l1/xch_dc12: Add channel coding for various channel types over DC12 bursts

Used in GMR-1 3G

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
This commit is contained in:
Sylvain Munaut 2016-09-11 22:05:39 -06:00
parent ccf3609ee5
commit 9ebb5aca34
4 changed files with 153 additions and 2 deletions

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@ -1,3 +1,3 @@
noinst_HEADERS = \
conv.h crc.h interleave.h punct.h scramb.h \
a5.h bcch.h ccch.h rach.h facch3.h tch3.h facch9.h tch9.h
a5.h bcch.h ccch.h rach.h facch3.h tch3.h facch9.h tch9.h xch_dc12.h

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/* GMR-1 xCH over DC12 channel coding */
/* See GMR-1 05.003 (ETSI TS 101 376-5-3 V3.3.1) - Section 6.1a */
/* (C) 2011-2019 by Sylvain Munaut <tnt@246tNt.com>
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __OSMO_GMR1_L1_XCH_DC12_H__
#define __OSMO_GMR1_L1_XCH_DC12_H__
/*! \defgroup xch_dc12 xCH over DC12 channel coding
* \ingroup l1_chan
* @{
*/
/*! \file l1/xch_dc12.h
* \brief Osmocom GMR-1 xCH over DC12 channel coding header
*/
#include <stdint.h>
#include <osmocom/core/bits.h>
int gmr1_xch_dc12_encode(ubit_t *bits_e, const uint8_t *l2);
int gmr1_xch_dc12_decode(uint8_t *l2, const sbit_t *bits_e, int *conv_rv);
/*! @} */
#endif /* __OSMO_GMR1_L1_XCH_DC12_H__ */

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@ -6,4 +6,4 @@ noinst_LIBRARIES = libgmr1-l1.a
libgmr1_l1_a_SOURCES = \
conv.c crc.c interleave.c punct.c scramb.c \
a5.c bcch.c ccch.c rach.c facch3.c facch9.c tch3.c tch9.c
a5.c bcch.c ccch.c rach.c facch3.c facch9.c tch3.c tch9.c xch_dc12.c

108
src/l1/xch_dc12.c Normal file
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/* GMR-1 xCH over DC12 channel coding */
/* See GMR-1 05.003 (ETSI TS 101 376-5-3 V3.3.1) - Section 6.1a */
/* (C) 2011-2019 by Sylvain Munaut <tnt@246tNt.com>
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*! \addtogroup xch_dc12
* @{
*/
/*! \file l1/xch_dc12.c
* \brief Osmocom GMR-1 xCH over DC12 channel coding implementation
*/
#include <stdint.h>
#include <string.h>
#include <osmocom/core/bits.h>
#include <osmocom/core/conv.h>
#include <osmocom/core/crc16gen.h>
#include <osmocom/gmr1/l1/conv.h>
#include <osmocom/gmr1/l1/crc.h>
#include <osmocom/gmr1/l1/interleave.h>
#include <osmocom/gmr1/l1/punct.h>
#include <osmocom/gmr1/l1/scramb.h>
static struct osmo_conv_code gmr1_conv_xch_dc12;
static void __attribute__ ((constructor))
gmr1_xch_dc12_init(void)
{
/* Init convolutional coder */
memcpy(&gmr1_conv_xch_dc12, &gmr1_conv_k9_13, sizeof(struct osmo_conv_code));
gmr1_conv_xch_dc12.len = 208;
gmr1_conv_xch_dc12.term = CONV_TERM_TAIL_BITING;
gmr1_puncturer_generate(&gmr1_conv_xch_dc12, NULL, &gmr1_punct_k9_13_P1213, NULL, 0);
}
/*! \brief Stateless GMR-1 xCH over DC12 channel coder
* \param[out] bits_e Data bits of a burst
* \param[in] l2 L2 packet data
*
* L2 data is 24 byte long, and bits_e is a 432 hard bit array to be
* mapped on a burst.
*/
void
gmr1_xch_dc12_encode(ubit_t *bits_e, const uint8_t *l2)
{
ubit_t bits_u[208];
ubit_t bits_c[432];
ubit_t bits_ep[432];
osmo_pbit2ubit_ext(bits_u, 0, l2, 0, 192, 1);
osmo_crc16gen_set_bits(&gmr1_crc16, bits_u, 192, bits_u+192);
osmo_conv_encode(&gmr1_conv_xch_dc12, bits_u, bits_c);
gmr1_interleave_intra(bits_ep, bits_c, 54);
gmr1_scramble_ubit(bits_e, bits_ep, 432);
}
/*! \brief Stateless GMR-1 xCH over DC12 channel decoder
* \param[out] l2 L2 packet data
* \param[in] bits_e Data bits of a burst
* \param[out] conv_rv Return of the convolutional decode (can be NULL)
* \return 0 if CRC check pass, any other value for fail.
*
* L2 data is 24 byte long, and bits_e is a 432 soft bit array
* unmapped from a burst.
*/
int
gmr1_xch_dc12_decode(uint8_t *l2, const sbit_t *bits_e, int *conv_rv)
{
sbit_t bits_ep[432];
sbit_t bits_c[432];
ubit_t bits_u[208];
int rv;
gmr1_scramble_sbit(bits_ep, bits_e, 432);
gmr1_deinterleave_intra(bits_c, bits_ep, 54);
rv = osmo_conv_decode(&gmr1_conv_xch_dc12, bits_c, bits_u);
if (conv_rv)
*conv_rv = rv;
rv = osmo_crc16gen_check_bits(&gmr1_crc16, bits_u, 192, bits_u+192);
osmo_ubit2pbit_ext(l2, 0, bits_u, 0, 192, 1);
return rv;
}
/*! @} */