update readme

Update for Swift 4/5

README.md

@@ -1,5 +1,5 @@
 # SwiftSerial
-A Swift 3 Linux and Mac library for reading and writing to serial ports. This library has been tested to work on macOS Sierra, Linux Mint 18 (based on Ubuntu 16.04) and on the [Raspberry Pi 3 on Ubuntu 16.04](https://wiki.ubuntu.com/ARM/RaspberryPi). Other platforms using Ubuntu like the Beaglebone might work as well.
+A Swift Linux and Mac library for reading and writing to serial ports. This library has been tested to work on macOS Sierra, Linux Mint 18 (based on Ubuntu 16.04) and on the [Raspberry Pi 3 on Ubuntu 16.04](https://wiki.ubuntu.com/ARM/RaspberryPi). Other platforms using Ubuntu like the Beaglebone might work as well.
 
 This library is an improvement over my previous now deprecated library [SwiftLinuxSerial](https://github.com/yeokm1/SwiftLinuxSerial) which was less Swifty and supported only Linux. This library is thanks largely to [Jay Jun](https://github.com/jayjun). His original pull request can be found [here](https://github.com/yeokm1/SwiftLinuxSerial/pull/1).
 
@@ -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.
@@ -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
     }
@@ -378,7 +386,7 @@ extension SerialPort {
     public func readData(ofLength length: Int) throws -> Data {
         let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: length)
         defer {
-            buffer.deallocate(capacity: length)
+            buffer.deallocate()
         }
 
         let bytesRead = try readBytes(into: buffer, size: length)
@@ -417,13 +425,16 @@ extension SerialPort {
         var data = Data()
         let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: 1)
         defer {
-            buffer.deallocate(capacity: 1)
+            buffer.deallocate()
         }
 
         while true {
             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 {
@@ -446,22 +457,26 @@ extension SerialPort {
         return try readUntilChar(newlineChar)
     }
 
-    public func readChar() throws -> UnicodeScalar {
+    public func readByte() throws -> UInt8 {
         let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: 1)
 
         defer {
-            buffer.deallocate(capacity: 1)
+            buffer.deallocate()
         }
 
         while true {
             let bytesRead = try readBytes(into: buffer, size: 1)
 
             if bytesRead > 0 {
-                let character = UnicodeScalar(buffer[0])
+                return buffer[0]
-                return character     
             }
         }
+    }
 
+    public func readChar() throws -> UnicodeScalar {
+        let byteRead = try readByte()
+        let character = UnicodeScalar(byteRead)
+        return character
     }
 
 }
@@ -483,7 +498,7 @@ extension SerialPort {
         let size = data.count
         let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: size)
         defer {
-            buffer.deallocate(capacity: size)
+            buffer.deallocate()
         }
 
         data.copyBytes(to: buffer, count: size)