interval.h File Reference

Compute the interpretation interval for LSB and W-LSB encoding. More...

#include <stdlib.h>
#include <stdint.h>

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Enumerations
enum	rohc_lsb_shift_t {   ROHC_LSB_SHIFT_IP_ID = 0, ROHC_LSB_SHIFT_RTP_TS = 2, ROHC_LSB_SHIFT_RTP_SN = 3, ROHC_LSB_SHIFT_ESP_SN = 3,   ROHC_LSB_SHIFT_SN = -1, ROHC_LSB_SHIFT_STATS = -1 }
	the different values of the shift parameter of the LSB algorithm More...
Functions
void	rohc_f_16bits (const uint16_t v_ref, const size_t k, const rohc_lsb_shift_t p, uint16_t *const min, uint16_t *const max)
	The f function as defined in LSB encoding for 16-bit fields.
void	rohc_f_32bits (const uint32_t v_ref, const size_t k, const rohc_lsb_shift_t p, uint32_t *const min, uint32_t *const max)
	The f function as defined in LSB encoding for 32-bit fields.

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Detailed Description

Compute the interpretation interval for LSB and W-LSB encoding.

Author:

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

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Enumeration Type Documentation

enum rohc_lsb_shift_t

the different values of the shift parameter of the LSB algorithm

The shift parameter is also named 'p' in some RFCs.

Some values are the real values to use directly. Some others are code that means that the real value to use shall be computed from the number of least significant bits that are transmitted.

Enumerator:

ROHC_LSB_SHIFT_IP_ID	real value for IP-ID
ROHC_LSB_SHIFT_RTP_TS	need to compute real value for RTP TS
ROHC_LSB_SHIFT_RTP_SN	need to compute real value for RTP SN
ROHC_LSB_SHIFT_ESP_SN	need to compute real value for ESP SN
ROHC_LSB_SHIFT_SN	real value for non-RTP SN
ROHC_LSB_SHIFT_STATS	real value for internal statistics

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Function Documentation

void rohc_f_16bits	(	const uint16_t	v_ref,
		const size_t	k,
		const rohc_lsb_shift_t	p,
		uint16_t *const	min,
		uint16_t *const	max
	)

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

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

As stated RFC, the values to be encoded have a finite range and the interpretation interval can straddle the wraparound boundary. So, the min value may be greater than the max value!

Parameters:

v_ref	The reference value
k	The number of least significant bits of the value that are transmitted
p	The shift parameter (may be negative)
min	OUT: The lower limit of the interval
max	OUT: The upper limit of the interval

References rohc_f_32bits().

void rohc_f_32bits	(	const uint32_t	v_ref,
		const size_t	k,
		const rohc_lsb_shift_t	p,
		uint32_t *const	min,
		uint32_t *const	max
	)

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

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

As stated RFC, the values to be encoded have a finite range and the interpretation interval can straddle the wraparound boundary. So, the min value may be greater than the max value!

Parameters:

v_ref	The reference value
k	The number of least significant bits of the value that are transmitted
p	The shift parameter (may be negative)
min	OUT: The lower limit of the interval
max	OUT: The upper limit of the interval

References ROHC_LSB_SHIFT_RTP_SN, and ROHC_LSB_SHIFT_RTP_TS.

Referenced by rohc_f_16bits(), and rohc_lsb_decode32().