rfc4996.h File Reference

Library of encoding methods from RFC4997 and RFC4996. More...

#include "protocols/tcp.h"
#include "schemes/wlsb.h"
#include <stdint.h>
#include "dllexport.h"

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Data Structures
union	multi_ptr_t
	Define union of different compressed datas pointers. More...
Functions
uint32_t ROHC_EXPORT	c_lsb (const struct rohc_comp_ctxt *const context, int num_lsbs_param, unsigned int offset_param, unsigned int context_value, unsigned int original_value)
	Compress the lower bits of the given value.
int	c_static_or_irreg8 (const uint8_t context_value, const uint8_t packet_value, uint8_t *const rohc_data, int *const indicator)
	Compress the 8 bits given, depending of the context value.
int	c_static_or_irreg16 (const uint16_t context_value, const uint16_t packet_value, uint8_t *const rohc_data, int *const indicator)
	Compress the 16 bits given, depending of the context value.
int	c_zero_or_irreg8 (const uint8_t packet_value, uint8_t *const rohc_data, int *const indicator)
	Compress the 8 bits value, regarding if null or not.
int	c_zero_or_irreg16 (const uint16_t packet_value, uint8_t *const rohc_data, int *const indicator)
	Compress the 16 bits value, regarding if null or not.
int	c_zero_or_irreg32 (const uint32_t packet_value, uint8_t *const rohc_data, int *const indicator)
	Compress the 32 bits value, regarding if null or not.
size_t ROHC_EXPORT	variable_length_32_enc (const uint32_t old_value, const uint32_t new_value, const size_t nr_bits_63, const size_t nr_bits_16383, uint8_t *const rohc_data, int *const indicator)
	Compress the given 32-bit value.
int	c_optional32 (const int indicator, const uint32_t packet_value, uint8_t *const rohc_data)
	Compress a 32 bits value, regarding the context value.
int	c_lsb_7_or_31 (const uint32_t context_value, const uint32_t packet_value, uint8_t *const rohc_data)
	Compress a 32 bits value to 7 or 31 bits.
void	c_field_scaling (uint32_t *const scaled_value, uint32_t *const residue_field, const uint32_t scaling_factor, const uint32_t unscaled_value)
	Calculate the scaled and residue values from unscaled value and scaling factor.
unsigned int	rsf_index_enc (const struct rohc_comp_ctxt *const context, unsigned int rsf_flags)
	Calculate the rsf_index from the rsf flags.
uint16_t	c_ip_id_lsb (const struct rohc_comp_ctxt *const context, const int behavior, const unsigned int k, const unsigned int p, const uint16_t context_ip_id, const uint16_t ip_id, const uint16_t msn)
	Compress the lower bits of IP-ID.
int	c_optional_ip_id_lsb (const struct rohc_comp_ctxt *const context, const int behavior, const uint16_t context_ip_id, const uint16_t ip_id, const uint16_t msn, uint8_t *const rohc_data, int *const indicator)
	Compress or not the IP-ID.
unsigned int	dscp_encode (multi_ptr_t *pmptr, const uint8_t context_value, const uint8_t value)
	Encode the DSCP field.
Variables
unsigned int ROHC_EXPORT	lsb_xor_masks []
	Table of the mask for lsb()

---

Detailed Description

Library of encoding methods from RFC4997 and RFC4996.

Author:

FWX <rohc_team@dialine.fr>

Didier Barvaux <didier@barvaux.org>

---

Function Documentation

void c_field_scaling	(	uint32_t *const	scaled_value,
		uint32_t *const	residue_field,
		const uint32_t	scaling_factor,
		const uint32_t	unscaled_value
	)

Calculate the scaled and residue values from unscaled value and scaling factor.

See RFC4996 page 49

Parameters:

scaled_value	TODO
residue_field	TODO
scaling_factor	TODO
unscaled_value	TODO

uint16_t c_ip_id_lsb	(	const struct rohc_comp_ctxt *const	context,
		const int	behavior,
		const unsigned int	k,
		const unsigned int	p,
		const uint16_t	context_ip_id,
		const uint16_t	ip_id,
		const uint16_t	msn
	)

Compress the lower bits of IP-ID.

See RFC4996 page 75

Parameters:

context	The compressor context
behavior	The IP-ID behavior
k	The num_lsbs_param parameter for c_lsb()
p	The offset parameter for c_lsb()
context_ip_id	The context value of IP-ID
ip_id	The IP-ID value to compress
msn	The Master Sequence Number

Returns:

The lsb of offset between IP-ID and MSN

uint32_t ROHC_EXPORT c_lsb	(	const struct rohc_comp_ctxt *const	context,
		int	num_lsbs_param,
		unsigned int	offset_param,
		unsigned int	context_value,
		unsigned int	original_value
	)

Compress the lower bits of the given value.

See RFC4997 page 27

Parameters:

context	The compressor context
num_lsbs_param	The number of bits
offset_param	The offset
context_value	The value of the context
original_value	The value to compress

Returns:

The compressed value with num_lsbs_param bits

int c_lsb_7_or_31	(	const uint32_t	context_value,
		const uint32_t	packet_value,
		uint8_t *const	rohc_data
	)

Compress a 32 bits value to 7 or 31 bits.

See RFC4996 page 47

Parameters:

	context_value	The context value
	packet_value	The packet value
[out]	rohc_data	The compressed value

Returns:

The number of ROHC bytes written, -1 if a problem occurs

int c_optional32	(	const int	indicator,
		const uint32_t	packet_value,
		uint8_t *const	rohc_data
	)

Compress a 32 bits value, regarding the context value.

See RFC4996 page 47

Parameters:

indicator	The indicator: 1 if present, 0 if not
packet_value	The packet value
rohc_data	The compressed value

Returns:

The number of ROHC bytes written, -1 if a problem occurs

int c_optional_ip_id_lsb	(	const struct rohc_comp_ctxt *const	context,
		const int	behavior,
		const uint16_t	context_ip_id,
		const uint16_t	ip_id,
		const uint16_t	msn,
		uint8_t *const	rohc_data,
		int *const	indicator
	)

Compress or not the IP-ID.

See RFC4996 page 76

Parameters:

	context	The compressor context
	behavior	The IP-ID behavior
	context_ip_id	The context value of IP-ID
	ip_id	The IP-ID value to compress
	msn	The Master Sequence Number
[out]	rohc_data	The compressed value
[out]	indicator	The indicator: 0 if short, 1 if long

Returns:

The number of ROHC bytes written, -1 if a problem occurs

int c_static_or_irreg16	(	const uint16_t	context_value,
		const uint16_t	packet_value,
		uint8_t *const	rohc_data,
		int *const	indicator
	)

Compress the 16 bits given, depending of the context value.

Parameters:

	context_value	The context value
	packet_value	The packet value
[out]	rohc_data	The compressed value
[out]	indicator	The indicator: 1 if present, 0 if not

Returns:

The number of ROHC bytes written, -1 if a problem occurs

int c_static_or_irreg8	(	const uint8_t	context_value,
		const uint8_t	packet_value,
		uint8_t *const	rohc_data,
		int *const	indicator
	)

Compress the 8 bits given, depending of the context value.

See RFC4996 page 46

Parameters:

	context_value	The context value
	packet_value	The packet value
[out]	rohc_data	The compressed value
[out]	indicator	The indicator: 1 if present, 0 if not

Returns:

The number of ROHC bytes written, -1 if a problem occurs

int c_zero_or_irreg16	(	const uint16_t	packet_value,
		uint8_t *const	rohc_data,
		int *const	indicator
	)

Compress the 16 bits value, regarding if null or not.

Parameters:

	packet_value	The packet value
[out]	rohc_data	The compressed value
[out]	indicator	The indicator: 1 if present, 0 if not

Returns:

The number of ROHC bytes written, -1 if a problem occurs

int c_zero_or_irreg32	(	const uint32_t	packet_value,
		uint8_t *const	rohc_data,
		int *const	indicator
	)

Compress the 32 bits value, regarding if null or not.

Parameters:

	packet_value	The packet value
[out]	rohc_data	The compressed value
[out]	indicator	The indicator: 1 if present, 0 if not

Returns:

The number of ROHC bytes written, -1 if a problem occurs

int c_zero_or_irreg8	(	const uint8_t	packet_value,
		uint8_t *const	rohc_data,
		int *const	indicator
	)

Compress the 8 bits value, regarding if null or not.

Parameters:

	packet_value	The packet value
[out]	rohc_data	The compressed value
[out]	indicator	The indicator: 1 if present, 0 if not

Returns:

The number of ROHC bytes written, -1 if a problem occurs

unsigned int dscp_encode	(	multi_ptr_t *	pmptr,
		const uint8_t	context_value,
		const uint8_t	packet_value
	)

Encode the DSCP field.

See RFC4996 page 75

Parameters:

pmptr	The destination for the compressed value
context_value	The DSCP value in the compression context
packet_value	The DSCP value in the packet to compress

Returns:

Indicator 1 if value compressed, 0 otherwise

unsigned int rsf_index_enc	(	const struct rohc_comp_ctxt *const	context,
		unsigned int	rsf_flags
	)

Calculate the rsf_index from the rsf flags.

See RFC4996 page 71

Parameters:

context	The compressor context
rsf_flags	The RSF flags

Returns:

The rsf index

size_t ROHC_EXPORT variable_length_32_enc	(	const uint32_t	old_value,
		const uint32_t	new_value,
		const size_t	nr_bits_63,
		const size_t	nr_bits_16383,
		uint8_t *const	rohc_data,
		int *const	indicator
	)

Compress the given 32-bit value.

See variable_length_32_enc in RFC4996 page 46.

Parameters:

	old_value	The previous 32-bit value
	new_value	The 32-bit value to compress
	nr_bits_63	The number of bits required for W-LSB encoding with p = 63
	nr_bits_16383	The number of bits required for W-LSB encoding with p = 16383
[out]	rohc_data	The compressed value
[out]	indicator	The indicator for the compressed value

Returns:

The number of ROHC bytes written

---

Variable Documentation

unsigned int ROHC_EXPORT lsb_xor_masks[]

Table of the mask for lsb()