software: communication: Use Go channels

Go channels help to decouple the communication layers defined by the OSI
model [1]. The physical layer can be abstracted by an RX and TX byte
channel and the data link layer by two frame channels.

[1]: https://en.wikipedia.org/wiki/OSI_model

3 files changed, 51 insertions, 32 deletions

diff --git a/software/communication/interface.go b/software/communication/interface.go
index 672617e..ebd8d6b 100644
--- a/software/communication/interface.go
+++ b/software/communication/interface.go
@@ -2,28 +2,17 @@ package communication
 
 import (
 	"fmt"
-
-	"go.bug.st/serial"
 )
 
 type SerialInterface struct {
-	port serial.Port
+	phy physical
 }
 
 func NewSerialInterface() (SerialInterface, error) {
 	iface := SerialInterface{}
+	var err error
 
-	devices, err := getStSerials()
-	if err != nil {
-		return iface, err
-	}
-
-	if len(devices) != 1 {
-		return iface, fmt.Errorf("Require exactly one serial device from STMicroelectronics but %d attached", len(devices))
-	}
-	device := devices[0]
-
-	iface.port, err = openSerial(device)
+	iface.phy, err = newPhysical()
 	if err != nil {
 		return iface, err
 	}
@@ -31,21 +20,9 @@ func NewSerialInterface() (SerialInterface, error) {
 	return iface, nil
 }
 
-func (i *SerialInterface) Cat() error {
+func (i *SerialInterface) Cat() {
 	for {
-		data, err := i.Read()
-		if err != nil {
-			return err
-		}
+		data := <-i.phy.rx
 		fmt.Printf("%s", string(data))
 	}
 }
-
-func (i *SerialInterface) Read() ([]byte, error) {
-	buff := make([]byte, 100)
-	n, err := i.port.Read(buff)
-	if err != nil {
-		return []byte{}, err
-	}
-	return buff[:n], nil
-}
diff --git a/software/communication/physical.go b/software/communication/physical.go
index 853e4c4..0ba3690 100644
--- a/software/communication/physical.go
+++ b/software/communication/physical.go
@@ -1,6 +1,9 @@
 package communication
 
 import (
+	"fmt"
+	"log"
+
 	"go.bug.st/serial"
 	"go.bug.st/serial/enumerator"
 )
@@ -9,6 +12,35 @@ const (
 	ST_VID = `0483`
 )
 
+type physical struct {
+	port serial.Port
+	rx   chan byte
+}
+
+func newPhysical() (physical, error) {
+	p := physical{}
+
+	devices, err := getStSerials()
+	if err != nil {
+		return p, err
+	}
+
+	if len(devices) != 1 {
+		return p, fmt.Errorf("Require exactly one serial device from STMicroelectronics but %d attached", len(devices))
+	}
+	device := devices[0]
+
+	p.port, err = openSerial(device)
+	if err != nil {
+		return p, err
+	}
+
+	p.rx = make(chan byte)
+	go p.Receive()
+
+	return p, nil
+}
+
 func getStSerials() ([]string, error) {
 	retval := make([]string, 0)
 
@@ -39,3 +71,16 @@ func openSerial(device string) (serial.Port, error) {
 	}
 	return port, nil
 }
+
+func (p *physical) Receive() {
+	for {
+		buff := make([]byte, 100)
+		n, err := p.port.Read(buff)
+		if err != nil {
+			log.Fatal(err)
+		}
+		for i := 0; i < n; i++ {
+			p.rx <- buff[i]
+		}
+	}
+}
diff --git a/software/main.go b/software/main.go
index d0ca2cd..0a6b590 100644
--- a/software/main.go
+++ b/software/main.go
@@ -12,8 +12,5 @@ func main() {
 		log.Fatal(err)
 	}
 
-	err = iface.Cat()
-	if err != nil {
-		log.Fatal(err)
-	}
+	iface.Cat()
 }