Function NewReader

zstd/decoder.go:84–118

NewReader creates a new decoder. A nil Reader can be provided in which case Reset can be used to start a decode. A Decoder can be used in two modes: 1) As a stream, or 2) For stateless decoding using DecodeAll. Only a single stream can be decoded concurrently, but the same decoder can run multipl

(r io.Reader, opts ...DOption)

// The Reset function can be used to initiate a new stream, which will considerably
// reduce the allocations normally caused by NewReader.
func NewReader(r io.Reader, opts ...DOption) (*Decoder, error) {
	initPredefined()
	var d Decoder
	d.o.setDefault()
	for _, o := range opts {
		err := o(&d.o)
		if err != nil {
			return nil, err
		}
	}
	d.current.crc = xxhash.New()
	d.current.flushed = true

	if r == nil {
		d.current.err = ErrDecoderNilInput
	}

	// Initialize dict map if needed.
	if d.o.dicts == nil {
		d.o.dicts = make(map[uint32]*dict)
	}

	// Create decoders
	d.decoders = make(chan *blockDec, d.o.concurrent)
	for i := 0; i < d.o.concurrent; i++ {
		dec := newBlockDec(d.o.lowMem)
		dec.localFrame = newFrameDec(d.o)
		d.decoders <- dec
	}

	if r == nil {
		return &d, nil
	}
	return &d, d.Reset(r)
}

// Read bytes from the decompressed stream into p.
// Returns the number of bytes read and any error that occurred.