Correctly handle 8086 extended record

Fixes arduino/arduino-cli#1009

Author: facchinm

gohex.go

@@ -9,10 +9,11 @@ import (
 
 // Constants definitions of IntelHex record types
 const (
-	_DATA_RECORD    byte = 0 // Record with data bytes
-	_EOF_RECORD     byte = 1 // Record with end of file indicator
-	_ADDRESS_RECORD byte = 4 // Record with extended linear address
-	_START_RECORD   byte = 5 // Record with start linear address
+	_DATA_RECORD     byte = 0 // Record with data bytes
+	_EOF_RECORD      byte = 1 // Record with end of file indicator
+	_EXTENDED_RECORD byte = 2 // Record with end of file indicator
+	_ADDRESS_RECORD  byte = 4 // Record with extended linear address
+	_START_RECORD    byte = 5 // Record with start linear address
 )
 
 // Structure with binary data segment fields
@@ -33,6 +34,7 @@ type Memory struct {
 	dataSegments     []*DataSegment // Slice with pointers to DataSegments
 	startAddress     uint32         // Start linear address
 	extendedAddress  uint32         // Extended linear address
+	offset           uint32         // Extended offset inside same linear address
 	eofFlag          bool           // End of file record exist flag
 	startFlag        bool           // Start address record exist flag
 	lineNum          uint           // Parser input line number
@@ -211,7 +213,7 @@ func (m *Memory) parseIntelHexRecord(bytes []byte) error {
 	switch record_type := bytes[3]; record_type {
 	case _DATA_RECORD:
 		a, data := getDataLine(bytes)
-		adr := uint32(a) + m.extendedAddress
+		adr := uint32(a) + m.extendedAddress + m.offset
 		err = m.AddBinary(adr, data)
 		if err != nil {
 			return err
@@ -222,6 +224,12 @@ func (m *Memory) parseIntelHexRecord(bytes []byte) error {
 			return newParseError(_RECORD_ERROR, err.Error(), m.lineNum)
 		}
 		m.eofFlag = true
+	case _EXTENDED_RECORD:
+		//Extended 8086 Segment Record
+		m.offset, err = getExtendedSegmentAddress(bytes)
+		if err != nil {
+			return newParseError(_RECORD_ERROR, err.Error(), m.lineNum)
+		}
 	case _ADDRESS_RECORD:
 		m.extendedAddress, err = getExtendedAddress(bytes)
 		if err != nil {

helper.go

@@ -56,6 +56,17 @@ func getExtendedAddress(bytes []byte) (adr uint32, err error) {
 	return adr, nil
 }
 
+func getExtendedSegmentAddress(bytes []byte) (adr uint32, err error) {
+	if bytes[0] != 2 {
+		return 0, errors.New("incorrect data length field in extended linear address line")
+	}
+	if binary.BigEndian.Uint16(bytes[1:3]) != 0 {
+		return 0, errors.New("incorrect address field in extended linear address line")
+	}
+	adr = uint32(binary.BigEndian.Uint16(bytes[4:6])) << 4
+	return adr, nil
+}
+
 func getDataLine(bytes []byte) (adr uint16, data []byte) {
 	size := bytes[0]
 	adr = binary.BigEndian.Uint16(bytes[1:3])