psi: wrote test for gpsUpdate - appears to be working

stream/mts/psi/op.go

@@ -33,7 +33,7 @@ import (
 )
 
 func TimeBytes(time uint64) (s []byte) {
-	s = make([]byte, timeSize)
+	s = make([]byte, timeDataSize)
 	binary.BigEndian.PutUint64(s[:], time)
 	return s
 }
@@ -45,6 +45,13 @@ func chkTime(d []byte) error {
 	return nil
 }
 
+func chkGps(d []byte) error {
+	if d[gpsTagIndx] != gpsDescTag {
+		return errors.New("PSI does not contain a gps descriptor, cannot update")
+	}
+	return nil
+}
+
 // Updatetime
 func UpdateTime(d []byte, t int) error {
 	err := chkTime(d)
@@ -52,8 +59,8 @@ func UpdateTime(d []byte, t int) error {
 		return err
 	}
 	ts := TimeBytes(uint64(t))
-	for i := range d[timeIndx : timeIndx+8] {
-		d[i+timeIndx] = ts[i]
+	for i := range d[timeDataIndx : timeDataIndx+timeDataSize] {
+		d[i+timeDataIndx] = ts[i]
 	}
 	return nil
 }
@@ -63,14 +70,27 @@ func TimeOf(d []byte) (t uint64, err error) {
 	if err != nil {
 		return 0, err
 	}
-	for i := range d[timeIndx : timeIndx+8] {
-		t |= uint64(d[i+timeIndx]) << uint(56-i*8)
+	for i := range d[timeDataIndx : timeDataIndx+timeDataSize] {
+		t |= uint64(d[i+timeDataIndx]) << uint(56-i*timeDataSize)
 	}
 	return t, nil
 }
 
 func GpsStrBytes(l string) (out []byte) {
-	out = make([]byte, gpsSize)
+	out = make([]byte, gpsDataSize)
 	copy(out, []byte(l))
 	return
 }
+
+func UpdateGps(d []byte, s string) error {
+	// First check if there is a GPS descriptor
+	err := chkGps(d)
+	if err != nil {
+		return err
+	}
+	gb := GpsStrBytes(s)
+	for i := range d[gpsDataIndx : gpsDataIndx+gpsDataSize] {
+		d[i+gpsDataIndx] = gb[i]
+	}
+	return nil
+}

stream/mts/psi/psi.go

@@ -51,16 +51,16 @@ const (
 const (
 	timeDescTag  = 234
 	timeTagIndx  = 13
-	timeIndx    = 15
-	timeSize    = 8
+	timeDataIndx = 15
+	timeDataSize = 8
 )
 
 // Consts relating to gps description
 const (
 	gpsDescTag  = 235
 	gpsTagIndx  = 23
-	gpsIndx    = 25
-	gpsSize    = 32 // bytes
+	gpsDataIndx = 25
+	gpsDataSize = 32 // bytes
 )
 
 // Program specific information

stream/mts/psi/psi_test.go

@@ -60,10 +60,10 @@ var (
 	pmtTimeGpsBytesPart1 = []byte{
 		0x00, 0x02, 0xb0, 0x12, 0x00, 0x01, 0xc1, 0x00, 0x00, 0xe1, 0x00, 0xf0, 0x0a,
 		byte(timeDescTag),                              // Descriptor tag for timestamp
-		byte(timeSize),                                 // Length of bytes to follow
+		byte(timeDataSize),                             // Length of bytes to follow
 		0x00, 0x00, 0x00, 0x00, 0x67, 0x6F, 0x74, 0x5F, // Timestamp data
 		byte(gpsDescTag),  // Descriptor tag for gps
-		byte(gpsSize),    // Length of bytes to follow
+		byte(gpsDataSize), // Length of bytes to follow
 	}
 	pmtTimeGpsBytesPart2 = []byte{
 		0x1b, 0xe1, 0x00, 0xf0, 0x00,
@@ -75,7 +75,7 @@ var (
 	pmtTimeBytes1 = []byte{
 		0x00, 0x02, 0xb0, 0x12, 0x00, 0x01, 0xc1, 0x00, 0x00, 0xe1, 0x00, 0xf0, 0x0a,
 		byte(timeDescTag),                              // Descriptor tag
-		byte(timeSize),                                 // Length of bytes to follow
+		byte(timeDataSize),                             // Length of bytes to follow
 		0x00, 0x00, 0x00, 0x00, 0x49, 0xA2, 0x36, 0x0B, // timestamp
 		0x1b, 0xe1, 0x00, 0xf0, 0x00,
 	}
@@ -84,7 +84,7 @@ var (
 	pmtTimeBytes2 = []byte{
 		0x00, 0x02, 0xb0, 0x12, 0x00, 0x01, 0xc1, 0x00, 0x00, 0xe1, 0x00, 0xf0, 0x0a,
 		byte(timeDescTag),                              // Descriptor tag
-		byte(timeSize),                                 // Length of bytes to follow
+		byte(timeDataSize),                             // Length of bytes to follow
 		0x00, 0x00, 0x00, 0x00, 0x67, 0x6F, 0x74, 0x5F, // timestamp
 		0x1b, 0xe1, 0x00, 0xf0, 0x00,
 	}
@@ -136,7 +136,7 @@ var bytesTests = []struct {
 					Pd: []Desc{
 						Desc{
 							Dt: byte(timeDescTag),
-							Dl: byte(timeSize),
+							Dl: byte(timeDataSize),
 							Dd: TimeBytes(tstTime1),
 						},
 					},
@@ -171,12 +171,12 @@ var bytesTests = []struct {
 					Pd: []Desc{
 						Desc{
 							Dt: byte(timeDescTag),
-							Dl: byte(timeSize),
+							Dl: byte(timeDataSize),
 							Dd: TimeBytes(tstTime2),
 						},
 						Desc{
 							Dt: byte(gpsDescTag),
-							Dl: byte(gpsSize),
+							Dl: byte(gpsDataSize),
 							Dd: GpsStrBytes(gpsTstStr1),
 						},
 					},
@@ -239,7 +239,7 @@ func TestTimeGet(t *testing.T) {
 func TestGpsUpdate(t *testing.T) {
 	cpy := make([]byte, len(pmtTimeGpsBytes1))
 	copy(cpy, pmtTimeGpsBytes1)
-	err := UpdateGps(cpy, tstTime2)
+	err := UpdateGps(cpy, gpsTstStr2)
 	if err != nil {
 		t.Errorf("Update time returned err: %v", err)
 	}