wifi: simplify calculations in wifi-utils

src/wifi/model/wifi-utils.cc

@@ -38,21 +38,19 @@ Log2 (double val)
 double
 DbToRatio (double dB)
 {
-  double ratio = std::pow (10.0, dB / 10.0);
-  return ratio;
+  return std::pow (10.0, 0.1 * dB);
 }
 
 double
 DbmToW (double dBm)
 {
-  double mW = std::pow (10.0, dBm / 10.0);
-  return mW / 1000.0;
+  return std::pow (10.0, 0.1 * (dBm - 30.0));
 }
 
 double
 WToDbm (double w)
 {
-  return 10.0 * std::log10 (w * 1000.0);
+  return 10.0 * std::log10 (w) + 30.0;
 }
 
 double
@@ -64,21 +62,13 @@ RatioToDb (double ratio)
 bool
 Is2_4Ghz (double frequency)
 {
-  if (frequency >= 2400 && frequency <= 2500)
-    {
-      return true;
-    }
-  return false;
+  return frequency >= 2400 && frequency <= 2500;
 }
 
 bool
 Is5Ghz (double frequency)
 {
-  if (frequency >= 5000 && frequency <= 6000)
-    {
-      return true;
-    }
-  return false;
+  return frequency >= 5000 && frequency <= 6000;
 }
 
 uint16_t