Limit slice range

uncanny/display.go

@@ -6,6 +6,22 @@ import (
 	"golang.org/x/text/encoding/charmap"
 )
 
+// min returns the smaller of two integers {
+func min(x, y int) int {
+	if x < y {
+		return x
+	}
+	return y
+}
+
+// max returns the larger of two integers {
+func max(x, y int) int {
+	if x > y {
+		return x
+	}
+	return y
+}
+
 // encodeString encodes a Unicode string into a given charmap.
 // Unsupported characters are replaced by the default replacement symbol.
 // Mysteriously, this functionality is missing from x/text/encoding.
@@ -30,8 +46,8 @@ func (c *Can) DisplayWrite(line int, a []byte) error {
 	}
 	// print in separate chunks, as one frame payload is limited to 7 bytes
 	// the display has only 16 characters per line, so we truncate there
-	for i := 0; i < len(a) && i < 16; i += 7 {
+	for i := 0; i < min(len(a), 16); i += 7 {
-		err := c.bus.Publish(DisplayCommand{addr, a[i:i+7]}.Encode())
+		err := c.bus.Publish(DisplayCommand{addr, a[i:min(i+7,len(a))]}.Encode())
 		if err != nil {
 			return err
 		}