diff options
Diffstat (limited to 'src/host/trxcon/sched_prim.c')
| -rw-r--r-- | src/host/trxcon/sched_prim.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/src/host/trxcon/sched_prim.c b/src/host/trxcon/sched_prim.c index fb5f0a0d..c17fb2a4 100644 --- a/src/host/trxcon/sched_prim.c +++ b/src/host/trxcon/sched_prim.c @@ -23,6 +23,7 @@ */ #include <errno.h> +#include <stdlib.h> #include <string.h> #include <talloc.h> @@ -31,6 +32,7 @@ #include <osmocom/core/linuxlist.h> #include <osmocom/gsm/protocol/gsm_04_08.h> +#include <osmocom/gsm/protocol/gsm_08_58.h> #include "scheduler.h" #include "sched_trx.h" @@ -227,6 +229,93 @@ void sched_prim_drop(struct trx_lchan_state *lchan) } /** + * Assigns a dummy primitive to a lchan depending on its type. + * Could be used when there is nothing to transmit, but + * CBTX (Continuous Burst Transmission) is assumed. + * + * @param lchan lchan to assign a primitive + * @return zero in case of success, otherwise a error code + */ +int sched_prim_dummy(struct trx_lchan_state *lchan) +{ + enum trx_lchan_type chan = lchan->type; + uint8_t tch_mode = lchan->tch_mode; + struct trx_ts_prim *prim; + uint8_t prim_buffer[40]; + size_t prim_len = 0; + int i; + + /** + * TS 144.006, section 8.4.2.3 "Fill frames" + * A fill frame is a UI command frame for SAPI 0, P=0 + * and with an information field of 0 octet length. + */ + static const uint8_t lapdm_fill_frame[] = { + 0x01, 0x03, 0x01, + /* Pending part is to be randomized */ + }; + + /* Make sure that there is no existing primitive */ + OSMO_ASSERT(lchan->prim == NULL); + + /** + * Determine what actually should be generated: + * TCH in GSM48_CMODE_SIGN: LAPDm fill frame; + * TCH in other modes: silence frame; + * other channels: LAPDm fill frame. + */ + if (CHAN_IS_TCH(chan) && TCH_MODE_IS_SPEECH(tch_mode)) { + /** + * Silence frame indication + * HACK: use actual rsl_cmode! + */ + prim_len = sched_bad_frame_ind(prim_buffer, + RSL_CMOD_SPD_SPEECH, tch_mode); + } else if (CHAN_IS_TCH(chan) && TCH_MODE_IS_DATA(tch_mode)) { + /* FIXME: should we do anything for CSD? */ + return 0; + } else { + /** + * TS 144.006, section 8.1.2.3 "Fill frames" + * A fill frame is a UI command frame for SAPI 0, P=0 + * and with an information field of 0 octet length. + */ + memcpy(prim_buffer, lapdm_fill_frame, 3); + + /* Randomize pending unused bytes */ + for (i = 3; i < GSM_MACBLOCK_LEN; i++) + prim_buffer[i] = (uint8_t) rand(); + + /* Define a prim length */ + prim_len = GSM_MACBLOCK_LEN; + } + + /* Nothing to allocate / assign */ + if (!prim_len) + return 0; + + /* Allocate a new primitive */ + prim = talloc_zero_size(lchan, sizeof(struct trx_ts_prim) + prim_len); + if (prim == NULL) + return -ENOMEM; + + /* Init primitive header */ + prim->payload_len = prim_len; + prim->chan = lchan->type; + + /* Fill in the payload */ + memcpy(prim->payload, prim_buffer, prim_len); + + /* Assign the current prim */ + lchan->prim = prim; + + LOGP(DSCHD, LOGL_DEBUG, "Transmitting a dummy / silence frame " + "on lchan=%s\n", trx_lchan_desc[chan].name); + + return 0; +} + +/** * Flushes a queue of primitives * * @param list list of prims going to be flushed |