Pablo Neira Ayuso | 0ba77d5 | 2011-06-05 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 | |
Pablo Neira Ayuso | 177094b | 2011-06-07 12:21:51 +0200 | [diff] [blame] | 28 | #include <osmocom/abis/trau_frame.h> |
| 29 | #include <osmocom/abis/subchan_demux.h> |
Pablo Neira Ayuso | 7b2d18b | 2011-06-05 18:38:43 +0200 | [diff] [blame] | 30 | #include <osmocom/core/logging.h> |
Pablo Neira Ayuso | 0ba77d5 | 2011-06-05 18:32:44 +0200 | [diff] [blame] | 31 | |
| 32 | static 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 */ |
| 46 | static 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 */ |
| 67 | static 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 | |
| 89 | int 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 | |
| 124 | const uint8_t ft_fr_down_bits[] = { 1, 1, 1, 0, 0 }; |
| 125 | const uint8_t ft_idle_down_bits[] = { 0, 1, 1, 1, 0 }; |
| 126 | |
| 127 | /* modify an uplink TRAU frame so we can send it downlink */ |
| 128 | int 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 | |
| 182 | static 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 | |
| 208 | int 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 | |
| 244 | static 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 | }; |
| 248 | static uint8_t encoded_idle_frame[TRAU_FRAME_BITS]; |
| 249 | static int dbits_initted; |
| 250 | |
| 251 | uint8_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 | } |