wlsb.c File Reference

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

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

Include dependency graph for comp/schemes/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
static void	c_ack_remove (struct c_wlsb *const s, const size_t pos)
	Removes all W-LSB window entries prior to the given position.
static size_t	rohc_g_16bits (const uint16_t v_ref, const uint16_t v, const rohc_lsb_shift_t p, const size_t bits_nr)
	The g function as defined in LSB encoding for 16-bit fields.
static size_t	rohc_g_32bits (const uint32_t v_ref, const uint32_t v, const rohc_lsb_shift_t p, const size_t bits_nr)
	The g function as defined in LSB encoding for 32-bit fields.
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.
bool	wlsb_get_kp_32bits (const struct c_wlsb *const wlsb, const uint32_t value, const rohc_lsb_shift_t p, 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 *const s, const uint32_t sn)
	Acknowledge based on the Sequence Number (SN)

---

Detailed Description

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

Author:

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

Didier Barvaux <didier@barvaux.org>

David Moreau from TAS

---

Function Documentation

static void c_ack_remove	(	struct c_wlsb *const	s,
		const size_t	pos
	)		[static]

Removes all W-LSB window entries prior to the given position.

Parameters:

s	The W-LSB object
pos	The position to set as the oldest

void c_ack_sn_wlsb	(	struct c_wlsb *const	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

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

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

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

static size_t rohc_g_16bits	(	const uint16_t	v_ref,
		const uint16_t	v,
		const rohc_lsb_shift_t	p,
		const size_t	bits_nr
	)		[static]

The g function as defined in LSB encoding for 16-bit fields.

Find the minimal k value so that v falls into the interval given by . See 4.5.1 in the RFC 3095.

Parameters:

v_ref	The reference value
v	The value to encode
p	The shift parameter
bits_nr	The number of bits that may be used to represent the LSB-encoded value

Returns:

The minimal k value as defined by the LSB algorithm

static size_t rohc_g_32bits	(	const uint32_t	v_ref,
		const uint32_t	v,
		const rohc_lsb_shift_t	p,
		const size_t	bits_nr
	)		[static]

The g function as defined in LSB encoding for 32-bit fields.

Find the minimal k value so that v falls into the interval given by . See 4.5.1 in the RFC 3095.

Parameters:

v_ref	The reference value
v	The value to encode
p	The shift parameter
bits_nr	The number of bits that may be used to represent the LSB-encoded value

Returns:

The minimal k value as defined by the LSB algorithm

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

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

bool wlsb_get_kp_32bits	(	const struct c_wlsb *const	wlsb,
		const uint32_t	value,
		const rohc_lsb_shift_t	p,
		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
p	The shift parameter p
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