(wip) Add support for AF Method B (#88)

src/util.cc

@@ -121,7 +121,7 @@ std::string CarrierFrequency::str() const {
 
 bool operator== (const CarrierFrequency &f1,
                  const CarrierFrequency &f2) {
-  return (f1.kHz() == f2.kHz());
+  return (f1.code_ == f2.code_);
 }
 
 bool operator< (const CarrierFrequency &f1,
@@ -134,31 +134,40 @@ void AltFreqList::insert(uint16_t af_code) {
                                                        CarrierFrequency::Band::FM);
   lf_mf_follows_ = false;
 
-  if (frequency.isValid()) {
-    alt_freqs_.insert(frequency);
+  if (frequency.isValid() && num_expected_ > 0) {
+    // Something has gone wrong; stop receiving this list
+    if (num_received_ >= num_expected_) {
+      num_expected_ = 0;
+      alt_freqs_.clear();
+    } else {
+      alt_freqs_.insert(frequency);
+      num_received_++;
+    }
   } else if (af_code == 205) {
     // filler
   } else if (af_code == 224) {
     // no AF exists
   } else if (af_code >= 225 && af_code <= 249) {
-    num_alt_freqs_ = af_code - 224;
+    num_expected_ = af_code - 224;
+    num_received_ = 0;
+    alt_freqs_.clear();
   } else if (af_code == 250) {
     // AM/LF freq follows
     lf_mf_follows_ = true;
   }
 }
 
 bool AltFreqList::isComplete() const {
-  return (alt_freqs_.size() == num_alt_freqs_ &&
-          num_alt_freqs_ > 0);
+  return num_expected_ == num_received_ &&
+         num_received_ > 0;
 }
 
 std::set<CarrierFrequency> AltFreqList::get() const {
   return alt_freqs_;
 }
 
 void AltFreqList::clear() {
-  alt_freqs_.clear();
+  num_expected_ = num_received_ = 0;
 }
 
 std::vector<std::string> splitLine(const std::string& line, char delimiter) {

src/util.h

@@ -83,7 +83,7 @@ class CarrierFrequency {
                          const CarrierFrequency &f2);
 
  private:
-  uint16_t code_;
+  uint16_t code_ {};
   Band band_ { Band::FM };
 };
 
@@ -97,8 +97,9 @@ class AltFreqList {
 
  private:
   std::set<CarrierFrequency> alt_freqs_;
-  unsigned num_alt_freqs_ { 0 };
-  bool lf_mf_follows_     { false };
+  size_t num_expected_ { 0 };
+  size_t num_received_ { 0 };
+  bool lf_mf_follows_  { false };
 };
 
 template<typename T, size_t N>