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Side by Side Diff: xz/src/liblzma/rangecoder/price.h

Issue 2869016: Add an unpatched version of xz, XZ Utils, to /trunk/deps/third_party (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/deps/third_party/
Patch Set: Created 10 years, 6 months ago
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1 ///////////////////////////////////////////////////////////////////////////////
2 //
3 /// \file price.h
4 /// \brief Probability price calculation
5 //
6 // Author: Igor Pavlov
7 //
8 // This file has been put into the public domain.
9 // You can do whatever you want with this file.
10 //
11 ///////////////////////////////////////////////////////////////////////////////
12
13 #ifndef LZMA_PRICE_H
14 #define LZMA_PRICE_H
15
16
17 #define RC_MOVE_REDUCING_BITS 4
18 #define RC_BIT_PRICE_SHIFT_BITS 4
19 #define RC_PRICE_TABLE_SIZE (RC_BIT_MODEL_TOTAL >> RC_MOVE_REDUCING_BITS)
20
21 #define RC_INFINITY_PRICE (UINT32_C(1) << 30)
22
23
24 /// Lookup table for the inline functions defined in this file.
25 extern const uint8_t lzma_rc_prices[RC_PRICE_TABLE_SIZE];
26
27
28 static inline uint32_t
29 rc_bit_price(const probability prob, const uint32_t bit)
30 {
31 return lzma_rc_prices[(prob ^ ((UINT32_C(0) - bit)
32 & (RC_BIT_MODEL_TOTAL - 1))) >> RC_MOVE_REDUCING_BITS];
33 }
34
35
36 static inline uint32_t
37 rc_bit_0_price(const probability prob)
38 {
39 return lzma_rc_prices[prob >> RC_MOVE_REDUCING_BITS];
40 }
41
42
43 static inline uint32_t
44 rc_bit_1_price(const probability prob)
45 {
46 return lzma_rc_prices[(prob ^ (RC_BIT_MODEL_TOTAL - 1))
47 >> RC_MOVE_REDUCING_BITS];
48 }
49
50
51 static inline uint32_t
52 rc_bittree_price(const probability *const probs,
53 const uint32_t bit_levels, uint32_t symbol)
54 {
55 uint32_t price = 0;
56 symbol += UINT32_C(1) << bit_levels;
57
58 do {
59 const uint32_t bit = symbol & 1;
60 symbol >>= 1;
61 price += rc_bit_price(probs[symbol], bit);
62 } while (symbol != 1);
63
64 return price;
65 }
66
67
68 static inline uint32_t
69 rc_bittree_reverse_price(const probability *const probs,
70 uint32_t bit_levels, uint32_t symbol)
71 {
72 uint32_t price = 0;
73 uint32_t model_index = 1;
74
75 do {
76 const uint32_t bit = symbol & 1;
77 symbol >>= 1;
78 price += rc_bit_price(probs[model_index], bit);
79 model_index = (model_index << 1) + bit;
80 } while (--bit_levels != 0);
81
82 return price;
83 }
84
85
86 static inline uint32_t
87 rc_direct_price(const uint32_t bits)
88 {
89 return bits << RC_BIT_PRICE_SHIFT_BITS;
90 }
91
92 #endif
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