Osmocom Packet control Unit (PCU): Network-side GPRS (RLC/MAC); BTS- or BSC-colocated https://osmocom.org/projects/osmopcu
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osmo-pcu/src/decoding.cpp

787 lines
22 KiB

/* decoding
*
* Copyright (C) 2012 Ivan Klyuchnikov
* Copyright (C) 2012 Andreas Eversberg <jolly@eversberg.eu>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <decoding.h>
#include <rlc.h>
#include <gprs_debug.h>
#include <egprs_rlc_compression.h>
extern "C" {
#include <osmocom/core/utils.h>
#include <osmocom/core/bitcomp.h>
#include <osmocom/gprs/protocol/gsm_04_60.h>
}
#include <arpa/inet.h>
#include <errno.h>
#include <string.h>
#define LENGTH_TO_END 255
/*!
* \returns num extensions fields (num frames == offset) on success,
* -errno otherwise.
*/
static int parse_extensions_egprs(const uint8_t *data, unsigned int data_len,
unsigned int *offs,
bool is_last_block,
Decoding::RlcData *chunks, unsigned int chunks_size)
{
const struct rlc_li_field_egprs *li;
uint8_t e;
unsigned int num_chunks = 0;
e = 0;
while (!e) {
if (*offs > data_len) {
LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA LI extended, "
"but no more data\n");
return -EINVAL;
}
/* get new E */
li = (struct rlc_li_field_egprs *)&data[*offs];
e = li->e;
*offs += 1;
if (!chunks)
continue;
if (num_chunks == chunks_size) {
LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA LI extended, "
"but no more chunks possible\n");
return -ENOSPC;
}
if (li->li == 0 && num_chunks == 0) {
/* TS 44.060, table 10.4.14a.1, row 2a */
/* TS 44.060, table 10.4.14a.1, row 4 */
chunks[num_chunks].length = 0;
chunks[num_chunks].is_complete = true;
} else if (li->li == 127 && li->e == 1) {
/* TS 44.060, table 10.4.14a.1, row 3 & 5 */
/* only filling bytes left */
LOGP(DRLCMACUL, LOGL_DEBUG, "UL DATA LI contains "
"only filling bytes with extension octet: LI=%d, E=%d, count=%d\n",
li->li, li->e, num_chunks);
break;
} else if (li->li > 0) {
/* TS 44.060, table 10.4.14a.1, row 1 & 2b */
chunks[num_chunks].length = li->li;
chunks[num_chunks].is_complete = true;
} else {
LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA LI contains "
"invalid extension octet: LI=%d, E=%d, count=%d\n",
li->li, li->e, num_chunks);
return -EINVAL;
}
LOGP(DRLCMACUL, LOGL_DEBUG, "UL DATA LI contains "
"extension octet: LI=%d, E=%d, count=%d\n",
li->li, li->e, num_chunks);
num_chunks += 1;
if (e == 1) {
/* There is space after the last chunk, add a final one */
if (num_chunks == chunks_size) {
LOGP(DRLCMACUL, LOGL_NOTICE,
"UL DATA LI possibly extended, "
"but no more chunks possible\n");
return -ENOSPC;
}
chunks[num_chunks].length = LENGTH_TO_END;
chunks[num_chunks].is_complete = is_last_block;
num_chunks += 1;
}
}
return num_chunks;
}
static int parse_extensions_gprs(const uint8_t *data, unsigned int data_len,
unsigned int *offs,
bool is_last_block,
Decoding::RlcData *chunks, unsigned int chunks_size)
{
const struct rlc_li_field *li;
uint8_t m, e;
unsigned int num_chunks = 0;
e = 0;
while (!e) {
if (*offs > data_len) {
LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA LI extended, "
"but no more data\n");
return -EINVAL;
}
/* get new E */
li = (const struct rlc_li_field *)&data[*offs];
e = li->e;
m = li->m;
*offs += 1;
if (li->li == 0) {
/* TS 44.060, 10.4.14, par 6 */
e = 1;
m = 0;
}
/* TS 44.060, table 10.4.13.1 */
if (m == 0 && e == 0) {
LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA "
"ignored, because M='0' and E='0'.\n");
return 0;
}
if (!chunks)
continue;
if (num_chunks == chunks_size) {
LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA LI extended, "
"but no more chunks possible\n");
return -ENOSPC;
}
if (li->li == 0)
/* e is 1 here */
chunks[num_chunks].length = LENGTH_TO_END;
else
chunks[num_chunks].length = li->li;
chunks[num_chunks].is_complete = li->li || is_last_block;
LOGP(DRLCMACUL, LOGL_DEBUG, "UL DATA LI contains "
"extension octet: LI=%d, M=%d, E=%d, count=%d\n",
li->li, li->m, li->e, num_chunks);
num_chunks += 1;
if (e == 1 && m == 1) {
if (num_chunks == chunks_size) {
LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA LI extended, "
"but no more chunks possible\n");
return -ENOSPC;
}
/* TS 44.060, 10.4.13.1, row 4 */
chunks[num_chunks].length = LENGTH_TO_END;
chunks[num_chunks].is_complete = is_last_block;
num_chunks += 1;
}
}
return num_chunks;
}
int Decoding::rlc_data_from_ul_data(
const struct gprs_rlc_data_block_info *rdbi, enum CodingScheme cs,
const uint8_t *data, RlcData *chunks, unsigned int chunks_size,
uint32_t *tlli)
{
uint8_t e;
unsigned int data_len = rdbi->data_len;
int num_chunks = 0, i;
unsigned int offs = 0;
bool is_last_block = (rdbi->cv == 0);
if (!chunks)
chunks_size = 0;
e = rdbi->e;
if (e) {
if (chunks_size > 0) {
/* Block without LI means it only contains data of one LLC PDU */
chunks[num_chunks].offset = offs;
chunks[num_chunks].length = LENGTH_TO_END;
chunks[num_chunks].is_complete = is_last_block;
num_chunks += 1;
} else if (chunks) {
LOGP(DRLCMACUL, LOGL_NOTICE, "No extension, "
"but no more chunks possible\n");
return -ENOSPC;
}
} else if (mcs_is_edge(cs)) {
/* if E is not set (LI follows), EGPRS */
num_chunks = parse_extensions_egprs(data, data_len, &offs,
is_last_block,
chunks, chunks_size);
} else {
/* if E is not set (LI follows), GPRS */
num_chunks = parse_extensions_gprs(data, data_len, &offs,
is_last_block,
chunks, chunks_size);
}
if (num_chunks < 0)
return num_chunks;
/* TLLI */
if (rdbi->ti) {
uint32_t tlli_enc;
if (offs + 4 > data_len) {
LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TLLI out of block "
"border\n");
return -EINVAL;
}
memcpy(&tlli_enc, data + offs, sizeof(tlli_enc));
if (mcs_is_gprs(cs))
/* The TLLI is encoded in big endian for GPRS (see
* TS 44.060, figure 10.2.2.1, note) */
*tlli = be32toh(tlli_enc);
else
/* The TLLI is encoded in little endian for EGPRS (see
* TS 44.060, figure 10.3a.2.1, note 2) */
*tlli = le32toh(tlli_enc);
offs += sizeof(tlli_enc);
} else {
*tlli = 0;
}
/* PFI */
if (rdbi->pi) {
LOGP(DRLCMACUL, LOGL_ERROR, "ERROR: PFI not supported, "
"please disable in SYSTEM INFORMATION\n");
return -ENOTSUP;
/* TODO: Skip all extensions with E=0 (see TS 44.060, 10.4.11 */
}
if (chunks_size == 0)
return num_chunks;
/* LLC */
for (i = 0; i < num_chunks; i++) {
chunks[i].offset = offs;
if (chunks[i].length == LENGTH_TO_END) {
if (offs == data_len) {
/* There is no place for an additional chunk,
* so drop it (this may happen with EGPRS since
* there is no M flag. */
num_chunks -= 1;
break;
}
chunks[i].length = data_len - offs;
}
offs += chunks[i].length;
if (offs > data_len) {
LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA out of block "
"border, chunk idx: %d, offset: %u, size: %d, data_len: %u\n",
i, offs, chunks[i].length, data_len);
return -EINVAL;
}
}
return num_chunks;
}
uint8_t get_ms_class_by_capability(MS_Radio_Access_capability_t *cap)
{
int i;
for (i = 0; i < cap->Count_MS_RA_capability_value; i++) {
if (!cap->MS_RA_capability_value[i].u.Content.Exist_Multislot_capability)
continue;
if (!cap->MS_RA_capability_value[i].u.Content.Multislot_capability.Exist_GPRS_multislot_class)
continue;
return cap->MS_RA_capability_value[i].u.Content.Multislot_capability.GPRS_multislot_class;
}
return 0;
}
uint8_t get_egprs_ms_class_by_capability(MS_Radio_Access_capability_t *cap)
{
int i;
for (i = 0; i < cap->Count_MS_RA_capability_value; i++) {
if (!cap->MS_RA_capability_value[i].u.Content.Exist_Multislot_capability)
continue;
if (!cap->MS_RA_capability_value[i].u.Content.Multislot_capability.Exist_EGPRS_multislot_class)
continue;
return cap->MS_RA_capability_value[i].u.Content.Multislot_capability.EGPRS_multislot_class;
}
return 0;
}
/**
* show_rbb needs to be an array with 65 elements
* The index of the array is the bit position in the rbb
* (show_rbb[63] relates to BSN ssn-1)
*/
void Decoding::extract_rbb(const struct bitvec *rbb, char *show_rbb)
{
unsigned int i;
for (i = 0; i < rbb->cur_bit; i++) {
uint8_t bit;
bit = bitvec_get_bit_pos(rbb, i);
show_rbb[i] = bit == 1 ? 'R' : 'I';
}
show_rbb[i] = '\0';
}
int Decoding::rlc_parse_ul_data_header(struct gprs_rlc_data_info *rlc,
const uint8_t *data, enum CodingScheme cs)
{
unsigned int cur_bit = 0;
switch(mcs_header_type(cs)) {
case HEADER_GPRS_DATA :
cur_bit = rlc_parse_ul_data_header_gprs(rlc, data, cs);
break;
case HEADER_EGPRS_DATA_TYPE_3 :
cur_bit = rlc_parse_ul_data_header_egprs_type_3(rlc, data, cs);
break;
case HEADER_EGPRS_DATA_TYPE_2 :
cur_bit = rlc_parse_ul_data_header_egprs_type_2(rlc, data, cs);
break;
case HEADER_EGPRS_DATA_TYPE_1 :
cur_bit = rlc_parse_ul_data_header_egprs_type_1(rlc, data, cs);
break;
default:
LOGP(DRLCMACDL, LOGL_ERROR,
"Decoding of uplink %s data blocks not yet supported.\n",
mcs_name(cs));
return -ENOTSUP;
};
return cur_bit;
}
int Decoding::rlc_parse_ul_data_header_egprs_type_3(
struct gprs_rlc_data_info *rlc,
const uint8_t *data,
const enum CodingScheme &cs)
{
int punct, punct2, with_padding, cps;
unsigned int e_ti_header, offs, cur_bit = 0;
const struct gprs_rlc_ul_header_egprs_3 *egprs3;
egprs3 = static_cast < struct gprs_rlc_ul_header_egprs_3 * >
((void *)data);
cps = (egprs3->cps_hi << 0) | (egprs3->cps_lo << 2);
gprs_rlc_mcs_cps_decode(cps, cs, &punct, &punct2, &with_padding);
gprs_rlc_data_info_init_ul(rlc, cs, with_padding);
rlc->r = egprs3->r;
rlc->si = egprs3->si;
rlc->tfi = (egprs3->tfi_hi << 0) | (egprs3->tfi_lo << 2);
rlc->cps = cps;
rlc->rsb = egprs3->rsb;
rlc->num_data_blocks = 1;
rlc->block_info[0].cv = egprs3->cv;
rlc->block_info[0].pi = egprs3->pi;
rlc->block_info[0].spb = egprs3->spb;
rlc->block_info[0].bsn =
(egprs3->bsn1_hi << 0) | (egprs3->bsn1_lo << 5);
cur_bit += rlc->data_offs_bits[0] - 2;
offs = rlc->data_offs_bits[0] / 8;
OSMO_ASSERT(rlc->data_offs_bits[0] % 8 == 1);
e_ti_header = (data[offs-1] + (data[offs] << 8)) >> 7;
rlc->block_info[0].e = !!(e_ti_header & 0x01);
rlc->block_info[0].ti = !!(e_ti_header & 0x02);
cur_bit += 2;
/* skip data area */
cur_bit += mcs_max_data_block_bytes(cs) * 8;
return cur_bit;
}
int Decoding::rlc_parse_ul_data_header_egprs_type_2(
struct gprs_rlc_data_info *rlc,
const uint8_t *data,
const enum CodingScheme &cs)
{
const struct gprs_rlc_ul_header_egprs_2 *egprs2;
unsigned int e_ti_header, offs, cur_bit = 0;
int punct, punct2, with_padding, cps;
egprs2 = static_cast < struct gprs_rlc_ul_header_egprs_2 * >
((void *)data);
cps = (egprs2->cps_hi << 0) | (egprs2->cps_lo << 2);
gprs_rlc_mcs_cps_decode(cps, cs, &punct, &punct2, &with_padding);
gprs_rlc_data_info_init_ul(rlc, cs, with_padding);
rlc->r = egprs2->r;
rlc->si = egprs2->si;
rlc->tfi = (egprs2->tfi_hi << 0) | (egprs2->tfi_lo << 2);
rlc->cps = cps;
rlc->rsb = egprs2->rsb;
rlc->num_data_blocks = 1;
rlc->block_info[0].cv = egprs2->cv;
rlc->block_info[0].pi = egprs2->pi;
rlc->block_info[0].bsn =
(egprs2->bsn1_hi << 0) | (egprs2->bsn1_lo << 5);
cur_bit += rlc->data_offs_bits[0] - 2;
offs = rlc->data_offs_bits[0] / 8;
OSMO_ASSERT(rlc->data_offs_bits[0] % 8 == 7);
e_ti_header = (data[offs] & 0x60) >> 5;
rlc->block_info[0].e = !!(e_ti_header & 0x01);
rlc->block_info[0].ti = !!(e_ti_header & 0x02);
cur_bit += 2;
/* skip data area */
cur_bit += mcs_max_data_block_bytes(cs) * 8;
return cur_bit;
}
int Decoding::rlc_parse_ul_data_header_egprs_type_1(
struct gprs_rlc_data_info *rlc,
const uint8_t *data, const enum CodingScheme &cs)
{
struct gprs_rlc_ul_header_egprs_1 *egprs1;
unsigned int e_ti_header, cur_bit = 0, offs;
int punct, punct2, with_padding;
egprs1 = static_cast < struct gprs_rlc_ul_header_egprs_1 * >
((void *)data);
gprs_rlc_mcs_cps_decode(egprs1->cps, cs, &punct, &punct2,
&with_padding);
gprs_rlc_data_info_init_ul(rlc, cs, with_padding);
rlc->r = egprs1->r;
rlc->si = egprs1->si;
rlc->tfi = (egprs1->tfi_hi << 0) | (egprs1->tfi_lo << 2);
rlc->cps = egprs1->cps;
rlc->rsb = egprs1->rsb;
rlc->num_data_blocks = 2;
rlc->block_info[0].cv = egprs1->cv;
rlc->block_info[0].pi = egprs1->pi;
rlc->block_info[0].bsn =
(egprs1->bsn1_hi << 0) | (egprs1->bsn1_lo << 5);
cur_bit += rlc->data_offs_bits[0] - 2;
offs = rlc->data_offs_bits[0] / 8;
OSMO_ASSERT(rlc->data_offs_bits[0] % 8 == 0);
e_ti_header = data[offs - 1] >> 6;
rlc->block_info[0].e = (e_ti_header & 0x01);
rlc->block_info[0].ti = !!(e_ti_header & 0x02);
cur_bit += 2;
rlc->block_info[1].cv = egprs1->cv;
rlc->block_info[1].pi = egprs1->pi;
rlc->block_info[1].bsn = rlc->block_info[0].bsn +
((egprs1->bsn2_hi << 0) | (egprs1->bsn2_lo << 2));
rlc->block_info[1].bsn = rlc->block_info[1].bsn & (RLC_EGPRS_SNS - 1);
if ((rlc->block_info[1].bsn != rlc->block_info[0].bsn) &&
(rlc->block_info[0].cv == 0))
rlc->block_info[0].cv = 1;
cur_bit = rlc->data_offs_bits[1] - 2;
offs = rlc->data_offs_bits[1] / 8;
OSMO_ASSERT(rlc->data_offs_bits[1] % 8 == 2);
e_ti_header = (data[offs] & (0x03));
rlc->block_info[1].e = (e_ti_header & 0x01);
rlc->block_info[1].ti = !!(e_ti_header & 0x02);
cur_bit += 2;
/* skip data area */
cur_bit += mcs_max_data_block_bytes(cs) * 8;
return cur_bit;
}
int Decoding::rlc_parse_ul_data_header_gprs(struct gprs_rlc_data_info *rlc,
const uint8_t *data, const enum CodingScheme &cs)
{
const struct rlc_ul_header *gprs;
unsigned int cur_bit = 0;
gprs = static_cast < struct rlc_ul_header * >
((void *)data);
gprs_rlc_data_info_init_ul(rlc, cs, false);
rlc->r = gprs->r;
rlc->si = gprs->si;
rlc->tfi = gprs->tfi;
rlc->cps = 0;
rlc->rsb = 0;
rlc->num_data_blocks = 1;
rlc->block_info[0].cv = gprs->cv;
rlc->block_info[0].pi = gprs->pi;
rlc->block_info[0].bsn = gprs->bsn;
rlc->block_info[0].e = gprs->e;
rlc->block_info[0].ti = gprs->ti;
rlc->block_info[0].spb = 0;
cur_bit += rlc->data_offs_bits[0];
/* skip data area */
cur_bit += mcs_max_data_block_bytes(cs) * 8;
return cur_bit;
}
/**
* \brief Copy LSB bitstream RLC data block to byte aligned buffer.
*
* Note that the bitstream is encoded in LSB first order, so the two octets
* 654321xx xxxxxx87 contain the octet 87654321 starting at bit position 3
* (LSB has bit position 1). This is a different order than the one used by
* CSN.1.
*
* \param data_block_idx The block index, 0..1 for header type 1, 0 otherwise
* \param src A pointer to the start of the RLC block (incl. the header)
* \param buffer A data area of a least the size of the RLC block
* \returns the number of bytes copied
*/
unsigned int Decoding::rlc_copy_to_aligned_buffer(
const struct gprs_rlc_data_info *rlc,
unsigned int data_block_idx,
const uint8_t *src, uint8_t *buffer)
{
unsigned int hdr_bytes;
unsigned int extra_bits;
unsigned int i;
uint8_t c, last_c;
uint8_t *dst;
const struct gprs_rlc_data_block_info *rdbi;
OSMO_ASSERT(data_block_idx < rlc->num_data_blocks);
rdbi = &rlc->block_info[data_block_idx];
hdr_bytes = rlc->data_offs_bits[data_block_idx] >> 3;
extra_bits = (rlc->data_offs_bits[data_block_idx] & 7);
if (extra_bits == 0) {
/* It is aligned already */
memmove(buffer, src + hdr_bytes, rdbi->data_len);
return rdbi->data_len;
}
dst = buffer;
src = src + hdr_bytes;
last_c = *(src++);
for (i = 0; i < rdbi->data_len; i++) {
c = src[i];
*(dst++) = (last_c >> extra_bits) | (c << (8 - extra_bits));
last_c = c;
}
return rdbi->data_len;
}
/**
* \brief Get a pointer to byte aligned RLC data.
*
* Since the RLC data may not be byte aligned to the RLC block data such that a
* single RLC data byte is spread over two RLC block bytes, this function
* eventually uses the provided buffer as data storage.
*
* \param src A pointer to the start of the RLC block (incl. the header)
* \param buffer A data area of a least the size of the RLC block
* \returns A pointer to the RLC data start within src if it is aligned, and
* buffer otherwise.
*/
const uint8_t *Decoding::rlc_get_data_aligned(
const struct gprs_rlc_data_info *rlc,
unsigned int data_block_idx,
const uint8_t *src, uint8_t *buffer)
{
unsigned int hdr_bytes;
unsigned int extra_bits;
OSMO_ASSERT(data_block_idx < ARRAY_SIZE(rlc->data_offs_bits));
hdr_bytes = rlc->data_offs_bits[data_block_idx] >> 3;
extra_bits = (rlc->data_offs_bits[data_block_idx] & 7);
if (extra_bits == 0)
/* It is aligned already, return a pointer that refers to the
* original data. */
return src + hdr_bytes;
Decoding::rlc_copy_to_aligned_buffer(rlc, data_block_idx, src, buffer);
return buffer;
}
static int handle_final_ack(bitvec *bits, int *bsn_begin, int *bsn_end,
gprs_rlc_dl_window *window)
{
int num_blocks, i;
num_blocks = window->mod_sns(window->v_s() - window->v_a());
for (i = 0; i < num_blocks; i++)
bitvec_set_bit(bits, ONE);
*bsn_begin = window->v_a();
*bsn_end = window->mod_sns(*bsn_begin + num_blocks);
return num_blocks;
}
int Decoding::decode_egprs_acknack_bits(const EGPRS_AckNack_Desc_t *desc,
bitvec *bits, int *bsn_begin, int *bsn_end, gprs_rlc_dl_window *window)
{
int urbb_len = desc->URBB_LENGTH;
int crbb_len = 0;
int num_blocks = 0;
struct bitvec urbb;
int i;
bool have_bitmap;
int implicitly_acked_blocks;
int ssn = desc->STARTING_SEQUENCE_NUMBER;
int rc;
if (desc->FINAL_ACK_INDICATION)
return handle_final_ack(bits, bsn_begin, bsn_end, window);
if (desc->Exist_CRBB)
crbb_len = desc->CRBB_LENGTH;
have_bitmap = (urbb_len + crbb_len) > 0;
/*
* bow & bitmap present:
* V(A)-> [ 11111...11111 0 SSN-> BBBBB...BBBBB ] (SSN+Nbits) .... V(S)
* bow & not bitmap present:
* V(A)-> [ 11111...11111 ] . SSN .... V(S)
* not bow & bitmap present:
* V(A)-> ... [ 0 SSN-> BBBBB...BBBBB ](SSN+N) .... V(S)
* not bow & not bitmap present:
* V(A)-> ... [] . SSN .... V(S)
*/
if (desc->BEGINNING_OF_WINDOW) {
implicitly_acked_blocks = window->mod_sns(ssn - 1 - window->v_a());
for (i = 0; i < implicitly_acked_blocks; i++)
bitvec_set_bit(bits, ONE);
num_blocks += implicitly_acked_blocks;
}
if (!have_bitmap)
goto aborted;
/* next bit refers to V(Q) and thus is always zero (and not
* transmitted) */
bitvec_set_bit(bits, ZERO);
num_blocks += 1;
if (crbb_len > 0) {
int old_len = bits->cur_bit;
LOGP(DRLCMACDL, LOGL_DEBUG, "Compress bitmap exists, "
"CRBB LEN = %d and Starting color code = %d",
desc->CRBB_LENGTH, desc->CRBB_STARTING_COLOR_CODE);
rc = egprs_compress::decompress_crbb(desc->CRBB_LENGTH,
desc->CRBB_STARTING_COLOR_CODE, desc->CRBB, bits);
if (rc < 0) {
LOGP(DRLCMACUL, LOGL_NOTICE,
"Failed to decode CRBB: length %d, data '%s'\n",
desc->CRBB_LENGTH, osmo_hexdump(
desc->CRBB, (desc->CRBB_LENGTH + 7)/8));
/* We don't know the SSN offset for the URBB,
* return what we have so far and assume the
* bitmap has stopped here */
goto aborted;
}
LOGP(DRLCMACDL, LOGL_DEBUG,
"CRBB len: %d, decoded len: %d, cc: %d, crbb: '%s'\n",
desc->CRBB_LENGTH, bits->cur_bit - old_len,
desc->CRBB_STARTING_COLOR_CODE,
osmo_hexdump(
desc->CRBB, (desc->CRBB_LENGTH + 7)/8)
);
num_blocks += (bits->cur_bit - old_len);
}
urbb.cur_bit = 0;
urbb.data = (uint8_t *)desc->URBB;
urbb.data_len = sizeof(desc->URBB);
for (i = urbb_len; i > 0; i--) {
/*
* Set bit at the appropriate position (see 3GPP TS
* 44.060 12.3.1)
*/
int is_ack = bitvec_get_bit_pos(&urbb, i-1);
bitvec_set_bit(bits, is_ack == 1 ? ONE : ZERO);
}
num_blocks += urbb_len;
aborted:
*bsn_begin = window->v_a();
*bsn_end = window->mod_sns(*bsn_begin + num_blocks);
return num_blocks;
}
int Decoding::decode_gprs_acknack_bits(const Ack_Nack_Description_t *desc,
bitvec *bits, int *bsn_begin, int *bsn_end, gprs_rlc_dl_window *window)
{
int urbb_len = RLC_GPRS_WS;
int num_blocks;
struct bitvec urbb;
if (desc->FINAL_ACK_INDICATION)
return handle_final_ack(bits, bsn_begin, bsn_end, window);
*bsn_begin = window->v_a();
*bsn_end = desc->STARTING_SEQUENCE_NUMBER;
num_blocks = window->mod_sns(*bsn_end - *bsn_begin);
if (num_blocks < 0 || num_blocks > urbb_len) {
*bsn_end = *bsn_begin;
LOGP(DRLCMACUL, LOGL_NOTICE,
"Invalid GPRS Ack/Nack window %d:%d (length %d)\n",
*bsn_begin, *bsn_end, num_blocks);
return -EINVAL;
}
urbb.cur_bit = 0;
urbb.data = (uint8_t *)desc->RECEIVED_BLOCK_BITMAP;
urbb.data_len = sizeof(desc->RECEIVED_BLOCK_BITMAP);
/*
* TS 44.060, 12.3:
* BSN = (SSN - bit_number) modulo 128, for bit_number = 1 to 64.
* The BSN values represented range from (SSN - 1) mod 128 to (SSN - 64) mod 128.
*
* We are only interested in the range from V(A) to SSN-1 which is
* num_blocks large. The RBB is laid out as
* [SSN-1] [SSN-2] ... [V(A)] ... [SSN-64]
* so we want to start with [V(A)] and go backwards until we reach
* [SSN-1] to get the needed BSNs in an increasing order. Note that
* the bit numbers are counted from the end of the buffer.
*/
for (int i = num_blocks; i > 0; i--) {
int is_ack = bitvec_get_bit_pos(&urbb, urbb_len - i);
bitvec_set_bit(bits, is_ack == 1 ? ONE : ZERO);
}
return num_blocks;
}