| /////////////////////////////////////////////////////////////////////////////// |
| // |
| /// \file range_common.h |
| /// \brief Common things for range encoder and decoder |
| // |
| // Copyright (C) 1999-2006 Igor Pavlov |
| // Copyright (C) 2006 Lasse Collin |
| // |
| // 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_RANGE_COMMON_H |
| #define LZMA_RANGE_COMMON_H |
| |
| #include "common.h" |
| |
| |
| /////////////// |
| // Constants // |
| /////////////// |
| |
| #define SHIFT_BITS 8 |
| #define TOP_BITS 24 |
| #define TOP_VALUE (UINT32_C(1) << TOP_BITS) |
| #define BIT_MODEL_TOTAL_BITS 11 |
| #define BIT_MODEL_TOTAL (UINT32_C(1) << BIT_MODEL_TOTAL_BITS) |
| #define MOVE_BITS 5 |
| |
| #define MOVE_REDUCING_BITS 2 |
| #define BIT_PRICE_SHIFT_BITS 6 |
| |
| |
| //////////// |
| // Macros // |
| //////////// |
| |
| // Resets the probability so that both 0 and 1 have probability of 50 % |
| #define bit_reset(prob) \ |
| prob = BIT_MODEL_TOTAL >> 1 |
| |
| // This does the same for a complete bit tree. |
| // (A tree represented as an array.) |
| #define bittree_reset(probs, bit_levels) \ |
| for (uint32_t bt_i = 0; bt_i < (1 << (bit_levels)); ++bt_i) \ |
| bit_reset((probs)[bt_i]) |
| |
| |
| ////////////////////// |
| // Type definitions // |
| ////////////////////// |
| |
| // Bit coder speed optimization |
| // uint16_t is enough for probability, but usually uint32_t is faster and it |
| // doesn't waste too much memory. If uint64_t is fastest on 64-bit CPU, you |
| // probably want to use that instead of uint32_t. With uint64_t you will |
| // waste RAM _at maximum_ of 4.5 MiB (same for both encoding and decoding). |
| typedef uint32_t probability; |
| |
| #endif |
