Disable Hamlib caching while determining rig VFO resolution

CMakeLists.txt

@@ -846,6 +846,8 @@ endif (APPLE)
 #
 # find some useful tools
 #
+include (CheckSymbolExists)
+
 find_program(CTAGS ctags)
 find_program(ETAGS etags)
 
@@ -881,6 +883,10 @@ message (STATUS "hamlib_INCLUDE_DIRS: ${hamlib_INCLUDE_DIRS}")
 message (STATUS "hamlib_LIBRARIES: ${hamlib_LIBRARIES}")
 message (STATUS "hamlib_LIBRARY_DIRS: ${hamlib_LIBRARY_DIRS}")
 
+set (CMAKE_REQUIRED_INCLUDES "${hamlib_INCLUDE_DIRS}")
+set (CMAKE_REQUIRED_LIBRARIES "${hamlib_LIBRARIES}")
+check_symbol_exists (rig_set_cache_timeout_ms "hamlib/rig.h" HAVE_HAMLIB_CACHING)
+
 
 #
 # Qt5 setup

Transceiver/HamlibTransceiver.cpp

@@ -606,6 +606,13 @@ int HamlibTransceiver::do_start ()
         }
     }
 
+#if HAVE_HAMLIB_CACHING
+  // we must disable Hamlib caching because it lies about frequency
+  // for less than 1 Hz resolution rigs
+  auto orig_cache_timeout = rig_get_cache_timeout_ms (rig_.data (), HAMLIB_CACHE_ALL);
+  rig_set_cache_timeout_ms (rig_.data (), CACHE_ALL, 0);
+#endif
+
   int resolution {0};
   if (freq_query_works_)
     {
@@ -646,6 +653,11 @@ int HamlibTransceiver::do_start ()
       resolution = -1;          // best guess
     }
 
+#if HAVE_HAMLIB_CACHING
+  // revert Hamlib cache timeout
+  rig_set_cache_timeout_ms (rig_.data (), HAMLIB_CACHE_ALL, orig_cache_timeout);
+#endif
+
   do_poll ();
 
   TRACE_CAT ("HamlibTransceiver", "exit" << state () << "reversed =" << reversed_ << "resolution = " << resolution);

wsjtx_config.h.in

@@ -19,6 +19,8 @@ extern "C"  {
 #cmakedefine PROJECT_SAMPLES_URL "@PROJECT_SAMPLES_URL@"
 #cmakedefine PROJECT_SUMMARY_DESCRIPTION "@PROJECT_SUMMARY_DESCRIPTION@"
 
+#cmakedefine01 HAVE_HAMLIB_CACHING
+
 #cmakedefine01 WSJT_SHARED_RUNTIME
 #cmakedefine01 WSJT_QDEBUG_TO_FILE
 #cmakedefine01 WSJT_QDEBUG_IN_RELEASE