Merge pull request #7 from DasenB/master

catch type conversion error and prevent infinite loop

Examples/SwiftSerialIM/Sources/main.swift

@@ -44,10 +44,10 @@ func printToScreenFrom(myself: Bool, characterToPrint: UnicodeScalar){
 
     if(myturn && !myself){
         myturn = false
-        print("\nOther: ", terminator:"")
+        print("\n\nOther: ", terminator:"")
     } else if (!myturn && myself){
         myturn = true
-        print("\nMe: ", terminator:"")
+        print("\n\nMe: ", terminator:"")
     }
 
     print(characterToPrint, terminator:"")
@@ -95,6 +95,7 @@ do {
         observer in
 
         backgroundRead()
+        return nil
     }
 
     pthread_create(&readingThread, nil, pthreadFunc, nil)

README.md

@@ -9,6 +9,14 @@ This library is an improvement over my previous now deprecated library [SwiftLin
 <a href="https://developer.apple.com/swift"><img src="https://img.shields.io/badge/swift3-compatible-orange.svg?style=flat" alt="Swift 3 compatible" /></a>
 <a href="https://raw.githubusercontent.com/uraimo/SwiftyGPIO/master/LICENSE"><img src="http://img.shields.io/badge/license-MIT-blue.svg?style=flat" alt="License: MIT" /></a>
 
+## Talk on this library
+
+I gave a talk on this library and one of its examples SwiftSerialIM. Click on the links below to see the slides and video.
+
+[![My slides on slideshare](first-slide.png)](http://www.slideshare.net/yeokm1/a-science-project-swift-serial-chat)
+
+[![](http://img.youtube.com/vi/6PWP1eZo53s/0.jpg)](https://www.youtube.com/watch?v=6PWP1eZo53s)
+
 ## Mac OS Preparation
 
 You should have Xcode 8 installed with the command line tools.
@@ -63,7 +71,7 @@ To get started quickly, you can take a look at my example projects [here](Exampl
 
 ### Example 1: Loopback Test
 
-In order to run this example properly, you need to connect one of your (USB/UART) serial ports in a loopback manner. Basically, you short the TX and RX pins of the serial port.
+In order to run this example properly, you need to connect one of your (USB/UART) serial ports in a loopback manner. Basically, you short the TX and RX pins of the serial port. This library currently only support the `/dev/cu.*` variant on Mac. Read the beginning of the API usage section for more details.
 
 ```bash
 git clone https://github.com/yeokm1/SwiftSerial.git
@@ -79,7 +87,7 @@ sudo ./.build/debug/SwiftSerialExample /dev/ttyUSB0
 #If all goes well you should see a series of messages informing you that data transmitted has been received properly.
 ```
 
-### Example 2: An chat app between 2 machines
+### Example 2: A chat app between 2 machines
 
 In order to run this example properly, you need 2 machines connected by a [null-modem cable](https://en.wikipedia.org/wiki/Null_modem) or 2 USB-Serial adapters with the TX-RX pins connected to each other. Run a copy of my program on both machines.
 
@@ -124,7 +132,7 @@ let serialPort: SerialPort = SerialPort(path: portName)
 ```
 Supply the portname that you wish to open like `/dev/ttyUSB0` or `/dev/cu.usbserial`.
 
-For Macs, this library currently only works with the `/dev/cu.*` ports instead of the `/dev/tty.*`. I have enabled blocking on the serial port to prevent high CPU usage which will prevent the `/dev/tty.*` from working. Read more about the differences between the two [here](http://stackoverflow.com/questions/8632586/macos-whats-the-difference-between-dev-tty-and-dev-cu). If there is an problem, open an issue describing your situation and let me look into it.
+For Macs, this library currently only works with the `/dev/cu.*` ports instead of the `/dev/tty.*`. I have enabled blocking on the serial port to prevent high CPU usage which will prevent the `/dev/tty.*` from working. Read more about the differences between the two [here](http://stackoverflow.com/questions/8632586/macos-whats-the-difference-between-dev-tty-and-dev-cu). If there is a problem, open an issue describing your situation and let me look into it.
 
 ### Opening the Serial Port
 
@@ -188,10 +196,15 @@ func readUntilChar(_ terminator: CChar) throws -> String
 ```
 Keep reading until the specified CChar is encountered. Return the string read so far without that value.
 
+```swift
+func readByte() throws -> UInt8
+```
+Read only one byte. This works best if `minimumBytesToRead` has been set to `1` when opening the port. This function internally calls `readBytes()`.
+
 ```swift
 func readChar() throws -> UnicodeScalar
 ```
-Read only one character. This works best if `minimumBytesToRead` has been set to `1` when opening the port. This function internally calls `readBytes()`.
+Read only one character. This works best if `minimumBytesToRead` has been set to `1` when opening the port. This function internally calls `readByte()`.
 
 ### Writing data to the port
 

Sources/SwiftSerial.swift

@@ -209,6 +209,8 @@ public enum PortError: Int32, Error {
     case mustReceiveOrTransmit
     case mustBeOpen
     case stringsMustBeUTF8
+    case unableToConvertByteToCharacter
+    case deviceNotConnected
 }
 
 public class SerialPort {
@@ -371,6 +373,12 @@ extension SerialPort {
             throw PortError.mustBeOpen
         }
         
+        var s: stat = stat()
+        fstat(fileDescriptor, &s)
+        if s.st_nlink != 1 {
+            throw PortError.deviceNotConnected
+        }
+        
         let bytesRead = read(fileDescriptor, buffer, size)
         return bytesRead
     }
@@ -424,6 +432,9 @@ extension SerialPort {
             let bytesRead = try readBytes(into: buffer, size: 1)
 
             if bytesRead > 0 {
+                if ( buffer[0] > 127) {
+                    throw PortError.unableToConvertByteToCharacter
+                }
                 let character = CChar(buffer[0])
                 
                 if character == terminator {
@@ -446,7 +457,7 @@ extension SerialPort {
         return try readUntilChar(newlineChar)
     }
 
-    public func readChar() throws -> UnicodeScalar {
+    public func readByte() throws -> UInt8 {
         let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: 1)
         
         defer {
@@ -457,11 +468,15 @@ extension SerialPort {
             let bytesRead = try readBytes(into: buffer, size: 1)
             
             if bytesRead > 0 {
-                let character = UnicodeScalar(buffer[0])
-                return character     
+                return buffer[0]
+            }
         }
     }
 
+    public func readChar() throws -> UnicodeScalar {
+        let byteRead = try readByte()
+        let character = UnicodeScalar(byteRead)
+        return character
     }
    
 }