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
178
179
180
181
182
183
184
185
|
/* GMR-1 TCH3 channel coding */
/* See GMR-1 05.003 (ETSI TS 101 376-5-3 V1.2.1) - Section 5.1 */
/* (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 tch3
* @{
*/
/*! \file l1/tch3.c
* \brief Osmocom GMR-1 TCH3 channel coding implementation
*/
#include <stdint.h>
#include <string.h>
#include <osmocom/core/bits.h>
#include <osmocom/core/conv.h>
#include <osmocom/gmr1/l1/conv.h>
#include <osmocom/gmr1/l1/punct.h>
#include <osmocom/gmr1/l1/scramb.h>
static struct osmo_conv_code gmr1_conv_tch3_speech;
static void __attribute__ ((constructor))
gmr1_tch3_init(void)
{
/* Init convolutional coder */
memcpy(&gmr1_conv_tch3_speech, &gmr1_conv_tch3, sizeof(struct osmo_conv_code));
gmr1_conv_tch3_speech.len = 48;
gmr1_puncturer_generate(&gmr1_conv_tch3_speech, NULL, &gmr1_punct12_P12, NULL, 0);
}
/*! \brief Stateless GMR-1 TCH3 channel coder
* \param[out] bits_e 212 encoded bits to be mapped on a burst
* \param[in] frame0 1st speech frame (10 byte / 80 bits, msb first)
* \param[in] frame1 2nd speech frame (10 byte / 80 bits, msb first)
* \param[in] bits_s 4 status bits to be multiplexed
* \param[in] ciph 208 bits of cipher stream (can be NULL)
* \param[in] m Multiplexing mode (0 or 1)
*/
void
gmr1_tch3_encode(ubit_t *bits_e,
const uint8_t *frame0, const uint8_t *frame1,
const ubit_t *bits_s, const ubit_t *ciph, int m)
{
ubit_t bits_epp[208];
ubit_t bits_xmy[208];
int i, j;
for (i=0; i<2; i++)
{
const uint8_t *frame = i ? frame1 : frame0;
ubit_t bits_d[80];
ubit_t bits_c[104];
ubit_t bits_ep[104];
int kc;
osmo_pbit2ubit(bits_d, frame, 80);
osmo_conv_encode(&gmr1_conv_tch3_speech, bits_c, bits_d);
memcpy(bits_c+72, bits_d+48, 32);
for (kc=0; kc<104; kc++) {
int ii, ij, kep;
ii = kc % 24;
ij = kc / 24;
kep = (ii < 8) ? (ij + 5*ii) : (ij + 4*ii + 8);
bits_ep[kep] = bits_c[kc];
}
if (m) {
for (j=0; j<104; j++)
bits_epp[(104*i)+j] = bits_ep[j];
} else {
for (j=0; j<104; j++)
bits_epp[(j<<1)+i] = bits_ep[j];
}
}
gmr1_scramble_ubit(bits_xmy, bits_epp, 208);
if (ciph) {
for (i=0; i<208; i++)
bits_xmy[i] ^= ciph[i];
}
memcpy(bits_e, bits_xmy, 52);
memcpy(bits_e+52, bits_s, 4);
memcpy(bits_e+56, bits_xmy+52, 156);
}
/*! \brief Stateless GMR-1 TCH3 channel decoder
* \param[out] frame0 1st speech frame (10 byte / 80 bits, msb first)
* \param[out] frame1 2nd speech frame (10 byte / 80 bits, msb first)
* \param[out] bits_s 4 status bits that were demultiplexed
* \param[in] bits_e 212 softbits demodulated from a burst
* \param[in] ciph 208 bits of cipher stream (can be NULL)
* \param[in] m Multiplexing mode (0 or 1)
* \param[out] conv0_rv Return of the conv. decode of frame 0 (can be NULL)
* \param[out] conv1_rv Return of the conv. decode of frame 1 (can be NULL)
* \return 0 if CRC check pass, any other value for fail.
*/
void
gmr1_tch3_decode(uint8_t *frame0, uint8_t *frame1, ubit_t *bits_s,
const sbit_t *bits_e, const ubit_t *ciph, int m,
int *conv0_rv, int *conv1_rv)
{
sbit_t bits_xmy[208];
sbit_t bits_epp[208];
int rv, i, j;
for (i=0; i<4; i++)
bits_s[i] = bits_e[52+i] < 0;
memcpy(bits_xmy, bits_e, 52);
memcpy(bits_xmy+52, bits_e+56, 156);
if (ciph) {
for (i=0; i<208; i++)
if (ciph[i])
bits_xmy[i] *= -1;
}
gmr1_scramble_sbit(bits_epp, bits_xmy, 208);
for (i=0; i<2; i++)
{
int *conv_rv = i ? conv1_rv : conv0_rv;
uint8_t *frame = i ? frame1 : frame0;
sbit_t bits_ep[104];
sbit_t bits_c[104];
ubit_t bits_d[80];
int kc;
if (m) {
for (j=0; j<104; j++)
bits_ep[j] = bits_epp[(104*i)+j];
} else {
for (j=0; j<104; j++)
bits_ep[j] = bits_epp[(j<<1)+i];
}
for (kc=0; kc<104; kc++) {
int ii, ij, kep;
ii = kc % 24;
ij = kc / 24;
kep = (ii < 8) ? (ij + 5*ii) : (ij + 4*ii + 8);
bits_c[kc] = bits_ep[kep];
}
rv = osmo_conv_decode(&gmr1_conv_tch3_speech, bits_c, bits_d);
if (conv_rv)
*conv_rv = rv;
for (j=48; j<80; j++)
bits_d[j] = bits_c[j+24] < 0;
osmo_ubit2pbit(frame, bits_d, 80);
}
}
/*! @} */
|
