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/* 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);
}
/* Decode according to 3.1.2 */
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_IDLE_UP:
case TRAU_FT_IDLE_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;
}
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