diff options
author | Harald Welte <laforge@gnumonks.org> | 2011-09-09 22:32:45 +0200 |
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committer | Harald Welte <laforge@gnumonks.org> | 2011-09-09 22:32:45 +0200 |
commit | 9508fb80a4c8284daf52b1beb154a86df7d5ee07 (patch) | |
tree | 9b65c7c2e712d031136705329a36ab4b72b5416d /src/common/amr.c | |
parent | 4ccca1ce36067d5f52d2feb7c2c6f37510618530 (diff) |
Introduce new amr.[ch] for AMR related functions
Diffstat (limited to 'src/common/amr.c')
-rw-r--r-- | src/common/amr.c | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/src/common/amr.c b/src/common/amr.c new file mode 100644 index 00000000..eeb6e7f2 --- /dev/null +++ b/src/common/amr.c @@ -0,0 +1,115 @@ +#include <stdint.h> +#include <errno.h> + +#include <osmocom/core/logging.h> + +#include <osmo-bts/logging.h> +#include <osmo-bts/amr.h> + +void amr_log_mr_conf(int ss, int logl, const char *pfx, + struct amr_multirate_conf *amr_mrc) +{ + int i; + + LOGP(ss, logl, "%s AMR MR Conf: num_modes=%u", + pfx, amr_mrc->num_modes); + + for (i = 0; i < amr_mrc->num_modes; i++) + LOGPC(ss, logl, ", mode[%u] = %u/%u/%u", + i, amr_mrc->mode[i].mode, amr_mrc->mode[i].threshold, + amr_mrc->mode[i].hysteresis); + LOGPC(ss, logl, "\n"); +} + + +/* parse a GSM 04.08 MultiRate Config IE (10.5.2.21aa) in a more + * comfortable internal data structure */ +int amr_parse_mr_conf(struct amr_multirate_conf *amr_mrc, + const uint8_t *mr_conf, unsigned int len) +{ + uint8_t mr_version = mr_conf[0] >> 5; + uint8_t num_codecs = 0; + int i, j = 0; + + if (mr_version != 1) { + LOGP(DRSL, LOGL_ERROR, "AMR Multirate Version %u unknonw\n", + mr_version); + goto ret_einval; + } + + /* check number of active codecs */ + for (i = 0; i < 8; i++) { + if (mr_conf[1] & (1 << i)) + num_codecs++; + } + + /* check for minimum length */ + if (num_codecs == 0 || + (num_codecs == 1 && len < 2) || + (num_codecs == 2 && len < 4) || + (num_codecs == 3 && len < 5) || + (num_codecs == 4 && len < 6) || + (num_codecs > 4)) { + LOGP(DRSL, LOGL_ERROR, "AMR Multirate with %u modes len=%u " + "not possible\n", num_codecs, len); + goto ret_einval; + } + + /* copy the first two octets of the IE */ + amr_mrc->gsm48_ie[0] = mr_conf[0]; + amr_mrc->gsm48_ie[1] = mr_conf[1]; + + amr_mrc->num_modes = num_codecs; + + for (i = 0; i < 8; i++) { + if (mr_conf[1] & (1 << i)) { + amr_mrc->mode[j++].mode = i; + } + } + + if (num_codecs >= 2) { + amr_mrc->mode[0].threshold = mr_conf[1] & 0x3F; + amr_mrc->mode[0].hysteresis = mr_conf[2] >> 4; + } + if (num_codecs >= 3) { + amr_mrc->mode[1].threshold = + ((mr_conf[2] & 0xF) << 2) | (mr_conf[3] >> 6); + amr_mrc->mode[1].hysteresis = (mr_conf[3] >> 2) & 0x7; + } + if (num_codecs >= 4) { + amr_mrc->mode[3].threshold = + ((mr_conf[3] & 0x3) << 4) | (mr_conf[4] >> 4); + amr_mrc->mode[3].hysteresis = mr_conf[4] & 0xF; + } + + return num_codecs; + +ret_einval: + return -EINVAL; +} + + +unsigned int amr_get_initial_mode(struct gsm_lchan *lchan) +{ + struct amr_multirate_conf *amr_mrc = &lchan->tch.amr_mr; + + if (lchan->mr_conf.icmi) { + /* initial mode given, coding in TS 05.09 3.4.1 */ + return amr_mrc->mode[lchan->mr_conf.smod].mode; + } else { + /* implicit rule according to TS 05.09 Chapter 3.4.3 */ + switch (amr_mrc->num_modes) { + case 2: + case 3: + /* return the most robust */ + return amr_mrc->mode[0].mode; + case 4: + /* return the second-most robust */ + return amr_mrc->mode[1].mode; + case 1: + default: + /* return the only mode we have */ + return amr_mrc->mode[0].mode; + } + } +} |