--- /dev/null
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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 <stdlib.h>
+#include <stdbool.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, 52+5 is enough
+/// (match with big distance and length followed by range encoder flush).
+#define RC_SYMBOLS_MAX 58
+
+
+typedef struct {
+ uint64_t low;
+ uint64_t cache_size;
+ uint32_t range;
+ uint8_t cache;
+
+ /// 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->count = 0;
+ rc->pos = 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->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;
+}
+
+
+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 uint64_t
+rc_pending(const lzma_range_encoder *rc)
+{
+ return rc->cache_size + 5 - 1;
+}
+
+#endif
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