Method Encode

zstd/enc_better.go:579–1089

Encode improves compression...

(blk *blockEnc, src []byte)

// Encode improves compression...
func (e *betterFastEncoderDict) 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] = prevEntry{}
			}
			e.cur = e.maxMatchOff
			e.allDirty = true
			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
			v2 := e.longTable[i].prev
			if v < minOff {
				v = 0
				v2 = 0
			} else {
				v = v - e.cur + e.maxMatchOff
				if v2 < minOff {
					v2 = 0
				} else {
					v2 = v2 - e.cur + e.maxMatchOff
				}
			}
			e.longTable[i] = prevEntry{
				offset: v,
				prev:   v2,
			}
		}
		e.allDirty = true
		e.cur = e.maxMatchOff
		break
	}

	s := e.addBlock(src)
	blk.size = len(src)