datarun

Documentation

Index

• Variables
• type Decoder
  • func NewDecoder(r io.Reader) *Decoder
  • func (d *Decoder) Read() (MappingPair, error)
• type Header
  • func (h Header) DataBytes() int
  • func (h Header) LengthBytes() int
  • func (h Header) OffsetBytes() int
  • func (h Header) Valid() bool
• type MappingPair
  • func Decode(data []byte) (pairs []MappingPair, err error)

Variables

var (
	// ErrTruncatedData is returned when attempting to read data from a buffer
	// or reader with insufficient data.
	ErrTruncatedData = errors.New("insufficient or truncated data")

	// ErrInvalidHeader is returned when attempting to decode a data run
	// header that has an invalid size.
	ErrInvalidHeader = errors.New("invalid data run header")
)

Types

type Decoder

type Decoder struct {
	// contains filtered or unexported fields
}

Decoder decodes data in an underlying reader as a serires of data run mapping pairs.

func NewDecoder

func NewDecoder(r io.Reader) *Decoder

NewDecoder returns a new decoder that reads from r until it encounters an end-of-stream header.

func (*Decoder) Read

func (d *Decoder) Read() (MappingPair, error)

Read returns the next mapping pair from d. It returns io.EOF when there is no more data to return.

type Header

type Header byte

Header describes the allocation of bytes in a mapping pair.

const EOF Header = 0

EOF is a sentinel header value indicating the end of a series of mapping pairs.

It is not to be confused with io.EOF, which is a sentinel error value.

func (Header) DataBytes

func (h Header) DataBytes() int

DataBytes returns the number of data bytes in a mapping pair, excluding the header itself.

func (Header) LengthBytes

func (h Header) LengthBytes() int

LengthBytes returns the number of length bytes in a mapping pair.

func (Header) OffsetBytes

func (h Header) OffsetBytes() int

OffsetBytes returns the number of offset bytes in a mapping pair.

func (Header) Valid

func (h Header) Valid() bool

Valid returns false if the header contains invalid data.

type MappingPair

type MappingPair struct {
	Length uint64 // In clusters
	Offset int64  // Relative to previous data run, may be negative
}

MappingPair stores the length and offset of a logical cluster number so that it can be mapped to a virtual cluster number.

func Decode

func Decode(data []byte) (pairs []MappingPair, err error)

Decode decodes data until it encounters EOF in the data stream or encounters an error. It returns a slice of all the mapping pairs it decoded. If the data is decoded successfully err will be nil.