Imported to git.

1 files changed, 189 insertions, 0 deletions

diff --git a/src/liblzma/rangecoder/range_decoder.h b/src/liblzma/rangecoder/range_decoder.h
new file mode 100644
index 00000000..0583faaf
--- /dev/null
+++ b/src/liblzma/rangecoder/range_decoder.h
@@ -0,0 +1,189 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       range_decoder.h
+/// \brief      Range Decoder
+//
+//  Copyright (C) 1999-2006 Igor Pavlov
+//  Copyright (C) 2007 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_DECODER_H
+#define LZMA_RANGE_DECODER_H
+
+#include "range_common.h"
+
+
+typedef struct {
+	uint32_t range;
+	uint32_t code;
+} lzma_range_decoder;
+
+
+/// Makes local copies of range decoder variables.
+#define rc_to_local(rc) \
+	uint32_t rc_range = (rc).range; \
+	uint32_t rc_code = (rc).code; \
+	uint32_t rc_bound
+
+/// Stores the local copes back to the range decoder structure.
+#define rc_from_local(rc) \
+do {\
+	(rc).range = rc_range; \
+	(rc).code = rc_code; \
+} while (0)
+
+/// Resets the range decoder structure.
+#define rc_reset(rc) \
+do { \
+	(rc).range = UINT32_MAX; \
+	(rc).code = 0; \
+} while (0)
+
+
+// All of the macros in this file expect the following variables being defined:
+//  - uint32_t rc_range;
+//  - uint32_t rc_code;
+//  - uint32_t rc_bound;   // Temporary variable
+//  - uint8_t  *in;
+//  - size_t   in_pos_local; // Local alias for *in_pos
+
+
+//////////////////
+// Buffer "I/O" //
+//////////////////
+
+// Read the next byte of compressed data from buffer_in, if needed.
+#define rc_normalize() \
+do { \
+	if (rc_range < TOP_VALUE) { \
+		rc_range <<= SHIFT_BITS; \
+		rc_code = (rc_code << SHIFT_BITS) | in[in_pos_local++]; \
+	} \
+} while (0)
+
+
+//////////////////
+// Bit decoding //
+//////////////////
+
+// Range decoder's DecodeBit() is splitted into three macros:
+//    if_bit_0(prob) {
+//        update_bit_0(prob)
+//        ...
+//    } else {
+//        update_bit_1(prob)
+//        ...
+//    }
+
+#define if_bit_0(prob) \
+	rc_normalize(); \
+	rc_bound = (rc_range >> BIT_MODEL_TOTAL_BITS) * (prob); \
+	if (rc_code < rc_bound)
+
+
+#define update_bit_0(prob) \
+do { \
+	rc_range = rc_bound; \
+	prob += (BIT_MODEL_TOTAL - (prob)) >> MOVE_BITS; \
+} while (0)
+
+
+#define update_bit_1(prob) \
+do { \
+	rc_range -= rc_bound; \
+	rc_code -= rc_bound; \
+	prob -= (prob) >> MOVE_BITS; \
+} while (0)
+
+
+// Dummy versions don't update prob.
+#define update_bit_0_dummy() \
+	rc_range = rc_bound
+
+
+#define update_bit_1_dummy() \
+do { \
+	rc_range -= rc_bound; \
+	rc_code -= rc_bound; \
+} while (0)
+
+
+///////////////////////
+// Bit tree decoding //
+///////////////////////
+
+#define bittree_decode(target, probs, bit_levels) \
+do { \
+	uint32_t model_index = 1; \
+	for (uint32_t bit_index = (bit_levels); bit_index != 0; --bit_index) { \
+		if_bit_0((probs)[model_index]) { \
+			update_bit_0((probs)[model_index]); \
+			model_index <<= 1; \
+		} else { \
+			update_bit_1((probs)[model_index]); \
+			model_index = (model_index << 1) | 1; \
+		} \
+	} \
+	target += model_index - (1 << bit_levels); \
+} while (0)
+
+
+#define bittree_reverse_decode(target, probs, bit_levels) \
+do { \
+	uint32_t model_index = 1; \
+	for (uint32_t bit_index = 0; bit_index < bit_levels; ++bit_index) { \
+		if_bit_0((probs)[model_index]) { \
+			update_bit_0((probs)[model_index]); \
+			model_index <<= 1; \
+		} else { \
+			update_bit_1((probs)[model_index]); \
+			model_index = (model_index << 1) | 1; \
+			target += 1 << bit_index; \
+		} \
+	} \
+} while (0)
+
+
+// Dummy versions don't update prob.
+#define bittree_decode_dummy(target, probs, bit_levels) \
+do { \
+	uint32_t model_index = 1; \
+	for (uint32_t bit_index = (bit_levels); bit_index != 0; --bit_index) { \
+		if_bit_0((probs)[model_index]) { \
+			update_bit_0_dummy(); \
+			model_index <<= 1; \
+		} else { \
+			update_bit_1_dummy(); \
+			model_index = (model_index << 1) | 1; \
+		} \
+	} \
+	target += model_index - (1 << bit_levels); \
+} while (0)
+
+
+#define bittree_reverse_decode_dummy(probs, bit_levels) \
+do { \
+	uint32_t model_index = 1; \
+	for (uint32_t bit_index = 0; bit_index < bit_levels; ++bit_index) { \
+		if_bit_0((probs)[model_index]) { \
+			update_bit_0_dummy(); \
+			model_index <<= 1; \
+		} else { \
+			update_bit_1_dummy(); \
+			model_index = (model_index << 1) | 1; \
+		} \
+	} \
+} while (0)
+
+#endif