116 lines
2.8 KiB
C
116 lines
2.8 KiB
C
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/* TRAU frame handling according to GSM TS 08.60 */
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/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include <openbsc/trau_frame.h>
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static u_int32_t get_bits(u_int8_t *bitbuf, int offset, int num)
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{
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int i;
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u_int32_t ret = 0;
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for (i = offset; i < offset + num; i++) {
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ret = ret << 1;
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if (bitbuf[i])
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ret |= 1;
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}
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return ret;
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}
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/* Decode according to 3.1.1 */
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static void decode_fr(struct decoded_trau_frame *fr, u_int8_t *trau_bits)
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{
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int i;
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int d_idx = 0;
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/* C1 .. C15 */
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memcpy(fr->c_bits+0, trau_bits+17, 15);
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/* C16 .. C21 */
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memcpy(fr->c_bits+15, trau_bits+310, 6);
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/* T1 .. T4 */
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memcpy(fr->t_bits+0, trau_bits+316, 4);
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/* D1 .. D255 */
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for (i = 32; i < 304; i+= 16) {
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memcpy(fr->d_bits + d_idx, trau_bits+i+1, 15);
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d_idx += 15;
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}
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/* D256 .. D260 */
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memcpy(fr->d_bits + d_idx, trau_bits + 305, 5);
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}
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static void decode_amr(struct decoded_trau_frame *fr, u_int8_t *trau_bits)
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{
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int i;
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int d_idx = 0;
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/* C1 .. C15 */
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memcpy(fr->c_bits+0, trau_bits+17, 15);
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/* C16 .. C25 */
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memcpy(fr->c_bits+15, trau_bits+33, 10);
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/* T1 .. T4 */
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memcpy(fr->t_bits+0, trau_bits+316, 4);
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/* D1 .. D5 */
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memcpy(fr->d_bits, trau_bits+43, 5);
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/* D6 .. D245 */
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for (i = 48; i < 304; i += 16) {
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memcpy(fr->d_bits + d_idx, trau_bits+i+1, 15);
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d_idx += 15;
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}
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/* D246 .. D256 */
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memcpy(fr->d_bits + d_idx, trau_bits + 305, 11);
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}
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int decode_trau_frame(struct decoded_trau_frame *fr, u_int8_t *trau_bits)
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{
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u_int8_t cbits5 = get_bits(trau_bits, 17, 5);
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switch (cbits5) {
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case TRAU_FT_FR_UP:
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case TRAU_FT_FR_DOWN:
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case TRAU_FT_EFR:
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decode_fr(fr, trau_bits);
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break;
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case TRAU_FT_AMR:
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decode_amr(fr, trau_bits);
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break;
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case TRAU_FT_OM_UP:
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case TRAU_FT_OM_DOWN:
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case TRAU_FT_DATA_UP:
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case TRAU_FT_DATA_DOWN:
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case TRAU_FT_D145_SYNC:
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case TRAU_FT_EDATA:
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fprintf(stderr, "unimplemented TRAU Frame Type 0x%02x\n", cbits5);
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return -1;
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break;
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default:
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fprintf(stderr, "unknown TRAU Frame Type 0x%02x\n", cbits5);
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return -1;
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break;
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}
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return 0;
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}
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