1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
/* GMR-1 TCH9 channel coding */
/* See GMR-1 05.003 (ETSI TS 101 376-5-3 V1.2.1) - Section 5.3 */
/* (C) 2011-2016 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 tch9
* @{
*/
/*! \file l1/tch9.c
* \brief Osmocom GMR-1 TCH9 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>
#include <osmocom/gmr1/l1/tch9.h>
static struct osmo_conv_code gmr1_conv_tch9_24;
static struct osmo_conv_code gmr1_conv_tch9_48;
static struct osmo_conv_code gmr1_conv_tch9_96;
static const struct osmo_conv_code *gmr1_conv_tch9[GMR1_TCH9_MAX] = {
[GMR1_TCH9_2k4] = &gmr1_conv_tch9_24,
[GMR1_TCH9_4k8] = &gmr1_conv_tch9_48,
[GMR1_TCH9_9k6] = &gmr1_conv_tch9_96,
};
static void __attribute__ ((constructor))
gmr1_tch9_init(void)
{
/* Init convolutional coders */
memcpy(&gmr1_conv_tch9_24, &gmr1_conv_k5_15, sizeof(struct osmo_conv_code));
gmr1_conv_tch9_24.len = 144;
gmr1_puncturer_generate(
&gmr1_conv_tch9_24,
&gmr1_punct_k5_15_P53, &gmr1_punct_k5_15_P23, &gmr1_punct_k5_15_Ps53, 41
);
memcpy(&gmr1_conv_tch9_48, &gmr1_conv_k5_13, sizeof(struct osmo_conv_code));
gmr1_conv_tch9_48.len = 240;
gmr1_puncturer_generate(
&gmr1_conv_tch9_48,
&gmr1_punct_k5_13_P15, &gmr1_punct_k5_13_P25, &gmr1_punct_k5_13_Ps15, 41
);
memcpy(&gmr1_conv_tch9_96, &gmr1_conv_k5_12, sizeof(struct osmo_conv_code));
gmr1_conv_tch9_96.len = 480;
gmr1_puncturer_generate(
&gmr1_conv_tch9_96,
&gmr1_punct_k5_12_P25, &gmr1_punct_k5_12_P23, &gmr1_punct_k5_12_Ps25, 158
);
}
/*! \brief GMR-1 TCH9 channel coder
* \param[out] bits_e 662 encoded bits of one NT9 burst
* \param[in] l2 L2 packet data
* \param[in] mode Channel encoding mode
* \param[in] bits_sacch 10 saach bits to be multiplexed
* \param[in] bits_status 4 status bits to be multiplexed
* \param[in] ciph 658 bits of cipher stream (can be NULL)
* \param[inout] il Inter-burst interleaver state
*
* L2 data size depends on the mode (18 bytes for 2k4, 30 bytes for 4k8,
* 60 bytes for 9k6).
*/
void
gmr1_tch9_encode(ubit_t *bits_e, const uint8_t *l2, enum gmr1_tch9_mode mode,
const ubit_t *bits_sacch, const ubit_t *bits_status,
const ubit_t *ciph, struct gmr1_interleaver *il)
{
const struct osmo_conv_code *cc = gmr1_conv_tch9[mode];
ubit_t bits_u[480];
ubit_t bits_c[648];
ubit_t bits_ep_epp_x[648];
ubit_t bits_my[658];
int i;
osmo_pbit2ubit_ext(bits_u, 0, l2, 0, cc->len, 1);
osmo_conv_encode(cc, bits_u, bits_c);
gmr1_interleave_intra(bits_ep_epp_x, bits_c, 81);
gmr1_interleave_inter(il, bits_ep_epp_x, bits_ep_epp_x);
gmr1_scramble_ubit(bits_ep_epp_x, bits_ep_epp_x, 648);
memcpy(bits_my, bits_ep_epp_x, 52);
memcpy(bits_my+52, bits_sacch, 10);
memcpy(bits_my+62, bits_ep_epp_x+52, 596);
if (ciph) {
for (i=0; i<658; i++)
bits_my[i] ^= ciph[i];
}
memcpy(bits_e, bits_my, 52);
memcpy(bits_e+52, bits_status, 4);
memcpy(bits_e+56, bits_my+52, 606);
}
/*! \brief GMR-1 TCH9 channel decoder
* \param[out] l2 L2 packet data
* \param[out] bits_sacch 10 saach bits demultiplexed
* \param[out] bits_status 4 status bits demultiplexed
* \param[in] bits_e 662 encoded bits of one NT9 burst
* \param[in] mode Channel encoding mode
* \param[in] ciph 658 bits of cipher stream (can be NULL)
* \param[inout] il Inter-burst interleaver state
* \param[out] conv_rv Return of the convolutional decode (can be NULL)
*
* L2 data size depends on the mode (18 bytes for 2k4, 30 bytes for 4k8,
* 60 bytes for 9k6).
*/
void
gmr1_tch9_decode(uint8_t *l2, sbit_t *bits_sacch, sbit_t *bits_status,
const sbit_t *bits_e, enum gmr1_tch9_mode mode,
const ubit_t *ciph, struct gmr1_interleaver *il,
int *conv_rv)
{
const struct osmo_conv_code *cc = gmr1_conv_tch9[mode];
sbit_t bits_my[658];
sbit_t bits_ep_epp_x[648];
sbit_t bits_c[648];
ubit_t bits_u[480];
int i, rv;
memcpy(bits_my, bits_e, 52);
memcpy(bits_status, bits_e+52, 4);
memcpy(bits_my+52, bits_e+56, 606);
if (ciph) {
for (i=0; i<658; i++)
if (ciph[i])
bits_my[i] *= -1;
}
memcpy(bits_ep_epp_x, bits_my, 52);
memcpy(bits_sacch, bits_my+52, 10);
memcpy(bits_ep_epp_x+52, bits_my+62, 596);
gmr1_scramble_sbit(bits_ep_epp_x, bits_ep_epp_x, 648);
gmr1_deinterleave_inter(il, bits_ep_epp_x, bits_ep_epp_x);
gmr1_deinterleave_intra(bits_c, bits_ep_epp_x, 81);
rv = osmo_conv_decode(cc, bits_c, bits_u);
if (conv_rv)
*conv_rv = rv;
osmo_ubit2pbit_ext(l2, 0, bits_u, 0, cc->len, 1);
}
/*! @} */
|
