92 lines
2 KiB
C
92 lines
2 KiB
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file price.h
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/// \brief Probability price calculation
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//
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// Author: Igor Pavlov
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//
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// This file has been put into the public domain.
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// You can do whatever you want with this file.
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//
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///////////////////////////////////////////////////////////////////////////////
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#ifndef LZMA_PRICE_H
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#define LZMA_PRICE_H
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#define RC_MOVE_REDUCING_BITS 4
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#define RC_BIT_PRICE_SHIFT_BITS 4
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#define RC_PRICE_TABLE_SIZE (RC_BIT_MODEL_TOTAL >> RC_MOVE_REDUCING_BITS)
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#define RC_INFINITY_PRICE (UINT32_C(1) << 30)
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/// Lookup table for the inline functions defined in this file.
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extern const uint8_t lzma_rc_prices[RC_PRICE_TABLE_SIZE];
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static inline uint32_t
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rc_bit_price(const probability prob, const uint32_t bit)
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{
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return lzma_rc_prices[(prob ^ ((UINT32_C(0) - bit)
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& (RC_BIT_MODEL_TOTAL - 1))) >> RC_MOVE_REDUCING_BITS];
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}
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static inline uint32_t
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rc_bit_0_price(const probability prob)
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{
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return lzma_rc_prices[prob >> RC_MOVE_REDUCING_BITS];
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}
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static inline uint32_t
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rc_bit_1_price(const probability prob)
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{
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return lzma_rc_prices[(prob ^ (RC_BIT_MODEL_TOTAL - 1))
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>> RC_MOVE_REDUCING_BITS];
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}
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static inline uint32_t
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rc_bittree_price(const probability *const probs,
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const uint32_t bit_levels, uint32_t symbol)
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{
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uint32_t price = 0;
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symbol += UINT32_C(1) << bit_levels;
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do {
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const uint32_t bit = symbol & 1;
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symbol >>= 1;
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price += rc_bit_price(probs[symbol], bit);
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} while (symbol != 1);
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return price;
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}
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static inline uint32_t
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rc_bittree_reverse_price(const probability *const probs,
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uint32_t bit_levels, uint32_t symbol)
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{
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uint32_t price = 0;
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uint32_t model_index = 1;
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do {
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const uint32_t bit = symbol & 1;
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symbol >>= 1;
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price += rc_bit_price(probs[model_index], bit);
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model_index = (model_index << 1) + bit;
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} while (--bit_levels != 0);
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return price;
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}
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static inline uint32_t
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rc_direct_price(const uint32_t bits)
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{
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return bits << RC_BIT_PRICE_SHIFT_BITS;
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}
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#endif
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