Add Fast LZMA2 codec

C/fast-lzma2/range_enc.h

@@ -0,0 +1,157 @@
+/*
+* Bitwise range encoder by Igor Pavlov
+* Modified by Conor McCarthy
+*
+* Public domain
+*/
+
+#ifndef RANGE_ENCODER_H
+#define RANGE_ENCODER_H
+
+#include "mem.h"
+#include "compiler.h"
+
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
+#ifdef LZMA_ENC_PROB32
+typedef U32 Probability;
+#else
+typedef U16 Probability;
+#endif
+
+#define kNumTopBits 24U
+#define kTopValue (1UL << kNumTopBits)
+#define kNumBitModelTotalBits 11U
+#define kBitModelTotal (1 << kNumBitModelTotalBits)
+#define kNumMoveBits 5U
+#define kProbInitValue (kBitModelTotal >> 1U)
+#define kNumMoveReducingBits 4U
+#define kNumBitPriceShiftBits 4U
+
+extern const unsigned price_table[kBitModelTotal >> kNumMoveReducingBits];
+
+typedef struct
+{
+	BYTE *out_buffer;
+	size_t out_index;
+	size_t chunk_size;
+	U64 cache_size;
+	U64 low;
+	U32 range;
+	BYTE cache;
+} RangeEncoder;
+
+void RangeEncReset(RangeEncoder* const rc);
+
+void SetOutputBuffer(RangeEncoder* const rc, BYTE *const out_buffer, size_t chunk_size);
+
+void RangeEncReset(RangeEncoder* const rc);
+
+void ShiftLow(RangeEncoder* const rc);
+
+void EncodeBitTree(RangeEncoder* const rc, Probability *const probs, unsigned bit_count, unsigned symbol);
+
+void EncodeBitTreeReverse(RangeEncoder* const rc, Probability *const probs, unsigned bit_count, unsigned symbol);
+
+void EncodeDirect(RangeEncoder* const rc, unsigned value, unsigned bit_count);
+
+HINT_INLINE
+void EncodeBit0(RangeEncoder* const rc, Probability *const rprob)
+{
+	unsigned prob = *rprob;
+    rc->range = (rc->range >> kNumBitModelTotalBits) * prob;
+	prob += (kBitModelTotal - prob) >> kNumMoveBits;
+	*rprob = (Probability)prob;
+	if (rc->range < kTopValue) {
+        rc->range <<= 8;
+		ShiftLow(rc);
+	}
+}
+
+HINT_INLINE
+void EncodeBit1(RangeEncoder* const rc, Probability *const rprob)
+{
+	unsigned prob = *rprob;
+	U32 new_bound = (rc->range >> kNumBitModelTotalBits) * prob;
+    rc->low += new_bound;
+    rc->range -= new_bound;
+	prob -= prob >> kNumMoveBits;
+	*rprob = (Probability)prob;
+	if (rc->range < kTopValue) {
+        rc->range <<= 8;
+		ShiftLow(rc);
+	}
+}
+
+HINT_INLINE
+void EncodeBit(RangeEncoder* const rc, Probability *const rprob, unsigned const bit)
+{
+	unsigned prob = *rprob;
+	if (bit != 0) {
+		U32 new_bound = (rc->range >> kNumBitModelTotalBits) * prob;
+        rc->low += new_bound;
+        rc->range -= new_bound;
+		prob -= prob >> kNumMoveBits;
+	}
+	else {
+        rc->range = (rc->range >> kNumBitModelTotalBits) * prob;
+		prob += (kBitModelTotal - prob) >> kNumMoveBits;
+	}
+	*rprob = (Probability)prob;
+	if (rc->range < kTopValue) {
+        rc->range <<= 8;
+		ShiftLow(rc);
+	}
+}
+
+#define GET_PRICE(rc, prob, symbol) \
+  price_table[((prob) ^ ((-(int)(symbol)) & (kBitModelTotal - 1))) >> kNumMoveReducingBits];
+
+#define GET_PRICE_0(rc, prob) price_table[(prob) >> kNumMoveReducingBits]
+
+#define GET_PRICE_1(rc, prob) price_table[((prob) ^ (kBitModelTotal - 1)) >> kNumMoveReducingBits]
+
+HINT_INLINE
+unsigned GetTreePrice(RangeEncoder* const rc, const Probability* const prob_table, unsigned const bit_count, size_t symbol)
+{
+	unsigned price = 0;
+	symbol |= ((size_t)1 << bit_count);
+	while (symbol != 1) {
+		size_t next_symbol = symbol >> 1;
+		unsigned prob = prob_table[next_symbol];
+		unsigned bit = (unsigned)symbol & 1;
+		price += GET_PRICE(rc, prob, bit);
+		symbol = next_symbol;
+	}
+	return price;
+}
+
+HINT_INLINE
+unsigned GetReverseTreePrice(RangeEncoder* const rc, const Probability* const prob_table, unsigned const bit_count, size_t symbol)
+{
+	unsigned price = 0;
+	size_t m = 1;
+	for (unsigned i = bit_count; i != 0; --i) {
+		unsigned prob = prob_table[m];
+		unsigned bit = symbol & 1;
+		symbol >>= 1;
+		price += GET_PRICE(rc, prob, bit);
+		m = (m << 1) | bit;
+	}
+	return price;
+}
+
+HINT_INLINE
+void Flush(RangeEncoder* const rc)
+{
+    for (int i = 0; i < 5; ++i)
+        ShiftLow(rc);
+}
+
+#if defined (__cplusplus)
+}
+#endif
+
+#endif /* RANGE_ENCODER_H */