Add msgpack wire protocol with halfsiphash checksums

lib/picoserial/picoserial.go

@@ -2,6 +2,7 @@ package picoserial
 
 import (
 	"fmt"
+	"time"
 
 	"go.bug.st/serial"
 	"go.bug.st/serial/enumerator"
@@ -20,8 +21,12 @@ func FindDevice() (string, error) {
 	return "", nil
 }
 
+func Open(portName string) (serial.Port, error) {
+	return serial.Open(portName, &serial.Mode{BaudRate: 115200})
+}
+
 func SendByte(portName string, b byte) error {
-	port, err := serial.Open(portName, &serial.Mode{BaudRate: 115200})
+	port, err := Open(portName)
 	if err != nil {
 		return fmt.Errorf("opening %s: %w", portName, err)
 	}
@@ -33,3 +38,32 @@ func SendByte(portName string, b byte) error {
 	}
 	return nil
 }
+
+// SendByteAndRead sends a byte and reads the response with a timeout.
+func SendByteAndRead(portName string, b byte, timeout time.Duration) ([]byte, error) {
+	port, err := Open(portName)
+	if err != nil {
+		return nil, fmt.Errorf("opening %s: %w", portName, err)
+	}
+	defer port.Close()
+
+	port.SetReadTimeout(timeout)
+
+	_, err = port.Write([]byte{b})
+	if err != nil {
+		return nil, fmt.Errorf("writing to %s: %w", portName, err)
+	}
+
+	var resp []byte
+	buf := make([]byte, 256)
+	for {
+		n, err := port.Read(buf)
+		if n > 0 {
+			resp = append(resp, buf[:n]...)
+		}
+		if err != nil || n == 0 {
+			break
+		}
+	}
+	return resp, nil
+}