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/*
* (C) 2017-2018 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
* All Rights Reserved
*
* Author: Philipp Maier
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <osmocom/core/msgb.h>
#include <osmocom/gsm/gsm0808_utils.h>
#include <osmocom/bsc/bsc_msc_data.h>
#include <osmocom/bsc/codec_pref.h>
/* Helper function for match_codec_pref(), looks up a matching chan mode for
* a given permitted speech value */
enum gsm48_chan_mode gsm88_to_chan_mode(enum gsm0808_permitted_speech speech)
{
switch (speech) {
case GSM0808_PERM_HR1:
case GSM0808_PERM_FR1:
return GSM48_CMODE_SPEECH_V1;
break;
case GSM0808_PERM_HR2:
case GSM0808_PERM_FR2:
return GSM48_CMODE_SPEECH_EFR;
break;
case GSM0808_PERM_HR3:
case GSM0808_PERM_FR3:
return GSM48_CMODE_SPEECH_AMR;
break;
default:
LOGP(DMSC, LOGL_FATAL, "Unsupported permitted speech selected, assuming AMR as channel mode...\n");
return GSM48_CMODE_SPEECH_AMR;
}
}
/* Helper function for match_codec_pref(), looks up a matching permitted speech
* value for a given msc audio codec pref */
enum gsm0808_permitted_speech audio_support_to_gsm88(struct gsm_audio_support *audio)
{
if (audio->hr) {
switch (audio->ver) {
case 1:
return GSM0808_PERM_HR1;
break;
case 2:
return GSM0808_PERM_HR2;
break;
case 3:
return GSM0808_PERM_HR3;
break;
default:
LOGP(DMSC, LOGL_ERROR, "Wrong speech mode: hr%d, using hr1 instead\n", audio->ver);
return GSM0808_PERM_HR1;
}
} else {
switch (audio->ver) {
case 1:
return GSM0808_PERM_FR1;
break;
case 2:
return GSM0808_PERM_FR2;
break;
case 3:
return GSM0808_PERM_FR3;
break;
default:
LOGP(DMSC, LOGL_ERROR, "Wrong speech mode: fr%d, using fr1 instead\n", audio->ver);
return GSM0808_PERM_FR1;
}
}
}
/* Helper function for match_codec_pref(), tests if a given audio support
* matches one of the permitted speech settings of the channel type element.
* The matched permitted speech value is then also compared against the
* speech codec list. (optional, only relevant for AoIP) */
static bool test_codec_pref(const struct gsm0808_channel_type *ct,
const struct gsm0808_speech_codec_list *scl, uint8_t perm_spch)
{
unsigned int i;
bool match = false;
struct gsm0808_speech_codec sc;
int rc;
/* Try to find the given permitted speech value in the
* codec list of the channel type element */
for (i = 0; i < ct->perm_spch_len; i++) {
if (ct->perm_spch[i] == perm_spch) {
match = true;
break;
}
}
/* If we do not have a speech codec list to test against,
* we just exit early (will be always the case in non-AoIP networks) */
if (!scl)
return match;
/* If we failed to match until here, there is no
* point in testing further */
if (match == false)
return false;
/* Extrapolate speech codec data */
rc = gsm0808_speech_codec_from_chan_type(&sc, perm_spch);
if (rc < 0)
return false;
/* Try to find extrapolated speech codec data in
* the speech codec list */
for (i = 0; i < scl->len; i++) {
if (sc.type == scl->codec[i].type)
return true;
}
return false;
}
/*! Helper function for bssmap_handle_assignm_req(), matches the codec
* preferences from the MSC with the codec preferences
* \param[out] full_rate '1' if full-rate, '0' if half-rate, '-1' if no match
* \param[out] chan_mode GSM 04.08 channel mode
* \param[in] ct GSM 08.08 channel type
* \param[in] scl GSM 08.08 speech codec list
* \param[in] msc MSC data [for configuration]
* \returns 0 on success, -1 in case no match was found */
int match_codec_pref(int *full_rate, enum gsm48_chan_mode *chan_mode,
const struct gsm0808_channel_type *ct,
const struct gsm0808_speech_codec_list *scl, const struct bsc_msc_data *msc)
{
unsigned int i;
uint8_t perm_spch;
bool match = false;
for (i = 0; i < msc->audio_length; i++) {
perm_spch = audio_support_to_gsm88(msc->audio_support[i]);
if (test_codec_pref(ct, scl, perm_spch)) {
match = true;
break;
}
}
/* Exit without result, in case no match can be deteched */
if (!match) {
*full_rate = -1;
*chan_mode = GSM48_CMODE_SIGN;
return -1;
}
/* Check if the result is a half or full rate codec */
if (perm_spch == GSM0808_PERM_HR1 || perm_spch == GSM0808_PERM_HR2 || perm_spch == GSM0808_PERM_HR3
|| perm_spch == GSM0808_PERM_HR4 || perm_spch == GSM0808_PERM_HR6)
*full_rate = 0;
else
*full_rate = 1;
/* Lookup a channel mode for the selected codec */
*chan_mode = gsm88_to_chan_mode(perm_spch);
return 0;
}
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