vendor/github.com/klauspost/compress/zstd/decoder.go - voltha-go - Gitiles

 // Copyright 2019+ Klaus Post. All rights reserved.
 // License information can be found in the LICENSE file.
 // Based on work by Yann Collet, released under BSD License.

 package zstd

 import (
 	"errors"
 	"io"
 	"sync"
 )

 // Decoder provides decoding of zstandard streams.
 // The decoder has been designed to operate without allocations after a warmup.
 // This means that you should store the decoder for best performance.
 // To re-use a stream decoder, use the Reset(r io.Reader) error to switch to another stream.
 // A decoder can safely be re-used even if the previous stream failed.
 // To release the resources, you must call the Close() function on a decoder.
 type Decoder struct {
 	o decoderOptions

 	// Unreferenced decoders, ready for use.
 	decoders chan *blockDec

 	// Streams ready to be decoded.
 	stream chan decodeStream

 	// Current read position used for Reader functionality.
 	current decoderState

 	// Custom dictionaries.
 	// Always uses copies.
 	dicts map[uint32]dict

 	// streamWg is the waitgroup for all streams
 	streamWg sync.WaitGroup
 }

 // decoderState is used for maintaining state when the decoder
 // is used for streaming.
 type decoderState struct {
 	// current block being written to stream.
 	decodeOutput

 	// output in order to be written to stream.
 	output chan decodeOutput

 	// cancel remaining output.
 	cancel chan struct{}

 	flushed bool
 }

 var (
 	// Check the interfaces we want to support.
 	_ = io.WriterTo(&Decoder{})
 	_ = io.Reader(&Decoder{})
 )

 // 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 multiple concurrent stateless decodes. It is even possible to
 // use stateless decodes while a stream is being decoded.
 //
 // The Reset function can be used to initiate a new stream, which is 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.output = make(chan decodeOutput, d.o.concurrent)
 	d.current.flushed = true

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

 	// Transfer option dicts.
 	d.dicts = make(map[uint32]dict, len(d.o.dicts))
 	for _, dc := range d.o.dicts {
 		d.dicts[dc.id] = dc
 	}
 	d.o.dicts = nil

 	// 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 written and any error that occurred.
 // When the stream is done, io.EOF will be returned.
 func (d *Decoder) Read(p []byte) (int, error) {
 	if d.stream == nil {
 		return 0, ErrDecoderNilInput
 	}
 	var n int
 	for {
 		if len(d.current.b) > 0 {
 			filled := copy(p, d.current.b)
 			p = p[filled:]
 			d.current.b = d.current.b[filled:]
 			n += filled
 		}
 		if len(p) == 0 {
 			break
 		}
 		if len(d.current.b) == 0 {
 			// We have an error and no more data
 			if d.current.err != nil {
 				break
 			}
 			if !d.nextBlock(n == 0) {
 				return n, nil
 			}
 		}
 	}
 	if len(d.current.b) > 0 {
 		if debug {
 			println("returning", n, "still bytes left:", len(d.current.b))
 		}
 		// Only return error at end of block
 		return n, nil
 	}
 	if d.current.err != nil {
 		d.drainOutput()
 	}
 	if debug {
 		println("returning", n, d.current.err, len(d.decoders))
 	}
 	return n, d.current.err
 }

 // Reset will reset the decoder the supplied stream after the current has finished processing.
 // Note that this functionality cannot be used after Close has been called.
 // Reset can be called with a nil reader to release references to the previous reader.
 // After being called with a nil reader, no other operations than Reset or DecodeAll or Close
 // should be used.
 func (d *Decoder) Reset(r io.Reader) error {
 	if d.current.err == ErrDecoderClosed {
 		return d.current.err
 	}

 	d.drainOutput()

 	if r == nil {
 		d.current.err = ErrDecoderNilInput
 		d.current.flushed = true
 		return nil
 	}

 	if d.stream == nil {
 		d.stream = make(chan decodeStream, 1)
 		d.streamWg.Add(1)
 		go d.startStreamDecoder(d.stream)
 	}

 	// If bytes buffer and < 1MB, do sync decoding anyway.
 	if bb, ok := r.(byter); ok && bb.Len() < 1<<20 {
 		bb2 := bb
 		if debug {
 			println("*bytes.Buffer detected, doing sync decode, len:", bb.Len())
 		}
 		b := bb2.Bytes()
 		var dst []byte
 		if cap(d.current.b) > 0 {
 			dst = d.current.b
 		}

 		dst, err := d.DecodeAll(b, dst[:0])
 		if err == nil {
 			err = io.EOF
 		}
 		d.current.b = dst
 		d.current.err = err
 		d.current.flushed = true
 		if debug {
 			println("sync decode to", len(dst), "bytes, err:", err)
 		}
 		return nil
 	}

 	// Remove current block.
 	d.current.decodeOutput = decodeOutput{}
 	d.current.err = nil
 	d.current.cancel = make(chan struct{})
 	d.current.flushed = false
 	d.current.d = nil

 	d.stream <- decodeStream{
 		r:      r,
 		output: d.current.output,
 		cancel: d.current.cancel,
 	}
 	return nil
 }

 // drainOutput will drain the output until errEndOfStream is sent.
 func (d *Decoder) drainOutput() {
 	if d.current.cancel != nil {
 		println("cancelling current")
 		close(d.current.cancel)
 		d.current.cancel = nil
 	}
 	if d.current.d != nil {
 		if debug {
 			printf("re-adding current decoder %p, decoders: %d", d.current.d, len(d.decoders))
 		}
 		d.decoders <- d.current.d
 		d.current.d = nil
 		d.current.b = nil
 	}
 	if d.current.output == nil || d.current.flushed {
 		println("current already flushed")
 		return
 	}
 	for v := range d.current.output {
 		if v.d != nil {
 			if debug {
 				printf("re-adding decoder %p", v.d)
 			}
 			d.decoders <- v.d
 		}
 		if v.err == errEndOfStream {
 			println("current flushed")
 			d.current.flushed = true
 			return
 		}
 	}
 }

 // WriteTo writes data to w until there's no more data to write or when an error occurs.
 // The return value n is the number of bytes written.
 // Any error encountered during the write is also returned.
 func (d *Decoder) WriteTo(w io.Writer) (int64, error) {
 	if d.stream == nil {
 		return 0, ErrDecoderNilInput
 	}
 	var n int64
 	for {
 		if len(d.current.b) > 0 {
 			n2, err2 := w.Write(d.current.b)
 			n += int64(n2)
 			if err2 != nil && d.current.err == nil {
 				d.current.err = err2
 				break
 			}
 		}
 		if d.current.err != nil {
 			break
 		}
 		d.nextBlock(true)
 	}
 	err := d.current.err
 	if err != nil {
 		d.drainOutput()
 	}
 	if err == io.EOF {
 		err = nil
 	}
 	return n, err
 }

 // DecodeAll allows stateless decoding of a blob of bytes.
 // Output will be appended to dst, so if the destination size is known
 // you can pre-allocate the destination slice to avoid allocations.
 // DecodeAll can be used concurrently.
 // The Decoder concurrency limits will be respected.
 func (d *Decoder) DecodeAll(input, dst []byte) ([]byte, error) {
 	if d.current.err == ErrDecoderClosed {
 		return dst, ErrDecoderClosed
 	}

 	// Grab a block decoder and frame decoder.
 	block := <-d.decoders
 	frame := block.localFrame
 	defer func() {
 		if debug {
 			printf("re-adding decoder: %p", block)
 		}
 		frame.rawInput = nil
 		frame.bBuf = nil
 		d.decoders <- block
 	}()
 	frame.bBuf = input

 	for {
 		frame.history.reset()
 		err := frame.reset(&frame.bBuf)
 		if err == io.EOF {
 			if debug {
 				println("frame reset return EOF")
 			}
 			return dst, nil
 		}
 		if frame.DictionaryID != nil {
 			dict, ok := d.dicts[*frame.DictionaryID]
 			if !ok {
 				return nil, ErrUnknownDictionary
 			}
 			frame.history.setDict(&dict)
 		}
 		if err != nil {
 			return dst, err
 		}
 		if frame.FrameContentSize > d.o.maxDecodedSize-uint64(len(dst)) {
 			return dst, ErrDecoderSizeExceeded
 		}
 		if frame.FrameContentSize > 0 && frame.FrameContentSize < 1<<30 {
 			// Never preallocate moe than 1 GB up front.
 			if cap(dst)-len(dst) < int(frame.FrameContentSize) {
 				dst2 := make([]byte, len(dst), len(dst)+int(frame.FrameContentSize))
 				copy(dst2, dst)
 				dst = dst2
 			}
 		}
 		if cap(dst) == 0 {
 			// Allocate len(input) * 2 by default if nothing is provided
 			// and we didn't get frame content size.
 			size := len(input) * 2
 			// Cap to 1 MB.
 			if size > 1<<20 {
 				size = 1 << 20
 			}
 			if uint64(size) > d.o.maxDecodedSize {
 				size = int(d.o.maxDecodedSize)
 			}
 			dst = make([]byte, 0, size)
 		}

 		dst, err = frame.runDecoder(dst, block)
 		if err != nil {
 			return dst, err
 		}
 		if len(frame.bBuf) == 0 {
 			if debug {
 				println("frame dbuf empty")
 			}
 			break
 		}
 	}
 	return dst, nil
 }

 // nextBlock returns the next block.
 // If an error occurs d.err will be set.
 // Optionally the function can block for new output.
 // If non-blocking mode is used the returned boolean will be false
 // if no data was available without blocking.
 func (d *Decoder) nextBlock(blocking bool) (ok bool) {
 	if d.current.d != nil {
 		if debug {
 			printf("re-adding current decoder %p", d.current.d)
 		}
 		d.decoders <- d.current.d
 		d.current.d = nil
 	}
 	if d.current.err != nil {
 		// Keep error state.
 		return blocking
 	}

 	if blocking {
 		d.current.decodeOutput = <-d.current.output
 	} else {
 		select {
 		case d.current.decodeOutput = <-d.current.output:
 		default:
 			return false
 		}
 	}
 	if debug {
 		println("got", len(d.current.b), "bytes, error:", d.current.err)
 	}
 	return true
 }

 // Close will release all resources.
 // It is NOT possible to reuse the decoder after this.
 func (d *Decoder) Close() {
 	if d.current.err == ErrDecoderClosed {
 		return
 	}
 	d.drainOutput()
 	if d.stream != nil {
 		close(d.stream)
 		d.streamWg.Wait()
 		d.stream = nil
 	}
 	if d.decoders != nil {
 		close(d.decoders)
 		for dec := range d.decoders {
 			dec.Close()
 		}
 		d.decoders = nil
 	}
 	if d.current.d != nil {
 		d.current.d.Close()
 		d.current.d = nil
 	}
 	d.current.err = ErrDecoderClosed
 }

 // IOReadCloser returns the decoder as an io.ReadCloser for convenience.
 // Any changes to the decoder will be reflected, so the returned ReadCloser
 // can be reused along with the decoder.
 // io.WriterTo is also supported by the returned ReadCloser.
 func (d *Decoder) IOReadCloser() io.ReadCloser {
 	return closeWrapper{d: d}
 }

 // closeWrapper wraps a function call as a closer.
 type closeWrapper struct {
 	d *Decoder
 }

 // WriteTo forwards WriteTo calls to the decoder.
 func (c closeWrapper) WriteTo(w io.Writer) (n int64, err error) {
 	return c.d.WriteTo(w)
 }

 // Read forwards read calls to the decoder.
 func (c closeWrapper) Read(p []byte) (n int, err error) {
 	return c.d.Read(p)
 }

 // Close closes the decoder.
 func (c closeWrapper) Close() error {
 	c.d.Close()
 	return nil
 }

 type decodeOutput struct {
 	d   *blockDec
 	b   []byte
 	err error
 }

 type decodeStream struct {
 	r io.Reader

 	// Blocks ready to be written to output.
 	output chan decodeOutput

 	// cancel reading from the input
 	cancel chan struct{}
 }

 // errEndOfStream indicates that everything from the stream was read.
 var errEndOfStream = errors.New("end-of-stream")

 // Create Decoder:
 // Spawn n block decoders. These accept tasks to decode a block.
 // Create goroutine that handles stream processing, this will send history to decoders as they are available.
 // Decoders update the history as they decode.
 // When a block is returned:
 // 		a) history is sent to the next decoder,
 // 		b) content written to CRC.
 // 		c) return data to WRITER.
 // 		d) wait for next block to return data.
 // Once WRITTEN, the decoders reused by the writer frame decoder for re-use.
 func (d *Decoder) startStreamDecoder(inStream chan decodeStream) {
 	defer d.streamWg.Done()
 	frame := newFrameDec(d.o)
 	for stream := range inStream {
 		if debug {
 			println("got new stream")
 		}
 		br := readerWrapper{r: stream.r}
 	decodeStream:
 		for {
 			frame.history.reset()
 			err := frame.reset(&br)
 			if debug && err != nil {
 				println("Frame decoder returned", err)
 			}
 			if err == nil && frame.DictionaryID != nil {
 				dict, ok := d.dicts[*frame.DictionaryID]
 				if !ok {
 					err = ErrUnknownDictionary
 				} else {
 					frame.history.setDict(&dict)
 				}
 			}
 			if err != nil {
 				stream.output <- decodeOutput{
 					err: err,
 				}
 				break
 			}
 			if debug {
 				println("starting frame decoder")
 			}

 			// This goroutine will forward history between frames.
 			frame.frameDone.Add(1)
 			frame.initAsync()

 			go frame.startDecoder(stream.output)
 		decodeFrame:
 			// Go through all blocks of the frame.
 			for {
 				dec := <-d.decoders
 				select {
 				case <-stream.cancel:
 					if !frame.sendErr(dec, io.EOF) {
 						// To not let the decoder dangle, send it back.
 						stream.output <- decodeOutput{d: dec}
 					}
 					break decodeStream
 				default:
 				}
 				err := frame.next(dec)
 				switch err {
 				case io.EOF:
 					// End of current frame, no error
 					println("EOF on next block")
 					break decodeFrame
 				case nil:
 					continue
 				default:
 					println("block decoder returned", err)
 					break decodeStream
 				}
 			}
 			// All blocks have started decoding, check if there are more frames.
 			println("waiting for done")
 			frame.frameDone.Wait()
 			println("done waiting...")
 		}
 		frame.frameDone.Wait()
 		println("Sending EOS")
 		stream.output <- decodeOutput{err: errEndOfStream}
 	}
 }
	// Copyright 2019+ Klaus Post. All rights reserved.
	// License information can be found in the LICENSE file.
	// Based on work by Yann Collet, released under BSD License.

	package zstd

	import (
	"errors"
	"io"
	"sync"
	)

	// Decoder provides decoding of zstandard streams.
	// The decoder has been designed to operate without allocations after a warmup.
	// This means that you should store the decoder for best performance.
	// To re-use a stream decoder, use the Reset(r io.Reader) error to switch to another stream.
	// A decoder can safely be re-used even if the previous stream failed.
	// To release the resources, you must call the Close() function on a decoder.
	type Decoder struct {
	o decoderOptions

	// Unreferenced decoders, ready for use.
	decoders chan *blockDec

	// Streams ready to be decoded.
	stream chan decodeStream

	// Current read position used for Reader functionality.
	current decoderState

	// Custom dictionaries.
	// Always uses copies.
	dicts map[uint32]dict

	// streamWg is the waitgroup for all streams
	streamWg sync.WaitGroup
	}

	// decoderState is used for maintaining state when the decoder
	// is used for streaming.
	type decoderState struct {
	// current block being written to stream.
	decodeOutput

	// output in order to be written to stream.
	output chan decodeOutput

	// cancel remaining output.
	cancel chan struct{}

	flushed bool
	}

	var (
	// Check the interfaces we want to support.
	_ = io.WriterTo(&Decoder{})
	_ = io.Reader(&Decoder{})
	)

	// 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 multiple concurrent stateless decodes. It is even possible to
	// use stateless decodes while a stream is being decoded.
	//
	// The Reset function can be used to initiate a new stream, which is 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.output = make(chan decodeOutput, d.o.concurrent)
	d.current.flushed = true

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

	// Transfer option dicts.
	d.dicts = make(map[uint32]dict, len(d.o.dicts))
	for _, dc := range d.o.dicts {
	d.dicts[dc.id] = dc
	}
	d.o.dicts = nil

	// 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 written and any error that occurred.
	// When the stream is done, io.EOF will be returned.
	func (d *Decoder) Read(p []byte) (int, error) {
	if d.stream == nil {
	return 0, ErrDecoderNilInput
	}
	var n int
	for {
	if len(d.current.b) > 0 {
	filled := copy(p, d.current.b)
	p = p[filled:]
	d.current.b = d.current.b[filled:]
	n += filled
	}
	if len(p) == 0 {
	break
	}
	if len(d.current.b) == 0 {
	// We have an error and no more data
	if d.current.err != nil {
	break
	}
	if !d.nextBlock(n == 0) {
	return n, nil
	}
	}
	}
	if len(d.current.b) > 0 {
	if debug {
	println("returning", n, "still bytes left:", len(d.current.b))
	}
	// Only return error at end of block
	return n, nil
	}
	if d.current.err != nil {
	d.drainOutput()
	}
	if debug {
	println("returning", n, d.current.err, len(d.decoders))
	}
	return n, d.current.err
	}

	// Reset will reset the decoder the supplied stream after the current has finished processing.
	// Note that this functionality cannot be used after Close has been called.
	// Reset can be called with a nil reader to release references to the previous reader.
	// After being called with a nil reader, no other operations than Reset or DecodeAll or Close
	// should be used.
	func (d *Decoder) Reset(r io.Reader) error {
	if d.current.err == ErrDecoderClosed {
	return d.current.err
	}

	d.drainOutput()

	if r == nil {
	d.current.err = ErrDecoderNilInput
	d.current.flushed = true
	return nil
	}

	if d.stream == nil {
	d.stream = make(chan decodeStream, 1)
	d.streamWg.Add(1)
	go d.startStreamDecoder(d.stream)
	}

	// If bytes buffer and < 1MB, do sync decoding anyway.
	if bb, ok := r.(byter); ok && bb.Len() < 1<<20 {
	bb2 := bb
	if debug {
	println("*bytes.Buffer detected, doing sync decode, len:", bb.Len())
	}
	b := bb2.Bytes()
	var dst []byte
	if cap(d.current.b) > 0 {
	dst = d.current.b
	}

	dst, err := d.DecodeAll(b, dst[:0])
	if err == nil {
	err = io.EOF
	}
	d.current.b = dst
	d.current.err = err
	d.current.flushed = true
	if debug {
	println("sync decode to", len(dst), "bytes, err:", err)
	}
	return nil
	}

	// Remove current block.
	d.current.decodeOutput = decodeOutput{}
	d.current.err = nil
	d.current.cancel = make(chan struct{})
	d.current.flushed = false
	d.current.d = nil

	d.stream <- decodeStream{
	r: r,
	output: d.current.output,
	cancel: d.current.cancel,
	}
	return nil
	}

	// drainOutput will drain the output until errEndOfStream is sent.
	func (d *Decoder) drainOutput() {
	if d.current.cancel != nil {
	println("cancelling current")
	close(d.current.cancel)
	d.current.cancel = nil
	}
	if d.current.d != nil {
	if debug {
	printf("re-adding current decoder %p, decoders: %d", d.current.d, len(d.decoders))
	}
	d.decoders <- d.current.d
	d.current.d = nil
	d.current.b = nil
	}
	if d.current.output == nil \|\| d.current.flushed {
	println("current already flushed")
	return
	}
	for v := range d.current.output {
	if v.d != nil {
	if debug {
	printf("re-adding decoder %p", v.d)
	}
	d.decoders <- v.d
	}
	if v.err == errEndOfStream {
	println("current flushed")
	d.current.flushed = true
	return
	}
	}
	}

	// WriteTo writes data to w until there's no more data to write or when an error occurs.
	// The return value n is the number of bytes written.
	// Any error encountered during the write is also returned.
	func (d *Decoder) WriteTo(w io.Writer) (int64, error) {
	if d.stream == nil {
	return 0, ErrDecoderNilInput
	}
	var n int64
	for {
	if len(d.current.b) > 0 {
	n2, err2 := w.Write(d.current.b)
	n += int64(n2)
	if err2 != nil && d.current.err == nil {
	d.current.err = err2
	break
	}
	}
	if d.current.err != nil {
	break
	}
	d.nextBlock(true)
	}
	err := d.current.err
	if err != nil {
	d.drainOutput()
	}
	if err == io.EOF {
	err = nil
	}
	return n, err
	}

	// DecodeAll allows stateless decoding of a blob of bytes.
	// Output will be appended to dst, so if the destination size is known
	// you can pre-allocate the destination slice to avoid allocations.
	// DecodeAll can be used concurrently.
	// The Decoder concurrency limits will be respected.
	func (d *Decoder) DecodeAll(input, dst []byte) ([]byte, error) {
	if d.current.err == ErrDecoderClosed {
	return dst, ErrDecoderClosed
	}

	// Grab a block decoder and frame decoder.
	block := <-d.decoders
	frame := block.localFrame
	defer func() {
	if debug {
	printf("re-adding decoder: %p", block)
	}
	frame.rawInput = nil
	frame.bBuf = nil
	d.decoders <- block
	}()
	frame.bBuf = input

	for {
	frame.history.reset()
	err := frame.reset(&frame.bBuf)
	if err == io.EOF {
	if debug {
	println("frame reset return EOF")
	}
	return dst, nil
	}
	if frame.DictionaryID != nil {
	dict, ok := d.dicts[*frame.DictionaryID]
	if !ok {
	return nil, ErrUnknownDictionary
	}
	frame.history.setDict(&dict)
	}
	if err != nil {
	return dst, err
	}
	if frame.FrameContentSize > d.o.maxDecodedSize-uint64(len(dst)) {
	return dst, ErrDecoderSizeExceeded
	}
	if frame.FrameContentSize > 0 && frame.FrameContentSize < 1<<30 {
	// Never preallocate moe than 1 GB up front.
	if cap(dst)-len(dst) < int(frame.FrameContentSize) {
	dst2 := make([]byte, len(dst), len(dst)+int(frame.FrameContentSize))
	copy(dst2, dst)
	dst = dst2
	}
	}
	if cap(dst) == 0 {
	// Allocate len(input) * 2 by default if nothing is provided
	// and we didn't get frame content size.
	size := len(input) * 2
	// Cap to 1 MB.
	if size > 1<<20 {
	size = 1 << 20
	}
	if uint64(size) > d.o.maxDecodedSize {
	size = int(d.o.maxDecodedSize)
	}
	dst = make([]byte, 0, size)
	}

	dst, err = frame.runDecoder(dst, block)
	if err != nil {
	return dst, err
	}
	if len(frame.bBuf) == 0 {
	if debug {
	println("frame dbuf empty")
	}
	break
	}
	}
	return dst, nil
	}

	// nextBlock returns the next block.
	// If an error occurs d.err will be set.
	// Optionally the function can block for new output.
	// If non-blocking mode is used the returned boolean will be false
	// if no data was available without blocking.
	func (d *Decoder) nextBlock(blocking bool) (ok bool) {
	if d.current.d != nil {
	if debug {
	printf("re-adding current decoder %p", d.current.d)
	}
	d.decoders <- d.current.d
	d.current.d = nil
	}
	if d.current.err != nil {
	// Keep error state.
	return blocking
	}

	if blocking {
	d.current.decodeOutput = <-d.current.output
	} else {
	select {
	case d.current.decodeOutput = <-d.current.output:
	default:
	return false
	}
	}
	if debug {
	println("got", len(d.current.b), "bytes, error:", d.current.err)
	}
	return true
	}

	// Close will release all resources.
	// It is NOT possible to reuse the decoder after this.
	func (d *Decoder) Close() {
	if d.current.err == ErrDecoderClosed {
	return
	}
	d.drainOutput()
	if d.stream != nil {
	close(d.stream)
	d.streamWg.Wait()
	d.stream = nil
	}
	if d.decoders != nil {
	close(d.decoders)
	for dec := range d.decoders {
	dec.Close()
	}
	d.decoders = nil
	}
	if d.current.d != nil {
	d.current.d.Close()
	d.current.d = nil
	}
	d.current.err = ErrDecoderClosed
	}

	// IOReadCloser returns the decoder as an io.ReadCloser for convenience.
	// Any changes to the decoder will be reflected, so the returned ReadCloser
	// can be reused along with the decoder.
	// io.WriterTo is also supported by the returned ReadCloser.
	func (d *Decoder) IOReadCloser() io.ReadCloser {
	return closeWrapper{d: d}
	}

	// closeWrapper wraps a function call as a closer.
	type closeWrapper struct {
	d *Decoder
	}

	// WriteTo forwards WriteTo calls to the decoder.
	func (c closeWrapper) WriteTo(w io.Writer) (n int64, err error) {
	return c.d.WriteTo(w)
	}

	// Read forwards read calls to the decoder.
	func (c closeWrapper) Read(p []byte) (n int, err error) {
	return c.d.Read(p)
	}

	// Close closes the decoder.
	func (c closeWrapper) Close() error {
	c.d.Close()
	return nil
	}

	type decodeOutput struct {
	d *blockDec
	b []byte
	err error
	}

	type decodeStream struct {
	r io.Reader

	// Blocks ready to be written to output.
	output chan decodeOutput

	// cancel reading from the input
	cancel chan struct{}
	}

	// errEndOfStream indicates that everything from the stream was read.
	var errEndOfStream = errors.New("end-of-stream")

	// Create Decoder:
	// Spawn n block decoders. These accept tasks to decode a block.
	// Create goroutine that handles stream processing, this will send history to decoders as they are available.
	// Decoders update the history as they decode.
	// When a block is returned:
	// a) history is sent to the next decoder,
	// b) content written to CRC.
	// c) return data to WRITER.
	// d) wait for next block to return data.
	// Once WRITTEN, the decoders reused by the writer frame decoder for re-use.
	func (d *Decoder) startStreamDecoder(inStream chan decodeStream) {
	defer d.streamWg.Done()
	frame := newFrameDec(d.o)
	for stream := range inStream {
	if debug {
	println("got new stream")
	}
	br := readerWrapper{r: stream.r}
	decodeStream:
	for {
	frame.history.reset()
	err := frame.reset(&br)
	if debug && err != nil {
	println("Frame decoder returned", err)
	}
	if err == nil && frame.DictionaryID != nil {
	dict, ok := d.dicts[*frame.DictionaryID]
	if !ok {
	err = ErrUnknownDictionary
	} else {
	frame.history.setDict(&dict)
	}
	}
	if err != nil {
	stream.output <- decodeOutput{
	err: err,
	}
	break
	}
	if debug {
	println("starting frame decoder")
	}

	// This goroutine will forward history between frames.
	frame.frameDone.Add(1)
	frame.initAsync()

	go frame.startDecoder(stream.output)
	decodeFrame:
	// Go through all blocks of the frame.
	for {
	dec := <-d.decoders
	select {
	case <-stream.cancel:
	if !frame.sendErr(dec, io.EOF) {
	// To not let the decoder dangle, send it back.
	stream.output <- decodeOutput{d: dec}
	}
	break decodeStream
	default:
	}
	err := frame.next(dec)
	switch err {
	case io.EOF:
	// End of current frame, no error
	println("EOF on next block")
	break decodeFrame
	case nil:
	continue
	default:
	println("block decoder returned", err)
	break decodeStream
	}
	}
	// All blocks have started decoding, check if there are more frames.
	println("waiting for done")
	frame.frameDone.Wait()
	println("done waiting...")
	}
	frame.frameDone.Wait()
	println("Sending EOS")
	stream.output <- decodeOutput{err: errEndOfStream}
	}
	}