fix some integer underflows in MS power calculation
diff --git a/openbsc/src/gsm_utils.c b/openbsc/src/gsm_utils.c
index ddfd7f3..fe0b496 100644
--- a/openbsc/src/gsm_utils.c
+++ b/openbsc/src/gsm_utils.c
@@ -90,8 +90,10 @@
return 0;
else if (dbm < 5)
return 19;
- else
+ else {
+ /* we are guaranteed to have (5 <= dbm < 39) */
return 2 + ((39 - dbm) / 2);
+ }
break;
case GSM_BAND_1800:
if (dbm >= 36)
@@ -100,16 +102,24 @@
return 30;
else if (dbm >= 32)
return 31;
- else
+ else if (dbm == 31)
+ return 0;
+ else {
+ /* we are guaranteed to have (0 <= dbm < 31) */
return (30 - dbm) / 2;
+ }
break;
case GSM_BAND_1900:
if (dbm >= 33)
return 30;
else if (dbm >= 32)
return 31;
- else
+ else if (dbm == 31)
+ return 0;
+ else {
+ /* we are guaranteed to have (0 <= dbm < 31) */
return (30 - dbm) / 2;
+ }
break;
}
return -EINVAL;