Method nextBlock

zstd/decoder.go:417–484

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.

(blocking bool)

// 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.err != nil {
		// Keep error state.
		return false
	}
	d.current.b = d.current.b[:0]

	// SYNC:
	if d.syncStream.enabled {
		if !blocking {
			return false
		}
		ok = d.nextBlockSync()
		if !ok {
			d.stashDecoder()
		}
		return ok
	}

	//ASYNC:
	d.stashDecoder()
	if blocking {
		d.current.decodeOutput, ok = <-d.current.output
	} else {
		select {
		case d.current.decodeOutput, ok = <-d.current.output:
		default:
			return false
		}
	}
	if !ok {
		// This should not happen, so signal error state...
		d.current.err = io.ErrUnexpectedEOF
		return false
	}
	next := d.current.decodeOutput
	if next.d != nil && next.d.async.newHist != nil {
		d.current.crc.Reset()
	}
	if debugDecoder {
		var tmp [4]byte
		binary.LittleEndian.PutUint32(tmp[:], uint32(xxhash.Sum64(next.b)))
		println("got", len(d.current.b), "bytes, error:", d.current.err, "data crc:", tmp)
	}

	if d.o.ignoreChecksum {
		return true
	}

	if len(next.b) > 0 {
		d.current.crc.Write(next.b)
	}
	if next.err == nil && next.d != nil && next.d.hasCRC {
		got := uint32(d.current.crc.Sum64())
		if got != next.d.checkCRC {
			if debugDecoder {
				printf("CRC Check Failed: %08x (got) != %08x (on stream)\n", got, next.d.checkCRC)
			}