Merge branch 'master' of https://github.com/fwolter/nrjavaserial.git …

…into java11

README.md

@@ -32,6 +32,8 @@ ease of use and embeddability in other libraries.
 * [RFC 2217](http://tools.ietf.org/html/rfc2217) support provided by
   incorporating the [jvser library](http://github.com/archiecobbs/jvser).
 
+* RS485 support for Linux
+
 ## And a bunch of bug fixes
 
 * Fixed the memory access error that causes OS X to crash the JVM when

src/main/c/src/SerialImp.c

@@ -602,6 +602,48 @@ cf{get,set}{i,o}speed and shouldn't be provided or used.
 	(*env)->SetIntField(env, jobj, jfparity, ( jint ) jparity );
 }
 /*----------------------------------------------------------
+RXTXPort.controlRs485
+
+   accept:      fd of the preopened device,
+                boolean if the bus enable (RTS) is active low,
+                delay of RTS edge to first data edge (not supported by all serial drivers),
+                delay of RTS edge after end of transmission (not supported by all serial drivers)
+   perform:     set the rs485 config via ioctl
+   return:      return code of ioctl
+----------------------------------------------------------*/
+JNIEXPORT jint JNICALL RXTXPort(controlRs485)(
+        JNIEnv *env,
+        jobject jobj,
+        jint fd,
+        jboolean enable,
+        jboolean busEnableActiveLow,
+        jint delayRtsBeforeSendMs,
+        jint delayRtsAfterSendMs
+        )
+{
+#if defined(__linux__)
+    struct serial_rs485 rs485conf;
+    memset(&rs485conf, 0, sizeof(struct serial_rs485));
+
+    if(enable) {
+        rs485conf.flags |= SER_RS485_ENABLED;
+    }
+
+    if(busEnableActiveLow) {
+        rs485conf.flags |= SER_RS485_RTS_AFTER_SEND;
+    } else {
+        rs485conf.flags |= SER_RS485_RTS_ON_SEND;
+    }
+
+    rs485conf.delay_rts_before_send = delayRtsBeforeSendMs;
+    rs485conf.delay_rts_after_send = delayRtsAfterSendMs;
+
+    return ioctl (fd, TIOCSRS485, &rs485conf);
+#else
+    return -1;
+#endif
+}
+/*----------------------------------------------------------
 RXTXPort.open
 
    accept:      The device to open.  ie "/dev/ttyS0"

src/main/java/gnu/io/NRSerialPort.java

@@ -222,6 +222,32 @@ public int getBaud()
         return baud;
     }
 
+    /**
+     * Enables RS485 half-duplex bus communication for Linux. The Linux kernel uses the RTS pin as bus enable. If you use a device that is configured via the Linux
+     * device tree, take care to add "uart-has-rtscts" and to configure the RTS GPIO correctly.
+     *
+     * Before enabling RS485, the serial port must be connected/opened.
+     *
+     * See also:
+     * <ul>
+     * <li>https://www.kernel.org/doc/Documentation/serial/serial-rs485.txt
+     * <li>https://www.kernel.org/doc/Documentation/devicetree/bindings/serial/serial.txt
+     * </ul>
+     *
+     * @param busEnableActiveLow
+     *            true, if the bus enable signal (RTS) shall be low during transmission
+     * @param delayBusEnableBeforeSendMs
+     *            delay of bus enable signal (RTS) edge to first data edge in ms (not supported by all serial drivers)
+     * @param delayBusEnableAfterSendMs
+     *            delay of bus enable signal (RTS) edge after end of transmission in ms (not supported by all serial drivers)
+     * @return the ioctl() return value
+     */
+    public int enableRs485(boolean busEnableActiveLow, int delayBusEnableBeforeSendMs, int delayBusEnableAfterSendMs) {
+        if(serial == null)
+            return -1;
+
+        return serial.enableRs485(busEnableActiveLow, delayBusEnableBeforeSendMs, delayBusEnableAfterSendMs);
+    }
 
     public void notifyOnDataAvailable(boolean b)
     {

src/main/java/gnu/io/RXTXPort.java

@@ -1075,6 +1075,7 @@ public void close()
                                 z.reportln(  "RXTXPort:close detected bad File Descriptor" );
                                 return;
                         }
+                        disableRs485();
                         setDTR(false);
                         setDSR(false);
                         if (debug)
@@ -2238,5 +2239,16 @@ public boolean clearCommInput()
 		return nativeClearCommInput();
 	}
 
+
+	public int enableRs485(boolean busEnableActiveLow, int delayBusEnableBeforeSendMs, int delayBusEnableAfterSendMs) {
+		return controlRs485(fd, true, busEnableActiveLow, delayBusEnableBeforeSendMs, delayBusEnableAfterSendMs);
+	}
+
+	public int disableRs485() {
+		return controlRs485(fd, false, false, 0, 0);
+	}
+
+	private native synchronized int controlRs485(int fd, boolean enable, boolean busEnableActiveLow, int delayBusEnableBeforeSendMs, int delayBusEnableAfterSendMs);
+
 /*------------------------  END OF CommAPI Extensions -----------------------*/
 }