1 files changed, 267 insertions, 0 deletions
diff --git a/roms/edk2/MdeModulePkg/Library/BrotliCustomDecompressLib/brotli/research/find_opt_references.cc b/roms/edk2/MdeModulePkg/Library/BrotliCustomDecompressLib/brotli/research/find_opt_references.cc
new file mode 100644
index 000000000..378d3b521
--- /dev/null
+++ b/roms/edk2/MdeModulePkg/Library/BrotliCustomDecompressLib/brotli/research/find_opt_references.cc
@@ -0,0 +1,267 @@
+/* Copyright 2016 Google Inc. All Rights Reserved.
+   Author: zip753@gmail.com (Ivan Nikulin)
+
+   Distributed under MIT license.
+   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+/* Tool for generating optimal backward references for the input file. Uses
+   sais-lite library for building suffix array. */
+
+#include <algorithm>
+#include <cassert>
+#include <cstdio>
+#include <cstring>
+#include <functional>
+#include <utility>
+#include <vector>
+
+#include <gflags/gflags.h>
+using gflags::ParseCommandLineFlags;
+
+#include "./esaxx/sais.hxx"
+
+DEFINE_bool(advanced, false, "Advanced searching mode: finds all longest "
+    "matches at positions that are not covered by matches of length at least "
+    "max_length. WARNING: uses much more memory than simple mode, especially "
+    "for small values of min_length.");
+DEFINE_int32(min_length, 1, "Minimal length of found backward references.");
+/* For advanced mode. */
+DEFINE_int32(long_length, 32,
+             "Maximal length of found backward references for advanced mode.");
+DEFINE_int32(skip, 1, "Number of bytes to skip.");
+
+const size_t kFileBufferSize = (1 << 16);  // 64KB
+
+typedef int sarray_type;  // Can't make it unsigned because of templates :(
+typedef uint8_t input_type;
+typedef uint32_t lcp_type;
+typedef std::pair<int, std::vector<int> > entry_type;
+typedef std::function<void(sarray_type*, lcp_type*, size_t, int, int, int, int,
+                           int)> Fn;
+
+void ReadInput(FILE* fin, input_type* storage, size_t input_size) {
+  size_t last_pos = 0;
+  size_t available_in;
+  fseek(fin, 0, SEEK_SET);
+  do {
+    available_in = fread(storage + last_pos, 1, kFileBufferSize, fin);
+    last_pos += available_in;
+  } while (available_in != 0);
+  assert(last_pos == input_size);
+}
+
+void BuildLCP(input_type* storage, sarray_type* sarray, lcp_type* lcp,
+              size_t size, uint32_t* pos) {
+  for (int i = 0; i < size; ++i) {
+    pos[sarray[i]] = i;
+  }
+  uint32_t k = 0;
+  lcp[size - 1] = 0;
+  for (int i = 0; i < size; ++i) {
+    if (pos[i] == size - 1) {
+      k = 0;
+      continue;
+    }
+    uint32_t j = sarray[pos[i] + 1];  // Suffix which follow i-th suffix in SA.
+    while (i + k < size && j + k < size && storage[i + k] == storage[j + k]) {
+      ++k;
+    }
+    lcp[pos[i]] = k;
+    if (k > 0) --k;
+  }
+}
+
+inline void PrintReference(sarray_type* sarray, lcp_type* lcp, size_t size,
+                           int idx, int left_ix, int right_ix, int left_lcp,
+                           int right_lcp, FILE* fout) {
+  int max_lcp_ix;
+  if (right_ix == size - 1 || (left_ix >= 0 && left_lcp >= right_lcp)) {
+    max_lcp_ix = left_ix;
+  } else {
+    max_lcp_ix = right_ix;
+  }
+  int dist = idx - sarray[max_lcp_ix];
+  assert(dist > 0);
+  fputc(1, fout);
+  fwrite(&idx, sizeof(int), 1, fout);   // Position in input.
+  fwrite(&dist, sizeof(int), 1, fout);  // Backward distance.
+}
+
+inline void GoLeft(sarray_type* sarray, lcp_type* lcp, int idx, int left_ix,
+                   int left_lcp, entry_type* entry) {
+  entry->first = left_lcp;
+  if (left_lcp > FLAGS_long_length) return;
+  for (; left_ix >= 0; --left_ix) {
+    if (lcp[left_ix] < left_lcp) break;
+    if (sarray[left_ix] < idx) {
+      entry->second.push_back(idx - sarray[left_ix]);
+    }
+  }
+}
+
+inline void GoRight(sarray_type* sarray, lcp_type* lcp, int idx, size_t size,
+                    int right_ix, int right_lcp, entry_type* entry) {
+  entry->first = right_lcp;
+  if (right_lcp > FLAGS_long_length) return;
+  for (; right_ix < size - 1; ++right_ix) {
+    if (lcp[right_ix] < right_lcp) break;
+    if (sarray[right_ix] < idx) {
+      entry->second.push_back(idx - sarray[right_ix]);
+    }
+  }
+}
+
+inline void StoreReference(sarray_type* sarray, lcp_type* lcp, size_t size,
+                           int idx, int left_ix, int right_ix, int left_lcp,
+                           int right_lcp, entry_type* entries) {
+  if (right_ix == size - 1 || (left_ix >= 0 && left_lcp > right_lcp)) {
+    // right is invalid or left is better
+    GoLeft(sarray, lcp, idx, left_ix, left_lcp, &entries[idx]);
+  } else if (left_ix < 0 || (right_ix < size - 1 && right_lcp > left_lcp)) {
+    // left is invalid or right is better
+    GoRight(sarray, lcp, idx, size, right_ix, right_lcp, &entries[idx]);
+  } else {  // both are valid and of equal length
+    GoLeft(sarray, lcp, idx, left_ix, left_lcp, &entries[idx]);
+    GoRight(sarray, lcp, idx, size, right_ix, right_lcp, &entries[idx]);
+  }
+}
+
+void ProcessReferences(sarray_type* sarray, lcp_type* lcp, size_t size,
+                       uint32_t* pos, const Fn& process_output) {
+  int min_length = FLAGS_min_length;
+  for (int idx = FLAGS_skip; idx < size; ++idx) {
+    int left_lcp = -1;
+    int left_ix;
+    for (left_ix = pos[idx] - 1; left_ix >= 0; --left_ix) {
+      if (left_lcp == -1 || left_lcp > lcp[left_ix]) {
+        left_lcp = lcp[left_ix];
+      }
+      if (left_lcp == 0) break;
+      if (sarray[left_ix] < idx) break;
+    }
+
+    int right_lcp = -1;
+    int right_ix;
+    for (right_ix = pos[idx]; right_ix < size - 1; ++right_ix) {
+      if (right_lcp == -1 || right_lcp > lcp[right_ix]) {
+        right_lcp = lcp[right_ix];
+      }
+      // Stop if we have better result from the left side already.
+      if (right_lcp < left_lcp && left_ix >= 0) break;
+      if (right_lcp == 0) break;
+      if (sarray[right_ix] < idx) break;
+    }
+
+    if ((left_ix >= 0 && left_lcp >= min_length) ||
+        (right_ix < size - 1 && right_lcp >= min_length)) {
+      process_output(sarray, lcp, size, idx, left_ix, right_ix, left_lcp,
+                     right_lcp);
+    }
+  }
+}
+
+void ProcessEntries(entry_type* entries, size_t size, FILE* fout) {
+  int long_length = FLAGS_long_length;
+  std::vector<std::pair<int, int> > segments;
+  size_t idx;
+  for (idx = 0; idx < size;) {
+    entry_type& entry = entries[idx];
+    if (entry.first > long_length) {
+      // Add segment.
+      if (segments.empty() || segments.back().second < idx) {
+        segments.push_back({idx, idx + entry.first});
+      } else {
+        segments.back().second = idx + entry.first;
+      }
+    }
+    ++idx;
+  }
+  printf("Segments generated.\n");
+  size_t segments_ix = 0;
+  for (idx = 0; idx < size;) {
+    if (idx == segments[segments_ix].first) {
+      // Skip segment.
+      idx = segments[segments_ix].second;
+    } else {
+      for (auto& dist : entries[idx].second) {
+        fputc(1, fout);
+        fwrite(&idx, sizeof(int), 1, fout);   // Position in input.
+        fwrite(&dist, sizeof(int), 1, fout);  // Backward distance.
+      }
+      ++idx;
+    }
+  }
+}
+
+int main(int argc, char* argv[]) {
+  ParseCommandLineFlags(&argc, &argv, true);
+  if (argc != 3) {
+    printf("usage: %s input_file output_file\n", argv[0]);
+    return 1;
+  }
+
+  FILE* fin = fopen(argv[1], "rb");
+  FILE* fout = fopen(argv[2], "w");
+
+  fseek(fin, 0, SEEK_END);
+  int input_size = ftell(fin);
+  fseek(fin, 0, SEEK_SET);
+  printf("The file size is %u bytes\n", input_size);
+
+  input_type* storage = new input_type[input_size];
+
+  ReadInput(fin, storage, input_size);
+  fclose(fin);
+
+  sarray_type* sarray = new sarray_type[input_size];
+  saisxx(storage, sarray, input_size);
+  printf("Suffix array calculated.\n");
+
+  // Inverse suffix array.
+  uint32_t* pos = new uint32_t[input_size];
+
+  lcp_type* lcp = new lcp_type[input_size];
+  BuildLCP(storage, sarray, lcp, input_size, pos);
+  printf("LCP array constructed.\n");
+  delete[] storage;
+
+  using std::placeholders::_1;
+  using std::placeholders::_2;
+  using std::placeholders::_3;
+  using std::placeholders::_4;
+  using std::placeholders::_5;
+  using std::placeholders::_6;
+  using std::placeholders::_7;
+  using std::placeholders::_8;
+  entry_type* entries;
+  if (FLAGS_advanced) {
+    entries = new entry_type[input_size];
+    for (size_t i = 0; i < input_size; ++i) entries[i].first = -1;
+  }
+  Fn print = std::bind(PrintReference, _1, _2, _3, _4, _5, _6, _7, _8, fout);
+  Fn store = std::bind(StoreReference, _1, _2, _3, _4, _5, _6, _7, _8, entries);
+
+  ProcessReferences(sarray, lcp, input_size, pos,
+                    FLAGS_advanced ? store : print);
+  printf("References processed.\n");
+
+  if (FLAGS_advanced) {
+    int good_cnt = 0;
+    uint64_t avg_cnt = 0;
+    for (size_t i = 0; i < input_size; ++i) {
+      if (entries[i].first != -1) {
+        ++good_cnt;
+        avg_cnt += entries[i].second.size();
+      }
+    }
+    printf("Number of covered positions = %d\n", good_cnt);
+    printf("Average number of references per covered position = %.4lf\n",
+            static_cast<double>(avg_cnt) / good_cnt);
+    ProcessEntries(entries, input_size, fout);
+    printf("Entries processed.\n");
+  }
+
+  fclose(fout);
+  return 0;
+}