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69 lines
2 KiB
C
69 lines
2 KiB
C
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///////////////////////////////////////////////////////////////////////////////
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//
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/// \file range_common.h
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/// \brief Common things for range encoder and decoder
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//
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// Copyright (C) 1999-2006 Igor Pavlov
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// Copyright (C) 2006 Lasse Collin
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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///////////////////////////////////////////////////////////////////////////////
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#ifndef LZMA_RANGE_COMMON_H
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#define LZMA_RANGE_COMMON_H
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#include "common.h"
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///////////////
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// Constants //
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///////////////
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#define SHIFT_BITS 8
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#define TOP_BITS 24
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#define TOP_VALUE (UINT32_C(1) << TOP_BITS)
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#define BIT_MODEL_TOTAL_BITS 11
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#define BIT_MODEL_TOTAL (UINT32_C(1) << BIT_MODEL_TOTAL_BITS)
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#define MOVE_BITS 5
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#define MOVE_REDUCING_BITS 2
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#define BIT_PRICE_SHIFT_BITS 6
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////////////
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// Macros //
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////////////
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// Resets the probability so that both 0 and 1 have probability of 50 %
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#define bit_reset(prob) \
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prob = BIT_MODEL_TOTAL >> 1
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// This does the same for a complete bit tree.
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// (A tree represented as an array.)
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#define bittree_reset(probs, bit_levels) \
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for (uint32_t bt_i = 0; bt_i < (1 << (bit_levels)); ++bt_i) \
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bit_reset((probs)[bt_i])
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//////////////////////
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// Type definitions //
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//////////////////////
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// Bit coder speed optimization
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// uint16_t is enough for probability, but usually uint32_t is faster and it
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// doesn't waste too much memory. If uint64_t is fastest on 64-bit CPU, you
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// probably want to use that instead of uint32_t. With uint64_t you will
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// waste RAM _at maximum_ of 4.5 MiB (same for both encoding and decoding).
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typedef uint32_t probability;
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#endif
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