fixeria has submitted this change. ( https://gerrit.osmocom.org/c/libosmocore/+/34520?usp=email )
Change subject: gsm: add gsm0502_fn_compare() for comparing TDMA FNs ......................................................................
gsm: add gsm0502_fn_compare() for comparing TDMA FNs
We need this function in:
* osmocom-bb.git for trxcon and l1gprs, * osmo-pcu.git replacing fn_cmp().
Change-Id: I9590f2e836fc48650decf1564b6ab46306c4fe2d Related: OS#5500 --- M include/osmocom/gsm/gsm0502.h M tests/gsm0502/gsm0502_test.c 2 files changed, 54 insertions(+), 0 deletions(-)
Approvals: Jenkins Builder: Verified pespin: Looks good to me, approved laforge: Looks good to me, but someone else must approve
diff --git a/include/osmocom/gsm/gsm0502.h b/include/osmocom/gsm/gsm0502.h index ffd6e20..6624e70 100644 --- a/include/osmocom/gsm/gsm0502.h +++ b/include/osmocom/gsm/gsm0502.h @@ -64,6 +64,25 @@ #define GSM_NBITS_AB_GMSK_TAIL GSM_NBITS_NB_GMSK_TAIL #define GSM_NBITS_AB_GMSK_BURST GSM_NBITS_NB_GMSK_BURST
+/*! Compare the given TDMA FNs, taking the wrapping into account. + * \param[in] fn1 First TDMA Fn value to compare. + * \param[in] fn2 Second TDMA Fn value to compare. + * \returns similarly to memcmp(), -1 if fn1 goes before fn2; + * 0 if fn1 equals fn2; + * 1 if fn1 goes after fn2. */ +static inline int gsm0502_fn_compare(uint32_t fn1, uint32_t fn2) +{ + const uint32_t thresh = GSM_TDMA_HYPERFRAME / 2; + + if (fn1 == fn2) + return 0; + if ((fn1 < fn2 && (fn2 - fn1) < thresh) || + (fn1 > fn2 && (fn1 - fn2) > thresh)) + return -1; + + return 1; +} + /* Table 5 Clause 7 TS 05.02 */ static inline unsigned int gsm0502_get_n_pag_blocks(const struct gsm48_control_channel_descr *chan_desc) diff --git a/tests/gsm0502/gsm0502_test.c b/tests/gsm0502/gsm0502_test.c index e9deaa9..d78a94d 100644 --- a/tests/gsm0502/gsm0502_test.c +++ b/tests/gsm0502/gsm0502_test.c @@ -148,8 +148,28 @@ printf("\n"); }
+static void test_gsm0502_fn_compare(void) +{ + OSMO_ASSERT(gsm0502_fn_compare(1337, 1337) == 0); + OSMO_ASSERT(gsm0502_fn_compare(42, 1337) == -1); + OSMO_ASSERT(gsm0502_fn_compare(1337, 42) == 1); + OSMO_ASSERT(gsm0502_fn_compare(42, 0) == 1); + + /* 2715642 is very close to the Fn period (GSM_TDMA_HYPERFRAME) */ + OSMO_ASSERT(gsm0502_fn_compare(2715642, 42) == -1); + OSMO_ASSERT(gsm0502_fn_compare(42, 2715642) == 1); + OSMO_ASSERT(gsm0502_fn_compare(0, 2715642) == 1); + + /* 1357824 is half of the Fn period (GSM_TDMA_HYPERFRAME) */ + OSMO_ASSERT(gsm0502_fn_compare(1357820, 1357824) == -1); + OSMO_ASSERT(gsm0502_fn_compare(1357820, 1357825) == -1); + OSMO_ASSERT(gsm0502_fn_compare(1357824, 1357820) == 1); + OSMO_ASSERT(gsm0502_fn_compare(1357825, 1357820) == 1); +} + int main(int argc, char **argv) { test_gsm0502_fn_remap(); + test_gsm0502_fn_compare(); return EXIT_SUCCESS; }
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fixeria