gprs: Add GPRS timer conversion functions
Currently, all GPRS timer values are hard-coded. To make these values
configurable in seconds and to show them, conversion functions from
and to seconds are needed.
This patch adds gprs_tmr_to_secs and gprs_secs_to_tmr_floor. Due to
the limited number of bits used to encode GPRS timer values, only a
few durations can be represented. gprs_secs_to_tmr_floor therefore
always returns the timer value that represents either the exact
number (if an exact representation exists) or the next lower number
for that an exact representation exists.
Sponsored-by: On-Waves ehf
diff --git a/openbsc/tests/gprs/gprs_test.c b/openbsc/tests/gprs/gprs_test.c
index 37dc832..e445ae7 100644
--- a/openbsc/tests/gprs/gprs_test.c
+++ b/openbsc/tests/gprs/gprs_test.c
@@ -614,6 +614,73 @@
}
}
+static void test_gprs_timer_enc_dec(void)
+{
+ int i, u, secs, tmr;
+ const int upper_secs_test_limit = 12000;
+ int dec_secs, last_dec_secs = -1;
+
+ printf("Test GPRS timer decoding/encoding\n");
+
+ /* Check gprs_tmr_to_secs with all 256 encoded values */
+ for (u = 0; u <= GPRS_TMR_DEACTIVATED; u += 32) {
+ fprintf(stderr, "Testing decoding with timer value unit %u\n",
+ u / 32);
+ for (i = 0; i < 32; i++) {
+ switch (u) {
+ case GPRS_TMR_2SECONDS:
+ OSMO_ASSERT(gprs_tmr_to_secs(u + i) == 2 * i);
+ break;
+
+ default:
+ case GPRS_TMR_MINUTE:
+ OSMO_ASSERT(gprs_tmr_to_secs(u + i) == 60 * i);
+ break;
+
+ case GPRS_TMR_6MINUTE:
+ OSMO_ASSERT(gprs_tmr_to_secs(u + i) == 360 * i);
+ break;
+
+ case GPRS_TMR_DEACTIVATED:
+ OSMO_ASSERT(gprs_tmr_to_secs(u + i) == -1);
+ break;
+ }
+
+ OSMO_ASSERT(gprs_tmr_to_secs(u + i) < upper_secs_test_limit);
+ }
+ }
+
+ /* Check gprs_secs_to_tmr_floor for secs that can exactly be
+ * represented as GPRS timer values */
+ for (i = 0; i < GPRS_TMR_DEACTIVATED; i++) {
+ int j;
+ secs = gprs_tmr_to_secs(i);
+ tmr = gprs_secs_to_tmr_floor(secs);
+ OSMO_ASSERT(secs == gprs_tmr_to_secs(tmr));
+
+ /* Check that the highest resolution is used */
+ for (j = 0; j < tmr; j++)
+ OSMO_ASSERT(secs != gprs_tmr_to_secs(j));
+ }
+ OSMO_ASSERT(GPRS_TMR_DEACTIVATED == gprs_secs_to_tmr_floor(-1));
+
+ /* Check properties of gprs_secs_to_tmr_floor */
+ for (secs = 0; secs <= upper_secs_test_limit; secs++) {
+ int tmr = gprs_secs_to_tmr_floor(secs);
+ int delta_secs = gprs_tmr_to_secs((tmr & ~0x1f) | 1);
+ dec_secs = gprs_tmr_to_secs(tmr);
+
+ /* Check floor */
+ OSMO_ASSERT(dec_secs <= secs);
+ /* Check monotonicity */
+ OSMO_ASSERT(dec_secs >= last_dec_secs);
+ /* Check max distance (<= resolution) */
+ OSMO_ASSERT(dec_secs - last_dec_secs <= delta_secs);
+
+ last_dec_secs = dec_secs;
+ }
+}
+
const struct log_info_cat default_categories[] = {
[DGPRS] = {
.name = "DGPRS",
@@ -635,6 +702,7 @@
test_gsm_03_03_apn();
test_tlv_shift_functions();
test_gsup_messages_dec_enc();
+ test_gprs_timer_enc_dec();
printf("Done.\n");
return EXIT_SUCCESS;