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 | |
| 30 | static u_int32_t get_bits(u_int8_t *bitbuf, int offset, int num) |
| 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 */ |
| 44 | static void decode_fr(struct decoded_trau_frame *fr, u_int8_t *trau_bits) |
| 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 | 2a8ee52 | 2009-01-05 19:01:01 +0000 | [diff] [blame] | 65 | static void decode_amr(struct decoded_trau_frame *fr, u_int8_t *trau_bits) |
| 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 | |
| 87 | int decode_trau_frame(struct decoded_trau_frame *fr, u_int8_t *trau_bits) |
| 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 | } |