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gerrit.osmocom.org / libosmo-abis / 0ba77d53a97906ee70a262083fb30f67fe8801c5 / . / src / trau_frame.c
blob: 7be6e8f859ccc082e8ff9ce57e1b397b51a8722c [file] [log] [blame]
Pablo Neira Ayuso0ba77d52011-06-05 18:32:44 +0200[diff] [blame^]1/* TRAU frame handling according to GSM TS 08.60 */
2
3/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
4 * All Rights Reserved
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU Affero General Public License as published by
8 * the Free Software Foundation; either version 3 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU Affero General Public License for more details.
15 *
16 * You should have received a copy of the GNU Affero General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 *
19 */
20#include "internal.h"
21
22#include <unistd.h>
23#include <stdlib.h>
24#include <stdio.h>
25#include <string.h>
26#include <errno.h>
27
28#include <osmocom/gsm/abis/trau_frame.h>
29#include <osmocom/gsm/abis/subchan_demux.h>
30//#include <openbsc/debug.h>
31
32static uint32_t get_bits(const uint8_t *bitbuf, int offset, int num)
33{
34 int i;
35 uint32_t ret = 0;
36
37 for (i = offset; i < offset + num; i++) {
38 ret = ret << 1;
39 if (bitbuf[i])
40 ret |= 1;
41 }
42 return ret;
43}
44
45/* Decode according to 3.1.1 */
46static void decode_fr(struct decoded_trau_frame *fr, const uint8_t *trau_bits)
47{
48 int i;
49 int d_idx = 0;
50
51 /* C1 .. C15 */
52 memcpy(fr->c_bits+0, trau_bits+17, 15);
53 /* C16 .. C21 */
54 memcpy(fr->c_bits+15, trau_bits+310, 6);
55 /* T1 .. T4 */
56 memcpy(fr->t_bits+0, trau_bits+316, 4);
57 /* D1 .. D255 */
58 for (i = 32; i < 304; i+= 16) {
59 memcpy(fr->d_bits + d_idx, trau_bits+i+1, 15);
60 d_idx += 15;
61 }
62 /* D256 .. D260 */
63 memcpy(fr->d_bits + d_idx, trau_bits + 305, 5);
64}
65
66/* Decode according to 3.1.2 */
67static void decode_amr(struct decoded_trau_frame *fr, const uint8_t *trau_bits)
68{
69 int i;
70 int d_idx = 0;
71
72 /* C1 .. C15 */
73 memcpy(fr->c_bits+0, trau_bits+17, 15);
74 /* C16 .. C25 */
75 memcpy(fr->c_bits+15, trau_bits+33, 10);
76 /* T1 .. T4 */
77 memcpy(fr->t_bits+0, trau_bits+316, 4);
78 /* D1 .. D5 */
79 memcpy(fr->d_bits, trau_bits+43, 5);
80 /* D6 .. D245 */
81 for (i = 48; i < 304; i += 16) {
82 memcpy(fr->d_bits + d_idx, trau_bits+i+1, 15);
83 d_idx += 15;
84 }
85 /* D246 .. D256 */
86 memcpy(fr->d_bits + d_idx, trau_bits + 305, 11);
87}
88
89int decode_trau_frame(struct decoded_trau_frame *fr, const uint8_t *trau_bits)
90{
91 uint8_t cbits5 = get_bits(trau_bits, 17, 5);
92
93 switch (cbits5) {
94 case TRAU_FT_FR_UP:
95 case TRAU_FT_FR_DOWN:
96 case TRAU_FT_IDLE_UP:
97 case TRAU_FT_IDLE_DOWN:
98 case TRAU_FT_EFR:
99 decode_fr(fr, trau_bits);
100 break;
101 case TRAU_FT_AMR:
102 decode_amr(fr, trau_bits);
103 break;
104 case TRAU_FT_OM_UP:
105 case TRAU_FT_OM_DOWN:
106 case TRAU_FT_DATA_UP:
107 case TRAU_FT_DATA_DOWN:
108 case TRAU_FT_D145_SYNC:
109 case TRAU_FT_EDATA:
110 LOGP(DMUX, LOGL_NOTICE, "can't decode unimplemented TRAU "
111 "Frame Type 0x%02x\n", cbits5);
112 return -1;
113 break;
114 default:
115 LOGP(DMUX, LOGL_NOTICE, "can't decode unknown TRAU "
116 "Frame Type 0x%02x\n", cbits5);
117 return -1;
118 break;
119 }
120
121 return 0;
122}
123
124const uint8_t ft_fr_down_bits[] = { 1, 1, 1, 0, 0 };
125const uint8_t ft_idle_down_bits[] = { 0, 1, 1, 1, 0 };
126
127/* modify an uplink TRAU frame so we can send it downlink */
128int trau_frame_up2down(struct decoded_trau_frame *fr)
129{
130 uint8_t cbits5 = get_bits(fr->c_bits, 0, 5);
131
132 switch (cbits5) {
133 case TRAU_FT_FR_UP:
134 memcpy(fr->c_bits, ft_fr_down_bits, 5);
135 /* clear time alignment */
136 memset(fr->c_bits+5, 0, 6);
137 /* FIXME: SP / BFI in case of DTx */
138 /* C12 .. C21 are spare and coded as '1' */
139 memset(fr->c_bits+11, 0x01, 10);
140 break;
141 case TRAU_FT_EFR:
142 /* clear time alignment */
143 memset(fr->c_bits+5, 0, 6);
144 /* FIXME: set UFE appropriately */
145 /* FIXME: SP / BFI in case of DTx */
146 break;
147 case TRAU_FT_IDLE_UP:
148 memcpy(fr->c_bits, ft_idle_down_bits, 5);
149 /* clear time alignment */
150 memset(fr->c_bits+5, 0, 6);
151 /* FIXME: SP / BFI in case of DTx */
152 /* C12 .. C21 are spare and coded as '1' */
153 memset(fr->c_bits+11, 0x01, 10);
154 break;
155 case TRAU_FT_FR_DOWN:
156 case TRAU_FT_IDLE_DOWN:
157 case TRAU_FT_OM_DOWN:
158 case TRAU_FT_DATA_DOWN:
159 /* we cannot convert a downlink to a downlink frame */
160 return -EINVAL;
161 break;
162 case TRAU_FT_AMR:
163 case TRAU_FT_OM_UP:
164 case TRAU_FT_DATA_UP:
165 case TRAU_FT_D145_SYNC:
166 case TRAU_FT_EDATA:
167 LOGP(DMUX, LOGL_NOTICE, "unimplemented TRAU Frame Type "
168 "0x%02x\n", cbits5);
169 return -1;
170 break;
171 default:
172 LOGP(DMUX, LOGL_NOTICE, "unknown TRAU Frame Type "
173 "0x%02x\n", cbits5);
174 return -1;
175 break;
176 }
177
178 return 0;
179
180}
181
182static void encode_fr(uint8_t *trau_bits, const struct decoded_trau_frame *fr)
183{
184 int i;
185 int d_idx = 0;
186
187 trau_bits[16] = 1;
188 /* C1 .. C15 */
189 memcpy(trau_bits+17, fr->c_bits+0, 15);
190 /* D1 .. D255 */
191 for (i = 32; i < 304; i+= 16) {
192 trau_bits[i] = 1;
193 memcpy(trau_bits+i+1, fr->d_bits + d_idx, 15);
194 d_idx += 15;
195 }
196 /* D256 .. D260 */
197 trau_bits[304] = 1;
198 memcpy(trau_bits + 305, fr->d_bits + d_idx, 5);
199 /* C16 .. C21 */
200 memcpy(trau_bits+310, fr->c_bits+15, 6);
201
202 /* FIXME: handle timing adjustment */
203
204 /* T1 .. T4 */
205 memcpy(trau_bits+316, fr->t_bits+0, 4);
206}
207
208int encode_trau_frame(uint8_t *trau_bits, const struct decoded_trau_frame *fr)
209{
210 uint8_t cbits5 = get_bits(fr->c_bits, 0, 5);
211
212 /* 16 bits of sync header */
213 memset(trau_bits, 0, 16);
214
215 switch (cbits5) {
216 case TRAU_FT_FR_UP:
217 case TRAU_FT_FR_DOWN:
218 case TRAU_FT_IDLE_UP:
219 case TRAU_FT_IDLE_DOWN:
220 case TRAU_FT_EFR:
221 encode_fr(trau_bits, fr);
222 break;
223 case TRAU_FT_AMR:
224 case TRAU_FT_OM_UP:
225 case TRAU_FT_OM_DOWN:
226 case TRAU_FT_DATA_UP:
227 case TRAU_FT_DATA_DOWN:
228 case TRAU_FT_D145_SYNC:
229 case TRAU_FT_EDATA:
230 LOGP(DMUX, LOGL_NOTICE, "unimplemented TRAU Frame Type "
231 "0x%02x\n", cbits5);
232 return -1;
233 break;
234 default:
235 LOGP(DMUX, LOGL_NOTICE, "unknown TRAU Frame Type "
236 "0x%02x\n", cbits5);
237 return -1;
238 break;
239 }
240
241 return 0;
242}
243
244static struct decoded_trau_frame fr_idle_frame = {
245 .c_bits = { 0, 1, 1, 1, 0 }, /* IDLE DOWNLINK 3.5.5 */
246 .t_bits = { 1, 1, 1, 1 },
247};
248static uint8_t encoded_idle_frame[TRAU_FRAME_BITS];
249static int dbits_initted;
250
251uint8_t *trau_idle_frame(void)
252{
253 /* only initialize during the first call */
254 if (!dbits_initted) {
255 /* set all D-bits to 1 */
256 memset(&fr_idle_frame.d_bits, 0x01, 260);
257 encode_fr(encoded_idle_frame, &fr_idle_frame);
258 }
259 return encoded_idle_frame;
260}