initial publication

examples/de.go

@@ -0,0 +1,74 @@
+package main
+
+import (
+	`fmt`
+	`log`
+	"strconv"
+)
+
+const (
+	/*
+		This is a nonsensical example.
+		The actual values are sort of scattered around a multitude of RFCs.
+	*/
+	deBits string = "01010101" // [0101 0101], or 85 (0x55)
+)
+
+var (
+	deLowerMask uint8 = 0x03 // 3
+)
+
+func ToDE(dscp, ecn uint8) (de byte) {
+
+	de = (dscp << 2) | (ecn & deLowerMask)
+
+	return
+}
+
+func FromDE(de byte) (dscp, ecn uint8) {
+
+	dscp = de >> 2
+	ecn = de & deLowerMask
+
+	return
+}
+
+func main() {
+
+	var err error
+	var u64 uint64
+	var de byte
+	var dscp uint8
+	var ecn uint8
+
+	// Given a D/E of deBits (see const at top)...
+	if u64, err = strconv.ParseUint(deBits, 2, 8); err != nil {
+		log.Panicln(err)
+	}
+	de = uint8(u64)
+	// Prints:
+	/*
+		D/E is:		85 (0x55)
+	*/
+	fmt.Printf("D/E is:\t\t%d (%#02x)\n", de, de)
+
+	dscp, ecn = FromDE(de)
+	// Prints:
+	/*
+		DSCP:		21 (0x15)
+		ECN:		1 (0x01)
+	*/
+	fmt.Printf(
+		"DSCP:\t\t%d (%#02x)\n"+
+			"ECN:\t\t%d (%#02x)\n",
+		dscp, dscp,
+		ecn, ecn,
+	)
+
+	de = ToDE(dscp, ecn)
+	// Prints:
+	/*
+		Confirmed D/E:	85 (0x55)
+	*/
+	fmt.Printf("Confirmed D/E:\t%d (%#02x)\n", de, de)
+}