83 lines
1.6 KiB
Go
83 lines
1.6 KiB
Go
package go_inthex
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import (
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"encoding/binary"
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"encoding/hex"
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"errors"
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"fmt"
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"io"
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"math"
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"strings"
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)
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type RecordCode uint8
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const ExtendedLinearAddressMask uint32 = 0xFFFF0000
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const RecordExtendedSegmentAddressMask uint32 = 0x000FFFF0
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const (
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RecordData = RecordCode(iota)
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RecordEOF
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RecordExtendedSegmentAddress
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RecordStartSegmentAddress
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RecordExtendedLinearAddress
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RecordStartLinearAddress
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)
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type Record struct {
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Code RecordCode
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Address uint16
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Data []byte
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}
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func (r Record) String() string {
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if len(r.Data) > math.MaxUint8 {
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panic("data too long")
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}
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buf := make([]byte, 1+1+2+len(r.Data)+1)
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buf[0] = uint8(len(r.Data))
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binary.BigEndian.PutUint16(buf[1:], r.Address)
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buf[3] = uint8(r.Code)
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copy(buf[4:], r.Data)
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buf[len(buf)-1] = Checksum(buf[:len(buf)-1])
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return ":" + strings.ToUpper(hex.EncodeToString(buf)) + "\r\n"
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}
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func RecordFromString(data string) (Record, error) {
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if data[0] != ':' {
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return Record{}, fmt.Errorf("expected :, got %s", data[:1])
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}
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if len(data) < 1+(1+2+1)*2 {
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return Record{}, io.ErrUnexpectedEOF
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}
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b, err := hex.DecodeString(strings.Trim(data[1:], "\r\n"))
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if err != nil {
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return Record{}, err
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}
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if len(b) < 1 {
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return Record{}, io.ErrUnexpectedEOF
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}
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byteCount := b[0]
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if len(b) != 1+1+2+int(byteCount)+1 {
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return Record{}, errors.New("data mismatch")
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}
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var r Record
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r.Address = binary.BigEndian.Uint16(b[1:])
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r.Code = RecordCode(b[3])
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r.Data = b[4 : 4+int(byteCount)]
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checkSum := b[4+int(byteCount)]
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calculatedCksum := Checksum(b[:len(b)-1])
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if calculatedCksum != checkSum {
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return Record{}, errors.New("wrong checksum")
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}
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return r, nil
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}
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