list.c File Reference

ROHC generic list compression. More...

#include "schemes/list.h"
#include <string.h>

Include dependency graph for comp/schemes/list.c:

Defines
#define	rohc_comp_list_warn(list_ctxt, format,...)
Functions
static int	rohc_list_decide_type (struct list_comp *const comp)
	Decide the encoding type for compression list.
static int	rohc_list_encode_type_0 (struct list_comp *const comp, unsigned char *const dest, int counter)
	Build encoding type 0 for list compression.
static int	rohc_list_encode_type_1 (struct list_comp *const comp, unsigned char *const dest, int counter)
	Build encoding type 1 for list compression.
static int	rohc_list_encode_type_2 (struct list_comp *const comp, unsigned char *const dest, int counter)
	Build encoding type 2 for list compression.
static int	rohc_list_encode_type_3 (struct list_comp *const comp, unsigned char *const dest, int counter)
	Build encoding type 3 for list compression.
bool	detect_ipv6_ext_changes (struct list_comp *const comp, const struct ip_packet *const ip, bool *const list_struct_changed, bool *const list_content_changed)
	Detect changes withint the list of IPv6 extension headers.
int	rohc_list_encode (struct list_comp *const comp, unsigned char *const dest, int counter, const int size)
	Generic encoding of compressed list.
void	rohc_list_update_context (struct list_comp *const comp)
	Update the list compression context.

---

Detailed Description

ROHC generic list compression.

Author:

Didier Barvaux <didier@barvaux.org>

---

Define Documentation

#define rohc_comp_list_warn	(		list_ctxt,
			format,
			...
	)

Value:

rohc_warning(list_ctxt, ROHC_TRACE_COMP, (list_ctxt)->profile_id, \
                     format, ##__VA_ARGS__)

Print a warning trace for the given list compression context

---

Function Documentation

bool detect_ipv6_ext_changes	(	struct list_comp *const	comp,
		const struct ip_packet *const	ip,
		bool *const	list_struct_changed,
		bool *const	list_content_changed
	)

Detect changes withint the list of IPv6 extension headers.

Parameters:

	comp	The list compressor
	ip	The IP packet to compress
[out]	list_struct_changed	Whether the structure of the list changed
[out]	list_content_changed	Whether the content of the list changed

Returns:

true if no error occurred, false if one error occurred

static int rohc_list_decide_type

(

struct list_comp *const

comp

)

[static]

Decide the encoding type for compression list.

Parameters:

comp	The list compressor

Returns:

the encoding type among [0-3]

int rohc_list_encode	(	struct list_comp *const	comp,
		unsigned char *const	dest,
		int	counter,
		const int	size
	)

Generic encoding of compressed list.

Parameters:

comp	The list compressor
dest	The ROHC packet under build
counter	The current position in the rohc-packet-under-build buffer
size	The number of element in current list

Returns:

The new position in the rohc-packet-under-build buffer, -1 in case of error

static int rohc_list_encode_type_0	(	struct list_comp *const	comp,
		unsigned char *const	dest,
		int	counter
	)		[static]

Build encoding type 0 for list compression.

 Encoding type 0 (5.8.6.1):

      0   1   2   3   4   5   6   7
     --- --- --- --- --- --- --- ---
 1  | ET = 0| GP| PS|   CC = m      |
    +---+---+---+---+---+---+---+---+
 2  :            gen_id             : 1 octet, if GP = 1
    +---+---+---+---+---+---+---+---+
    |       XI 1, ..., XI m         | m octets, or m * 4 bits
 3  /               --- --- --- --- /
    |               :    Padding    : if PS = 0 and m is odd
    +---+---+---+---+---+---+---+---+
    |                               |
 4  /      item 1, ..., item n      / variable length
    |                               |
    +---+---+---+---+---+---+---+---+

 ET: Encoding type is zero.

 GP: Indicates presence of gen_id field.

 PS: Indicates size of XI fields:
     PS = 0 indicates 4-bit XI fields;
     PS = 1 indicates 8-bit XI fields.

 CC: CSRC counter from original RTP header.

 gen_id: Identifier for a sequence of identical lists.  It is
     present in U/O-mode when the compressor decides that it may use
     this list as a future reference list.

 XI 1, ..., XI m: m XI items. The format of an XI item is as
     follows:

              +---+---+---+---+
     PS = 0:  | X |   Index   |
              +---+---+---+---+

                0   1   2   3   4   5   6   7
              +---+---+---+---+---+---+---+---+
     PS = 1:  | X |           Index           |
              +---+---+---+---+---+---+---+---+

     X = 1 indicates that the item corresponding to the Index
           is sent in the item 0, ..., item n list.
     X = 0 indicates that the item corresponding to the Index is
               not sent.

     When 4-bit XI items are used and m > 1, the XI items are placed in
     octets in the following manner:

          0   1   2   3   4   5   6   7
        +---+---+---+---+---+---+---+---+
        |     XI k      |    XI k + 1   |
        +---+---+---+---+---+---+---+---+

 Padding: A 4-bit padding field is present when PS = 0 and m is
     odd.  The Padding field is set to zero when sending and ignored
     when receiving.

 Item 1, ..., item n:
     Each item corresponds to an XI with X = 1 in XI 1, ..., XI m.

Parameters:

comp	The list compressor
dest	The ROHC packet under build
counter	The current position in the rohc-packet-under-build buffer

Returns:

The new position in the rohc-packet-under-build buffer

static int rohc_list_encode_type_1	(	struct list_comp *const	comp,
		unsigned char *const	dest,
		int	counter
	)		[static]

Build encoding type 1 for list compression.

 Encoding type 1 (5.8.6.2):

      0   1   2   3   4   5   6   7
     --- --- --- --- --- --- --- ---
 1  | ET = 1| GP| PS|     XI 1      |
    +---+---+---+---+---+---+---+---+
 2  :            gen_id             : 1 octet, if GP = 1
    +---+---+---+---+---+---+---+---+
 3  |            ref_id             |
    +---+---+---+---+---+---+---+---+
 4  /       insertion bit mask      / 1-2 octets
    +---+---+---+---+---+---+---+---+
    |           XI list             | k octets, or (k - 1) * 4 bits
 5  /               --- --- --- --- /
    |               :    Padding    : if PS = 0 and k is even
    +---+---+---+---+---+---+---+---+
    |                               |
 6  /      item 1, ..., item n      / variable
    |                               |
    +---+---+---+---+---+---+---+---+

 ET: Encoding type is one (1).

 GP: Indicates presence of gen_id field.

 PS: Indicates size of XI fields:
     PS = 0 indicates 4-bit XI fields;
     PS = 1 indicates 8-bit XI fields.

 XI 1: When PS = 0, the first 4-bit XI item is placed here.
       When PS = 1, the field is set to zero when sending, and
       ignored when receiving.

 ref_id: The identifier of the reference CSRC list used when the
       list was compressed.  It is the 8 least significant bits of
       the RTP Sequence Number in R-mode and gen_id (see section
       5.8.2) in U/O-mode.

 insertion bit mask: Bit mask indicating the positions where new
           items are to be inserted.  See Insertion Only scheme in
           section 5.8.3.  The bit mask can have either of the
           following two formats:

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
    | 0 |        7-bit mask         |  bit 1 is the first bit
    +---+---+---+---+---+---+---+---+

    +---+---+---+---+---+---+---+---+
    | 1 |                           |  bit 1 is the first bit
    +---+      15-bit mask          +
    |                               |  bit 7 is the last bit
    +---+---+---+---+---+---+---+---+

 XI list: XI fields for items to be inserted.  When the insertion
    bit mask has k ones, the total number of XI fields is k.  When
    PS = 1, all XI fields are in the XI list.  When PS = 0, the
    first XI field is in the XI 1 field, and the remaining k - 1
    XI fields are in the XI list.

 Padding: Present when PS = 0 and k is even.

 item 1, ..., item n: One item for each XI field with the X bit set.

Parameters:

comp	The list compressor
dest	The ROHC packet under build
counter	The current position in the rohc-packet-under-build buffer

Returns:

The new position in the rohc-packet-under-build buffer

static int rohc_list_encode_type_2	(	struct list_comp *const	comp,
		unsigned char *const	dest,
		int	counter
	)		[static]

Build encoding type 2 for list compression.

 Encoding type 2 (5.8.6.3):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 1  | ET = 2| GP|res|    Count      |
    +---+---+---+---+---+---+---+---+
 2  :            gen_id             : 1 octet, if GP = 1
    +---+---+---+---+---+---+---+---+
 3  |            ref_id             |
    +---+---+---+---+---+---+---+---+
 4  /        removal bit mask       / 1-2 octets
    +---+---+---+---+---+---+---+---+

 ET: Encoding type is 2.

 GP: Indicates presence of gen_id field.

 res: Reserved.  Set to zero when sending, ignored when
      received.

 Count: Number of elements in ref_list.

 removal bit mask: Indicates the elements in ref_list to be
    removed in order to obtain the current list.  See section
    5.8.3.  The bit mask can have either of the following two
    formats:

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
    | 0 |        7-bit mask         |  bit 1 is the first bit
    +---+---+---+---+---+---+---+---+

    +---+---+---+---+---+---+---+---+
    | 1 |                           |  bit 1 is the first bit
    +---+      15-bit mask          +
    |                               |  bit 7 is the last bit
    +---+---+---+---+---+---+---+---+

Parameters:

comp	The list compressor
dest	The ROHC packet under build
counter	The current position in the rohc-packet-under-build buffer

Returns:

The new position in the rohc-packet-under-build buffer

static int rohc_list_encode_type_3	(	struct list_comp *const	comp,
		unsigned char *const	dest,
		int	counter
	)		[static]

Build encoding type 3 for list compression.

 Encoding type 3 (5.8.6.4):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 1  | ET=3  |GP |PS |     XI 1      |
    +---+---+---+---+---+---+---+---+
 2  :            gen_id             : 1 octet, if GP = 1
    +---+---+---+---+---+---+---+---+
 3  |            ref_id             |
    +---+---+---+---+---+---+---+---+
 4  /        removal bit mask       / 1-2 octets
    +---+---+---+---+---+---+---+---+
 5  /       insertion bit mask      / 1-2 octets
    +---+---+---+---+---+---+---+---+
    |           XI list             | k octets, or (k - 1) * 4 bits
 6  /               --- --- --- --- /
    |               :    Padding    : if PS = 0 and k is even
    +---+---+---+---+---+---+---+---+
    |                               |
 7  /      item 1, ..., item n      / variable
    |                               |
    +---+---+---+---+---+---+---+---+

 ET: Encoding type is 3.

 GP: Indicates presence of gen_id field.

 PS: Indicates size of XI fields:
     PS = 0 indicates 4-bit XI fields;
     PS = 1 indicates 8-bit XI fields.

 gen_id: Identifier for a sequence of identical lists.  It is
     present in U/O-mode when the compressor decides that it may use
     this list as a future reference list.

 ref_id: The identifier of the reference CSRC list used when the
       list was compressed.  It is the 8 least significant bits of
       the RTP Sequence Number in R-mode and gen_id (see section
       5.8.2) in U/O-mode.

 removal bit mask: Indicates the elements in ref_list to be
    removed in order to obtain the current list.  See section
    5.8.3.  The bit mask can have either of the following two
    formats:

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
    | 0 |        7-bit mask         |  bit 1 is the first bit
    +---+---+---+---+---+---+---+---+

    +---+---+---+---+---+---+---+---+
    | 1 |                           |  bit 1 is the first bit
    +---+      15-bit mask          +
    |                               |  bit 7 is the last bit
    +---+---+---+---+---+---+---+---+

 insertion bit mask: Bit mask indicating the positions where new
           items are to be inserted.  See Insertion Only scheme in
           section 5.8.3.  The bit mask can have either of the
           following two formats:

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
    | 0 |        7-bit mask         |  bit 1 is the first bit
    +---+---+---+---+---+---+---+---+

    +---+---+---+---+---+---+---+---+
    | 1 |                           |  bit 1 is the first bit
    +---+      15-bit mask          +
    |                               |  bit 7 is the last bit
    +---+---+---+---+---+---+---+---+

 XI list: XI fields for items to be inserted.  When the insertion
    bit mask has k ones, the total number of XI fields is k.  When
    PS = 1, all XI fields are in the XI list.  When PS = 0, the
    first XI field is in the XI 1 field, and the remaining k - 1
    XI fields are in the XI list.

 Padding: Present when PS = 0 and k is even.

 item 1, ..., item n: One item for each XI field with the X bit set.

Parameters:

comp	The list compressor
dest	The ROHC packet under build
counter	The current position in the rohc-packet-under-build buffer

Returns:

The new position in the rohc-packet-under-build buffer

void rohc_list_update_context

(

struct list_comp *const

comp

)

Update the list compression context.

Update the counter of the current list. Update the counters of the items of the current list. Update the reference list with the current list if possible.

Parameters:

comp	The list compressor