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.
25extern const uint8_t lzma_rc_prices[RC_PRICE_TABLE_SIZE];
26
27
28static inline uint32_t
29rc_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
36static inline uint32_t
37rc_bit_0_price(const probability prob)
38{
39	return lzma_rc_prices[prob >> RC_MOVE_REDUCING_BITS];
40}
41
42
43static inline uint32_t
44rc_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
51static inline uint32_t
52rc_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
68static inline uint32_t
69rc_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
86static inline uint32_t
87rc_direct_price(const uint32_t bits)
88{
89	 return bits << RC_BIT_PRICE_SHIFT_BITS;
90}
91
92#endif
93