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Add support for little-endian byte order representation. #75

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27 changes: 27 additions & 0 deletions marshal.go
Original file line number Diff line number Diff line change
Expand Up @@ -36,3 +36,30 @@ func (uuid *UUID) UnmarshalBinary(data []byte) error {
copy(uuid[:], data)
return nil
}

// MarshalBinaryLittleEndian implements encoding.BinaryMarshaler.
func (uuid UUID) MarshalBinaryLittleEndian() ([]byte, error) {
var uuidLittleEndian UUID = UUID {
// convert first 3 fields from big-endian to little-endian
uuid[3], uuid[2], uuid[1], uuid[0],
uuid[5], uuid[4],
uuid[7], uuid[6],
}
// all the rest fields keep byte order
copy(uuidLittleEndian[8:], uuid[8:])
return uuidLittleEndian[:], nil
}

// UnmarshalBinaryLittleEndian implements encoding.BinaryUnmarshaler.
func (uuid *UUID) UnmarshalBinaryLittleEndian(data []byte) error {
if len(data) != 16 {
return fmt.Errorf("invalid UUID (got %d bytes)", len(data))
}
// convert first 3 fields from little-endian to big-endian
uuid[0] = data[3]; uuid[1] = data[2]; uuid[2] = data[1]; uuid[3] = data[0]
uuid[4] = data[5]; uuid[5] = data[4]
uuid[6] = data[7]; uuid[7] = data[6]
// all the rest fields keep byte order
copy(uuid[8:], data[8:])
return nil
}
8 changes: 8 additions & 0 deletions uuid.go
Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,14 @@ func FromBytes(b []byte) (uuid UUID, err error) {
return uuid, err
}

// FromBytesLittleEndian creates a new UUID from a byte slice with little-endian
// byte encoding for the first three fields. Returns an error if the slice
// does not have a length of 16. The bytes are copied from the slice.
func FromBytesLittleEndian(b []byte) (uuid UUID, err error) {
err = uuid.UnmarshalBinaryLittleEndian(b)
return uuid, err
}

// Must returns uuid if err is nil and panics otherwise.
func Must(uuid UUID, err error) UUID {
if err != nil {
Expand Down