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diff --git a/src/liblzma/rangecoder/range_common.h b/src/liblzma/rangecoder/range_common.h
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+++ b/src/liblzma/rangecoder/range_common.h
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+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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