Allow rig_set_split_mode to skip setting if mode already set

https://github.com/Hamlib/Hamlib/issues/1056

rigs/yaesu/ft991.c

@@ -141,7 +141,7 @@ const struct rig_caps ft991_caps =
     RIG_MODEL(RIG_MODEL_FT991),
     .model_name =         "FT-991",
     .mfg_name =           "Yaesu",
-    .version =            NEWCAT_VER ".11",
+    .version =            NEWCAT_VER ".12",
     .copyright =          "LGPL",
     .status =             RIG_STATUS_STABLE,
     .rig_type =           RIG_TYPE_TRANSCEIVER,
@@ -412,6 +412,12 @@ ft991_set_split_freq(RIG *rig, vfo_t vfo, freq_t tx_freq)
         return (rval);
     }
 
+    if (rig->state.cache.freqMainB == tx_freq)
+    {
+        rig_debug(RIG_DEBUG_TRACE, "%s: freq %.0f already set on VFOB\n", __func__, tx_freq);
+        return RIG_OK;
+    }
+
     if (is_split == RIG_SPLIT_OFF)
     {
         rval = newcat_set_tx_vfo(rig, RIG_VFO_B);
@@ -582,6 +588,12 @@ static int ft991_set_split_mode(RIG *rig, vfo_t vfo, rmode_t tx_mode,
         return -RIG_EINVAL;
     }
 
+    if (rig->state.cache.modeMainB == tx_mode)
+    {
+        rig_debug(RIG_DEBUG_TRACE, "%s: mode %s already set on VFOB\n", __func__, rig_strrmode(tx_mode));
+        return RIG_OK;
+    }
+
     err = ft991_get_tx_split(rig, &is_split);
 
     if (err != RIG_OK)

src/rig.c

@@ -4149,6 +4149,14 @@ int HAMLIB_API rig_set_split_mode(RIG *rig,
         RETURNFUNC(-RIG_EINVAL);
     }
 
+    // we check both VFOs are in the same tx mode -- the we can ignore
+    // this could be make more intelligent but this should cover all cases where we can skip this
+    if (tx_mode == rig->state.cache.modeMainA && tx_mode == rig->state.cache.modeMainB)
+    {
+        rig_debug(RIG_DEBUG_TRACE, "%s: mode already %s so no change required\n", __func__, rig_strrmode(tx_mode));
+        return RIG_OK;
+    }
+
     // do not mess with mode while PTT is on
     if (rig->state.cache.ptt)
     {