diff options
Diffstat (limited to 'vendor/github.com/ulikunitz/xz/lzma/state.go')
-rw-r--r-- | vendor/github.com/ulikunitz/xz/lzma/state.go | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/vendor/github.com/ulikunitz/xz/lzma/state.go b/vendor/github.com/ulikunitz/xz/lzma/state.go new file mode 100644 index 000000000..502351052 --- /dev/null +++ b/vendor/github.com/ulikunitz/xz/lzma/state.go @@ -0,0 +1,151 @@ +// Copyright 2014-2017 Ulrich Kunitz. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package lzma + +// states defines the overall state count +const states = 12 + +// State maintains the full state of the operation encoding or decoding +// process. +type state struct { + rep [4]uint32 + isMatch [states << maxPosBits]prob + isRepG0Long [states << maxPosBits]prob + isRep [states]prob + isRepG0 [states]prob + isRepG1 [states]prob + isRepG2 [states]prob + litCodec literalCodec + lenCodec lengthCodec + repLenCodec lengthCodec + distCodec distCodec + state uint32 + posBitMask uint32 + Properties Properties +} + +// initProbSlice initializes a slice of probabilities. +func initProbSlice(p []prob) { + for i := range p { + p[i] = probInit + } +} + +// Reset sets all state information to the original values. +func (s *state) Reset() { + p := s.Properties + *s = state{ + Properties: p, + // dict: s.dict, + posBitMask: (uint32(1) << uint(p.PB)) - 1, + } + initProbSlice(s.isMatch[:]) + initProbSlice(s.isRep[:]) + initProbSlice(s.isRepG0[:]) + initProbSlice(s.isRepG1[:]) + initProbSlice(s.isRepG2[:]) + initProbSlice(s.isRepG0Long[:]) + s.litCodec.init(p.LC, p.LP) + s.lenCodec.init() + s.repLenCodec.init() + s.distCodec.init() +} + +// initState initializes the state. +func initState(s *state, p Properties) { + *s = state{Properties: p} + s.Reset() +} + +// newState creates a new state from the give Properties. +func newState(p Properties) *state { + s := &state{Properties: p} + s.Reset() + return s +} + +// deepcopy initializes s as a deep copy of the source. +func (s *state) deepcopy(src *state) { + if s == src { + return + } + s.rep = src.rep + s.isMatch = src.isMatch + s.isRepG0Long = src.isRepG0Long + s.isRep = src.isRep + s.isRepG0 = src.isRepG0 + s.isRepG1 = src.isRepG1 + s.isRepG2 = src.isRepG2 + s.litCodec.deepcopy(&src.litCodec) + s.lenCodec.deepcopy(&src.lenCodec) + s.repLenCodec.deepcopy(&src.repLenCodec) + s.distCodec.deepcopy(&src.distCodec) + s.state = src.state + s.posBitMask = src.posBitMask + s.Properties = src.Properties +} + +// cloneState creates a new clone of the give state. +func cloneState(src *state) *state { + s := new(state) + s.deepcopy(src) + return s +} + +// updateStateLiteral updates the state for a literal. +func (s *state) updateStateLiteral() { + switch { + case s.state < 4: + s.state = 0 + return + case s.state < 10: + s.state -= 3 + return + } + s.state -= 6 +} + +// updateStateMatch updates the state for a match. +func (s *state) updateStateMatch() { + if s.state < 7 { + s.state = 7 + } else { + s.state = 10 + } +} + +// updateStateRep updates the state for a repetition. +func (s *state) updateStateRep() { + if s.state < 7 { + s.state = 8 + } else { + s.state = 11 + } +} + +// updateStateShortRep updates the state for a short repetition. +func (s *state) updateStateShortRep() { + if s.state < 7 { + s.state = 9 + } else { + s.state = 11 + } +} + +// states computes the states of the operation codec. +func (s *state) states(dictHead int64) (state1, state2, posState uint32) { + state1 = s.state + posState = uint32(dictHead) & s.posBitMask + state2 = (s.state << maxPosBits) | posState + return +} + +// litState computes the literal state. +func (s *state) litState(prev byte, dictHead int64) uint32 { + lp, lc := uint(s.Properties.LP), uint(s.Properties.LC) + litState := ((uint32(dictHead) & ((1 << lp) - 1)) << lc) | + (uint32(prev) >> (8 - lc)) + return litState +} |