Method Encode

zstd/enc_dfast.go:678–1030

Encode will encode the content, with a dictionary if initialized for it.

(blk *blockEnc, src []byte)

// Encode will encode the content, with a dictionary if initialized for it.
func (e *doubleFastEncoderDict) Encode(blk *blockEnc, src []byte) {
	const (
		// Input margin is the number of bytes we read (8)
		// and the maximum we will read ahead (2)
		inputMargin            = 8 + 2
		minNonLiteralBlockSize = 16
	)

	// Protect against e.cur wraparound.
	for e.cur >= e.bufferReset-int32(len(e.hist)) {
		if len(e.hist) == 0 {
			for i := range e.table[:] {
				e.table[i] = tableEntry{}
			}
			for i := range e.longTable[:] {
				e.longTable[i] = tableEntry{}
			}
			e.markAllShardsDirty()
			e.cur = e.maxMatchOff
			break
		}
		// Shift down everything in the table that isn't already too far away.
		minOff := e.cur + int32(len(e.hist)) - e.maxMatchOff
		for i := range e.table[:] {
			v := e.table[i].offset
			if v < minOff {
				v = 0
			} else {
				v = v - e.cur + e.maxMatchOff
			}
			e.table[i].offset = v
		}
		for i := range e.longTable[:] {
			v := e.longTable[i].offset
			if v < minOff {
				v = 0
			} else {
				v = v - e.cur + e.maxMatchOff
			}
			e.longTable[i].offset = v
		}
		e.markAllShardsDirty()
		e.cur = e.maxMatchOff
		break
	}

	s := e.addBlock(src)
	blk.size = len(src)
	if len(src) < minNonLiteralBlockSize {
		blk.extraLits = len(src)
		blk.literals = blk.literals[:len(src)]
		copy(blk.literals, src)
		return
	}

	// Override src
	src = e.hist
	sLimit := int32(len(src)) - inputMargin