Method encodeLits

zstd/blockenc.go:337–430

encodeLits can be used if the block is only litLen.

(lits []byte, raw bool)

// encodeLits can be used if the block is only litLen.
func (b *blockEnc) encodeLits(lits []byte, raw bool) error {
	var bh blockHeader
	bh.setLast(b.last)
	bh.setSize(uint32(len(lits)))

	// Don't compress extremely small blocks
	if len(lits) < 8 || (len(lits) < 32 && b.dictLitEnc == nil) || raw {
		if debugEncoder {
			println("Adding RAW block, length", len(lits), "last:", b.last)
		}
		bh.setType(blockTypeRaw)
		b.output = bh.appendTo(b.output)
		b.output = append(b.output, lits...)
		return nil
	}

	var (
		out            []byte
		reUsed, single bool
		err            error
	)
	if b.dictLitEnc != nil {
		b.litEnc.TransferCTable(b.dictLitEnc)
		b.litEnc.Reuse = huff0.ReusePolicyAllow
		b.dictLitEnc = nil
	}
	if len(lits) >= 1024 {
		// Use 4 Streams.
		out, reUsed, err = huff0.Compress4X(lits, b.litEnc)
	} else if len(lits) > 16 {
		// Use 1 stream
		single = true
		out, reUsed, err = huff0.Compress1X(lits, b.litEnc)
	} else {
		err = huff0.ErrIncompressible
	}
	if err == nil && len(out)+5 > len(lits) {
		// If we are close, we may still be worse or equal to raw.
		var lh literalsHeader
		lh.setSizes(len(out), len(lits), single)
		if len(out)+lh.size() >= len(lits) {
			err = huff0.ErrIncompressible
		}
	}
	switch err {
	case huff0.ErrIncompressible:
		if debugEncoder {
			println("Adding RAW block, length", len(lits), "last:", b.last)
		}
		bh.setType(blockTypeRaw)
		b.output = bh.appendTo(b.output)
		b.output = append(b.output, lits...)
		return nil
	case huff0.ErrUseRLE:
		if debugEncoder {
			println("Adding RLE block, length", len(lits))
		}
		bh.setType(blockTypeRLE)