Refactor client I/O into protocol package

shared/io.go

@@ -1,31 +1,43 @@
 package shared
 
 import (
-	"errors"
-	"go.bug.st/serial"
+	"fmt"
+	log "github.com/sirupsen/logrus"
 	"io"
 	"time"
 )
 
-// receive the requested number of bytes from serial port and stop after the given timeout in seconds
-func ReceiveBytes(port *serial.Port, count int, timeout time.Duration) ([]byte, error) {
-	timeoutCh := time.After(timeout * time.Second)
+// receive at maximum the requested number of bytes from serial port and stop after the given timeout
+func ReceiveBytes(port *io.ReadWriteCloser, count int, timeout time.Duration) ([]byte, error) {
 	readCh := make(chan []byte, 1)
 	errCh := make(chan error, 1)
 	go func() {
 		data := make([]byte, count)
-		if _, err := io.ReadAtLeast(*port, data, count); err != nil {
+		if readBytes, err := (*port).Read(data); err != nil {
 			errCh <- err
+		} else if readBytes > 0 {
+			log.Tracef("%d bytes read", readBytes)
+			readCh <- data[0:readBytes]
 		} else {
-			readCh <- data
+			readCh <- make([]byte, 0)
 		}
+		return
 	}()
 	select {
-	case <-timeoutCh:
-		return nil, errors.New("timeout")
+	case <-time.After(timeout):
+		return nil, fmt.Errorf("timeout passed %v: %v", timeout)
 	case err := <-errCh:
 		return nil, err
 	case data := <-readCh:
 		return data, nil
 	}
 }
+
+func SendByte(port *io.ReadWriteCloser, data byte) error {
+	if bytesWritten, err := (*port).Write([]byte{data}); err != nil {
+		return err
+	} else {
+		log.Tracef("wrote %d bytes of handshake info", bytesWritten)
+	}
+	return nil
+}

shared/shared.go

@@ -4,4 +4,4 @@ const MagicTrailer = "rie4Ech7"
 
 const HandshakeByte = 0x02
 const AckByte = 0x10
-const NackByte = 0x11
+const ResendByte = 0x11