wlsb.c File Reference

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

#include "wlsb.h"
#include "rohc_traces.h"

Include dependency graph for wlsb.c:

Functions
void	c_ack_remove (struct c_wlsb *s, int index, int by_time)
	Removes all W-LSB window entries prior to the given index.
struct c_wlsb *	c_create_wlsb (int bits, int window_width, int p)
	Create a new Window-based Least Significant Bits (W-LSB) encoding object.
void	c_destroy_wlsb (struct c_wlsb *s)
	Destroy a Window-based LSB (W-LSB) encoding object.
void	print_wlsb_stats (struct c_wlsb *s)
	Print statistics about a W-LSB encoding object.
void	c_add_wlsb (struct c_wlsb *s, int sn, int time, int value)
	Add a value into a W-LSB encoding object.
void	f (int v_ref, int k, int p, int *min, int *max)
	The f function as defined in the LSB calculation algorithm.
int	g (int v_ref, int v, int p, int bits)
	The g function as defined in the LSB calculation algorithm.
int	c_get_k_wlsb (struct c_wlsb *s, int 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.
void	c_ack_sn_wlsb (struct c_wlsb *s, int sn)
	Acknowledge based on the Sequence Number (SN)
void	c_ack_time_wlsb (struct c_wlsb *s, int time)
	Acknowledge based on the time stamp.
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_remove	(	struct c_wlsb *	s,
		int	index,
		int	by_time
	)

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

Parameters:

s	The W-LSB object
index	The position to set as the oldest
by_time	Whether the function is called by SN or time acknowledgement

References c_wlsb::next, c_wlsb::oldest, rohc_debugf, ROHC_FALSE, ROHC_TRUE, c_window::time, c_window::used, c_wlsb::window, and c_wlsb::window_width.

Referenced by c_ack_sn_wlsb(), and c_ack_time_wlsb().

void c_ack_sn_wlsb	(	struct c_wlsb *	s,
		int	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_ack_remove(), c_wlsb::oldest, ROHC_TRUE, c_window::sn, c_window::used, and c_wlsb::window.

Referenced by c_generic_feedback().

void c_ack_time_wlsb	(	struct c_wlsb *	s,
		int	time
	)

Acknowledge based on the time stamp.

Removes all entries older than the given time stamp in the window.

Parameters:

s	The W-LSB object
time	The time stamp to acknowledge

References c_ack_remove(), c_wlsb::oldest, ROHC_TRUE, c_window::time, c_window::used, c_wlsb::window, and c_wlsb::window_width.

void c_add_wlsb	(	struct c_wlsb *	s,
		int	sn,
		int	time,
		int	value
	)

Add a value into a W-LSB encoding object.

Parameters:

s	The W-LSB object
sn	The Sequence Number (SN) for the new entry
time	The time stamp for the new entry
value	The value to base the LSB coding on (i.e. sn)

References c_wlsb::next, c_wlsb::oldest, rohc_debugf, ROHC_TRUE, c_window::sn, sn, c_window::time, c_window::used, c_window::value, c_wlsb::window, and c_wlsb::window_width.

Referenced by add_scaled(), d_generic_decode_ir(), decode_irdyn(), decode_uo0(), decode_uo1(), decode_uor2(), rohc_compress(), rohc_decompress(), and update_variables().

struct c_wlsb* c_create_wlsb	(	int	bits,
		int	window_width,
		int	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
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::next, c_wlsb::oldest, c_wlsb::p, rohc_debugf, ROHC_FALSE, c_window::time, c_window::used, c_wlsb::window, c_wlsb::window_width, and zfree.

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

void c_destroy_wlsb

(

struct c_wlsb *

s

)

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

Parameters:

s	The W-LSB object to destory

References c_wlsb::window, and zfree.

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

int c_get_k_wlsb	(	struct c_wlsb *	s,
		int	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.

Parameters:

s	The W-LSB object
value	The value to encode using the LSB algorithm

Returns:

The number of bits required to uniquely recreate the value, 0 if an error occurs and -1 if the minimal number of bits can not be found

References c_wlsb::bits, g(), c_wlsb::p, rohc_debugf, ROHC_TRUE, c_window::used, c_window::value, c_wlsb::window, and c_wlsb::window_width.

Referenced by nb_bits_scaled(), and update_variables().

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 ROHC_TRUE, c_window::used, c_window::value, c_wlsb::window, and c_wlsb::window_width.

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 ROHC_TRUE, c_window::used, c_window::value, c_wlsb::window, and c_wlsb::window_width.

Referenced by rohc_c_context(), and rohc_d_context().

void f	(	int	v_ref,
		int	k,
		int	p,
		int *	min,
		int *	max
	)

The f function as defined in the LSB calculation algorithm.

Find out the interval for a given k. See 4.5.1 in the RFC 3095.

Parameters:

v_ref	The reference value
k	The number of least significant bits of the value that are transmitted
p	The shift parameter
min	The lower limit of the interval
max	The upper limit of the interval

Referenced by d_ip_id_decode(), d_lsb_decode(), and g().

int g	(	int	v_ref,
		int	v,
		int	p,
		int	bits
	)

The g function as defined in the LSB calculation algorithm.

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	The number of bits that may be used to represent the LSB-encoded value

Returns:

The minimal k value as defined by the LSB calculation algorithm

References f().

Referenced by c_get_k_wlsb().

void print_wlsb_stats

(

struct c_wlsb *

s

)

Print statistics about a W-LSB encoding object.

This function is a debug function.

Parameters:

s	The W-LSB object to print stats about

References c_wlsb::next, c_wlsb::oldest, rohc_debugf, ROHC_TRUE, c_window::sn, c_window::time, c_window::used, c_window::value, c_wlsb::window, and c_wlsb::window_width.