Add gitlab-ci file

Dtr support

See merge request vato007/SwiftSerial!1

.gitlab-ci.yml

@@ -0,0 +1,5 @@
+build:
+    stage: build
+    image: vato.ddns.net:8083/swift:5.2.4
+    script:
+        - swift build

Sources/SwiftSerial.swift

@@ -165,6 +165,11 @@ public enum BaudRate {
 }
 #endif
 
+#if os(OSX)
+// Darwin doesn't provide this
+private let FIONREAD: UInt = 0x541B
+#endif
+
 public enum DataBitsSize {
     case bits5
     case bits6
@@ -217,6 +222,7 @@ public class SerialPort {
 
     var path: String
     var fileDescriptor: Int32?
+    private var dtrState = false
 
     public init(path: String) {
         self.path = path
@@ -365,6 +371,29 @@ public class SerialPort {
         }
         fileDescriptor = nil
     }
+    
+    public var dtr: Bool {
+        get{
+            return dtrState
+        }
+        set (value){
+            guard let fileDescriptor = fileDescriptor else {
+                // Need to open port first.
+                return
+            }
+            dtrState = value
+            var flags = TIOCM_DTR
+            if(ioctl(fileDescriptor, UInt(dtrState ? TIOCMBIS : TIOCMBIC), &flags) != 0){
+                print("Failed to apply dtr")
+            }
+        }
+    }
+    
+    public var inWaiting: Int {
+        get{
+            return Int(ioctl(fileDescriptor!, UInt(FIONREAD)))
+        }
+    }
 }
 
 // MARK: Receiving