diff options
author | Harald Welte <laforge@gnumonks.org> | 2009-01-05 19:01:01 +0000 |
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committer | Harald Welte <laforge@gnumonks.org> | 2009-01-05 19:01:01 +0000 |
commit | 2a8ee52cedfe4cb147dab41dfa85bdd1973ba2fe (patch) | |
tree | afb9ab35ccd5292324f8b8bee76aa00f8a4c8f83 /src | |
parent | 54bd94d8b7cde19a40adebecf6e36a69400ca55c (diff) |
add (untested) TRAU frame decoder with support for FR/EFR and AMR
Diffstat (limited to 'src')
-rw-r--r-- | src/trau_frame.c | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/src/trau_frame.c b/src/trau_frame.c new file mode 100644 index 000000000..e0238ce02 --- /dev/null +++ b/src/trau_frame.c @@ -0,0 +1,115 @@ +/* TRAU frame handling according to GSM TS 08.60 */ + +/* (C) 2009 by Harald Welte <laforge@gnumonks.org> + * All Rights Reserved + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + * + */ + +#include <unistd.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <errno.h> + +#include <openbsc/trau_frame.h> + +static u_int32_t get_bits(u_int8_t *bitbuf, int offset, int num) +{ + int i; + u_int32_t ret = 0; + + for (i = offset; i < offset + num; i++) { + ret = ret << 1; + if (bitbuf[i]) + ret |= 1; + } + return ret; +} + +/* Decode according to 3.1.1 */ +static void decode_fr(struct decoded_trau_frame *fr, u_int8_t *trau_bits) +{ + int i; + int d_idx = 0; + + /* C1 .. C15 */ + memcpy(fr->c_bits+0, trau_bits+17, 15); + /* C16 .. C21 */ + memcpy(fr->c_bits+15, trau_bits+310, 6); + /* T1 .. T4 */ + memcpy(fr->t_bits+0, trau_bits+316, 4); + /* D1 .. D255 */ + for (i = 32; i < 304; i+= 16) { + memcpy(fr->d_bits + d_idx, trau_bits+i+1, 15); + d_idx += 15; + } + /* D256 .. D260 */ + memcpy(fr->d_bits + d_idx, trau_bits + 305, 5); +} + +static void decode_amr(struct decoded_trau_frame *fr, u_int8_t *trau_bits) +{ + int i; + int d_idx = 0; + + /* C1 .. C15 */ + memcpy(fr->c_bits+0, trau_bits+17, 15); + /* C16 .. C25 */ + memcpy(fr->c_bits+15, trau_bits+33, 10); + /* T1 .. T4 */ + memcpy(fr->t_bits+0, trau_bits+316, 4); + /* D1 .. D5 */ + memcpy(fr->d_bits, trau_bits+43, 5); + /* D6 .. D245 */ + for (i = 48; i < 304; i += 16) { + memcpy(fr->d_bits + d_idx, trau_bits+i+1, 15); + d_idx += 15; + } + /* D246 .. D256 */ + memcpy(fr->d_bits + d_idx, trau_bits + 305, 11); +} + +int decode_trau_frame(struct decoded_trau_frame *fr, u_int8_t *trau_bits) +{ + u_int8_t cbits5 = get_bits(trau_bits, 17, 5); + + switch (cbits5) { + case TRAU_FT_FR_UP: + case TRAU_FT_FR_DOWN: + case TRAU_FT_EFR: + decode_fr(fr, trau_bits); + break; + case TRAU_FT_AMR: + decode_amr(fr, trau_bits); + break; + case TRAU_FT_OM_UP: + case TRAU_FT_OM_DOWN: + case TRAU_FT_DATA_UP: + case TRAU_FT_DATA_DOWN: + case TRAU_FT_D145_SYNC: + case TRAU_FT_EDATA: + fprintf(stderr, "unimplemented TRAU Frame Type 0x%02x\n", cbits5); + return -1; + break; + default: + fprintf(stderr, "unknown TRAU Frame Type 0x%02x\n", cbits5); + return -1; + break; + } + + return 0; +} |