Add msgpack wire protocol with halfsiphash checksums

cmd/load/main.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/theater/picomap/lib/picoserial"
 	"github.com/theater/picomap/lib/picotool"
+	"github.com/theater/picomap/lib/wire"
 )
 
 func main() {
@@ -40,9 +41,23 @@ func run(buildDir string) error {
 	}
 	if dev != "" {
 		fmt.Printf("Sending 'b' to %s to enter BOOTSEL mode...\n", dev)
-		if err := picoserial.SendByte(dev, 'b'); err != nil {
+		resp, err := picoserial.SendByteAndRead(dev, 'b', 2*time.Second)
+		if err != nil {
 			return err
 		}
+		if len(resp) > 0 {
+			msg, err := wire.DecodeMessage(resp)
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "warning: failed to decode response: %v\n", err)
+			} else {
+				switch msg.(type) {
+				case *wire.RebootingBootsel:
+					fmt.Println("Device confirmed reboot into BOOTSEL mode.")
+				default:
+					fmt.Printf("Unexpected response type: %T\n", msg)
+				}
+			}
+		}
 		time.Sleep(2 * time.Second)
 	}