1 | /* |
2 | Copyright (C) 2005-2006 NSRT Team ( http://nsrt.edgeemu.com ) |
3 | Copyright (C) 2002 Andrea Mazzoleni ( http://advancemame.sf.net ) |
4 | Copyright (C) 2001-4 Igor Pavlov ( http://www.7-zip.org ) |
5 | |
6 | This library is free software; you can redistribute it and/or |
7 | modify it under the terms of the GNU Lesser General Public |
8 | License version 2.1 as published by the Free Software Foundation. |
9 | |
10 | This library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with this library; if not, write to the Free Software |
17 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
18 | */ |
19 | |
20 | #ifndef __LENCODER_H |
21 | #define __LENCODER_H |
22 | |
23 | #include "btreecd.h" |
24 | |
25 | namespace NLength { |
26 | |
27 | const UINT32 kNumPosStatesBitsMax = 4; |
28 | const int kNumPosStatesMax = (1 << kNumPosStatesBitsMax); |
29 | |
30 | |
31 | const int kNumPosStatesBitsEncodingMax = 4; |
32 | const int kNumPosStatesEncodingMax = (1 << kNumPosStatesBitsEncodingMax); |
33 | |
34 | |
35 | const int kNumMoveBits = 5; |
36 | |
37 | const int kNumLenBits = 3; |
38 | const int kNumLowSymbols = 1 << kNumLenBits; |
39 | const int kNumMidBits = 3; |
40 | const int kNumMidSymbols = 1 << kNumMidBits; |
41 | |
42 | const int kNumHighBits = 8; |
43 | |
44 | const int kNumSymbolsTotal = kNumLowSymbols + kNumMidSymbols + (1 << kNumHighBits); |
45 | |
46 | const int kNumSpecSymbols = kNumLowSymbols + kNumMidSymbols; |
47 | |
48 | class CDecoder |
49 | { |
50 | CMyBitDecoder<kNumMoveBits> m_Choice; |
51 | CBitTreeDecoder<kNumMoveBits, kNumLenBits> m_LowCoder[kNumPosStatesMax]; |
52 | CMyBitDecoder<kNumMoveBits> m_Choice2; |
53 | CBitTreeDecoder<kNumMoveBits, kNumMidBits> m_MidCoder[kNumPosStatesMax]; |
54 | CBitTreeDecoder<kNumMoveBits, kNumHighBits> m_HighCoder; |
55 | UINT32 m_NumPosStates; |
56 | public: |
57 | void Create(UINT32 aNumPosStates) |
58 | { m_NumPosStates = aNumPosStates; } |
59 | void Init() |
60 | { |
61 | m_Choice.Init(); |
62 | for (UINT32 aPosState = 0; aPosState < m_NumPosStates; aPosState++) |
63 | { |
64 | m_LowCoder[aPosState].Init(); |
65 | m_MidCoder[aPosState].Init(); |
66 | } |
67 | m_Choice2.Init(); |
68 | m_HighCoder.Init(); |
69 | } |
70 | UINT32 Decode(CMyRangeDecoder *aRangeDecoder, UINT32 aPosState) |
71 | { |
72 | if(m_Choice.Decode(aRangeDecoder) == 0) |
73 | return m_LowCoder[aPosState].Decode(aRangeDecoder); |
74 | else |
75 | { |
76 | UINT32 aSymbol = kNumLowSymbols; |
77 | if(m_Choice2.Decode(aRangeDecoder) == 0) |
78 | aSymbol += m_MidCoder[aPosState].Decode(aRangeDecoder); |
79 | else |
80 | { |
81 | aSymbol += kNumMidSymbols; |
82 | aSymbol += m_HighCoder.Decode(aRangeDecoder); |
83 | } |
84 | return aSymbol; |
85 | } |
86 | } |
87 | |
88 | }; |
89 | |
90 | } |
91 | |
92 | |
93 | #endif |
94 | |