1 files changed, 350 insertions, 0 deletions
diff --git a/src/liblzma/rangecoder/range_encoder.h b/src/liblzma/rangecoder/range_encoder.h
new file mode 100644
index 0000000..d794eab
--- /dev/null
+++ b/src/liblzma/rangecoder/range_encoder.h
@@ -0,0 +1,350 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       range_encoder.h
+/// \brief      Range Encoder
+///
+//  Authors:    Igor Pavlov
+//              Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef LZMA_RANGE_ENCODER_H
+#define LZMA_RANGE_ENCODER_H
+
+#include "range_common.h"
+#include "price.h"
+
+
+/// Maximum number of symbols that can be put pending into lzma_range_encoder
+/// structure between calls to lzma_rc_encode(). For LZMA, 48+5 is enough
+/// (match with big distance and length followed by range encoder flush).
+#define RC_SYMBOLS_MAX 53
+
+
+typedef struct {
+	uint64_t low;
+	uint64_t cache_size;
+	uint32_t range;
+	uint8_t cache;
+
+	/// Number of bytes written out by rc_encode() -> rc_shift_low()
+	uint64_t out_total;
+
+	/// Number of symbols in the tables
+	size_t count;
+
+	/// rc_encode()'s position in the tables
+	size_t pos;
+
+	/// Symbols to encode
+	enum {
+		RC_BIT_0,
+		RC_BIT_1,
+		RC_DIRECT_0,
+		RC_DIRECT_1,
+		RC_FLUSH,
+	} symbols[RC_SYMBOLS_MAX];
+
+	/// Probabilities associated with RC_BIT_0 or RC_BIT_1
+	probability *probs[RC_SYMBOLS_MAX];
+
+} lzma_range_encoder;
+
+
+static inline void
+rc_reset(lzma_range_encoder *rc)
+{
+	rc->low = 0;
+	rc->cache_size = 1;
+	rc->range = UINT32_MAX;
+	rc->cache = 0;
+	rc->out_total = 0;
+	rc->count = 0;
+	rc->pos = 0;
+}
+
+
+static inline void
+rc_forget(lzma_range_encoder *rc)
+{
+	// This must not be called when rc_encode() is partially done.
+	assert(rc->pos == 0);
+	rc->count = 0;
+}
+
+
+static inline void
+rc_bit(lzma_range_encoder *rc, probability *prob, uint32_t bit)
+{
+	rc->symbols[rc->count] = bit;
+	rc->probs[rc->count] = prob;
+	++rc->count;
+}
+
+
+static inline void
+rc_bittree(lzma_range_encoder *rc, probability *probs,
+		uint32_t bit_count, uint32_t symbol)
+{
+	uint32_t model_index = 1;
+
+	do {
+		const uint32_t bit = (symbol >> --bit_count) & 1;
+		rc_bit(rc, &probs[model_index], bit);
+		model_index = (model_index << 1) + bit;
+	} while (bit_count != 0);
+}
+
+
+static inline void
+rc_bittree_reverse(lzma_range_encoder *rc, probability *probs,
+		uint32_t bit_count, uint32_t symbol)
+{
+	uint32_t model_index = 1;
+
+	do {
+		const uint32_t bit = symbol & 1;
+		symbol >>= 1;
+		rc_bit(rc, &probs[model_index], bit);
+		model_index = (model_index << 1) + bit;
+	} while (--bit_count != 0);
+}
+
+
+static inline void
+rc_direct(lzma_range_encoder *rc,
+		uint32_t value, uint32_t bit_count)
+{
+	do {
+		rc->symbols[rc->count++]
+				= RC_DIRECT_0 + ((value >> --bit_count) & 1);
+	} while (bit_count != 0);
+}
+
+
+static inline void
+rc_flush(lzma_range_encoder *rc)
+{
+	for (size_t i = 0; i < 5; ++i)
+		rc->symbols[rc->count++] = RC_FLUSH;
+}
+
+
+static inline bool
+rc_shift_low(lzma_range_encoder *rc,
+		uint8_t *out, size_t *out_pos, size_t out_size)
+{
+	if ((uint32_t)(rc->low) < (uint32_t)(0xFF000000)
+			|| (uint32_t)(rc->low >> 32) != 0) {
+		do {
+			if (*out_pos == out_size)
+				return true;
+
+			out[*out_pos] = rc->cache + (uint8_t)(rc->low >> 32);
+			++*out_pos;
+			++rc->out_total;
+			rc->cache = 0xFF;
+
+		} while (--rc->cache_size != 0);
+
+		rc->cache = (rc->low >> 24) & 0xFF;
+	}
+
+	++rc->cache_size;
+	rc->low = (rc->low & 0x00FFFFFF) << RC_SHIFT_BITS;
+
+	return false;
+}
+
+
+// NOTE: The last two arguments are uint64_t instead of size_t because in
+// the dummy version these refer to the size of the whole range-encoded
+// output stream, not just to the currently available output buffer space.
+static inline bool
+rc_shift_low_dummy(uint64_t *low, uint64_t *cache_size, uint8_t *cache,
+		uint64_t *out_pos, uint64_t out_size)
+{
+	if ((uint32_t)(*low) < (uint32_t)(0xFF000000)
+			|| (uint32_t)(*low >> 32) != 0) {
+		do {
+			if (*out_pos == out_size)
+				return true;
+
+			++*out_pos;
+			*cache = 0xFF;
+
+		} while (--*cache_size != 0);
+
+		*cache = (*low >> 24) & 0xFF;
+	}
+
+	++*cache_size;
+	*low = (*low & 0x00FFFFFF) << RC_SHIFT_BITS;
+
+	return false;
+}
+
+
+static inline bool
+rc_encode(lzma_range_encoder *rc,
+		uint8_t *out, size_t *out_pos, size_t out_size)
+{
+	assert(rc->count <= RC_SYMBOLS_MAX);
+
+	while (rc->pos < rc->count) {
+		// Normalize
+		if (rc->range < RC_TOP_VALUE) {
+			if (rc_shift_low(rc, out, out_pos, out_size))
+				return true;
+
+			rc->range <<= RC_SHIFT_BITS;
+		}
+
+		// Encode a bit
+		switch (rc->symbols[rc->pos]) {
+		case RC_BIT_0: {
+			probability prob = *rc->probs[rc->pos];
+			rc->range = (rc->range >> RC_BIT_MODEL_TOTAL_BITS)
+					* prob;
+			prob += (RC_BIT_MODEL_TOTAL - prob) >> RC_MOVE_BITS;
+			*rc->probs[rc->pos] = prob;
+			break;
+		}
+
+		case RC_BIT_1: {
+			probability prob = *rc->probs[rc->pos];
+			const uint32_t bound = prob * (rc->range
+					>> RC_BIT_MODEL_TOTAL_BITS);
+			rc->low += bound;
+			rc->range -= bound;
+			prob -= prob >> RC_MOVE_BITS;
+			*rc->probs[rc->pos] = prob;
+			break;
+		}
+
+		case RC_DIRECT_0:
+			rc->range >>= 1;
+			break;
+
+		case RC_DIRECT_1:
+			rc->range >>= 1;
+			rc->low += rc->range;
+			break;
+
+		case RC_FLUSH:
+			// Prevent further normalizations.
+			rc->range = UINT32_MAX;
+
+			// Flush the last five bytes (see rc_flush()).
+			do {
+				if (rc_shift_low(rc, out, out_pos, out_size))
+					return true;
+			} while (++rc->pos < rc->count);
+
+			// Reset the range encoder so we are ready to continue
+			// encoding if we weren't finishing the stream.
+			rc_reset(rc);
+			return false;
+
+		default:
+			assert(0);
+			break;
+		}
+
+		++rc->pos;
+	}
+
+	rc->count = 0;
+	rc->pos = 0;
+
+	return false;
+}
+
+
+static inline bool
+rc_encode_dummy(const lzma_range_encoder *rc, uint64_t out_limit)
+{
+	assert(rc->count <= RC_SYMBOLS_MAX);
+
+	uint64_t low = rc->low;
+	uint64_t cache_size = rc->cache_size;
+	uint32_t range = rc->range;
+	uint8_t cache = rc->cache;
+	uint64_t out_pos = rc->out_total;
+
+	size_t pos = rc->pos;
+
+	while (true) {
+		// Normalize
+		if (range < RC_TOP_VALUE) {
+			if (rc_shift_low_dummy(&low, &cache_size, &cache,
+					&out_pos, out_limit))
+				return true;
+
+			range <<= RC_SHIFT_BITS;
+		}
+
+		// This check is here because the normalization above must
+		// be done before flushing the last bytes.
+		if (pos == rc->count)
+			break;
+
+		// Encode a bit
+		switch (rc->symbols[pos]) {
+		case RC_BIT_0: {
+			probability prob = *rc->probs[pos];
+			range = (range >> RC_BIT_MODEL_TOTAL_BITS)
+					* prob;
+			break;
+		}
+
+		case RC_BIT_1: {
+			probability prob = *rc->probs[pos];
+			const uint32_t bound = prob * (range
+					>> RC_BIT_MODEL_TOTAL_BITS);
+			low += bound;
+			range -= bound;
+			break;
+		}
+
+		case RC_DIRECT_0:
+			range >>= 1;
+			break;
+
+		case RC_DIRECT_1:
+			range >>= 1;
+			low += range;
+			break;
+
+		case RC_FLUSH:
+		default:
+			assert(0);
+			break;
+		}
+
+		++pos;
+	}
+
+	// Flush the last bytes. This isn't in rc->symbols[] so we do
+	// it after the above loop to take into account the size of
+	// the flushing that will be done at the end of the stream.
+	for (pos = 0; pos < 5; ++pos) {
+		if (rc_shift_low_dummy(&low, &cache_size,
+				&cache, &out_pos, out_limit))
+			return true;
+	}
+
+	return false;
+}
+
+
+static inline uint64_t
+rc_pending(const lzma_range_encoder *rc)
+{
+	return rc->cache_size + 5 - 1;
+}
+
+#endif