Method executeSimple

zstd/seqdec_asm.go:241–289

executeSimple handles cases when dictionary is not used.

(seqs []seqVals, hist []byte)

// executeSimple handles cases when dictionary is not used.
func (s *sequenceDecs) executeSimple(seqs []seqVals, hist []byte) error {
	// Ensure we have enough output size...
	if len(s.out)+s.seqSize+compressedBlockOverAlloc > cap(s.out) {
		addBytes := s.seqSize + len(s.out) + compressedBlockOverAlloc
		s.out = append(s.out, make([]byte, addBytes)...)
		s.out = s.out[:len(s.out)-addBytes]
	}

	if debugDecoder {
		printf("Execute %d seqs with literals: %d into %d bytes\n", len(seqs), len(s.literals), s.seqSize)
	}

	var t = len(s.out)
	out := s.out[:t+s.seqSize]

	ctx := executeAsmContext{
		seqs:        seqs,
		seqIndex:    0,
		out:         out,
		history:     hist,
		outPosition: t,
		litPosition: 0,
		literals:    s.literals,
		windowSize:  s.windowSize,
	}
	// useSafe avoids overwriting the output buffer when the literals slice has
	// not been allocated with the required over-allocation slack.
	useSafe := cap(s.literals) < len(s.literals)+compressedBlockOverAlloc

	ok := executeSimpleAsm(&ctx, useSafe)
	if !ok {
		return fmt.Errorf("match offset (%d) bigger than current history (%d)",
			seqs[ctx.seqIndex].mo, ctx.outPosition+len(hist))
	}
	s.literals = s.literals[ctx.litPosition:]
	t = ctx.outPosition

	// Add final literals
	copy(out[t:], s.literals)
	if debugDecoder {
		t += len(s.literals)
		if t != len(out) {
			panic(fmt.Errorf("length mismatch, want %d, got %d, ss: %d", len(out), t, s.seqSize))
		}
	}
	s.out = out

	return nil
}