Method decode

zstd/seqdec_generic.go:16–158

decode sequences from the stream without the provided history.

(seqs []seqVals)

// decode sequences from the stream without the provided history.
func (s *sequenceDecs) decode(seqs []seqVals) error {
	br := s.br

	// Grab full sizes tables, to avoid bounds checks.
	llTable, mlTable, ofTable := s.litLengths.fse.dt[:maxTablesize], s.matchLengths.fse.dt[:maxTablesize], s.offsets.fse.dt[:maxTablesize]
	llState, mlState, ofState := s.litLengths.state.state, s.matchLengths.state.state, s.offsets.state.state
	s.seqSize = 0
	litRemain := len(s.literals)

	maxBlockSize := maxCompressedBlockSize
	if s.windowSize < maxBlockSize {
		maxBlockSize = s.windowSize
	}
	for i := range seqs {
		var ll, mo, ml int
		if br.cursor > 4+((maxOffsetBits+16+16)>>3) {
			// inlined function:
			// ll, mo, ml = s.nextFast(br, llState, mlState, ofState)

			// Final will not read from stream.
			var llB, mlB, moB uint8
			ll, llB = llState.final()
			ml, mlB = mlState.final()
			mo, moB = ofState.final()

			// extra bits are stored in reverse order.
			br.fillFast()
			mo += br.getBits(moB)
			if s.maxBits > 32 {
				br.fillFast()
			}
			ml += br.getBits(mlB)
			ll += br.getBits(llB)

			if moB > 1 {
				s.prevOffset[2] = s.prevOffset[1]
				s.prevOffset[1] = s.prevOffset[0]
				s.prevOffset[0] = mo
			} else {
				// mo = s.adjustOffset(mo, ll, moB)
				// Inlined for rather big speedup
				if ll == 0 {
					// There is an exception though, when current sequence's literals_length = 0.
					// In this case, repeated offsets are shifted by one, so an offset_value of 1 means Repeated_Offset2,
					// an offset_value of 2 means Repeated_Offset3, and an offset_value of 3 means Repeated_Offset1 - 1_byte.
					mo++
				}

				if mo == 0 {
					mo = s.prevOffset[0]
				} else {
					var temp int
					if mo == 3 {
						temp = s.prevOffset[0] - 1
					} else {
						temp = s.prevOffset[mo]
					}