	const struct c_wlsb *const	wlsb,
		const uint32_t	value,
		size_t *const	bits_nr
	)

Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.

The function is dedicated to 32-bit fields.

Parameters:

wlsb	The W-LSB object
value	The value to encode using the LSB algorithm
bits_nr	OUT: The number of bits required to uniquely recreate the value

Returns:

true in case of success, false if the minimal number of bits can not be found

References c_wlsb::bits, c_wlsb::count, c_wlsb::oldest, c_wlsb::p, c_window::value, c_wlsb::window, and c_wlsb::window_mask.

Referenced by nb_bits_scaled().