Fix warnings from gometalinter

cgm.go

@@ -0,0 +1,51 @@
+/*
+Package dexcom provides functions to access a Dexcom G4 Share
+CGM receiver over a BLE or USB connection.
+
+Based on the Python version at github.com/bewest/decoding-dexcom
+*/
+package dexcom
+
+import (
+	"log"
+
+	"github.com/ecc1/usbserial"
+)
+
+// Connection is the interface satisfied by a CGM connection.
+type Connection interface {
+	Send([]byte) error
+	Receive([]byte) error
+	Close()
+}
+
+// CGM represents a CGM connection.
+type CGM struct {
+	Connection
+	err error
+}
+
+// Open first attempts to open a USB connection;
+// if that fails it tries a BLE connection.
+func Open() *CGM {
+	conn, err := OpenUSB()
+	if err == nil {
+		return &CGM{Connection: conn}
+	}
+	_, notFound := err.(usbserial.DeviceNotFoundError)
+	if !notFound {
+		log.Print(err)
+	}
+	conn, err = OpenBLE()
+	return &CGM{Connection: conn, err: err}
+}
+
+// Error returns the error state of the CGM.
+func (cgm *CGM) Error() error {
+	return cgm.err
+}
+
+// SetError sets the error state of the CGM.
+func (cgm *CGM) SetError(err error) {
+	cgm.err = err
+}

cmd/demo/main.go

@@ -20,14 +20,14 @@ func main() {
 		log.Fatal(cgm.Error())
 	}
 	fmt.Println("display time:", cgm.ReadDisplayTime())
-	fmt.Println("transmitter ID:", string(cgm.Cmd(dexcom.READ_TRANSMITTER_ID)))
+	fmt.Println("transmitter ID:", string(cgm.Cmd(dexcom.ReadTransmitterID)))
 	printXMLInfo("firmware header", cgm.ReadFirmwareHeader())
 
-	hw := cgm.ReadXMLRecord(dexcom.MANUFACTURING_DATA)
+	hw := cgm.ReadXMLRecord(dexcom.ManufacturingData)
 	printXMLInfo("manufacturing data", hw.XML)
 	fmt.Printf("    %+v\n", hw.Timestamp)
 
-	sw := cgm.ReadXMLRecord(dexcom.PC_SOFTWARE_PARAMETER)
+	sw := cgm.ReadXMLRecord(dexcom.SoftwareData)
 	printXMLInfo("PC software parameter", sw.XML)
 	fmt.Printf("    %+v\n", sw.Timestamp)
 }

cmd/g4ping/main.go

@@ -8,7 +8,7 @@ import (
 
 func main() {
 	cgm := dexcom.Open()
-	cgm.Cmd(dexcom.PING)
+	cgm.Cmd(dexcom.Ping)
 	if cgm.Error() != nil {
 		log.Fatal(cgm.Error())
 	}

cmd/glucose/main.go

@@ -28,10 +28,10 @@ var (
 		flag *bool
 		page dexcom.PageType
 	}{
-		{egv, dexcom.EGV_DATA},
-		{sensor, dexcom.SENSOR_DATA},
-		{calibration, dexcom.CAL_SET},
-		{meter, dexcom.METER_DATA},
+		{egv, dexcom.EGVData},
+		{sensor, dexcom.SensorData},
+		{calibration, dexcom.CalibrationData},
+		{meter, dexcom.MeterData},
 	}
 )
 
@@ -65,9 +65,9 @@ func main() {
 		}
 		var v []dexcom.Record
 		// Special case when both EGV and sensor records are requested.
-		if t.page == dexcom.EGV_DATA && *sensor {
+		if t.page == dexcom.EGVData && *sensor {
 			v = cgm.GlucoseReadings(cutoff)
-		} else if t.page == dexcom.SENSOR_DATA && *egv {
+		} else if t.page == dexcom.SensorData && *egv {
 			continue
 		} else {
 			v = cgm.ReadHistory(t.page, cutoff)

cmd/show/main.go

@@ -11,7 +11,7 @@ import (
 )
 
 var (
-	pageTypeFlag = flag.Int("p", int(dexcom.EGV_DATA), "`page type` to read")
+	pageTypeFlag = flag.Int("p", int(dexcom.EGVData), "`page type` to read")
 	numRecords   = flag.Int("n", 10, "number of `records` to get")
 	all          = flag.Bool("a", false, "get all records")
 )

commands.go

@@ -1,52 +1,53 @@
 package dexcom
 
-// A Command specifies an operation to be performed by the Dexcom CGM receiver.
+// Command represents a Dexcom CGM receiver command.
 type Command byte
 
 //go:generate stringer -type Command
 
+// Dexcom G4 receiver commands.
 const (
-	NULL                          Command = 0
-	ACK                           Command = 1
-	NAK                           Command = 2
-	INVALID_COMMAND               Command = 3
-	INVALID_PARAM                 Command = 4
-	INCOMPLETE_PACKET_RECEIVED    Command = 5
-	RECEIVER_ERROR                Command = 6
-	INVALID_MODE                  Command = 7
-	PING                          Command = 10
-	READ_FIRMWARE_HEADER          Command = 11
-	READ_DATABASE_PARTITION_INFO  Command = 15
-	READ_DATABASE_PAGE_RANGE      Command = 16
-	READ_DATABASE_PAGES           Command = 17
-	READ_DATABASE_PAGE_HEADER     Command = 18
-	READ_TRANSMITTER_ID           Command = 25
-	WRITE_TRANSMITTER_ID          Command = 26
-	READ_LANGUAGE                 Command = 27
-	WRITE_LANGUAGE                Command = 28
-	READ_DISPLAY_TIME_OFFSET      Command = 29
-	WRITE_DISPLAY_TIME_OFFSET     Command = 30
-	READ_RTC                      Command = 31
-	RESET_RECEIVER                Command = 32
-	READ_BATTERY_LEVEL            Command = 33
-	READ_SYSTEM_TIME              Command = 34
-	READ_SYSTEM_TIME_OFFSET       Command = 35
-	WRITE_SYSTEM_TIME             Command = 36
-	READ_GLUCOSE_UNIT             Command = 37
-	WRITE_GLUCOSE_UNIT            Command = 38
-	READ_BLINDED_MODE             Command = 39
-	WRITE_BLINDED_MODE            Command = 40
-	READ_CLOCK_MODE               Command = 41
-	WRITE_CLOCK_MODE              Command = 42
-	READ_DEVICE_MODE              Command = 43
-	ERASE_DATABASE                Command = 45
-	SHUTDOWN_RECEIVER             Command = 46
-	WRITE_PC_PARAMETERS           Command = 47
-	READ_BATTERY_STATE            Command = 48
-	READ_HARDWARE_BOARD_ID        Command = 49
-	READ_FIRMWARE_SETTINGS        Command = 54
-	READ_ENABLE_SETUP_WIZARD_FLAG Command = 55
-	READ_SETUP_WIZARD_STATE       Command = 57
-	READ_CHARGER_CURRENT_SETTING  Command = 59
-	WRITE_CHARGER_CURRENT_SETTING Command = 60
+	Null                       Command = 0
+	Ack                        Command = 1
+	Nak                        Command = 2
+	InvalidCommand             Command = 3
+	InvalidParam               Command = 4
+	IncompletePacketReceived   Command = 5
+	ReceiverError              Command = 6
+	InvalidMode                Command = 7
+	Ping                       Command = 10
+	ReadFirmwareHeader         Command = 11
+	ReadDatabasePartitionInfo  Command = 15
+	ReadDatabasePageRange      Command = 16
+	ReadDatabasePages          Command = 17
+	ReadDatabasePageHeader     Command = 18
+	ReadTransmitterID          Command = 25
+	WriteTransmitterID         Command = 26
+	ReadLanguage               Command = 27
+	WriteLanguage              Command = 28
+	ReadDisplayTimeOffset      Command = 29
+	WriteDisplayTimeOffset     Command = 30
+	ReadRTC                    Command = 31
+	ResetReceiver              Command = 32
+	ReadBatteryLevel           Command = 33
+	ReadSystemTime             Command = 34
+	ReadSystemTimeOffset       Command = 35
+	WriteSystemTime            Command = 36
+	ReadGlucoseUnits           Command = 37
+	WriteGlucoseUnits          Command = 38
+	ReadBlindMode              Command = 39
+	WriteBlindMode             Command = 40
+	ReadClockMode              Command = 41
+	WriteClockMode             Command = 42
+	ReadDeviceMode             Command = 43
+	EraseDatabase              Command = 45
+	ShutdownReceiver           Command = 46
+	WriteSoftwareParameters    Command = 47
+	ReadBatteryState           Command = 48
+	ReadHardwareID             Command = 49
+	ReadFirmwareSettings       Command = 54
+	ReadEnableSetupWizardFlag  Command = 55
+	ReadSetupWizardState       Command = 57
+	ReadChargerCurrentSetting  Command = 59
+	WriteChargerCurrentSetting Command = 60
 )

history.go

@@ -9,6 +9,7 @@ const (
 	userTimeLayout = "2006-01-02 15:04:05"
 )
 
+// ReadHistory returns records since the specified time.
 func (cgm *CGM) ReadHistory(pageType PageType, since time.Time) []Record {
 	first, last := cgm.ReadPageRange(pageType)
 	if cgm.Error() != nil {
@@ -28,6 +29,7 @@ func (cgm *CGM) ReadHistory(pageType PageType, since time.Time) []Record {
 	return results
 }
 
+// ReadCount returns a specified number of most recent records.
 func (cgm *CGM) ReadCount(pageType PageType, count int) []Record {
 	first, last := cgm.ReadPageRange(pageType)
 	if cgm.Error() != nil {
@@ -42,8 +44,8 @@ func (cgm *CGM) ReadCount(pageType PageType, count int) []Record {
 	return results
 }
 
-// Merge slices of records that are already in reverse chronological order
-// into a single ordered slice.
+// MergeHistory merges slices of records that are already
+// in reverse chronological order into a single ordered slice.
 func MergeHistory(slices ...[]Record) []Record {
 	n := len(slices)
 	if n == 0 {
@@ -60,7 +62,7 @@ func MergeHistory(slices ...[]Record) []Record {
 	}
 	results := make([]Record, total)
 	index := make([]int, n)
-	for next, _ := range results {
+	for next := range results {
 		// Find slice with latest current value.
 		which := -1
 		max := time.Time{}
@@ -84,12 +86,13 @@ const (
 	glucoseReadingWindow = 10 * time.Second
 )
 
+// GlucoseReadings returns sensor and EGV records since the specified time.
 func (cgm *CGM) GlucoseReadings(since time.Time) []Record {
-	sensor := cgm.ReadHistory(SENSOR_DATA, since)
+	sensor := cgm.ReadHistory(SensorData, since)
 	if cgm.Error() != nil {
 		return nil
 	}
-	egv := cgm.ReadHistory(EGV_DATA, since)
+	egv := cgm.ReadHistory(EGVData, since)
 	if cgm.Error() != nil {
 		return nil
 	}

marshal.go

@@ -4,52 +4,46 @@ import (
 	"math"
 )
 
-// MarshalUint16 marshals a uint16 value into 2 bytes in little-endian order.
-func MarshalUint16(n uint16) []byte {
+// Marshaling and unmarshaling of ints and floats in little-endian order.
+
+func marshalUint16(n uint16) []byte {
 	return []byte{byte(n & 0xFF), byte(n >> 8)}
 }
 
-// MarshalInt16 marshals an int16 value into 2 bytes in little-endian order.
-func MarshalInt16(n int16) []byte {
-	return MarshalUint16(uint16(n))
+// nolint
+func marshalInt16(n int16) []byte {
+	return marshalUint16(uint16(n))
 }
 
-// MarshalUint32 marshals a uint32 value into 4 bytes in little-endian order.
-func MarshalUint32(n uint32) []byte {
-	return append(MarshalUint16(uint16(n&0xFFFF)), MarshalUint16(uint16(n>>16))...)
+func marshalUint32(n uint32) []byte {
+	return append(marshalUint16(uint16(n&0xFFFF)), marshalUint16(uint16(n>>16))...)
 }
 
-// MarshalInt32 marshals an int32 value into 4 bytes in little-endian order.
-func MarshalInt32(n int32) []byte {
-	return MarshalUint32(uint32(n))
+func marshalInt32(n int32) []byte {
+	return marshalUint32(uint32(n))
 }
 
-// UnmarshalUint16 unmarshals 2 bytes in little-endian order into a uint16 value.
-func UnmarshalUint16(v []byte) uint16 {
+func unmarshalUint16(v []byte) uint16 {
 	return uint16(v[0]) | uint16(v[1])<<8
 }
 
-// UnmarshalInt16 unmarshals 2 bytes in little-endian order into an int16 value.
-func UnmarshalInt16(v []byte) int16 {
-	return int16(UnmarshalUint16(v))
+// nolint
+func unmarshalInt16(v []byte) int16 {
+	return int16(unmarshalUint16(v))
 }
 
-// UnmarshalUint32 unmarshals 4 bytes in little-endian order into a uint32 value.
-func UnmarshalUint32(v []byte) uint32 {
-	return uint32(UnmarshalUint16(v[0:2])) | uint32(UnmarshalUint16(v[2:4]))<<16
+func unmarshalUint32(v []byte) uint32 {
+	return uint32(unmarshalUint16(v[0:2])) | uint32(unmarshalUint16(v[2:4]))<<16
 }
 
-// UnmarshalInt32 unmarshals 4 bytes in little-endian order into an int32 value.
-func UnmarshalInt32(v []byte) int32 {
-	return int32(UnmarshalUint32(v))
+func unmarshalInt32(v []byte) int32 {
+	return int32(unmarshalUint32(v))
 }
 
-// UnmarshalUint64 unmarshals 8 bytes in little-endian order into a uint64 value.
-func UnmarshalUint64(v []byte) uint64 {
-	return uint64(UnmarshalUint32(v[0:4])) | uint64(UnmarshalUint32(v[4:8]))<<32
+func unmarshalUint64(v []byte) uint64 {
+	return uint64(unmarshalUint32(v[0:4])) | uint64(unmarshalUint32(v[4:8]))<<32
 }
 
-// UnmarshalFloat64 unmarshals 8 bytes in little-endian order into a float64 value.
-func UnmarshalFloat64(v []byte) float64 {
-	return math.Float64frombits(UnmarshalUint64(v))
+func unmarshalFloat64(v []byte) float64 {
+	return math.Float64frombits(unmarshalUint64(v))
 }