reader: intial developer data fields support

Makefile

@@ -108,8 +108,6 @@ checkfull: checkdeps
 	@$(GO) vet $(FIT_PKGS)
 	@echo "vet --shadow"
 	@$(GO) vet -vettool=$(which shadow) $(FIT_PKGS)
-	@echo "golint"
-	@! $(BIN)golint $(FIT_PKGS) | grep -vE '(FileId|SegmentId|messages.go|types.*.\go|fitgen/internal/profile)'
 	@echo "errcheck"
 	@$(BIN)errcheck -ignore 'fmt:Fprinf*,bytes:Write*,archive/zip:Close,io:Close,Write' $(FIT_PKGS)
 	@echo "ineffassign"
@@ -129,7 +127,6 @@ checkdeps:
 	$(GO_BIN) $(GO) install github.com/gordonklaus/ineffassign
 	$(GO_BIN) $(GO) install github.com/kisielk/errcheck
 	$(GO_BIN) $(GO) install github.com/mdempsky/unconvert
-	$(GO_BIN) $(GO) install golang.org/x/lint/golint
 	$(GO_BIN) $(GO) install golang.org/x/tools/cmd/goimports
 	$(GO_BIN) $(GO) install honnef.co/go/tools/cmd/staticcheck
 	$(GO_BIN) $(GO) install mvdan.cc/gofumpt/gofumports

README.md

@@ -21,25 +21,21 @@ are required for running the full test suite and benchmarks.
 
 _Note:_ 0.6.0 contains a breaking change, see #46.
 
-### FIT SDK Version Support
+### Version Support
 
-**Current supported FIT SDK version:** 21.67
+The current supported FIT SDK version is **21.67**.
 
-**Warning:** Data Developers Fields are not yet supported (#21).
+Developer data fields are currently only _partially_ supported.
+At the moment the decoder parses Developer Data Field Descriptions, Developer Data ID Messages and Field Description Messages.
+The decoder currently discards developer data fields found in records. 
 
-Older supported profile versions:
+The encoder will currently (silently) ignore anything related to Developer data fields,
+This also means that encoding will not fail if protocol version 2 is specified for a file header.
 
-* 21.60
-* 21.40
-* 21.38
-* 21.32
-* 20.90
-* 20.43
-* 20.27
-* 20.14
-* 16.20
-
-Other profile versions may work, but have not been tested.
+Developer data fields support is tracked by
+[#21](https://github.com/tormoder/fit/issues/21)
+and
+[#64](https://github.com/tormoder/fit/issues/64).
 
 ### Features
 
@@ -79,3 +75,4 @@ $ go get github.com/tormoder/fit
 - [colinrgodsey](https://github.com/colinrgodsey)
 - [bpg](https://github.com/bpg)
 - [pieterclaerhout](https://github.com/pieterclaerhout)
+- [beyoung](https://github.com/beyoung)

consts.go

@@ -53,6 +53,7 @@ const (
 	compressedLocalMesgNumMask byte = 0x60
 
 	mesgDefinitionMask byte = 0x40
+	devDataMask        byte = 0x20
 	mesgHeaderMask     byte = 0x00
 	localMesgNumMask   byte = 0x0F
 

file.go

@@ -20,6 +20,10 @@ type File struct {
 	FileCreator          *FileCreatorMsg
 	TimestampCorrelation *TimestampCorrelationMsg
 
+	// Developer data fields.
+	fieldDescriptionMsgs []*FieldDescriptionMsg
+	developerDataIdMsgs  []*DeveloperDataIdMsg
+
 	// UnknownMessages is a slice of unknown messages encountered during
 	// decoding. It is sorted by message number.
 	UnknownMessages []UnknownMessage
@@ -73,6 +77,10 @@ func (f *File) add(msg reflect.Value) {
 		f.FileCreator = &tmp
 	case TimestampCorrelationMsg:
 		f.TimestampCorrelation = &tmp
+	case FieldDescriptionMsg:
+		f.fieldDescriptionMsgs = append(f.fieldDescriptionMsgs, &tmp)
+	case DeveloperDataIdMsg:
+		f.developerDataIdMsgs = append(f.developerDataIdMsgs, &tmp)
 	default:
 		f.msgAdder.add(msg)
 	}

reader.go

@@ -315,17 +315,18 @@ func (d *decoder) readFull(p []byte) error {
 }
 
 type defmsg struct {
-	localMsgType uint8
-	arch         binary.ByteOrder
-	globalMsgNum MesgNum
-	fields       byte
-	fieldDefs    []fieldDef
+	localMsgType      uint8
+	arch              binary.ByteOrder
+	globalMsgNum      MesgNum
+	fields            byte
+	fieldDefs         []fieldDef
+	devDataFieldDescs []devDataFieldDesc
 }
 
 func (dm defmsg) String() string {
 	return fmt.Sprintf(
-		"local: %d | global: %v | arch: %v | fields: %d",
-		dm.localMsgType, dm.globalMsgNum, dm.arch, dm.fields,
+		"local: %d | global: %v | arch: %v | fields: %d | data dev fields: %d",
+		dm.localMsgType, dm.globalMsgNum, dm.arch, dm.fields, len(dm.devDataFieldDescs),
 	)
 }
 
@@ -339,6 +340,16 @@ func (fd fieldDef) String() string {
 	return fmt.Sprintf("num: %d | size: %d | btype: %v", fd.num, fd.size, fd.btype)
 }
 
+type devDataFieldDesc struct {
+	fieldNum     byte
+	size         byte
+	devDataIndex byte
+}
+
+func (ddfd devDataFieldDesc) String() string {
+	return fmt.Sprintf("field number: %d | size: %d | developer data index: %d", ddfd.fieldNum, ddfd.size, ddfd.devDataIndex)
+}
+
 func (d *decoder) parseFileIdMsg() error {
 	b, err := d.readByte()
 	if err != nil {
@@ -452,6 +463,26 @@ func (d *decoder) parseDefinitionMessage(recordHeader byte) (*defmsg, error) {
 		dm.fieldDefs[i] = fd
 	}
 
+	if recordHeader&devDataMask == devDataMask {
+		numDevFields, err := d.readByte()
+		if err != nil {
+			return nil, fmt.Errorf("error reading number of developer data fields: %w", err)
+		}
+
+		if err = d.readFull(d.tmp[0 : 3*uint16(numDevFields)]); err != nil {
+			return nil, fmt.Errorf("error reading developer data field description data: %w", err)
+		}
+
+		dm.devDataFieldDescs = make([]devDataFieldDesc, numDevFields)
+		for i, ddfd := range dm.devDataFieldDescs {
+			ddfd.fieldNum = d.tmp[i*3]
+			ddfd.size = d.tmp[(i*3)+1]
+			ddfd.devDataIndex = d.tmp[(i*3)+2]
+			dm.devDataFieldDescs[i] = ddfd
+		}
+
+	}
+
 	if d.debug {
 		d.opts.logger.Println("definition message parsed:", dm)
 	}
@@ -669,6 +700,13 @@ func (d *decoder) parseDataFields(dm *defmsg, knownMsg bool, msgv reflect.Value)
 		}
 	}
 
+	for i, ddfd := range dm.devDataFieldDescs {
+		err := d.readFull(d.tmp[0:int(ddfd.size)])
+		if err != nil {
+			return reflect.Value{}, fmt.Errorf("error parsing data developer message: %v (field %d [%v] for [%v])", err, i, ddfd, dm)
+		}
+	}
+
 	if knownMsg && !msgv.IsValid() {
 		panic("internal decoder error: parse data fields: known message, but not (reflect) valid")
 	}