Harald Welte | 2a8ee52 | 2009-01-05 19:01:01 +0000 | [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 General Public License as published by |
| 8 | * the Free Software Foundation; either version 2 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 General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU General Public License along |
| 17 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 18 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 19 | * |
| 20 | */ |
| 21 | |
| 22 | #include <unistd.h> |
| 23 | #include <stdlib.h> |
| 24 | #include <stdio.h> |
| 25 | #include <string.h> |
| 26 | #include <errno.h> |
| 27 | |
| 28 | #include <openbsc/trau_frame.h> |
| 29 | |
Harald Welte | 418f5a4 | 2009-01-05 20:12:47 +0000 | [diff] [blame] | 30 | static u_int32_t get_bits(const u_int8_t *bitbuf, int offset, int num) |
Harald Welte | 2a8ee52 | 2009-01-05 19:01:01 +0000 | [diff] [blame] | 31 | { |
| 32 | int i; |
| 33 | u_int32_t ret = 0; |
| 34 | |
| 35 | for (i = offset; i < offset + num; i++) { |
| 36 | ret = ret << 1; |
| 37 | if (bitbuf[i]) |
| 38 | ret |= 1; |
| 39 | } |
| 40 | return ret; |
| 41 | } |
| 42 | |
| 43 | /* Decode according to 3.1.1 */ |
Harald Welte | 418f5a4 | 2009-01-05 20:12:47 +0000 | [diff] [blame] | 44 | static void decode_fr(struct decoded_trau_frame *fr, const u_int8_t *trau_bits) |
Harald Welte | 2a8ee52 | 2009-01-05 19:01:01 +0000 | [diff] [blame] | 45 | { |
| 46 | int i; |
| 47 | int d_idx = 0; |
| 48 | |
| 49 | /* C1 .. C15 */ |
| 50 | memcpy(fr->c_bits+0, trau_bits+17, 15); |
| 51 | /* C16 .. C21 */ |
| 52 | memcpy(fr->c_bits+15, trau_bits+310, 6); |
| 53 | /* T1 .. T4 */ |
| 54 | memcpy(fr->t_bits+0, trau_bits+316, 4); |
| 55 | /* D1 .. D255 */ |
| 56 | for (i = 32; i < 304; i+= 16) { |
| 57 | memcpy(fr->d_bits + d_idx, trau_bits+i+1, 15); |
| 58 | d_idx += 15; |
| 59 | } |
| 60 | /* D256 .. D260 */ |
| 61 | memcpy(fr->d_bits + d_idx, trau_bits + 305, 5); |
| 62 | } |
| 63 | |
Harald Welte | 38e0437 | 2009-01-05 19:42:46 +0000 | [diff] [blame] | 64 | /* Decode according to 3.1.2 */ |
Harald Welte | 418f5a4 | 2009-01-05 20:12:47 +0000 | [diff] [blame] | 65 | static void decode_amr(struct decoded_trau_frame *fr, const u_int8_t *trau_bits) |
Harald Welte | 2a8ee52 | 2009-01-05 19:01:01 +0000 | [diff] [blame] | 66 | { |
| 67 | int i; |
| 68 | int d_idx = 0; |
| 69 | |
| 70 | /* C1 .. C15 */ |
| 71 | memcpy(fr->c_bits+0, trau_bits+17, 15); |
| 72 | /* C16 .. C25 */ |
| 73 | memcpy(fr->c_bits+15, trau_bits+33, 10); |
| 74 | /* T1 .. T4 */ |
| 75 | memcpy(fr->t_bits+0, trau_bits+316, 4); |
| 76 | /* D1 .. D5 */ |
| 77 | memcpy(fr->d_bits, trau_bits+43, 5); |
| 78 | /* D6 .. D245 */ |
| 79 | for (i = 48; i < 304; i += 16) { |
| 80 | memcpy(fr->d_bits + d_idx, trau_bits+i+1, 15); |
| 81 | d_idx += 15; |
| 82 | } |
| 83 | /* D246 .. D256 */ |
| 84 | memcpy(fr->d_bits + d_idx, trau_bits + 305, 11); |
| 85 | } |
| 86 | |
Harald Welte | 418f5a4 | 2009-01-05 20:12:47 +0000 | [diff] [blame] | 87 | int decode_trau_frame(struct decoded_trau_frame *fr, const u_int8_t *trau_bits) |
Harald Welte | 2a8ee52 | 2009-01-05 19:01:01 +0000 | [diff] [blame] | 88 | { |
| 89 | u_int8_t cbits5 = get_bits(trau_bits, 17, 5); |
| 90 | |
| 91 | switch (cbits5) { |
| 92 | case TRAU_FT_FR_UP: |
| 93 | case TRAU_FT_FR_DOWN: |
Harald Welte | 38e0437 | 2009-01-05 19:42:46 +0000 | [diff] [blame] | 94 | case TRAU_FT_IDLE_UP: |
| 95 | case TRAU_FT_IDLE_DOWN: |
Harald Welte | 2a8ee52 | 2009-01-05 19:01:01 +0000 | [diff] [blame] | 96 | case TRAU_FT_EFR: |
| 97 | decode_fr(fr, trau_bits); |
| 98 | break; |
| 99 | case TRAU_FT_AMR: |
| 100 | decode_amr(fr, trau_bits); |
| 101 | break; |
| 102 | case TRAU_FT_OM_UP: |
| 103 | case TRAU_FT_OM_DOWN: |
| 104 | case TRAU_FT_DATA_UP: |
| 105 | case TRAU_FT_DATA_DOWN: |
| 106 | case TRAU_FT_D145_SYNC: |
| 107 | case TRAU_FT_EDATA: |
| 108 | fprintf(stderr, "unimplemented TRAU Frame Type 0x%02x\n", cbits5); |
| 109 | return -1; |
| 110 | break; |
| 111 | default: |
| 112 | fprintf(stderr, "unknown TRAU Frame Type 0x%02x\n", cbits5); |
| 113 | return -1; |
| 114 | break; |
| 115 | } |
| 116 | |
| 117 | return 0; |
| 118 | } |
Harald Welte | 418f5a4 | 2009-01-05 20:12:47 +0000 | [diff] [blame] | 119 | |
| 120 | const u_int8_t ft_fr_down_bits[] = { 1, 1, 1, 0, 0 }; |
| 121 | const u_int8_t ft_idle_down_bits[] = { 0, 1, 1, 1, 0 }; |
| 122 | |
| 123 | /* modify an uplink TRAU frame so we can send it downlink */ |
| 124 | int trau_frame_up2down(struct decoded_trau_frame *fr) |
| 125 | { |
| 126 | u_int8_t cbits5 = get_bits(fr->c_bits, 0, 5); |
| 127 | |
| 128 | switch (cbits5) { |
| 129 | case TRAU_FT_FR_UP: |
| 130 | memcpy(fr->c_bits, ft_fr_down_bits, 5); |
| 131 | /* clear time alignment */ |
| 132 | memset(fr->c_bits+5, 0, 6); |
| 133 | /* FIXME: SP / BFI in case of DTx */ |
| 134 | /* C12 .. C21 are spare and coded as '1' */ |
| 135 | memset(fr->c_bits+11, 0, 10); |
| 136 | break; |
| 137 | case TRAU_FT_EFR: |
| 138 | /* clear time alignment */ |
| 139 | memset(fr->c_bits+5, 0, 6); |
| 140 | /* FIXME: set UFE appropriately */ |
| 141 | /* FIXME: SP / BFI in case of DTx */ |
| 142 | break; |
| 143 | case TRAU_FT_IDLE_UP: |
| 144 | memcpy(fr->c_bits, ft_idle_down_bits, 5); |
| 145 | /* clear time alignment */ |
| 146 | memset(fr->c_bits+5, 0, 6); |
| 147 | /* FIXME: SP / BFI in case of DTx */ |
| 148 | /* C12 .. C21 are spare and coded as '1' */ |
| 149 | memset(fr->c_bits+11, 0, 10); |
| 150 | break; |
| 151 | case TRAU_FT_FR_DOWN: |
| 152 | case TRAU_FT_IDLE_DOWN: |
| 153 | case TRAU_FT_OM_DOWN: |
| 154 | case TRAU_FT_DATA_DOWN: |
| 155 | /* we cannot convert a downlink to a downlink frame */ |
| 156 | return -EINVAL; |
| 157 | break; |
| 158 | case TRAU_FT_AMR: |
| 159 | case TRAU_FT_OM_UP: |
| 160 | case TRAU_FT_DATA_UP: |
| 161 | case TRAU_FT_D145_SYNC: |
| 162 | case TRAU_FT_EDATA: |
| 163 | fprintf(stderr, "unimplemented TRAU Frame Type 0x%02x\n", cbits5); |
| 164 | return -1; |
| 165 | break; |
| 166 | default: |
| 167 | fprintf(stderr, "unknown TRAU Frame Type 0x%02x\n", cbits5); |
| 168 | return -1; |
| 169 | break; |
| 170 | } |
| 171 | |
| 172 | return 0; |
| 173 | |
| 174 | } |
| 175 | |
| 176 | static void encode_fr(u_int8_t *trau_bits, const struct decoded_trau_frame *fr) |
| 177 | { |
| 178 | int i; |
| 179 | int d_idx = 0; |
| 180 | |
| 181 | trau_bits[16] = 1; |
| 182 | /* C1 .. C15 */ |
| 183 | memcpy(trau_bits+17, fr->c_bits+0, 15); |
| 184 | /* D1 .. D255 */ |
| 185 | for (i = 32; i < 304; i+= 16) { |
| 186 | trau_bits[i] = 1; |
| 187 | memcpy(trau_bits+i+1, fr->d_bits + d_idx, 15); |
| 188 | d_idx += 15; |
| 189 | } |
| 190 | /* D256 .. D260 */ |
| 191 | trau_bits[304] = 1; |
| 192 | memcpy(trau_bits + 305, fr->d_bits + d_idx, 5); |
| 193 | /* C16 .. C21 */ |
| 194 | memcpy(trau_bits+310, fr->c_bits+15, 6); |
| 195 | /* T1 .. T4 */ |
| 196 | memcpy(trau_bits+316, fr->t_bits+0, 4); |
| 197 | } |
| 198 | |
| 199 | |
| 200 | int encode_trau_frame(u_int8_t *trau_bits, const struct decoded_trau_frame *fr) |
| 201 | { |
| 202 | u_int8_t cbits5 = get_bits(fr->c_bits, 0, 5); |
| 203 | |
| 204 | /* 16 bits of sync header */ |
| 205 | memset(trau_bits, 0, 16); |
| 206 | |
| 207 | switch (cbits5) { |
| 208 | case TRAU_FT_FR_UP: |
| 209 | case TRAU_FT_FR_DOWN: |
| 210 | case TRAU_FT_IDLE_UP: |
| 211 | case TRAU_FT_IDLE_DOWN: |
| 212 | case TRAU_FT_EFR: |
| 213 | encode_fr(trau_bits, fr); |
| 214 | break; |
| 215 | case TRAU_FT_AMR: |
| 216 | case TRAU_FT_OM_UP: |
| 217 | case TRAU_FT_OM_DOWN: |
| 218 | case TRAU_FT_DATA_UP: |
| 219 | case TRAU_FT_DATA_DOWN: |
| 220 | case TRAU_FT_D145_SYNC: |
| 221 | case TRAU_FT_EDATA: |
| 222 | fprintf(stderr, "unimplemented TRAU Frame Type 0x%02x\n", cbits5); |
| 223 | return -1; |
| 224 | break; |
| 225 | default: |
| 226 | fprintf(stderr, "unknown TRAU Frame Type 0x%02x\n", cbits5); |
| 227 | return -1; |
| 228 | break; |
| 229 | } |
| 230 | |
| 231 | return 0; |
| 232 | } |