rfc4996.h File Reference

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

#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>

Include dependency graph for comp/schemes/rfc4996.h:

Go to the source code of this file.

Functions
int	c_static_or_irreg8 (const uint8_t context_value, const uint8_t packet_value, uint8_t *const rohc_data, const size_t rohc_max_len, int *const indicator)
	Compress the 8 bits given, depending of the context value.
int	c_static_or_irreg16 (const uint16_t packet_value, const bool is_static, uint8_t *const rohc_data, const size_t rohc_max_len, int *const indicator)
	Compress the 16 bits given, depending of the context value.
int	c_zero_or_irreg16 (const uint16_t packet_value, uint8_t *const rohc_data, const size_t rohc_max_len, 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, const size_t rohc_max_len, int *const indicator)
	Compress the 32 bits value, regarding if null or not.
int	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, const size_t rohc_max_len, int *const indicator)
	Compress the given 32-bit value.
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.
bool	rsf_index_enc_possible (const uint8_t rsf_flags)
	Is is possible to use the rsf_index_enc encoding?
unsigned int	rsf_index_enc (const uint8_t rsf_flags)
	Calculate the rsf_index from the rsf flags.
int	c_optional_ip_id_lsb (const int behavior, const uint16_t ip_id_nbo, const uint16_t ip_id_offset, const size_t nr_bits_wlsb, uint8_t *const rohc_data, const size_t rohc_max_len, int *const indicator)
	Compress or not the IP-ID.
int	dscp_encode (const uint8_t context_value, const uint8_t packet_value, uint8_t *const rohc_data, const size_t rohc_max_len, int *const indicator)
	Encode the DSCP field.

---

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

int c_optional_ip_id_lsb	(	const int	behavior,
		const uint16_t	ip_id_nbo,
		const uint16_t	ip_id_offset,
		const size_t	nr_bits_wlsb,
		uint8_t *const	rohc_data,
		const size_t	rohc_max_len,
		int *const	indicator
	)

Compress or not the IP-ID.

See RFC4996 page 76

Parameters:

	behavior	The IP-ID behavior
	ip_id_nbo	The IP-ID value to compress (in NBO)
	ip_id_offset	The IP-ID offset value to compress (in HBO)
	nr_bits_wlsb	The number of IP-ID offset bits required for W-LSB
[out]	rohc_data	The compressed value
	rohc_max_len	The max remaining length in the ROHC buffer
[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	packet_value,
		const bool	is_static,
		uint8_t *const	rohc_data,
		const size_t	rohc_max_len,
		int *const	indicator
	)

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

Parameters:

	packet_value	The packet value
	is_static	Whether the value is static or not
[out]	rohc_data	The compressed value
	rohc_max_len	The max remaining length in the ROHC buffer
[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,
		const size_t	rohc_max_len,
		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
	rohc_max_len	The max remaining length in the ROHC buffer
[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,
		const size_t	rohc_max_len,
		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
	rohc_max_len	The max remaining length in the ROHC buffer
[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,
		const size_t	rohc_max_len,
		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
	rohc_max_len	The max remaining length in the ROHC buffer
[out]	indicator	The indicator: 1 if present, 0 if not

Returns:

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

int dscp_encode	(	const uint8_t	context_value,
		const uint8_t	packet_value,
		uint8_t *const	rohc_data,
		const size_t	rohc_max_len,
		int *const	indicator
	)

Encode the DSCP field.

See RFC4996 page 75

Parameters:

	context_value	The DSCP value in the compression context
	packet_value	The DSCP value in the packet to compress
[out]	rohc_data	The compressed value
	rohc_max_len	The max remaining length in the ROHC buffer
[out]	indicator	The indicator: 1 if present, 1 if not

Returns:

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

unsigned int rsf_index_enc

(

const uint8_t

rsf_flags

)

Calculate the rsf_index from the rsf flags.

See RFC4996 page 71

Parameters:

rsf_flags

The RSF flags

Returns:

The rsf index

bool rsf_index_enc_possible

(

const uint8_t

rsf_flags

)

Is is possible to use the rsf_index_enc encoding?

See RFC4996 page 71

Parameters:

rsf_flags

The RSF flags

Returns:

true if the rsf_index_enc may be used, false if it cannot

int 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,
		const size_t	rohc_max_len,
		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
	rohc_max_len	The max remaining length in the ROHC buffer
[out]	indicator	The indicator for the compressed value

Returns:

The number of ROHC bytes written in case of success, -1 in case of error