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trxcon/scheduler: introduce TDMA frame math helpers 

The 'normal' math operations, such as addition and substraction,
are not applicable for TDMA frame numbers because they may result
in out-of-range values.

Having TDMA frame math helpers in a single place would allow
one to avoid possible out-of-range result mistakes.

Change-Id: Ibb66ba846cc3d6c2eaa88414569e5f3751128047
This commit is contained in:
Vadim Yanitskiy 2018-09-12 17:54:24 +07:00
parent 60da22a67b
commit 96419494d3
3 changed files with 16 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
src/host/trxcon/sched_clck.c
View File

@ -83,8 +83,7 @@ static void sched_clck_tick(void *data)
timespecadd(tv_clock, &frame_duration, tv_clock);
elapsed_us -= FRAME_DURATION_uS;
sched->fn_counter_proc = (sched->fn_counter_proc + 1)
% GSM_HYPERFRAME;
sched->fn_counter_proc = TDMA_FN_INC(sched->fn_counter_proc);
/* Call frame callback */
if (sched->clock_cb)
@ -142,8 +141,7 @@ int sched_clck_handle(struct trx_sched *sched, uint32_t fn)
/* Calculate elapsed time / frames since last processed fn */
timespecsub(&tv_now, tv_clock, &elapsed);
elapsed_us = (elapsed.tv_sec * 1000000) + (elapsed.tv_nsec / 1000);
elapsed_fn = (fn + GSM_HYPERFRAME - sched->fn_counter_proc)
% GSM_HYPERFRAME;
elapsed_fn = TDMA_FN_SUB(fn, sched->fn_counter_proc);
if (elapsed_fn >= 135774)
elapsed_fn -= GSM_HYPERFRAME;
@ -181,8 +179,7 @@ int sched_clck_handle(struct trx_sched *sched, uint32_t fn)
/* Transmit what we still need to transmit */
while (fn != sched->fn_counter_proc) {
sched->fn_counter_proc = (sched->fn_counter_proc + 1)
% GSM_HYPERFRAME;
sched->fn_counter_proc = TDMA_FN_INC(sched->fn_counter_proc);
/* Call frame callback */
if (sched->clock_cb)

11
src/host/trxcon/sched_trx.c
View File

@ -65,8 +65,8 @@ static void sched_frame_clck_cb(struct trx_sched *sched)
* Advance frame number, giving the transceiver more
* time until a burst must be transmitted...
*/
fn = (sched->fn_counter_proc + sched->fn_counter_advance)
% GSM_HYPERFRAME;
fn = TDMA_FN_SUM(sched->fn_counter_proc,
sched->fn_counter_advance);
/* Get frame from multiframe */
offset = fn % ts->mf_layout->period;
@ -608,15 +608,14 @@ int sched_trx_handle_rx_burst(struct trx_instance *trx, uint8_t tn,
}
/* Calculate how many frames have been elapsed */
elapsed = (burst_fn + GSM_HYPERFRAME - ts->mf_last_fn);
elapsed %= GSM_HYPERFRAME;
elapsed = TDMA_FN_SUB(burst_fn, ts->mf_last_fn);
/**
* If not too many frames have been elapsed,
* start counting from last fn + 1
*/
if (elapsed < 10)
fn = (ts->mf_last_fn + 1) % GSM_HYPERFRAME;
fn = TDMA_FN_INC(ts->mf_last_fn);
else
fn = burst_fn;
@ -658,7 +657,7 @@ next_frame:
if (fn == burst_fn)
break;
fn = (fn + 1) % GSM_HYPERFRAME;
fn = TDMA_FN_INC(fn);
}
/* Set last processed frame number */

8
src/host/trxcon/scheduler.h
View File

@ -10,6 +10,14 @@
#define GSM_SUPERFRAME (26 * 51)
#define GSM_HYPERFRAME (2048 * GSM_SUPERFRAME)
/* TDMA frame number arithmetics */
#define TDMA_FN_SUM(a, b) \
((a + b) % GSM_HYPERFRAME)
#define TDMA_FN_SUB(a, b) \
((a + GSM_HYPERFRAME - b) % GSM_HYPERFRAME)
#define TDMA_FN_INC(fn) \
TDMA_FN_SUM(fn, 1)
enum tdma_sched_clck_state {
SCH_CLCK_STATE_WAIT,
SCH_CLCK_STATE_OK,