bts: use GSM_TDMA_FN_ macros and uint32_t in bts_rfn_to_fn
The function bts_rfn_to_fn() uses int32_t for its internal variables and
the input parameter rfn while the callers and everything outside uses
uint32_t to store frame numbers. Lets convert this to uint32_t and use
GSM_TDMA_FN_ macros wherever possible.
Change-Id: Iedd493bb30dd1c342dec031883060c545432e740
Related: OS#5198
diff --git a/src/bts.cpp b/src/bts.cpp
index 650d4a3..d5d814d 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -716,15 +716,14 @@
}
/* Determine the full frame number from a relative frame number */
-uint32_t bts_rfn_to_fn(const struct gprs_rlcmac_bts *bts, int32_t rfn)
+uint32_t bts_rfn_to_fn(const struct gprs_rlcmac_bts *bts, uint32_t rfn)
{
- int32_t m_cur_rfn;
- int32_t fn;
- int32_t fn_rounded;
+ uint32_t m_cur_rfn;
+ uint32_t fn_rounded;
- /* double-check that relative FN is not negative and fits into int32_t */
+ /* make sure RFN does not exceed the maximum possible value of a valid
+ * GSM frame number. */
OSMO_ASSERT(rfn < GSM_MAX_FN);
- OSMO_ASSERT(rfn >= 0);
/* Note: If a BTS is sending in a rach request it will be fully aware
* of the frame number. If the PCU is used in a BSC-co-located setup.
@@ -744,13 +743,13 @@
/* Compute a "rounded" version of the internal frame number, which
* exactly fits in the RFN_MODULUS raster */
- fn_rounded = bts->cur_fn - m_cur_rfn;
+ fn_rounded = GSM_TDMA_FN_SUB(bts->cur_fn, m_cur_rfn);
/* If the delta between the internal and the external relative frame
* number exceeds a certain limit, we need to assume that the incoming
* rach request belongs to a the previous rfn period. To correct this,
* we roll back the rounded frame number by one RFN_MODULUS */
- if (abs(rfn - m_cur_rfn) > RFN_THRESHOLD) {
+ if (GSM_TDMA_FN_DIFF(rfn, m_cur_rfn) > RFN_THRESHOLD) {
LOGP(DRLCMAC, LOGL_DEBUG,
"Race condition between rfn (%u) and m_cur_fn (%u) detected: rfn belongs to the previous modulus %u cycle, wrapping...\n",
rfn, bts->cur_fn, RFN_MODULUS);
@@ -758,17 +757,15 @@
LOGP(DRLCMAC, LOGL_DEBUG,
"Cornercase detected: wrapping crosses %u border\n",
GSM_MAX_FN);
- fn_rounded = GSM_MAX_FN - (RFN_MODULUS - fn_rounded);
+ fn_rounded = GSM_TDMA_FN_SUB(GSM_MAX_FN, (GSM_TDMA_FN_SUB(RFN_MODULUS, fn_rounded)));
}
else
- fn_rounded -= RFN_MODULUS;
+ fn_rounded = GSM_TDMA_FN_SUB(fn_rounded, RFN_MODULUS);
}
/* The real frame number is the sum of the rounded frame number and the
* relative framenumber computed via RACH */
- fn = fn_rounded + rfn;
-
- return fn;
+ return GSM_TDMA_FN_SUM(fn_rounded, rfn);
}
/* 3GPP TS 44.060: