reorganise some of the internals of the package.

functional options added.

packet.go

@@ -1,50 +1,72 @@
-package main
+package vbantxt
 
-var r *requestHeader
+import (
+	"encoding/binary"
 
-const VBAN_PROTOCOL_TXT = 0x40
+	log "github.com/sirupsen/logrus"
+)
 
-// requestHeader represents a single request header
-type requestHeader struct {
+const (
+	vbanProtocolTxt = 0x40
+	streamNameSz    = 16
+	headerSz        = 4 + 1 + 1 + 1 + 1 + 16 + 4
+)
+
+var BpsOpts = []int{0, 110, 150, 300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 31250,
+	38400, 57600, 115200, 128000, 230400, 250000, 256000, 460800, 921600,
+	1000000, 1500000, 2000000, 3000000}
+
+type packet struct {
 	name         string
 	bpsIndex     int
 	channel      int
 	framecounter []byte
 }
 
-// newRequestHeader returns a pointer to a requestHeader struct as a singleton
-func newRequestHeader(streamname string, bpsI, channel int) *requestHeader {
-	if r != nil {
-		return r
+// newPacket returns a packet struct with default values, framecounter at 0.
+func newPacket(streamname string) packet {
+	return packet{
+		name:         streamname,
+		bpsIndex:     0,
+		channel:      0,
+		framecounter: make([]byte, 4),
 	}
-	return &requestHeader{streamname, bpsI, channel, make([]byte, 4)}
 }
 
 // sr defines the samplerate for the request
-func (r *requestHeader) sr() byte {
-	return byte(VBAN_PROTOCOL_TXT + r.bpsIndex)
+func (p *packet) sr() byte {
+	return byte(vbanProtocolTxt + p.bpsIndex)
 }
 
 // nbc defines the channel of the request
-func (r *requestHeader) nbc() byte {
-	return byte(r.channel)
+func (p *packet) nbc() byte {
+	return byte(p.channel)
 }
 
 // streamname defines the stream name of the text request
-func (r *requestHeader) streamname() []byte {
-	b := make([]byte, 16)
-	copy(b, r.name)
+func (p *packet) streamname() []byte {
+	b := make([]byte, streamNameSz)
+	copy(b, p.name)
 	return b
 }
 
-// header returns a fully formed text request packet header
-func (t *requestHeader) header() []byte {
-	h := []byte("VBAN")
-	h = append(h, t.sr())
+// header returns a fully formed packet header
+func (p *packet) header() []byte {
+	h := make([]byte, 0, headerSz)
+	h = append(h, []byte("VBAN")...)
+	h = append(h, p.sr())
 	h = append(h, byte(0))
-	h = append(h, t.nbc())
+	h = append(h, p.nbc())
 	h = append(h, byte(0x10))
-	h = append(h, t.streamname()...)
-	h = append(h, t.framecounter...)
+	h = append(h, p.streamname()...)
+	h = append(h, p.framecounter...)
 	return h
 }
+
+// bumpFrameCounter increments the frame counter by 1
+func (p *packet) bumpFrameCounter() {
+	x := binary.LittleEndian.Uint32(p.framecounter)
+	binary.LittleEndian.PutUint32(p.framecounter, x+1)
+
+	log.Tracef("framecounter: %d", x)
+}