GSM RLP (Radio Link Protocol) as used in CSD (3GPP TS 24.022)

RLP (Radio Link Protocol) as per 3GPP TS 24.022. More...

Files
file	rlp.h

Data Structures
struct	osmo_rlp_frame_decoded
	Data structure representing one decoded RLP frame. More...

Macros
#define	FCS_SIZE_BYTES   3

Enumerations
enum	osmo_rlp_ftype {   OSMO_RLP_FT_U ,   OSMO_RLP_FT_S ,   OSMO_RLP_FT_IS }
	RLP frame type as per 3GPP TS 24.022 Section 5.2.1. More...
enum	osmo_rlp_u_ftype {   OSMO_RLP_U_FT_SABM = 0x07 ,   OSMO_RLP_U_FT_UA = 0x0c ,   OSMO_RLP_U_FT_DISC = 0x08 ,   OSMO_RLP_U_FT_DM = 0x03 ,   OSMO_RLP_U_FT_NULL = 0x0f ,   OSMO_RLP_U_FT_UI = 0x00 ,   OSMO_RLP_U_FT_XID = 0x17 ,   OSMO_RLP_U_FT_TEST = 0x1c ,   OSMO_RLP_U_FT_REMAP = 0x11 }
	RLP U-Frame Type as per 3GPP TS 24.022 Section 5.2.1. More...
enum	osmo_rlp_s_ftype {   OSMO_RLP_S_FT_RR = 0 ,   OSMO_RLP_S_FT_REJ = 2 ,   OSMO_RLP_S_FT_RNR = 1 ,   OSMO_RLP_S_FT_SREJ = 3 }
	RLP S-Frame type as per 3GPP TS 24.022 Section 5.2.1. More...

Functions
int	osmo_rlp_decode (struct osmo_rlp_frame_decoded *out, uint8_t version, const uint8_t *data, size_t data_len)
	decode a RLP frame into its abstract representation. More...
int	osmo_rlp_encode (uint8_t *out, size_t out_size, const struct osmo_rlp_frame_decoded *in)
	encode a RLP frame from its abstract representation. More...
uint32_t	osmo_rlp_fcs_compute (const uint8_t *in, size_t in_len)
	compute RLP FCS according to 3GPP TS 24.022 Section 4.4. More...

Variables
const struct value_string	osmo_rlp_ftype_vals []
const struct value_string	osmo_rlp_ftype_u_vals []
const struct value_string	osmo_rlp_ftype_s_vals []
const struct value_string	osmo_rlp_ftype_vals []
const struct value_string	osmo_rlp_ftype_u_vals []
const struct value_string	osmo_rlp_ftype_s_vals []
static const uint32_t	rlp_fcs_table [256]

Detailed Description

RLP (Radio Link Protocol) as per 3GPP TS 24.022.

Macro Definition Documentation

FCS_SIZE_BYTES

#define FCS_SIZE_BYTES   3

Enumeration Type Documentation

osmo_rlp_ftype

enum osmo_rlp_ftype

RLP frame type as per 3GPP TS 24.022 Section 5.2.1.

Enumerator
OSMO_RLP_FT_U
OSMO_RLP_FT_S
OSMO_RLP_FT_IS

osmo_rlp_s_ftype

enum osmo_rlp_s_ftype

RLP S-Frame type as per 3GPP TS 24.022 Section 5.2.1.

Enumerator
OSMO_RLP_S_FT_RR
OSMO_RLP_S_FT_REJ
OSMO_RLP_S_FT_RNR
OSMO_RLP_S_FT_SREJ

osmo_rlp_u_ftype

enum osmo_rlp_u_ftype

RLP U-Frame Type as per 3GPP TS 24.022 Section 5.2.1.

Enumerator
OSMO_RLP_U_FT_SABM
OSMO_RLP_U_FT_UA
OSMO_RLP_U_FT_DISC
OSMO_RLP_U_FT_DM
OSMO_RLP_U_FT_NULL
OSMO_RLP_U_FT_UI
OSMO_RLP_U_FT_XID
OSMO_RLP_U_FT_TEST
OSMO_RLP_U_FT_REMAP

Function Documentation

osmo_rlp_decode()

int osmo_rlp_decode	(	struct osmo_rlp_frame_decoded *	out,
		uint8_t	version,
		const uint8_t *	data,
		size_t	data_len
	)

decode a RLP frame into its abstract representation.

Doesn't check FCS correctness.

Parameters

[out]	out	caller-allocated memory for output of decoded frame
[in]	version	RLP version number to use when decoding
[in]	data	raw RLP frame input data
[in]	data_len	length of data (in octets); must be 30 (240bit) or 72 (576bit)

Returns

0 in case of success; negative on error

References osmo_rlp_frame_decoded::c_r, data, ENOTSUP, osmo_rlp_frame_decoded::fcs, FCS_SIZE_BYTES, osmo_rlp_frame_decoded::ftype, hdr_len, osmo_rlp_frame_decoded::info, osmo_rlp_frame_decoded::info_len, osmo_rlp_frame_decoded::n_r, osmo_rlp_frame_decoded::n_s, OSMO_RLP_FT_IS, OSMO_RLP_FT_S, OSMO_RLP_FT_U, OSMO_RLP_U_FT_XID, osmo_rlp_frame_decoded::p_f, osmo_rlp_frame_decoded::s_ftype, osmo_rlp_frame_decoded::u_ftype, version, and osmo_rlp_frame_decoded::version.

osmo_rlp_encode()

int osmo_rlp_encode	(	uint8_t *	out,
		size_t	out_size,
		const struct osmo_rlp_frame_decoded *	in
	)

encode a RLP frame from its abstract representation.

Generates FCS.

Parameters

[out]	out	caller-allocated output buffer
[in]	out_size	size of output buffer (in octets); must be 30 (240bit) or 72 (576bit)
[in]	in	decoded RLP frame which is to be encoded

Returns

number of output bytes used; negative on error

References osmo_rlp_frame_decoded::c_r, ENOTSUP, FCS_SIZE_BYTES, osmo_rlp_frame_decoded::ftype, hdr_len, osmo_rlp_frame_decoded::info, osmo_rlp_frame_decoded::info_len, osmo_rlp_frame_decoded::n_r, osmo_rlp_frame_decoded::n_s, osmo_rlp_fcs_compute(), OSMO_RLP_FT_IS, OSMO_RLP_FT_S, OSMO_RLP_FT_U, OSMO_RLP_U_FT_XID, osmo_rlp_frame_decoded::p_f, osmo_rlp_frame_decoded::s_ftype, osmo_rlp_frame_decoded::u_ftype, and osmo_rlp_frame_decoded::version.

osmo_rlp_fcs_compute()

uint32_t osmo_rlp_fcs_compute	(	const uint8_t *	in,
		size_t	in_len
	)

compute RLP FCS according to 3GPP TS 24.022 Section 4.4.

Parameters

[in]	in	input data over which to compute FCS
[in]	in_len	length of input data (in octets)

Returns

computed frame check sequence (FCS).

References rlp_fcs_table.

Referenced by osmo_rlp_encode().

Variable Documentation

osmo_rlp_ftype_s_vals [1/2]

const struct value_string osmo_rlp_ftype_s_vals[]

extern

osmo_rlp_ftype_s_vals [2/2]

const struct value_string osmo_rlp_ftype_s_vals[]

Initial value:

= {
        { OSMO_RLP_S_FT_RR,     "RR" },
        { OSMO_RLP_S_FT_REJ,    "REJ" },
        { OSMO_RLP_S_FT_RNR,    "RNR" },
        { OSMO_RLP_S_FT_SREJ,   "SREJ" },
        { 0, NULL }
}

osmo_rlp_ftype_u_vals [1/2]

const struct value_string osmo_rlp_ftype_u_vals[]

extern

osmo_rlp_ftype_u_vals [2/2]

const struct value_string osmo_rlp_ftype_u_vals[]

Initial value:

= {
        { OSMO_RLP_U_FT_SABM,   "SABM" },
        { OSMO_RLP_U_FT_UA,     "UA" },
        { OSMO_RLP_U_FT_DISC,   "DISC" },
        { OSMO_RLP_U_FT_DM,     "DM" },
        { OSMO_RLP_U_FT_NULL,   "NULL" },
        { OSMO_RLP_U_FT_UI,     "UI" },
        { OSMO_RLP_U_FT_XID,    "XID" },
        { OSMO_RLP_U_FT_TEST,   "TEST" },
        { OSMO_RLP_U_FT_REMAP,  "REMAP" },
        { 0, NULL }
}

osmo_rlp_ftype_vals [1/2]

const struct value_string osmo_rlp_ftype_vals[]

extern

osmo_rlp_ftype_vals [2/2]

const struct value_string osmo_rlp_ftype_vals[]

Initial value:

= {
        { OSMO_RLP_FT_U,        "U" },
        { OSMO_RLP_FT_S,        "S" },
        { OSMO_RLP_FT_IS,       "IS" },
        { 0, NULL }
}

rlp_fcs_table

const uint32_t rlp_fcs_table[256]

static

Referenced by osmo_rlp_fcs_compute().