gsm0502: use parentheses in GSM_TDMA_FN_{SUM,SUB} macros
This makes it possible to pass expressions to the abovementioned
macros without any side-effects. Strictly speaking, this is only
necessary for argument 'b' of GSM_TDMA_FN_SUB, but let's also add
them to GSM_TDMA_FN_SUM for consistency.
Change-Id: I7f26156813139bbb7774e1eb342c91bc84fdad38
diff --git a/include/osmocom/gsm/gsm0502.h b/include/osmocom/gsm/gsm0502.h
index 1be2cc3..b6a1807 100644
--- a/include/osmocom/gsm/gsm0502.h
+++ b/include/osmocom/gsm/gsm0502.h
@@ -16,10 +16,10 @@
/*! Return the sum of two specified TDMA frame numbers (summation) */
#define GSM_TDMA_FN_SUM(a, b) \
- ((a + b) % GSM_TDMA_HYPERFRAME)
+ (((a) + (b)) % GSM_TDMA_HYPERFRAME)
/*! Return the difference of two specified TDMA frame numbers (subtraction) */
#define GSM_TDMA_FN_SUB(a, b) \
- ((a + GSM_TDMA_HYPERFRAME - b) % GSM_TDMA_HYPERFRAME)
+ (((a) + GSM_TDMA_HYPERFRAME - (b)) % GSM_TDMA_HYPERFRAME)
/*! Return the *minimum* difference of two specified TDMA frame numbers (distance) */
#define GSM_TDMA_FN_DIFF(a, b) \
OSMO_MIN(GSM_TDMA_FN_SUB(a, b), GSM_TDMA_FN_SUB(b, a))