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  lzma_attr_visibility_hidden
      26  extern const uint8_t lzma_rc_prices[RC_PRICE_TABLE_SIZE];
      27  
      28  
      29  static inline uint32_t
      30  rc_bit_price(const probability prob, const uint32_t bit)
      31  {
      32  	return lzma_rc_prices[(prob ^ ((UINT32_C(0) - bit)
      33  			& (RC_BIT_MODEL_TOTAL - 1))) >> RC_MOVE_REDUCING_BITS];
      34  }
      35  
      36  
      37  static inline uint32_t
      38  rc_bit_0_price(const probability prob)
      39  {
      40  	return lzma_rc_prices[prob >> RC_MOVE_REDUCING_BITS];
      41  }
      42  
      43  
      44  static inline uint32_t
      45  rc_bit_1_price(const probability prob)
      46  {
      47  	return lzma_rc_prices[(prob ^ (RC_BIT_MODEL_TOTAL - 1))
      48  			>> RC_MOVE_REDUCING_BITS];
      49  }
      50  
      51  
      52  static inline uint32_t
      53  rc_bittree_price(const probability *const probs,
      54  		const uint32_t bit_levels, uint32_t symbol)
      55  {
      56  	uint32_t price = 0;
      57  	symbol += UINT32_C(1) << bit_levels;
      58  
      59  	do {
      60  		const uint32_t bit = symbol & 1;
      61  		symbol >>= 1;
      62  		price += rc_bit_price(probs[symbol], bit);
      63  	} while (symbol != 1);
      64  
      65  	return price;
      66  }
      67  
      68  
      69  static inline uint32_t
      70  rc_bittree_reverse_price(const probability *const probs,
      71  		uint32_t bit_levels, uint32_t symbol)
      72  {
      73  	uint32_t price = 0;
      74  	uint32_t model_index = 1;
      75  
      76  	do {
      77  		const uint32_t bit = symbol & 1;
      78  		symbol >>= 1;
      79  		price += rc_bit_price(probs[model_index], bit);
      80  		model_index = (model_index << 1) + bit;
      81  	} while (--bit_levels != 0);
      82  
      83  	return price;
      84  }
      85  
      86  
      87  static inline uint32_t
      88  rc_direct_price(const uint32_t bits)
      89  {
      90  	 return bits << RC_BIT_PRICE_SHIFT_BITS;
      91  }
      92  
      93  #endif