Added brotli enc/ and tools/ directories.

third_party/brotli/enc/backward_references.h

+/* 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.
+
+#ifndef BROTLI_ENC_BACKWARD_REFERENCES_H_
+#define BROTLI_ENC_BACKWARD_REFERENCES_H_
+
+#include <vector>
+
+#include "./hash.h"
+#include "./command.h"
+#include "./types.h"
+
+namespace brotli {
+
+// "commands" points to the next output command to write to, "*num_commands" is
+// initially the total amount of commands output by previous
+// CreateBackwardReferences calls, and must be incremented by the amount written
+// by this call.
+void CreateBackwardReferences(size_t num_bytes,
+                              size_t position,
+                              bool is_last,
+                              const uint8_t* ringbuffer,
+                              size_t ringbuffer_mask,
+                              const int quality,
+                              const int lgwin,
+                              Hashers* hashers,
+                              int hash_type,
+                              int* dist_cache,
+                              size_t* last_insert_len,
+                              Command* commands,
+                              size_t* num_commands,
+                              size_t* num_literals);
+
+static const float kInfinity = std::numeric_limits<float>::infinity();
+
+struct ZopfliNode {
+  ZopfliNode(void) : length(1),
+                     distance(0),
+                     insert_length(0),
+                     cost(kInfinity) {}
+
+  inline uint32_t copy_length() const {
+    return length & 0xffffff;
+  }
+
+  inline uint32_t length_code() const {
+    const uint32_t modifier = length >> 24;
+    return copy_length() + 9u - modifier;
+  }
+
+  inline uint32_t copy_distance() const {
+    return distance & 0x1ffffff;
+  }
+
+  inline uint32_t distance_code() const {
+    const uint32_t short_code = distance >> 25;
+    return short_code == 0 ? copy_distance() + 15 : short_code - 1;
+  }
+
+  inline uint32_t command_length() const {
+    return copy_length() + insert_length;
+  }
+
+  // best length to get up to this byte (not including this byte itself)
+  // highest 8 bit is used to reconstruct the length code
+  uint32_t length;
+  // distance associated with the length
+  // highest 7 bit contains distance short code + 1 (or zero if no short code)
+  uint32_t distance;
+  // number of literal inserts before this copy
+  uint32_t insert_length;
+  // smallest cost to get to this byte from the beginning, as found so far
+  float cost;
+};
+
+// Computes the shortest path of commands from position to at most
+// position + num_bytes.
+//
+// On return, path->size() is the number of commands found and path[i] is the
+// length of the ith command (copy length plus insert length).
+// Note that the sum of the lengths of all commands can be less than num_bytes.
+//
+// On return, the nodes[0..num_bytes] array will have the following
+// "ZopfliNode array invariant":
+// For each i in [1..num_bytes], if nodes[i].cost < kInfinity, then
+//   (1) nodes[i].copy_length() >= 2
+//   (2) nodes[i].command_length() <= i and
+//   (3) nodes[i - nodes[i].command_length()].cost < kInfinity
+void ZopfliComputeShortestPath(size_t num_bytes,
+                               size_t position,
+                               const uint8_t* ringbuffer,
+                               size_t ringbuffer_mask,
+                               const size_t max_backward_limit,
+                               const int* dist_cache,
+                               Hashers::H10* hasher,
+                               ZopfliNode* nodes,
+                               std::vector<uint32_t>* path);
+
+void ZopfliCreateCommands(const size_t num_bytes,
+                          const size_t block_start,
+                          const size_t max_backward_limit,
+                          const std::vector<uint32_t>& path,
+                          const ZopfliNode* nodes,
+                          int* dist_cache,
+                          size_t* last_insert_len,
+                          Command* commands,
+                          size_t* num_literals);
+
+}  // namespace brotli
+
+#endif  // BROTLI_ENC_BACKWARD_REFERENCES_H_