wlsb.c File Reference

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

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

Include dependency graph for decomp/schemes/wlsb.c:

Data Structures
struct	rohc_lsb_decode
	The Least Significant Bits (LSB) decoding object. More...
Functions
static bool	rohc_lsb_decode32 (const struct rohc_lsb_decode *const lsb, const rohc_lsb_ref_t ref_type, const uint32_t v_ref_d_offset, const uint32_t m, const size_t k, const rohc_lsb_shift_t p, uint32_t *const decoded)
	Decode a 32-bit LSB-encoded value.
static bool	rohc_lsb_decode16 (const struct rohc_lsb_decode *const lsb, const rohc_lsb_ref_t ref_type, const uint16_t v_ref_d_offset, const uint16_t m, const size_t k, const rohc_lsb_shift_t p, uint16_t *const decoded)
	Decode a 16-bit LSB-encoded value.
struct rohc_lsb_decode *	rohc_lsb_new (const rohc_lsb_shift_t p, const size_t max_len)
	Create a new Least Significant Bits (LSB) decoding context.
void	rohc_lsb_free (struct rohc_lsb_decode *const lsb)
	Destroy a given Least Significant Bits (LSB) decoding context.
rohc_lsb_shift_t	lsb_get_p (const struct rohc_lsb_decode *const lsb)
	Get the shift parameter p of the LSB decoding context.
bool	rohc_lsb_decode (const struct rohc_lsb_decode *const lsb, const rohc_lsb_ref_t ref_type, const uint32_t v_ref_d_offset, const uint32_t m, const size_t k, const rohc_lsb_shift_t p, uint32_t *const decoded)
	Decode a LSB-encoded value.
void	rohc_lsb_set_ref (struct rohc_lsb_decode *const lsb, const uint32_t v_ref_d, const bool keep_ref_minus_1)
	Update the LSB reference value.
uint32_t	rohc_lsb_get_ref (const struct rohc_lsb_decode *const lsb, const rohc_lsb_ref_t ref_type)
	Get the current LSB reference value (ref 0)

---

Detailed Description

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

Author:

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

Didier Barvaux <didier@barvaux.org>

---

Function Documentation

rohc_lsb_shift_t lsb_get_p

(

const struct rohc_lsb_decode *const

lsb

)

Get the shift parameter p of the LSB decoding context.

Parameters:

lsb	The LSB object used to decode

Returns:

The shift parameter p

bool rohc_lsb_decode	(	const struct rohc_lsb_decode *const	lsb,
		const rohc_lsb_ref_t	ref_type,
		const uint32_t	v_ref_d_offset,
		const uint32_t	m,
		const size_t	k,
		const rohc_lsb_shift_t	p,
		uint32_t *const	decoded
	)

Decode a LSB-encoded value.

See 4.5.1 in the RFC 3095 for details about LSB encoding.

Parameters:

lsb	The LSB object used to decode
ref_type	The reference value to use to decode (used for context repair upon CRC failure)
v_ref_d_offset	The offset to apply on v_ref_d (used for context repair upon CRC failure)
m	The LSB value to decode
k	The length of the LSB value to decode
p	The shift value p used to efficiently encode/decode the values
decoded	OUT: The decoded value

Returns:

true in case of success, false otherwise

static bool rohc_lsb_decode16	(	const struct rohc_lsb_decode *const	lsb,
		const rohc_lsb_ref_t	ref_type,
		const uint16_t	v_ref_d_offset,
		const uint16_t	m,
		const size_t	k,
		const rohc_lsb_shift_t	p,
		uint16_t *const	decoded
	)		[static]

Decode a 16-bit LSB-encoded value.

See rohc_lsb_decode32 for details.

Parameters:

lsb	The LSB object used to decode
ref_type	The reference value to use to decode (used for context repair upon CRC failure)
v_ref_d_offset	The offset to apply on v_ref_d (used for context repair upon CRC failure)
m	The LSB value to decode
k	The length of the LSB value to decode
p	The shift value p used to efficiently encode/decode the values
decoded	OUT: The decoded value

Returns:

true in case of success, false otherwise

static bool rohc_lsb_decode32	(	const struct rohc_lsb_decode *const	lsb,
		const rohc_lsb_ref_t	ref_type,
		const uint32_t	v_ref_d_offset,
		const uint32_t	m,
		const size_t	k,
		const rohc_lsb_shift_t	p,
		uint32_t *const	decoded
	)		[static]

Decode a 32-bit LSB-encoded value.

See 4.5.1 in the RFC 3095 for details about LSB encoding.

Parameters:

lsb	The LSB object used to decode
ref_type	The reference value to use to decode (used for context repair upon CRC failure)
v_ref_d_offset	The offset to apply on v_ref_d (used for context repair upon CRC failure)
m	The LSB value to decode
k	The length of the LSB value to decode
p	The shift value p used to efficiently encode/decode the values
decoded	OUT: The decoded value

Returns:

true in case of success, false otherwise

void rohc_lsb_free

(

struct rohc_lsb_decode *const

lsb

)

Destroy a given Least Significant Bits (LSB) decoding context.

See 4.5.1 in the RFC 3095 for details about LSB encoding.

Parameters:

lsb	The LSB decoding context to destroy

uint32_t rohc_lsb_get_ref	(	const struct rohc_lsb_decode *const	lsb,
		const rohc_lsb_ref_t	ref_type
	)

Get the current LSB reference value (ref 0)

Parameters:

lsb	The LSB object
ref_type	The reference value to retrieve

Returns:

The current reference value

struct rohc_lsb_decode* rohc_lsb_new	(	const rohc_lsb_shift_t	p,
		const size_t	max_len
	)		[read]

Create a new Least Significant Bits (LSB) decoding context.

See 4.5.1 in the RFC 3095 for details about LSB encoding.

Parameters:

p	The p value used to efficiently encode/decode the values
max_len	The max length (in bits) of the non-compressed field

Returns:

The new LSB decoding context in case of success, NULL otherwise

void rohc_lsb_set_ref	(	struct rohc_lsb_decode *const	lsb,
		const uint32_t	v_ref_d,
		const bool	keep_ref_minus_1
	)

Update the LSB reference value.

This function is called after a CRC success to update the last decoded value (for example, the SN value). See 4.5.1 in the RFC 3095 for details about LSB encoding.

Parameters:

lsb	The LSB object
v_ref_d	The new reference value
keep_ref_minus_1	Keep ref -1 unchanged (used for SN context repair after CRC failure, see RFC3095 §5.3.2.2.5)