Change get_ptt RTS/DTR to keep serial port open

New option --set-conf=ptt_share=1 to revert to old behavior where serial port is opened/closed every get_ptt
https://github.com/Hamlib/Hamlib/issues/383

(cherry picked from commit 4faad82da7)

NEWS

@@ -30,6 +30,7 @@ Version 4.0
         * New rig backend for Elecraft K4.
         * New rig backend for PowerSDR (Flex and Apache users).
         * Many fixes and enhancements.  Mike, W9MDB and many contributors
+    * PTT port is no longer shared by default, use --set-conf=ptt_share=1 to enable
 
 Version 3.3
         2018-08-12

include/hamlib/rig.h

@@ -2039,6 +2039,7 @@ struct rig_state {
     int auto_disable_screensaver; /*!< Allow Hamlib to disable the
                                    rig's screen saver automatically if
                                    supported */
+    int ptt_share;              /*!< Share ptt port by open/close during get_ptt, set_ptt hogs the port while active */
     int power_now;              /*!< Current RF power level in rig units */
     int power_min;              /*!< Minimum RF power level in rig units */
     int power_max;              /*!< Maximum RF power level in rig units */

src/conf.c

@@ -138,6 +138,11 @@ static const struct confparams frontend_cfg_params[] =
         "True enables compatible rigs to have their screen saver disabled on open",
         "0", RIG_CONF_CHECKBUTTON, { }
     },
+    {
+        TOK_PTT_SHARE, "ptt_share", "Share ptt port with other apps",
+        "True enables ptt port to be shared with other apps",
+        "0", RIG_CONF_CHECKBUTTON, { }
+    },
 
     { RIG_CONF_END, NULL, }
 };
@@ -580,6 +585,16 @@ static int frontend_set_conf(RIG *rig, token_t token, const char *val)
         rs->auto_disable_screensaver = val_i ? 1 : 0;
         break;
 
+    case TOK_PTT_SHARE:
+        if (1 != sscanf(val, "%d", &val_i))
+        {
+            return -RIG_EINVAL; //value format error
+        }
+
+        rs->ptt_share = val_i ? 1 : 0;
+        break;
+
+
     default:
         return -RIG_EINVAL;
     }

src/rig.c

@@ -2233,9 +2233,9 @@ int HAMLIB_API rig_set_ptt(RIG *rig, vfo_t vfo, ptt_t ptt)
         retcode = ser_set_dtr(&rig->state.pttport, ptt != RIG_PTT_OFF);
 
         if (strcmp(rs->pttport.pathname, rs->rigport.pathname)
-                && ptt == RIG_PTT_OFF)
+                && ptt == RIG_PTT_OFF && rs->ptt_share != 0)
         {
-
+            rig_debug(RIG_DEBUG_TRACE, "%s: ptt_share=%d\n", __func__, rs->ptt_share);
             /* free the port */
             ser_close(&rs->pttport);
         }
@@ -2280,9 +2280,9 @@ int HAMLIB_API rig_set_ptt(RIG *rig, vfo_t vfo, ptt_t ptt)
         retcode = ser_set_rts(&rig->state.pttport, ptt != RIG_PTT_OFF);
 
         if (strcmp(rs->pttport.pathname, rs->rigport.pathname)
-                && ptt == RIG_PTT_OFF)
+                && ptt == RIG_PTT_OFF && rs->ptt_share != 0)
         {
-
+            rig_debug(RIG_DEBUG_TRACE, "%s: ptt_share=%d\n", __func__, rs->ptt_share);
             /* free the port */
             ser_close(&rs->pttport);
         }

src/token.h

@@ -87,6 +87,8 @@
 #define TOK_DCD_PATHNAME    TOKEN_FRONTEND(33)
 /** \brief  CM108 GPIO bit number for PTT */
 #define TOK_PTT_BITNUM        TOKEN_FRONTEND(34)
+/** \brief  PTT share with other applications */
+#define TOK_PTT_SHARE        TOKEN_FRONTEND(35)
 /*
  * rig specific tokens
  */