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///////////////////////////////////////////////////////////////////////////////
//
/// \file price.h
/// \brief Probability price calculation
//
// Copyright (C) 1999-2008 Igor Pavlov
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
///////////////////////////////////////////////////////////////////////////////
#ifndef LZMA_PRICE_H
#define LZMA_PRICE_H
#define RC_MOVE_REDUCING_BITS 4
#define RC_BIT_PRICE_SHIFT_BITS 4
#define RC_PRICE_TABLE_SIZE (RC_BIT_MODEL_TOTAL >> RC_MOVE_REDUCING_BITS)
#define RC_INFINITY_PRICE (UINT32_C(1) << 30)
#if !defined(LZMA_RANGE_ENCODER_H) || defined(HAVE_SMALL)
/// Probability prices used by *_get_price() macros. This is initialized
/// by lzma_rc_init() and is not modified later.
extern uint32_t lzma_rc_prices[RC_PRICE_TABLE_SIZE];
/// Initializes lzma_rc_prices[]. This needs to be called only once.
extern void lzma_rc_init(void);
#else
// Not building a size optimized version, so we use a precomputed
// constant table.
extern const uint32_t lzma_rc_prices[RC_PRICE_TABLE_SIZE];
#endif
static inline uint32_t
rc_bit_price(const probability prob, const uint32_t bit)
{
return lzma_rc_prices[(prob ^ ((UINT32_C(0) - bit)
& (RC_BIT_MODEL_TOTAL - 1))) >> RC_MOVE_REDUCING_BITS];
}
static inline uint32_t
rc_bit_0_price(const probability prob)
{
return lzma_rc_prices[prob >> RC_MOVE_REDUCING_BITS];
}
static inline uint32_t
rc_bit_1_price(const probability prob)
{
return lzma_rc_prices[(prob ^ (RC_BIT_MODEL_TOTAL - 1))
>> RC_MOVE_REDUCING_BITS];
}
static inline uint32_t
rc_bittree_price(const probability *const probs,
const uint32_t bit_levels, uint32_t symbol)
{
uint32_t price = 0;
symbol += UINT32_C(1) << bit_levels;
do {
const uint32_t bit = symbol & 1;
symbol >>= 1;
price += rc_bit_price(probs[symbol], bit);
} while (symbol != 1);
return price;
}
static inline uint32_t
rc_bittree_reverse_price(const probability *const probs,
uint32_t bit_levels, uint32_t symbol)
{
uint32_t price = 0;
uint32_t model_index = 1;
do {
const uint32_t bit = symbol & 1;
symbol >>= 1;
price += rc_bit_price(probs[model_index], bit);
model_index = (model_index << 1) + bit;
} while (--bit_levels != 0);
return price;
}
static inline uint32_t
rc_direct_price(const uint32_t bits)
{
return bits << RC_BIT_PRICE_SHIFT_BITS;
}
#endif
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