gsm_utils: Define 4 upper bits as "flags" and mask them out in utility functions

This way those function don't care about the flags they don't know about

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

diff --git a/include/osmocore/gsm_utils.h b/include/osmocore/gsm_utils.h
index 7dc2388..0aadd2e 100644 (file)
--- a/include/osmocore/gsm_utils.h
+++ b/include/osmocore/gsm_utils.h
@@ -87,6 +87,7 @@ static inline int rach_max_trans_raw2val(int raw) {
 
 #define        ARFCN_PCS       0x8000
 #define        ARFCN_UPLINK    0x4000
+#define        ARFCN_FLAG_MASK 0xf000  /* Reserve the upper 5 bits for flags */
 
 enum gsm_band gsm_arfcn2band(uint16_t arfcn);
 

diff --git a/src/gsm_utils.c b/src/gsm_utils.c
index 4b4e2c6..31e3cd6 100644 (file)
--- a/src/gsm_utils.c
+++ b/src/gsm_utils.c
@@ -359,7 +359,11 @@ void generate_backtrace()
 
 enum gsm_band gsm_arfcn2band(uint16_t arfcn)
 {
-       if (arfcn & ARFCN_PCS)
+       int is_pcs = arfcn & ARFCN_PCS;
+
+       arfcn &= ~ARFCN_FLAG_MASK;
+
+       if (is_pcs)
                return GSM_BAND_1900;
        else if (arfcn <= 124)
                return GSM_BAND_900;
@@ -386,8 +390,11 @@ uint16_t gsm_arfcn2freq10(uint16_t arfcn, int uplink)
 {
        uint16_t freq10_ul;
        uint16_t freq10_dl;
+       int is_pcs = arfcn & ARFCN_PCS;
+
+       arfcn &= ~ARFCN_FLAG_MASK;
 
-       if (arfcn & ARFCN_PCS) {
+       if (is_pcs) {
                /* DCS 1900 */
                arfcn &= ~ARFCN_PCS;
                freq10_ul = 18502 + 2 * (arfcn-512);