comp_wlsb.c File Reference

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

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

Include dependency graph for comp_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 size_t	wlsb_get_next_older (const size_t entry, const size_t max)
	Get the next older entry.
static size_t	wlsb_ack_remove (struct c_wlsb *const wlsb, const size_t pos)
	Removes all W-LSB window entries prior to the given position.
static size_t	rohc_g_8bits (const uint8_t v_ref, const uint8_t v, const rohc_lsb_shift_t p, const size_t bits_nr)
	The g function as defined in LSB encoding for 8-bit fields.
static size_t	rohc_g_16bits (const uint16_t v_ref, const uint16_t v, const size_t min_k, 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 size_t min_k, 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.
size_t	wlsb_get_k_8bits (const struct c_wlsb *const wlsb, const uint8_t value)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
size_t	wlsb_get_kp_8bits (const struct c_wlsb *const wlsb, const uint8_t value, const rohc_lsb_shift_t p)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
size_t	wlsb_get_k_16bits (const struct c_wlsb *const wlsb, const uint16_t value)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
size_t	wlsb_get_mink_16bits (const struct c_wlsb *const wlsb, const uint16_t value, const size_t min_k)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
size_t	wlsb_get_kp_16bits (const struct c_wlsb *const wlsb, const uint16_t value, const rohc_lsb_shift_t p)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
size_t	wlsb_get_minkp_16bits (const struct c_wlsb *const wlsb, const uint16_t value, const size_t min_k, const rohc_lsb_shift_t p)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
size_t	wlsb_get_k_32bits (const struct c_wlsb *const wlsb, const uint32_t value)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
size_t	wlsb_get_mink_32bits (const struct c_wlsb *const wlsb, const uint32_t value, const size_t min_k)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
size_t	wlsb_get_kp_32bits (const struct c_wlsb *const wlsb, const uint32_t value, const rohc_lsb_shift_t p)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
size_t	wlsb_get_minkp_32bits (const struct c_wlsb *const wlsb, const uint32_t value, const size_t min_k, const rohc_lsb_shift_t p)
	Find out the minimal number of bits of the to-be-encoded value required to be able to uniquely recreate it given the window.
size_t	wlsb_ack (struct c_wlsb *const wlsb, const uint32_t sn_bits, const size_t sn_bits_nr)
	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

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 size_t	min_k,
		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 f(v_ref, k). See 4.5.1 in the RFC 3095.

Parameters:

	v_ref	The reference value
	v	The value to encode
	min_k	The minimum number of bits to find out
	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 size_t	min_k,
		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 f(v_ref, k). See 4.5.1 in the RFC 3095.

Parameters:

	v_ref	The reference value
	v	The value to encode
	min_k	The minimum number of bits to find out
	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_8bits	(	const uint8_t	v_ref,
		const uint8_t	v,
		const rohc_lsb_shift_t	p,
		const size_t	bits_nr
	)			`[static]`

The g function as defined in LSB encoding for 8-bit fields.

Find the minimal k value so that v falls into the interval given by f(v_ref, k). 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

size_t wlsb_ack	(	struct c_wlsb *const	wlsb,
		const uint32_t	sn_bits,
		const size_t	sn_bits_nr
	)

Acknowledge based on the Sequence Number (SN).

Removes all window entries older (and including) than the one that matches the given SN bits.

Parameters:

	wlsb	The W-LSB object
	sn_bits	The LSB of the SN to acknowledge
	sn_bits_nr	The number of LSB of the SN to acknowledge

Returns:: The number of acked window entries

static size_t wlsb_ack_remove	(	struct c_wlsb *const	wlsb,
		const size_t	pos
	)			`[static]`

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

Parameters:

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

Returns:: The number of acked window entries

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