121 lines
2.9 KiB
C
121 lines
2.9 KiB
C
#include <stdint.h>
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#include <errno.h>
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#include <osmocom/core/logging.h>
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#include <osmo-bts/logging.h>
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#include <osmo-bts/amr.h>
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void amr_log_mr_conf(int ss, int logl, const char *pfx,
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struct amr_multirate_conf *amr_mrc)
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{
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int i;
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LOGP(ss, logl, "%s AMR MR Conf: num_modes=%u",
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pfx, amr_mrc->num_modes);
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for (i = 0; i < amr_mrc->num_modes; i++)
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LOGPC(ss, logl, ", mode[%u] = %u/%u/%u",
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i, amr_mrc->mode[i].mode,
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amr_mrc->mode[i].threshold_bts,
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amr_mrc->mode[i].hysteresis_bts);
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LOGPC(ss, logl, "\n");
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}
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/* parse a GSM 04.08 MultiRate Config IE (10.5.2.21aa) in a more
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* comfortable internal data structure */
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int amr_parse_mr_conf(struct amr_multirate_conf *amr_mrc,
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const uint8_t *mr_conf, unsigned int len)
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{
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uint8_t mr_version = mr_conf[0] >> 5;
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uint8_t num_codecs = 0;
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int i, j = 0;
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if (mr_version != 1) {
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LOGP(DRSL, LOGL_ERROR, "AMR Multirate Version %u unknonw\n",
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mr_version);
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goto ret_einval;
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}
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/* check number of active codecs */
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for (i = 0; i < 8; i++) {
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if (mr_conf[1] & (1 << i))
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num_codecs++;
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}
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/* check for minimum length */
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if (num_codecs == 0 ||
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(num_codecs == 1 && len < 2) ||
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(num_codecs == 2 && len < 4) ||
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(num_codecs == 3 && len < 5) ||
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(num_codecs == 4 && len < 6) ||
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(num_codecs > 4)) {
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LOGP(DRSL, LOGL_ERROR, "AMR Multirate with %u modes len=%u "
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"not possible\n", num_codecs, len);
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goto ret_einval;
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}
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/* copy the first two octets of the IE */
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amr_mrc->gsm48_ie[0] = mr_conf[0];
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amr_mrc->gsm48_ie[1] = mr_conf[1];
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amr_mrc->num_modes = num_codecs;
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for (i = 0; i < 8; i++) {
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if (mr_conf[1] & (1 << i)) {
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amr_mrc->mode[j++].mode = i;
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}
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}
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if (num_codecs >= 2) {
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amr_mrc->mode[0].threshold_bts = mr_conf[1] & 0x3F;
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amr_mrc->mode[0].hysteresis_bts = mr_conf[2] >> 4;
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}
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if (num_codecs >= 3) {
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amr_mrc->mode[1].threshold_bts =
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((mr_conf[2] & 0xF) << 2) | (mr_conf[3] >> 6);
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amr_mrc->mode[1].hysteresis_bts = (mr_conf[3] >> 2) & 0xF;
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}
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if (num_codecs >= 4) {
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amr_mrc->mode[2].threshold_bts =
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((mr_conf[3] & 0x3) << 4) | (mr_conf[4] >> 4);
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amr_mrc->mode[2].hysteresis_bts = mr_conf[4] & 0xF;
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}
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return num_codecs;
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ret_einval:
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return -EINVAL;
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}
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/*! \brief determine AMR initial codec mode for given logical channel
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* \returns integer between 0..3 for AMR codce mode 1..4 */
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unsigned int amr_get_initial_mode(struct gsm_lchan *lchan)
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{
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struct amr_multirate_conf *amr_mrc = &lchan->tch.amr_mr;
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struct gsm48_multi_rate_conf *mr_conf =
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(struct gsm48_multi_rate_conf *) amr_mrc->gsm48_ie;
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if (mr_conf->icmi) {
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/* initial mode given, coding in TS 05.09 3.4.1 */
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return mr_conf->smod;
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} else {
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/* implicit rule according to TS 05.09 Chapter 3.4.3 */
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switch (amr_mrc->num_modes) {
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case 2:
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case 3:
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/* return the most robust */
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return 0;
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case 4:
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/* return the second-most robust */
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return 1;
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case 1:
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default:
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/* return the only mode we have */
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return 0;
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}
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}
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}
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