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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
commite0c6872cf40896c7be36b11dcc744620f10adf1d (patch)
tree60335e10d2f4354b0674ec22d7b53f0f8abee672 /dviware/dvisvgm/libs/brotli/enc/backward_references_hq.c
Initial commit
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diff --git a/dviware/dvisvgm/libs/brotli/enc/backward_references_hq.c b/dviware/dvisvgm/libs/brotli/enc/backward_references_hq.c
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+/* Copyright 2013 Google Inc. All Rights Reserved.
+
+ Distributed under MIT license.
+ See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+/* Function to find backward reference copies. */
+
+#include "./backward_references_hq.h"
+
+#include <string.h> /* memcpy, memset */
+
+#include "../common/constants.h"
+#include "../common/platform.h"
+#include <brotli/types.h>
+#include "./command.h"
+#include "./fast_log.h"
+#include "./find_match_length.h"
+#include "./literal_cost.h"
+#include "./memory.h"
+#include "./params.h"
+#include "./prefix.h"
+#include "./quality.h"
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+#define BROTLI_MAX_EFFECTIVE_DISTANCE_ALPHABET_SIZE 544
+
+static const float kInfinity = 1.7e38f; /* ~= 2 ^ 127 */
+
+static const uint32_t kDistanceCacheIndex[] = {
+ 0, 1, 2, 3, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1,
+};
+static const int kDistanceCacheOffset[] = {
+ 0, 0, 0, 0, -1, 1, -2, 2, -3, 3, -1, 1, -2, 2, -3, 3
+};
+
+void BrotliInitZopfliNodes(ZopfliNode* array, size_t length) {
+ ZopfliNode stub;
+ size_t i;
+ stub.length = 1;
+ stub.distance = 0;
+ stub.dcode_insert_length = 0;
+ stub.u.cost = kInfinity;
+ for (i = 0; i < length; ++i) array[i] = stub;
+}
+
+static BROTLI_INLINE uint32_t ZopfliNodeCopyLength(const ZopfliNode* self) {
+ return self->length & 0x1FFFFFF;
+}
+
+static BROTLI_INLINE uint32_t ZopfliNodeLengthCode(const ZopfliNode* self) {
+ const uint32_t modifier = self->length >> 25;
+ return ZopfliNodeCopyLength(self) + 9u - modifier;
+}
+
+static BROTLI_INLINE uint32_t ZopfliNodeCopyDistance(const ZopfliNode* self) {
+ return self->distance;
+}
+
+static BROTLI_INLINE uint32_t ZopfliNodeDistanceCode(const ZopfliNode* self) {
+ const uint32_t short_code = self->dcode_insert_length >> 27;
+ return short_code == 0 ?
+ ZopfliNodeCopyDistance(self) + BROTLI_NUM_DISTANCE_SHORT_CODES - 1 :
+ short_code - 1;
+}
+
+static BROTLI_INLINE uint32_t ZopfliNodeCommandLength(const ZopfliNode* self) {
+ return ZopfliNodeCopyLength(self) + (self->dcode_insert_length & 0x7FFFFFF);
+}
+
+/* Histogram based cost model for zopflification. */
+typedef struct ZopfliCostModel {
+ /* The insert and copy length symbols. */
+ float cost_cmd_[BROTLI_NUM_COMMAND_SYMBOLS];
+ float* cost_dist_;
+ uint32_t distance_histogram_size;
+ /* Cumulative costs of literals per position in the stream. */
+ float* literal_costs_;
+ float min_cost_cmd_;
+ size_t num_bytes_;
+} ZopfliCostModel;
+
+static void InitZopfliCostModel(
+ MemoryManager* m, ZopfliCostModel* self, const BrotliDistanceParams* dist,
+ size_t num_bytes) {
+ uint32_t distance_histogram_size = dist->alphabet_size;
+ if (distance_histogram_size > BROTLI_MAX_EFFECTIVE_DISTANCE_ALPHABET_SIZE) {
+ distance_histogram_size = BROTLI_MAX_EFFECTIVE_DISTANCE_ALPHABET_SIZE;
+ }
+ self->num_bytes_ = num_bytes;
+ self->literal_costs_ = BROTLI_ALLOC(m, float, num_bytes + 2);
+ self->cost_dist_ = BROTLI_ALLOC(m, float, dist->alphabet_size);
+ self->distance_histogram_size = distance_histogram_size;
+ if (BROTLI_IS_OOM(m)) return;
+}
+
+static void CleanupZopfliCostModel(MemoryManager* m, ZopfliCostModel* self) {
+ BROTLI_FREE(m, self->literal_costs_);
+ BROTLI_FREE(m, self->cost_dist_);
+}
+
+static void SetCost(const uint32_t* histogram, size_t histogram_size,
+ BROTLI_BOOL literal_histogram, float* cost) {
+ size_t sum = 0;
+ size_t missing_symbol_sum;
+ float log2sum;
+ float missing_symbol_cost;
+ size_t i;
+ for (i = 0; i < histogram_size; i++) {
+ sum += histogram[i];
+ }
+ log2sum = (float)FastLog2(sum);
+ missing_symbol_sum = sum;
+ if (!literal_histogram) {
+ for (i = 0; i < histogram_size; i++) {
+ if (histogram[i] == 0) missing_symbol_sum++;
+ }
+ }
+ missing_symbol_cost = (float)FastLog2(missing_symbol_sum) + 2;
+ for (i = 0; i < histogram_size; i++) {
+ if (histogram[i] == 0) {
+ cost[i] = missing_symbol_cost;
+ continue;
+ }
+
+ /* Shannon bits for this symbol. */
+ cost[i] = log2sum - (float)FastLog2(histogram[i]);
+
+ /* Cannot be coded with less than 1 bit */
+ if (cost[i] < 1) cost[i] = 1;
+ }
+}
+
+static void ZopfliCostModelSetFromCommands(ZopfliCostModel* self,
+ size_t position,
+ const uint8_t* ringbuffer,
+ size_t ringbuffer_mask,
+ const Command* commands,
+ size_t num_commands,
+ size_t last_insert_len) {
+ uint32_t histogram_literal[BROTLI_NUM_LITERAL_SYMBOLS];
+ uint32_t histogram_cmd[BROTLI_NUM_COMMAND_SYMBOLS];
+ uint32_t histogram_dist[BROTLI_MAX_EFFECTIVE_DISTANCE_ALPHABET_SIZE];
+ float cost_literal[BROTLI_NUM_LITERAL_SYMBOLS];
+ size_t pos = position - last_insert_len;
+ float min_cost_cmd = kInfinity;
+ size_t i;
+ float* cost_cmd = self->cost_cmd_;
+
+ memset(histogram_literal, 0, sizeof(histogram_literal));
+ memset(histogram_cmd, 0, sizeof(histogram_cmd));
+ memset(histogram_dist, 0, sizeof(histogram_dist));
+
+ for (i = 0; i < num_commands; i++) {
+ size_t inslength = commands[i].insert_len_;
+ size_t copylength = CommandCopyLen(&commands[i]);
+ size_t distcode = commands[i].dist_prefix_ & 0x3FF;
+ size_t cmdcode = commands[i].cmd_prefix_;
+ size_t j;
+
+ histogram_cmd[cmdcode]++;
+ if (cmdcode >= 128) histogram_dist[distcode]++;
+
+ for (j = 0; j < inslength; j++) {
+ histogram_literal[ringbuffer[(pos + j) & ringbuffer_mask]]++;
+ }
+
+ pos += inslength + copylength;
+ }
+
+ SetCost(histogram_literal, BROTLI_NUM_LITERAL_SYMBOLS, BROTLI_TRUE,
+ cost_literal);
+ SetCost(histogram_cmd, BROTLI_NUM_COMMAND_SYMBOLS, BROTLI_FALSE,
+ cost_cmd);
+ SetCost(histogram_dist, self->distance_histogram_size, BROTLI_FALSE,
+ self->cost_dist_);
+
+ for (i = 0; i < BROTLI_NUM_COMMAND_SYMBOLS; ++i) {
+ min_cost_cmd = BROTLI_MIN(float, min_cost_cmd, cost_cmd[i]);
+ }
+ self->min_cost_cmd_ = min_cost_cmd;
+
+ {
+ float* literal_costs = self->literal_costs_;
+ float literal_carry = 0.0;
+ size_t num_bytes = self->num_bytes_;
+ literal_costs[0] = 0.0;
+ for (i = 0; i < num_bytes; ++i) {
+ literal_carry +=
+ cost_literal[ringbuffer[(position + i) & ringbuffer_mask]];
+ literal_costs[i + 1] = literal_costs[i] + literal_carry;
+ literal_carry -= literal_costs[i + 1] - literal_costs[i];
+ }
+ }
+}
+
+static void ZopfliCostModelSetFromLiteralCosts(ZopfliCostModel* self,
+ size_t position,
+ const uint8_t* ringbuffer,
+ size_t ringbuffer_mask) {
+ float* literal_costs = self->literal_costs_;
+ float literal_carry = 0.0;
+ float* cost_dist = self->cost_dist_;
+ float* cost_cmd = self->cost_cmd_;
+ size_t num_bytes = self->num_bytes_;
+ size_t i;
+ BrotliEstimateBitCostsForLiterals(position, num_bytes, ringbuffer_mask,
+ ringbuffer, &literal_costs[1]);
+ literal_costs[0] = 0.0;
+ for (i = 0; i < num_bytes; ++i) {
+ literal_carry += literal_costs[i + 1];
+ literal_costs[i + 1] = literal_costs[i] + literal_carry;
+ literal_carry -= literal_costs[i + 1] - literal_costs[i];
+ }
+ for (i = 0; i < BROTLI_NUM_COMMAND_SYMBOLS; ++i) {
+ cost_cmd[i] = (float)FastLog2(11 + (uint32_t)i);
+ }
+ for (i = 0; i < self->distance_histogram_size; ++i) {
+ cost_dist[i] = (float)FastLog2(20 + (uint32_t)i);
+ }
+ self->min_cost_cmd_ = (float)FastLog2(11);
+}
+
+static BROTLI_INLINE float ZopfliCostModelGetCommandCost(
+ const ZopfliCostModel* self, uint16_t cmdcode) {
+ return self->cost_cmd_[cmdcode];
+}
+
+static BROTLI_INLINE float ZopfliCostModelGetDistanceCost(
+ const ZopfliCostModel* self, size_t distcode) {
+ return self->cost_dist_[distcode];
+}
+
+static BROTLI_INLINE float ZopfliCostModelGetLiteralCosts(
+ const ZopfliCostModel* self, size_t from, size_t to) {
+ return self->literal_costs_[to] - self->literal_costs_[from];
+}
+
+static BROTLI_INLINE float ZopfliCostModelGetMinCostCmd(
+ const ZopfliCostModel* self) {
+ return self->min_cost_cmd_;
+}
+
+/* REQUIRES: len >= 2, start_pos <= pos */
+/* REQUIRES: cost < kInfinity, nodes[start_pos].cost < kInfinity */
+/* Maintains the "ZopfliNode array invariant". */
+static BROTLI_INLINE void UpdateZopfliNode(ZopfliNode* nodes, size_t pos,
+ size_t start_pos, size_t len, size_t len_code, size_t dist,
+ size_t short_code, float cost) {
+ ZopfliNode* next = &nodes[pos + len];
+ next->length = (uint32_t)(len | ((len + 9u - len_code) << 25));
+ next->distance = (uint32_t)dist;
+ next->dcode_insert_length = (uint32_t)(
+ (short_code << 27) | (pos - start_pos));
+ next->u.cost = cost;
+}
+
+typedef struct PosData {
+ size_t pos;
+ int distance_cache[4];
+ float costdiff;
+ float cost;
+} PosData;
+
+/* Maintains the smallest 8 cost difference together with their positions */
+typedef struct StartPosQueue {
+ PosData q_[8];
+ size_t idx_;
+} StartPosQueue;
+
+static BROTLI_INLINE void InitStartPosQueue(StartPosQueue* self) {
+ self->idx_ = 0;
+}
+
+static size_t StartPosQueueSize(const StartPosQueue* self) {
+ return BROTLI_MIN(size_t, self->idx_, 8);
+}
+
+static void StartPosQueuePush(StartPosQueue* self, const PosData* posdata) {
+ size_t offset = ~(self->idx_++) & 7;
+ size_t len = StartPosQueueSize(self);
+ size_t i;
+ PosData* q = self->q_;
+ q[offset] = *posdata;
+ /* Restore the sorted order. In the list of |len| items at most |len - 1|
+ adjacent element comparisons / swaps are required. */
+ for (i = 1; i < len; ++i) {
+ if (q[offset & 7].costdiff > q[(offset + 1) & 7].costdiff) {
+ BROTLI_SWAP(PosData, q, offset & 7, (offset + 1) & 7);
+ }
+ ++offset;
+ }
+}
+
+static const PosData* StartPosQueueAt(const StartPosQueue* self, size_t k) {
+ return &self->q_[(k - self->idx_) & 7];
+}
+
+/* Returns the minimum possible copy length that can improve the cost of any */
+/* future position. */
+static size_t ComputeMinimumCopyLength(const float start_cost,
+ const ZopfliNode* nodes,
+ const size_t num_bytes,
+ const size_t pos) {
+ /* Compute the minimum possible cost of reaching any future position. */
+ float min_cost = start_cost;
+ size_t len = 2;
+ size_t next_len_bucket = 4;
+ size_t next_len_offset = 10;
+ while (pos + len <= num_bytes && nodes[pos + len].u.cost <= min_cost) {
+ /* We already reached (pos + len) with no more cost than the minimum
+ possible cost of reaching anything from this pos, so there is no point in
+ looking for lengths <= len. */
+ ++len;
+ if (len == next_len_offset) {
+ /* We reached the next copy length code bucket, so we add one more
+ extra bit to the minimum cost. */
+ min_cost += 1.0f;
+ next_len_offset += next_len_bucket;
+ next_len_bucket *= 2;
+ }
+ }
+ return len;
+}
+
+/* REQUIRES: nodes[pos].cost < kInfinity
+ REQUIRES: nodes[0..pos] satisfies that "ZopfliNode array invariant". */
+static uint32_t ComputeDistanceShortcut(const size_t block_start,
+ const size_t pos,
+ const size_t max_backward_limit,
+ const size_t gap,
+ const ZopfliNode* nodes) {
+ const size_t clen = ZopfliNodeCopyLength(&nodes[pos]);
+ const size_t ilen = nodes[pos].dcode_insert_length & 0x7FFFFFF;
+ const size_t dist = ZopfliNodeCopyDistance(&nodes[pos]);
+ /* Since |block_start + pos| is the end position of the command, the copy part
+ starts from |block_start + pos - clen|. Distances that are greater than
+ this or greater than |max_backward_limit| + |gap| are static dictionary
+ references, and do not update the last distances.
+ Also distance code 0 (last distance) does not update the last distances. */
+ if (pos == 0) {
+ return 0;
+ } else if (dist + clen <= block_start + pos + gap &&
+ dist <= max_backward_limit + gap &&
+ ZopfliNodeDistanceCode(&nodes[pos]) > 0) {
+ return (uint32_t)pos;
+ } else {
+ return nodes[pos - clen - ilen].u.shortcut;
+ }
+}
+
+/* Fills in dist_cache[0..3] with the last four distances (as defined by
+ Section 4. of the Spec) that would be used at (block_start + pos) if we
+ used the shortest path of commands from block_start, computed from
+ nodes[0..pos]. The last four distances at block_start are in
+ starting_dist_cache[0..3].
+ REQUIRES: nodes[pos].cost < kInfinity
+ REQUIRES: nodes[0..pos] satisfies that "ZopfliNode array invariant". */
+static void ComputeDistanceCache(const size_t pos,
+ const int* starting_dist_cache,
+ const ZopfliNode* nodes,
+ int* dist_cache) {
+ int idx = 0;
+ size_t p = nodes[pos].u.shortcut;
+ while (idx < 4 && p > 0) {
+ const size_t ilen = nodes[p].dcode_insert_length & 0x7FFFFFF;
+ const size_t clen = ZopfliNodeCopyLength(&nodes[p]);
+ const size_t dist = ZopfliNodeCopyDistance(&nodes[p]);
+ dist_cache[idx++] = (int)dist;
+ /* Because of prerequisite, p >= clen + ilen >= 2. */
+ p = nodes[p - clen - ilen].u.shortcut;
+ }
+ for (; idx < 4; ++idx) {
+ dist_cache[idx] = *starting_dist_cache++;
+ }
+}
+
+/* Maintains "ZopfliNode array invariant" and pushes node to the queue, if it
+ is eligible. */
+static void EvaluateNode(
+ const size_t block_start, const size_t pos, const size_t max_backward_limit,
+ const size_t gap, const int* starting_dist_cache,
+ const ZopfliCostModel* model, StartPosQueue* queue, ZopfliNode* nodes) {
+ /* Save cost, because ComputeDistanceCache invalidates it. */
+ float node_cost = nodes[pos].u.cost;
+ nodes[pos].u.shortcut = ComputeDistanceShortcut(
+ block_start, pos, max_backward_limit, gap, nodes);
+ if (node_cost <= ZopfliCostModelGetLiteralCosts(model, 0, pos)) {
+ PosData posdata;
+ posdata.pos = pos;
+ posdata.cost = node_cost;
+ posdata.costdiff = node_cost -
+ ZopfliCostModelGetLiteralCosts(model, 0, pos);
+ ComputeDistanceCache(
+ pos, starting_dist_cache, nodes, posdata.distance_cache);
+ StartPosQueuePush(queue, &posdata);
+ }
+}
+
+/* Returns longest copy length. */
+static size_t UpdateNodes(
+ const size_t num_bytes, const size_t block_start, const size_t pos,
+ const uint8_t* ringbuffer, const size_t ringbuffer_mask,
+ const BrotliEncoderParams* params, const size_t max_backward_limit,
+ const int* starting_dist_cache, const size_t num_matches,
+ const BackwardMatch* matches, const ZopfliCostModel* model,
+ StartPosQueue* queue, ZopfliNode* nodes) {
+ const size_t cur_ix = block_start + pos;
+ const size_t cur_ix_masked = cur_ix & ringbuffer_mask;
+ const size_t max_distance = BROTLI_MIN(size_t, cur_ix, max_backward_limit);
+ const size_t max_len = num_bytes - pos;
+ const size_t max_zopfli_len = MaxZopfliLen(params);
+ const size_t max_iters = MaxZopfliCandidates(params);
+ size_t min_len;
+ size_t result = 0;
+ size_t k;
+ size_t gap = 0;
+
+ EvaluateNode(block_start, pos, max_backward_limit, gap, starting_dist_cache,
+ model, queue, nodes);
+
+ {
+ const PosData* posdata = StartPosQueueAt(queue, 0);
+ float min_cost = (posdata->cost + ZopfliCostModelGetMinCostCmd(model) +
+ ZopfliCostModelGetLiteralCosts(model, posdata->pos, pos));
+ min_len = ComputeMinimumCopyLength(min_cost, nodes, num_bytes, pos);
+ }
+
+ /* Go over the command starting positions in order of increasing cost
+ difference. */
+ for (k = 0; k < max_iters && k < StartPosQueueSize(queue); ++k) {
+ const PosData* posdata = StartPosQueueAt(queue, k);
+ const size_t start = posdata->pos;
+ const uint16_t inscode = GetInsertLengthCode(pos - start);
+ const float start_costdiff = posdata->costdiff;
+ const float base_cost = start_costdiff + (float)GetInsertExtra(inscode) +
+ ZopfliCostModelGetLiteralCosts(model, 0, pos);
+
+ /* Look for last distance matches using the distance cache from this
+ starting position. */
+ size_t best_len = min_len - 1;
+ size_t j = 0;
+ for (; j < BROTLI_NUM_DISTANCE_SHORT_CODES && best_len < max_len; ++j) {
+ const size_t idx = kDistanceCacheIndex[j];
+ const size_t backward =
+ (size_t)(posdata->distance_cache[idx] + kDistanceCacheOffset[j]);
+ size_t prev_ix = cur_ix - backward;
+ size_t len = 0;
+ uint8_t continuation = ringbuffer[cur_ix_masked + best_len];
+ if (cur_ix_masked + best_len > ringbuffer_mask) {
+ break;
+ }
+ if (BROTLI_PREDICT_FALSE(backward > max_distance + gap)) {
+ /* Word dictionary -> ignore. */
+ continue;
+ }
+ if (backward <= max_distance) {
+ /* Regular backward reference. */
+ if (prev_ix >= cur_ix) {
+ continue;
+ }
+
+ prev_ix &= ringbuffer_mask;
+ if (prev_ix + best_len > ringbuffer_mask ||
+ continuation != ringbuffer[prev_ix + best_len]) {
+ continue;
+ }
+ len = FindMatchLengthWithLimit(&ringbuffer[prev_ix],
+ &ringbuffer[cur_ix_masked],
+ max_len);
+ } else {
+ continue;
+ }
+ {
+ const float dist_cost = base_cost +
+ ZopfliCostModelGetDistanceCost(model, j);
+ size_t l;
+ for (l = best_len + 1; l <= len; ++l) {
+ const uint16_t copycode = GetCopyLengthCode(l);
+ const uint16_t cmdcode =
+ CombineLengthCodes(inscode, copycode, j == 0);
+ const float cost = (cmdcode < 128 ? base_cost : dist_cost) +
+ (float)GetCopyExtra(copycode) +
+ ZopfliCostModelGetCommandCost(model, cmdcode);
+ if (cost < nodes[pos + l].u.cost) {
+ UpdateZopfliNode(nodes, pos, start, l, l, backward, j + 1, cost);
+ result = BROTLI_MAX(size_t, result, l);
+ }
+ best_len = l;
+ }
+ }
+ }
+
+ /* At higher iterations look only for new last distance matches, since
+ looking only for new command start positions with the same distances
+ does not help much. */
+ if (k >= 2) continue;
+
+ {
+ /* Loop through all possible copy lengths at this position. */
+ size_t len = min_len;
+ for (j = 0; j < num_matches; ++j) {
+ BackwardMatch match = matches[j];
+ size_t dist = match.distance;
+ BROTLI_BOOL is_dictionary_match =
+ TO_BROTLI_BOOL(dist > max_distance + gap);
+ /* We already tried all possible last distance matches, so we can use
+ normal distance code here. */
+ size_t dist_code = dist + BROTLI_NUM_DISTANCE_SHORT_CODES - 1;
+ uint16_t dist_symbol;
+ uint32_t distextra;
+ uint32_t distnumextra;
+ float dist_cost;
+ size_t max_match_len;
+ PrefixEncodeCopyDistance(
+ dist_code, params->dist.num_direct_distance_codes,
+ params->dist.distance_postfix_bits, &dist_symbol, &distextra);
+ distnumextra = dist_symbol >> 10;
+ dist_cost = base_cost + (float)distnumextra +
+ ZopfliCostModelGetDistanceCost(model, dist_symbol & 0x3FF);
+
+ /* Try all copy lengths up until the maximum copy length corresponding
+ to this distance. If the distance refers to the static dictionary, or
+ the maximum length is long enough, try only one maximum length. */
+ max_match_len = BackwardMatchLength(&match);
+ if (len < max_match_len &&
+ (is_dictionary_match || max_match_len > max_zopfli_len)) {
+ len = max_match_len;
+ }
+ for (; len <= max_match_len; ++len) {
+ const size_t len_code =
+ is_dictionary_match ? BackwardMatchLengthCode(&match) : len;
+ const uint16_t copycode = GetCopyLengthCode(len_code);
+ const uint16_t cmdcode = CombineLengthCodes(inscode, copycode, 0);
+ const float cost = dist_cost + (float)GetCopyExtra(copycode) +
+ ZopfliCostModelGetCommandCost(model, cmdcode);
+ if (cost < nodes[pos + len].u.cost) {
+ UpdateZopfliNode(nodes, pos, start, len, len_code, dist, 0, cost);
+ result = BROTLI_MAX(size_t, result, len);
+ }
+ }
+ }
+ }
+ }
+ return result;
+}
+
+static size_t ComputeShortestPathFromNodes(size_t num_bytes,
+ ZopfliNode* nodes) {
+ size_t index = num_bytes;
+ size_t num_commands = 0;
+ while ((nodes[index].dcode_insert_length & 0x7FFFFFF) == 0 &&
+ nodes[index].length == 1) --index;
+ nodes[index].u.next = BROTLI_UINT32_MAX;
+ while (index != 0) {
+ size_t len = ZopfliNodeCommandLength(&nodes[index]);
+ index -= len;
+ nodes[index].u.next = (uint32_t)len;
+ num_commands++;
+ }
+ return num_commands;
+}
+
+/* REQUIRES: nodes != NULL and len(nodes) >= num_bytes + 1 */
+void BrotliZopfliCreateCommands(const size_t num_bytes,
+ const size_t block_start, const ZopfliNode* nodes, int* dist_cache,
+ size_t* last_insert_len, const BrotliEncoderParams* params,
+ Command* commands, size_t* num_literals) {
+ const size_t max_backward_limit = BROTLI_MAX_BACKWARD_LIMIT(params->lgwin);
+ size_t pos = 0;
+ uint32_t offset = nodes[0].u.next;
+ size_t i;
+ size_t gap = 0;
+ for (i = 0; offset != BROTLI_UINT32_MAX; i++) {
+ const ZopfliNode* next = &nodes[pos + offset];
+ size_t copy_length = ZopfliNodeCopyLength(next);
+ size_t insert_length = next->dcode_insert_length & 0x7FFFFFF;
+ pos += insert_length;
+ offset = next->u.next;
+ if (i == 0) {
+ insert_length += *last_insert_len;
+ *last_insert_len = 0;
+ }
+ {
+ size_t distance = ZopfliNodeCopyDistance(next);
+ size_t len_code = ZopfliNodeLengthCode(next);
+ size_t max_distance =
+ BROTLI_MIN(size_t, block_start + pos, max_backward_limit);
+ BROTLI_BOOL is_dictionary = TO_BROTLI_BOOL(distance > max_distance + gap);
+ size_t dist_code = ZopfliNodeDistanceCode(next);
+ InitCommand(&commands[i], &params->dist, insert_length,
+ copy_length, (int)len_code - (int)copy_length, dist_code);
+
+ if (!is_dictionary && dist_code > 0) {
+ dist_cache[3] = dist_cache[2];
+ dist_cache[2] = dist_cache[1];
+ dist_cache[1] = dist_cache[0];
+ dist_cache[0] = (int)distance;
+ }
+ }
+
+ *num_literals += insert_length;
+ pos += copy_length;
+ }
+ *last_insert_len += num_bytes - pos;
+}
+
+static size_t ZopfliIterate(size_t num_bytes, size_t position,
+ const uint8_t* ringbuffer, size_t ringbuffer_mask,
+ const BrotliEncoderParams* params, const size_t gap, const int* dist_cache,
+ const ZopfliCostModel* model, const uint32_t* num_matches,
+ const BackwardMatch* matches, ZopfliNode* nodes) {
+ const size_t max_backward_limit = BROTLI_MAX_BACKWARD_LIMIT(params->lgwin);
+ const size_t max_zopfli_len = MaxZopfliLen(params);
+ StartPosQueue queue;
+ size_t cur_match_pos = 0;
+ size_t i;
+ nodes[0].length = 0;
+ nodes[0].u.cost = 0;
+ InitStartPosQueue(&queue);
+ for (i = 0; i + 3 < num_bytes; i++) {
+ size_t skip = UpdateNodes(num_bytes, position, i, ringbuffer,
+ ringbuffer_mask, params, max_backward_limit, dist_cache,
+ num_matches[i], &matches[cur_match_pos], model, &queue, nodes);
+ if (skip < BROTLI_LONG_COPY_QUICK_STEP) skip = 0;
+ cur_match_pos += num_matches[i];
+ if (num_matches[i] == 1 &&
+ BackwardMatchLength(&matches[cur_match_pos - 1]) > max_zopfli_len) {
+ skip = BROTLI_MAX(size_t,
+ BackwardMatchLength(&matches[cur_match_pos - 1]), skip);
+ }
+ if (skip > 1) {
+ skip--;
+ while (skip) {
+ i++;
+ if (i + 3 >= num_bytes) break;
+ EvaluateNode(position, i, max_backward_limit, gap,
+ dist_cache, model, &queue, nodes);
+ cur_match_pos += num_matches[i];
+ skip--;
+ }
+ }
+ }
+ return ComputeShortestPathFromNodes(num_bytes, nodes);
+}
+
+/* REQUIRES: nodes != NULL and len(nodes) >= num_bytes + 1 */
+size_t BrotliZopfliComputeShortestPath(MemoryManager* m, size_t num_bytes,
+ size_t position, const uint8_t* ringbuffer, size_t ringbuffer_mask,
+ const BrotliEncoderParams* params,
+ const int* dist_cache, HasherHandle hasher, ZopfliNode* nodes) {
+ const size_t max_backward_limit = BROTLI_MAX_BACKWARD_LIMIT(params->lgwin);
+ const size_t max_zopfli_len = MaxZopfliLen(params);
+ ZopfliCostModel model;
+ StartPosQueue queue;
+ BackwardMatch matches[2 * (MAX_NUM_MATCHES_H10 + 64)];
+ const size_t store_end = num_bytes >= StoreLookaheadH10() ?
+ position + num_bytes - StoreLookaheadH10() + 1 : position;
+ size_t i;
+ size_t gap = 0;
+ size_t lz_matches_offset = 0;
+ nodes[0].length = 0;
+ nodes[0].u.cost = 0;
+ InitZopfliCostModel(m, &model, &params->dist, num_bytes);
+ if (BROTLI_IS_OOM(m)) return 0;
+ ZopfliCostModelSetFromLiteralCosts(
+ &model, position, ringbuffer, ringbuffer_mask);
+ InitStartPosQueue(&queue);
+ for (i = 0; i + HashTypeLengthH10() - 1 < num_bytes; i++) {
+ const size_t pos = position + i;
+ const size_t max_distance = BROTLI_MIN(size_t, pos, max_backward_limit);
+ size_t skip;
+ size_t num_matches;
+ num_matches = FindAllMatchesH10(hasher,
+ &params->dictionary,
+ ringbuffer, ringbuffer_mask, pos, num_bytes - i, max_distance,
+ gap, params, &matches[lz_matches_offset]);
+ if (num_matches > 0 &&
+ BackwardMatchLength(&matches[num_matches - 1]) > max_zopfli_len) {
+ matches[0] = matches[num_matches - 1];
+ num_matches = 1;
+ }
+ skip = UpdateNodes(num_bytes, position, i, ringbuffer, ringbuffer_mask,
+ params, max_backward_limit, dist_cache, num_matches, matches, &model,
+ &queue, nodes);
+ if (skip < BROTLI_LONG_COPY_QUICK_STEP) skip = 0;
+ if (num_matches == 1 && BackwardMatchLength(&matches[0]) > max_zopfli_len) {
+ skip = BROTLI_MAX(size_t, BackwardMatchLength(&matches[0]), skip);
+ }
+ if (skip > 1) {
+ /* Add the tail of the copy to the hasher. */
+ StoreRangeH10(hasher, ringbuffer, ringbuffer_mask, pos + 1, BROTLI_MIN(
+ size_t, pos + skip, store_end));
+ skip--;
+ while (skip) {
+ i++;
+ if (i + HashTypeLengthH10() - 1 >= num_bytes) break;
+ EvaluateNode(position, i, max_backward_limit, gap,
+ dist_cache, &model, &queue, nodes);
+ skip--;
+ }
+ }
+ }
+ CleanupZopfliCostModel(m, &model);
+ return ComputeShortestPathFromNodes(num_bytes, nodes);
+}
+
+void BrotliCreateZopfliBackwardReferences(MemoryManager* m, size_t num_bytes,
+ size_t position, const uint8_t* ringbuffer, size_t ringbuffer_mask,
+ const BrotliEncoderParams* params,
+ HasherHandle hasher, int* dist_cache, size_t* last_insert_len,
+ Command* commands, size_t* num_commands, size_t* num_literals) {
+ ZopfliNode* nodes;
+ nodes = BROTLI_ALLOC(m, ZopfliNode, num_bytes + 1);
+ if (BROTLI_IS_OOM(m)) return;
+ BrotliInitZopfliNodes(nodes, num_bytes + 1);
+ *num_commands += BrotliZopfliComputeShortestPath(m, num_bytes,
+ position, ringbuffer, ringbuffer_mask, params,
+ dist_cache, hasher, nodes);
+ if (BROTLI_IS_OOM(m)) return;
+ BrotliZopfliCreateCommands(num_bytes, position, nodes, dist_cache,
+ last_insert_len, params, commands, num_literals);
+ BROTLI_FREE(m, nodes);
+}
+
+void BrotliCreateHqZopfliBackwardReferences(MemoryManager* m, size_t num_bytes,
+ size_t position, const uint8_t* ringbuffer, size_t ringbuffer_mask,
+ const BrotliEncoderParams* params,
+ HasherHandle hasher, int* dist_cache, size_t* last_insert_len,
+ Command* commands, size_t* num_commands, size_t* num_literals) {
+ const size_t max_backward_limit = BROTLI_MAX_BACKWARD_LIMIT(params->lgwin);
+ uint32_t* num_matches = BROTLI_ALLOC(m, uint32_t, num_bytes);
+ size_t matches_size = 4 * num_bytes;
+ const size_t store_end = num_bytes >= StoreLookaheadH10() ?
+ position + num_bytes - StoreLookaheadH10() + 1 : position;
+ size_t cur_match_pos = 0;
+ size_t i;
+ size_t orig_num_literals;
+ size_t orig_last_insert_len;
+ int orig_dist_cache[4];
+ size_t orig_num_commands;
+ ZopfliCostModel model;
+ ZopfliNode* nodes;
+ BackwardMatch* matches = BROTLI_ALLOC(m, BackwardMatch, matches_size);
+ size_t gap = 0;
+ size_t shadow_matches = 0;
+ if (BROTLI_IS_OOM(m)) return;
+ for (i = 0; i + HashTypeLengthH10() - 1 < num_bytes; ++i) {
+ const size_t pos = position + i;
+ size_t max_distance = BROTLI_MIN(size_t, pos, max_backward_limit);
+ size_t max_length = num_bytes - i;
+ size_t num_found_matches;
+ size_t cur_match_end;
+ size_t j;
+ /* Ensure that we have enough free slots. */
+ BROTLI_ENSURE_CAPACITY(m, BackwardMatch, matches, matches_size,
+ cur_match_pos + MAX_NUM_MATCHES_H10 + shadow_matches);
+ if (BROTLI_IS_OOM(m)) return;
+ num_found_matches = FindAllMatchesH10(hasher,
+ &params->dictionary,
+ ringbuffer, ringbuffer_mask, pos, max_length,
+ max_distance, gap, params,
+ &matches[cur_match_pos + shadow_matches]);
+ cur_match_end = cur_match_pos + num_found_matches;
+ for (j = cur_match_pos; j + 1 < cur_match_end; ++j) {
+ BROTLI_DCHECK(BackwardMatchLength(&matches[j]) <=
+ BackwardMatchLength(&matches[j + 1]));
+ }
+ num_matches[i] = (uint32_t)num_found_matches;
+ if (num_found_matches > 0) {
+ const size_t match_len = BackwardMatchLength(&matches[cur_match_end - 1]);
+ if (match_len > MAX_ZOPFLI_LEN_QUALITY_11) {
+ const size_t skip = match_len - 1;
+ matches[cur_match_pos++] = matches[cur_match_end - 1];
+ num_matches[i] = 1;
+ /* Add the tail of the copy to the hasher. */
+ StoreRangeH10(hasher, ringbuffer, ringbuffer_mask, pos + 1,
+ BROTLI_MIN(size_t, pos + match_len, store_end));
+ memset(&num_matches[i + 1], 0, skip * sizeof(num_matches[0]));
+ i += skip;
+ } else {
+ cur_match_pos = cur_match_end;
+ }
+ }
+ }
+ orig_num_literals = *num_literals;
+ orig_last_insert_len = *last_insert_len;
+ memcpy(orig_dist_cache, dist_cache, 4 * sizeof(dist_cache[0]));
+ orig_num_commands = *num_commands;
+ nodes = BROTLI_ALLOC(m, ZopfliNode, num_bytes + 1);
+ if (BROTLI_IS_OOM(m)) return;
+ InitZopfliCostModel(m, &model, &params->dist, num_bytes);
+ if (BROTLI_IS_OOM(m)) return;
+ for (i = 0; i < 2; i++) {
+ BrotliInitZopfliNodes(nodes, num_bytes + 1);
+ if (i == 0) {
+ ZopfliCostModelSetFromLiteralCosts(
+ &model, position, ringbuffer, ringbuffer_mask);
+ } else {
+ ZopfliCostModelSetFromCommands(&model, position, ringbuffer,
+ ringbuffer_mask, commands, *num_commands - orig_num_commands,
+ orig_last_insert_len);
+ }
+ *num_commands = orig_num_commands;
+ *num_literals = orig_num_literals;
+ *last_insert_len = orig_last_insert_len;
+ memcpy(dist_cache, orig_dist_cache, 4 * sizeof(dist_cache[0]));
+ *num_commands += ZopfliIterate(num_bytes, position, ringbuffer,
+ ringbuffer_mask, params, gap, dist_cache, &model, num_matches, matches,
+ nodes);
+ BrotliZopfliCreateCommands(num_bytes, position, nodes, dist_cache,
+ last_insert_len, params, commands, num_literals);
+ }
+ CleanupZopfliCostModel(m, &model);
+ BROTLI_FREE(m, nodes);
+ BROTLI_FREE(m, matches);
+ BROTLI_FREE(m, num_matches);
+}
+
+#if defined(__cplusplus) || defined(c_plusplus)
+} /* extern "C" */
+#endif