Update brotli to v1.0.0-snapshot.

third_party/brotli/enc/brotli_bit_stream.c

+/* Copyright 2014 Google Inc. All Rights Reserved.
+
+   Distributed under MIT license.
+   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+/* Brotli bit stream functions to support the low level format. There are no
+   compression algorithms here, just the right ordering of bits to match the
+   specs. */
+
+#include "./brotli_bit_stream.h"
+
+#include <string.h>  /* memcpy, memset */
+
+#include "../common/constants.h"
+#include <brotli/types.h>
+#include "./context.h"
+#include "./entropy_encode.h"
+#include "./entropy_encode_static.h"
+#include "./fast_log.h"
+#include "./memory.h"
+#include "./port.h"
+#include "./write_bits.h"
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+#define MAX_HUFFMAN_TREE_SIZE (2 * BROTLI_NUM_COMMAND_SYMBOLS + 1)
+/* The size of Huffman dictionary for distances assuming that NPOSTFIX = 0 and
+ NDIRECT = 0. */
+#define SIMPLE_DISTANCE_ALPHABET_SIZE (BROTLI_NUM_DISTANCE_SHORT_CODES + \
+                                       (2 * BROTLI_MAX_DISTANCE_BITS))
+/* SIMPLE_DISTANCE_ALPHABET_SIZE == 64 */
+#define SIMPLE_DISTANCE_ALPHABET_BITS 6
+
+/* Represents the range of values belonging to a prefix code:
+   [offset, offset + 2^nbits) */
+typedef struct PrefixCodeRange {
+  uint32_t offset;
+  uint32_t nbits;
+} PrefixCodeRange;
+
+static const PrefixCodeRange
+    kBlockLengthPrefixCode[BROTLI_NUM_BLOCK_LEN_SYMBOLS] = {
+  { 1, 2}, { 5, 2}, { 9, 2}, {13, 2}, {17, 3}, { 25, 3}, { 33, 3},
+  {41, 3}, {49, 4}, {65, 4}, {81, 4}, {97, 4}, {113, 5}, {145, 5},
+  {177, 5}, { 209,  5}, { 241,  6}, { 305,  6}, { 369,  7}, {  497,  8},
+  {753, 9}, {1265, 10}, {2289, 11}, {4337, 12}, {8433, 13}, {16625, 24}
+};
+
+static BROTLI_INLINE uint32_t BlockLengthPrefixCode(uint32_t len) {
+  uint32_t code = (len >= 177) ? (len >= 753 ? 20 : 14) : (len >= 41 ? 7 : 0);
+  while (code < (BROTLI_NUM_BLOCK_LEN_SYMBOLS - 1) &&
+      len >= kBlockLengthPrefixCode[code + 1].offset) ++code;
+  return code;
+}
+
+static BROTLI_INLINE void GetBlockLengthPrefixCode(uint32_t len, size_t* code,
+    uint32_t* n_extra, uint32_t* extra) {
+  *code = BlockLengthPrefixCode(len);
+  *n_extra = kBlockLengthPrefixCode[*code].nbits;
+  *extra = len - kBlockLengthPrefixCode[*code].offset;
+}
+
+typedef struct BlockTypeCodeCalculator {
+  size_t last_type;
+  size_t second_last_type;
+} BlockTypeCodeCalculator;
+
+static void InitBlockTypeCodeCalculator(BlockTypeCodeCalculator* self) {
+  self->last_type = 1;
+  self->second_last_type = 0;
+}
+
+static BROTLI_INLINE size_t NextBlockTypeCode(
+    BlockTypeCodeCalculator* calculator, uint8_t type) {
+  size_t type_code = (type == calculator->last_type + 1) ? 1u :
+      (type == calculator->second_last_type) ? 0u : type + 2u;
+  calculator->second_last_type = calculator->last_type;
+  calculator->last_type = type;
+  return type_code;
+}
+
+/* |nibblesbits| represents the 2 bits to encode MNIBBLES (0-3)
+   REQUIRES: length > 0
+   REQUIRES: length <= (1 << 24) */
+static void BrotliEncodeMlen(size_t length, uint64_t* bits,
+                             size_t* numbits, uint64_t* nibblesbits) {
+  size_t lg = (length == 1) ? 1 : Log2FloorNonZero((uint32_t)(length - 1)) + 1;
+  size_t mnibbles = (lg < 16 ? 16 : (lg + 3)) / 4;
+  assert(length > 0);
+  assert(length <= (1 << 24));
+  assert(lg <= 24);
+  *nibblesbits = mnibbles - 4;
+  *numbits = mnibbles * 4;
+  *bits = length - 1;
+}
+
+static BROTLI_INLINE void StoreCommandExtra(
+    const Command* cmd, size_t* storage_ix, uint8_t* storage) {
+  uint32_t copylen_code = CommandCopyLenCode(cmd);
+  uint16_t inscode = GetInsertLengthCode(cmd->insert_len_);
+  uint16_t copycode = GetCopyLengthCode(copylen_code);
+  uint32_t insnumextra = GetInsertExtra(inscode);
+  uint64_t insextraval = cmd->insert_len_ - GetInsertBase(inscode);
+  uint64_t copyextraval = copylen_code - GetCopyBase(copycode);
+  uint64_t bits = (copyextraval << insnumextra) | insextraval;
+  BrotliWriteBits(
+      insnumextra + GetCopyExtra(copycode), bits, storage_ix, storage);
+}
+
+/* Data structure that stores almost everything that is needed to encode each
+   block switch command. */
+typedef struct BlockSplitCode {
+  BlockTypeCodeCalculator type_code_calculator;
+  uint8_t type_depths[BROTLI_MAX_BLOCK_TYPE_SYMBOLS];
+  uint16_t type_bits[BROTLI_MAX_BLOCK_TYPE_SYMBOLS];
+  uint8_t length_depths[BROTLI_NUM_BLOCK_LEN_SYMBOLS];
+  uint16_t length_bits[BROTLI_NUM_BLOCK_LEN_SYMBOLS];
+} BlockSplitCode;
+
+/* Stores a number between 0 and 255. */
+static void StoreVarLenUint8(size_t n, size_t* storage_ix, uint8_t* storage) {
+  if (n == 0) {
+    BrotliWriteBits(1, 0, storage_ix, storage);
+  } else {
+    size_t nbits = Log2FloorNonZero(n);
+    BrotliWriteBits(1, 1, storage_ix, storage);
+    BrotliWriteBits(3, nbits, storage_ix, storage);
+    BrotliWriteBits(nbits, n - ((size_t)1 << nbits), storage_ix, storage);
+  }
+}
+
+/* Stores the compressed meta-block header.
+   REQUIRES: length > 0
+   REQUIRES: length <= (1 << 24) */
+static void StoreCompressedMetaBlockHeader(BROTLI_BOOL is_final_block,
+                                           size_t length,
+                                           size_t* storage_ix,
+                                           uint8_t* storage) {
+  uint64_t lenbits;
+  size_t nlenbits;
+  uint64_t nibblesbits;
+
+  /* Write ISLAST bit. */
+  BrotliWriteBits(1, (uint64_t)is_final_block, storage_ix, storage);
+  /* Write ISEMPTY bit. */
+  if (is_final_block) {
+    BrotliWriteBits(1, 0, storage_ix, storage);
+  }
+
+  BrotliEncodeMlen(length, &lenbits, &nlenbits, &nibblesbits);
+  BrotliWriteBits(2, nibblesbits, storage_ix, storage);
+  BrotliWriteBits(nlenbits, lenbits, storage_ix, storage);
+
+  if (!is_final_block) {
+    /* Write ISUNCOMPRESSED bit. */
+    BrotliWriteBits(1, 0, storage_ix, storage);
+  }
+}
+
+/* Stores the uncompressed meta-block header.
+   REQUIRES: length > 0
+   REQUIRES: length <= (1 << 24) */
+static void BrotliStoreUncompressedMetaBlockHeader(size_t length,
+                                                   size_t* storage_ix,
+                                                   uint8_t* storage) {
+  uint64_t lenbits;
+  size_t nlenbits;
+  uint64_t nibblesbits;
+
+  /* Write ISLAST bit.
+     Uncompressed block cannot be the last one, so set to 0. */
+  BrotliWriteBits(1, 0, storage_ix, storage);
+  BrotliEncodeMlen(length, &lenbits, &nlenbits, &nibblesbits);
+  BrotliWriteBits(2, nibblesbits, storage_ix, storage);
+  BrotliWriteBits(nlenbits, lenbits, storage_ix, storage);
+  /* Write ISUNCOMPRESSED bit. */
+  BrotliWriteBits(1, 1, storage_ix, storage);
+}
+
+static void BrotliStoreHuffmanTreeOfHuffmanTreeToBitMask(
+    const int num_codes, const uint8_t* code_length_bitdepth,
+    size_t* storage_ix, uint8_t* storage) {
+  static const uint8_t kStorageOrder[BROTLI_CODE_LENGTH_CODES] = {
+    1, 2, 3, 4, 0, 5, 17, 6, 16, 7, 8, 9, 10, 11, 12, 13, 14, 15
+  };
+  /* The bit lengths of the Huffman code over the code length alphabet
+     are compressed with the following static Huffman code:
+       Symbol   Code
+       ------   ----
+       0          00
+       1        1110
+       2         110
+       3          01
+       4          10
+       5        1111 */
+  static const uint8_t kHuffmanBitLengthHuffmanCodeSymbols[6] = {
+     0, 7, 3, 2, 1, 15
+  };
+  static const uint8_t kHuffmanBitLengthHuffmanCodeBitLengths[6] = {
+    2, 4, 3, 2, 2, 4
+  };
+
+  size_t skip_some = 0;  /* skips none. */
+
+  /* Throw away trailing zeros: */
+  size_t codes_to_store = BROTLI_CODE_LENGTH_CODES;
+  if (num_codes > 1) {
+    for (; codes_to_store > 0; --codes_to_store) {
+      if (code_length_bitdepth[kStorageOrder[codes_to_store - 1]] != 0) {
+        break;
+      }
+    }
+  }
+  if (code_length_bitdepth[kStorageOrder[0]] == 0 &&
+      code_length_bitdepth[kStorageOrder[1]] == 0) {
+    skip_some = 2;  /* skips two. */
+    if (code_length_bitdepth[kStorageOrder[2]] == 0) {
+      skip_some = 3;  /* skips three. */
+    }
+  }
+  BrotliWriteBits(2, skip_some, storage_ix, storage);
+  {
+    size_t i;
+    for (i = skip_some; i < codes_to_store; ++i) {
+      size_t l = code_length_bitdepth[kStorageOrder[i]];
+      BrotliWriteBits(kHuffmanBitLengthHuffmanCodeBitLengths[l],
+          kHuffmanBitLengthHuffmanCodeSymbols[l], storage_ix, storage);
+    }
+  }
+}
+
+static void BrotliStoreHuffmanTreeToBitMask(
+    const size_t huffman_tree_size, const uint8_t* huffman_tree,
+    const uint8_t* huffman_tree_extra_bits, const uint8_t* code_length_bitdepth,
+    const uint16_t* code_length_bitdepth_symbols,
+    size_t* BROTLI_RESTRICT storage_ix, uint8_t* BROTLI_RESTRICT storage) {
+  size_t i;
+  for (i = 0; i < huffman_tree_size; ++i) {
+    size_t ix = huffman_tree[i];
+    BrotliWriteBits(code_length_bitdepth[ix], code_length_bitdepth_symbols[ix],
+                    storage_ix, storage);
+    /* Extra bits */
+    switch (ix) {
+      case BROTLI_REPEAT_PREVIOUS_CODE_LENGTH:
+        BrotliWriteBits(2, huffman_tree_extra_bits[i], storage_ix, storage);
+        break;
+      case BROTLI_REPEAT_ZERO_CODE_LENGTH:
+        BrotliWriteBits(3, huffman_tree_extra_bits[i], storage_ix, storage);
+        break;
+    }
+  }
+}
+
+static void StoreSimpleHuffmanTree(const uint8_t* depths,
+                                   size_t symbols[4],
+                                   size_t num_symbols,
+                                   size_t max_bits,
+                                   size_t *storage_ix, uint8_t *storage) {
+  /* value of 1 indicates a simple Huffman code */
+  BrotliWriteBits(2, 1, storage_ix, storage);
+  BrotliWriteBits(2, num_symbols - 1, storage_ix, storage);  /* NSYM - 1 */
+
+  {
+    /* Sort */
+    size_t i;
+    for (i = 0; i < num_symbols; i++) {
+      size_t j;
+      for (j = i + 1; j < num_symbols; j++) {
+        if (depths[symbols[j]] < depths[symbols[i]]) {
+          BROTLI_SWAP(size_t, symbols, j, i);
+        }
+      }
+    }
+  }
+
+  if (num_symbols == 2) {
+    BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
+    BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
+  } else if (num_symbols == 3) {
+    BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
+    BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
+    BrotliWriteBits(max_bits, symbols[2], storage_ix, storage);
+  } else {
+    BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
+    BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
+    BrotliWriteBits(max_bits, symbols[2], storage_ix, storage);
+    BrotliWriteBits(max_bits, symbols[3], storage_ix, storage);
+    /* tree-select */
+    BrotliWriteBits(1, depths[symbols[0]] == 1 ? 1 : 0, storage_ix, storage);
+  }
+}
+
+/* num = alphabet size
+   depths = symbol depths */
+void BrotliStoreHuffmanTree(const uint8_t* depths, size_t num,
+                            HuffmanTree* tree,
+                            size_t *storage_ix, uint8_t *storage) {
+  /* Write the Huffman tree into the brotli-representation.
+     The command alphabet is the largest, so this allocation will fit all
+     alphabets. */
+  uint8_t huffman_tree[BROTLI_NUM_COMMAND_SYMBOLS];
+  uint8_t huffman_tree_extra_bits[BROTLI_NUM_COMMAND_SYMBOLS];
+  size_t huffman_tree_size = 0;
+  uint8_t code_length_bitdepth[BROTLI_CODE_LENGTH_CODES] = { 0 };
+  uint16_t code_length_bitdepth_symbols[BROTLI_CODE_LENGTH_CODES];
+  uint32_t huffman_tree_histogram[BROTLI_CODE_LENGTH_CODES] = { 0 };
+  size_t i;
+  int num_codes = 0;
+  size_t code = 0;
+
+  assert(num <= BROTLI_NUM_COMMAND_SYMBOLS);
+
+  BrotliWriteHuffmanTree(depths, num, &huffman_tree_size, huffman_tree,
+                         huffman_tree_extra_bits);
+
+  /* Calculate the statistics of the Huffman tree in brotli-representation. */
+  for (i = 0; i < huffman_tree_size; ++i) {
+    ++huffman_tree_histogram[huffman_tree[i]];
+  }
+
+  for (i = 0; i < BROTLI_CODE_LENGTH_CODES; ++i) {
+    if (huffman_tree_histogram[i]) {
+      if (num_codes == 0) {
+        code = i;
+        num_codes = 1;
+      } else if (num_codes == 1) {
+        num_codes = 2;
+        break;
+      }
+    }
+  }
+
+  /* Calculate another Huffman tree to use for compressing both the
+     earlier Huffman tree with. */
+  BrotliCreateHuffmanTree(huffman_tree_histogram, BROTLI_CODE_LENGTH_CODES,
+                          5, tree, code_length_bitdepth);
+  BrotliConvertBitDepthsToSymbols(code_length_bitdepth,
+                                  BROTLI_CODE_LENGTH_CODES,
+                                  code_length_bitdepth_symbols);
+
+  /* Now, we have all the data, let's start storing it */
+  BrotliStoreHuffmanTreeOfHuffmanTreeToBitMask(num_codes, code_length_bitdepth,
+                                               storage_ix, storage);
+
+  if (num_codes == 1) {
+    code_length_bitdepth[code] = 0;
+  }
+
+  /* Store the real Huffman tree now. */
+  BrotliStoreHuffmanTreeToBitMask(huffman_tree_size,
+                                  huffman_tree,
+                                  huffman_tree_extra_bits,
+                                  code_length_bitdepth,
+                                  code_length_bitdepth_symbols,
+                                  storage_ix, storage);
+}
+
+/* Builds a Huffman tree from histogram[0:length] into depth[0:length] and
+   bits[0:length] and stores the encoded tree to the bit stream. */
+static void BuildAndStoreHuffmanTree(const uint32_t *histogram,
+                                     const size_t length,
+                                     HuffmanTree* tree,
+                                     uint8_t* depth,
+                                     uint16_t* bits,
+                                     size_t* storage_ix,
+                                     uint8_t* storage) {
+  size_t count = 0;
+  size_t s4[4] = { 0 };
+  size_t i;
+  size_t max_bits = 0;
+  for (i = 0; i < length; i++) {
+    if (histogram[i]) {
+      if (count < 4) {
+        s4[count] = i;
+      } else if (count > 4) {
+        break;
+      }
+      count++;
+    }
+  }
+
+  {
+    size_t max_bits_counter = length - 1;
+    while (max_bits_counter) {
+      max_bits_counter >>= 1;
+      ++max_bits;
+    }
+  }
+
+  if (count <= 1) {
+    BrotliWriteBits(4, 1, storage_ix, storage);
+    BrotliWriteBits(max_bits, s4[0], storage_ix, storage);
+    depth[s4[0]] = 0;
+    bits[s4[0]] = 0;
+    return;
+  }
+
+  memset(depth, 0, length * sizeof(depth[0]));
+  BrotliCreateHuffmanTree(histogram, length, 15, tree, depth);
+  BrotliConvertBitDepthsToSymbols(depth, length, bits);
+
+  if (count <= 4) {
+    StoreSimpleHuffmanTree(depth, s4, count, max_bits, storage_ix, storage);
+  } else {
+    BrotliStoreHuffmanTree(depth, length, tree, storage_ix, storage);
+  }
+}
+
+static BROTLI_INLINE BROTLI_BOOL SortHuffmanTree(
+    const HuffmanTree* v0, const HuffmanTree* v1) {
+  return TO_BROTLI_BOOL(v0->total_count_ < v1->total_count_);
+}
+
+void BrotliBuildAndStoreHuffmanTreeFast(MemoryManager* m,
+                                        const uint32_t* histogram,
+                                        const size_t histogram_total,
+                                        const size_t max_bits,
+                                        uint8_t* depth, uint16_t* bits,
+                                        size_t* storage_ix,
+                                        uint8_t* storage) {
+  size_t count = 0;
+  size_t symbols[4] = { 0 };
+  size_t length = 0;
+  size_t total = histogram_total;
+  while (total != 0) {
+    if (histogram[length]) {
+      if (count < 4) {
+        symbols[count] = length;
+      }
+      ++count;
+      total -= histogram[length];
+    }
+    ++length;
+  }
+
+  if (count <= 1) {
+    BrotliWriteBits(4, 1, storage_ix, storage);
+    BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
+    depth[symbols[0]] = 0;
+    bits[symbols[0]] = 0;
+    return;
+  }
+
+  memset(depth, 0, length * sizeof(depth[0]));
+  {
+    const size_t max_tree_size = 2 * length + 1;
+    HuffmanTree* tree = BROTLI_ALLOC(m, HuffmanTree, max_tree_size);
+    uint32_t count_limit;
+    if (BROTLI_IS_OOM(m)) return;
+    for (count_limit = 1; ; count_limit *= 2) {
+      HuffmanTree* node = tree;
+      size_t l;
+      for (l = length; l != 0;) {
+        --l;
+        if (histogram[l]) {
+          if (BROTLI_PREDICT_TRUE(histogram[l] >= count_limit)) {
+            InitHuffmanTree(node, histogram[l], -1, (int16_t)l);
+          } else {
+            InitHuffmanTree(node, count_limit, -1, (int16_t)l);
+          }
+          ++node;
+        }
+      }
+      {
+        const int n = (int)(node - tree);
+        HuffmanTree sentinel;
+        int i = 0;      /* Points to the next leaf node. */
+        int j = n + 1;  /* Points to the next non-leaf node. */
+        int k;
+
+        SortHuffmanTreeItems(tree, (size_t)n, SortHuffmanTree);
+        /* The nodes are:
+           [0, n): the sorted leaf nodes that we start with.
+           [n]: we add a sentinel here.
+           [n + 1, 2n): new parent nodes are added here, starting from
+                        (n+1). These are naturally in ascending order.
+           [2n]: we add a sentinel at the end as well.
+           There will be (2n+1) elements at the end. */
+        InitHuffmanTree(&sentinel, BROTLI_UINT32_MAX, -1, -1);
+        *node++ = sentinel;
+        *node++ = sentinel;
+
+        for (k = n - 1; k > 0; --k) {
+          int left, right;
+          if (tree[i].total_count_ <= tree[j].total_count_) {
+            left = i;
+            ++i;
+          } else {
+            left = j;
+            ++j;
+          }
+          if (tree[i].total_count_ <= tree[j].total_count_) {
+            right = i;
+            ++i;
+          } else {
+            right = j;
+            ++j;
+          }
+          /* The sentinel node becomes the parent node. */
+          node[-1].total_count_ =
+              tree[left].total_count_ + tree[right].total_count_;
+          node[-1].index_left_ = (int16_t)left;
+          node[-1].index_right_or_value_ = (int16_t)right;
+          /* Add back the last sentinel node. */
+          *node++ = sentinel;
+        }
+        if (BrotliSetDepth(2 * n - 1, tree, depth, 14)) {
+          /* We need to pack the Huffman tree in 14 bits. If this was not
+             successful, add fake entities to the lowest values and retry. */
+          break;
+        }
+      }
+    }
+    BROTLI_FREE(m, tree);
+  }
+  BrotliConvertBitDepthsToSymbols(depth, length, bits);
+  if (count <= 4) {
+    size_t i;
+    /* value of 1 indicates a simple Huffman code */
+    BrotliWriteBits(2, 1, storage_ix, storage);
+    BrotliWriteBits(2, count - 1, storage_ix, storage);  /* NSYM - 1 */
+
+    /* Sort */
+    for (i = 0; i < count; i++) {
+      size_t j;
+      for (j = i + 1; j < count; j++) {
+        if (depth[symbols[j]] < depth[symbols[i]]) {
+          BROTLI_SWAP(size_t, symbols, j, i);
+        }
+      }
+    }
+
+    if (count == 2) {
+      BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
+      BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
+    } else if (count == 3) {
+      BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
+      BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
+      BrotliWriteBits(max_bits, symbols[2], storage_ix, storage);
+    } else {
+      BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
+      BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
+      BrotliWriteBits(max_bits, symbols[2], storage_ix, storage);
+      BrotliWriteBits(max_bits, symbols[3], storage_ix, storage);
+      /* tree-select */
+      BrotliWriteBits(1, depth[symbols[0]] == 1 ? 1 : 0, storage_ix, storage);
+    }
+  } else {
+    uint8_t previous_value = 8;
+    size_t i;
+    /* Complex Huffman Tree */
+    StoreStaticCodeLengthCode(storage_ix, storage);
+
+    /* Actual RLE coding. */
+    for (i = 0; i < length;) {
+      const uint8_t value = depth[i];
+      size_t reps = 1;
+      size_t k;
+      for (k = i + 1; k < length && depth[k] == value; ++k) {
+        ++reps;
+      }
+      i += reps;
+      if (value == 0) {
+        BrotliWriteBits(kZeroRepsDepth[reps], kZeroRepsBits[reps],
+                        storage_ix, storage);
+      } else {
+        if (previous_value != value) {
+          BrotliWriteBits(kCodeLengthDepth[value], kCodeLengthBits[value],
+                          storage_ix, storage);
+          --reps;
+        }
+        if (reps < 3) {
+          while (reps != 0) {
+            reps--;
+            BrotliWriteBits(kCodeLengthDepth[value], kCodeLengthBits[value],
+                            storage_ix, storage);
+          }
+        } else {
+          reps -= 3;
+          BrotliWriteBits(kNonZeroRepsDepth[reps], kNonZeroRepsBits[reps],
+                          storage_ix, storage);
+        }
+        previous_value = value;
+      }
+    }
+  }
+}
+
+static size_t IndexOf(const uint8_t* v, size_t v_size, uint8_t value) {
+  size_t i = 0;
+  for (; i < v_size; ++i) {
+    if (v[i] == value) return i;
+  }
+  return i;
+}
+
+static void MoveToFront(uint8_t* v, size_t index) {
+  uint8_t value = v[index];
+  size_t i;
+  for (i = index; i != 0; --i) {
+    v[i] = v[i - 1];
+  }
+  v[0] = value;
+}
+
+static void MoveToFrontTransform(const uint32_t* BROTLI_RESTRICT v_in,
+                                 const size_t v_size,
+                                 uint32_t* v_out) {
+  size_t i;
+  uint8_t mtf[256];
+  uint32_t max_value;
+  if (v_size == 0) {
+    return;
+  }
+  max_value = v_in[0];
+  for (i = 1; i < v_size; ++i) {
+    if (v_in[i] > max_value) max_value = v_in[i];
+  }
+  assert(max_value < 256u);
+  for (i = 0; i <= max_value; ++i) {
+    mtf[i] = (uint8_t)i;
+  }
+  {
+    size_t mtf_size = max_value + 1;
+    for (i = 0; i < v_size; ++i) {
+      size_t index = IndexOf(mtf, mtf_size, (uint8_t)v_in[i]);
+      assert(index < mtf_size);
+      v_out[i] = (uint32_t)index;
+      MoveToFront(mtf, index);
+    }
+  }
+}
+
+/* Finds runs of zeros in v[0..in_size) and replaces them with a prefix code of
+   the run length plus extra bits (lower 9 bits is the prefix code and the rest
+   are the extra bits). Non-zero values in v[] are shifted by
+   *max_length_prefix. Will not create prefix codes bigger than the initial
+   value of *max_run_length_prefix. The prefix code of run length L is simply
+   Log2Floor(L) and the number of extra bits is the same as the prefix code. */
+static void RunLengthCodeZeros(const size_t in_size,
+    uint32_t* BROTLI_RESTRICT v, size_t* BROTLI_RESTRICT out_size,
+    uint32_t* BROTLI_RESTRICT max_run_length_prefix) {
+  uint32_t max_reps = 0;
+  size_t i;
+  uint32_t max_prefix;
+  for (i = 0; i < in_size;) {
+    uint32_t reps = 0;
+    for (; i < in_size && v[i] != 0; ++i) ;
+    for (; i < in_size && v[i] == 0; ++i) {
+      ++reps;
+    }
+    max_reps = BROTLI_MAX(uint32_t, reps, max_reps);
+  }
+  max_prefix = max_reps > 0 ? Log2FloorNonZero(max_reps) : 0;
+  max_prefix = BROTLI_MIN(uint32_t, max_prefix, *max_run_length_prefix);
+  *max_run_length_prefix = max_prefix;
+  *out_size = 0;
+  for (i = 0; i < in_size;) {
+    assert(*out_size <= i);
+    if (v[i] != 0) {
+      v[*out_size] = v[i] + *max_run_length_prefix;
+      ++i;
+      ++(*out_size);
+    } else {
+      uint32_t reps = 1;
+      size_t k;
+      for (k = i + 1; k < in_size && v[k] == 0; ++k) {
+        ++reps;
+      }
+      i += reps;
+      while (reps != 0) {
+        if (reps < (2u << max_prefix)) {
+          uint32_t run_length_prefix = Log2FloorNonZero(reps);
+          const uint32_t extra_bits = reps - (1u << run_length_prefix);
+          v[*out_size] = run_length_prefix + (extra_bits << 9);
+          ++(*out_size);
+          break;
+        } else {
+          const uint32_t extra_bits = (1u << max_prefix) - 1u;
+          v[*out_size] = max_prefix + (extra_bits << 9);
+          reps -= (2u << max_prefix) - 1u;
+          ++(*out_size);
+        }
+      }
+    }
+  }
+}
+
+#define SYMBOL_BITS 9
+
+static void EncodeContextMap(MemoryManager* m,
+                             const uint32_t* context_map,
+                             size_t context_map_size,
+                             size_t num_clusters,
+                             HuffmanTree* tree,
+                             size_t* storage_ix, uint8_t* storage) {
+  size_t i;
+  uint32_t* rle_symbols;
+  uint32_t max_run_length_prefix = 6;
+  size_t num_rle_symbols = 0;
+  uint32_t histogram[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
+  static const uint32_t kSymbolMask = (1u << SYMBOL_BITS) - 1u;
+  uint8_t depths[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
+  uint16_t bits[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
+
+  StoreVarLenUint8(num_clusters - 1, storage_ix, storage);
+
+  if (num_clusters == 1) {
+    return;
+  }
+
+  rle_symbols = BROTLI_ALLOC(m, uint32_t, context_map_size);
+  if (BROTLI_IS_OOM(m)) return;
+  MoveToFrontTransform(context_map, context_map_size, rle_symbols);
+  RunLengthCodeZeros(context_map_size, rle_symbols,
+                     &num_rle_symbols, &max_run_length_prefix);
+  memset(histogram, 0, sizeof(histogram));
+  for (i = 0; i < num_rle_symbols; ++i) {
+    ++histogram[rle_symbols[i] & kSymbolMask];
+  }
+  {
+    BROTLI_BOOL use_rle = TO_BROTLI_BOOL(max_run_length_prefix > 0);
+    BrotliWriteBits(1, (uint64_t)use_rle, storage_ix, storage);
+    if (use_rle) {
+      BrotliWriteBits(4, max_run_length_prefix - 1, storage_ix, storage);
+    }
+  }
+  BuildAndStoreHuffmanTree(histogram, num_clusters + max_run_length_prefix,
+                           tree, depths, bits, storage_ix, storage);
+  for (i = 0; i < num_rle_symbols; ++i) {
+    const uint32_t rle_symbol = rle_symbols[i] & kSymbolMask;
+    const uint32_t extra_bits_val = rle_symbols[i] >> SYMBOL_BITS;
+    BrotliWriteBits(depths[rle_symbol], bits[rle_symbol], storage_ix, storage);
+    if (rle_symbol > 0 && rle_symbol <= max_run_length_prefix) {
+      BrotliWriteBits(rle_symbol, extra_bits_val, storage_ix, storage);
+    }
+  }
+  BrotliWriteBits(1, 1, storage_ix, storage);  /* use move-to-front */
+  BROTLI_FREE(m, rle_symbols);
+}
+
+/* Stores the block switch command with index block_ix to the bit stream. */
+static BROTLI_INLINE void StoreBlockSwitch(BlockSplitCode* code,
+                                           const uint32_t block_len,
+                                           const uint8_t block_type,
+                                           BROTLI_BOOL is_first_block,
+                                           size_t* storage_ix,
+                                           uint8_t* storage) {
+  size_t typecode = NextBlockTypeCode(&code->type_code_calculator, block_type);
+  size_t lencode;
+  uint32_t len_nextra;
+  uint32_t len_extra;
+  if (!is_first_block) {
+    BrotliWriteBits(code->type_depths[typecode], code->type_bits[typecode],
+                    storage_ix, storage);
+  }
+  GetBlockLengthPrefixCode(block_len, &lencode, &len_nextra, &len_extra);
+
+  BrotliWriteBits(code->length_depths[lencode], code->length_bits[lencode],
+                  storage_ix, storage);
+  BrotliWriteBits(len_nextra, len_extra, storage_ix, storage);
+}
+
+/* Builds a BlockSplitCode data structure from the block split given by the
+   vector of block types and block lengths and stores it to the bit stream. */
+static void BuildAndStoreBlockSplitCode(const uint8_t* types,
+                                        const uint32_t* lengths,
+                                        const size_t num_blocks,
+                                        const size_t num_types,
+                                        HuffmanTree* tree,
+                                        BlockSplitCode* code,
+                                        size_t* storage_ix,
+                                        uint8_t* storage) {
+  uint32_t type_histo[BROTLI_MAX_BLOCK_TYPE_SYMBOLS];
+  uint32_t length_histo[BROTLI_NUM_BLOCK_LEN_SYMBOLS];
+  size_t i;
+  BlockTypeCodeCalculator type_code_calculator;
+  memset(type_histo, 0, (num_types + 2) * sizeof(type_histo[0]));
+  memset(length_histo, 0, sizeof(length_histo));
+  InitBlockTypeCodeCalculator(&type_code_calculator);
+  for (i = 0; i < num_blocks; ++i) {
+    size_t type_code = NextBlockTypeCode(&type_code_calculator, types[i]);
+    if (i != 0) ++type_histo[type_code];
+    ++length_histo[BlockLengthPrefixCode(lengths[i])];
+  }
+  StoreVarLenUint8(num_types - 1, storage_ix, storage);
+  if (num_types > 1) {  /* TODO: else? could StoreBlockSwitch occur? */
+    BuildAndStoreHuffmanTree(&type_histo[0], num_types + 2, tree,
+                             &code->type_depths[0], &code->type_bits[0],
+                             storage_ix, storage);
+    BuildAndStoreHuffmanTree(&length_histo[0], BROTLI_NUM_BLOCK_LEN_SYMBOLS,
+                             tree, &code->length_depths[0],
+                             &code->length_bits[0], storage_ix, storage);
+    StoreBlockSwitch(code, lengths[0], types[0], 1, storage_ix, storage);
+  }
+}
+
+/* Stores a context map where the histogram type is always the block type. */
+static void StoreTrivialContextMap(size_t num_types,
+                                   size_t context_bits,
+                                   HuffmanTree* tree,
+                                   size_t* storage_ix,
+                                   uint8_t* storage) {
+  StoreVarLenUint8(num_types - 1, storage_ix, storage);
+  if (num_types > 1) {
+    size_t repeat_code = context_bits - 1u;
+    size_t repeat_bits = (1u << repeat_code) - 1u;
+    size_t alphabet_size = num_types + repeat_code;
+    uint32_t histogram[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
+    uint8_t depths[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
+    uint16_t bits[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
+    size_t i;
+    memset(histogram, 0, alphabet_size * sizeof(histogram[0]));
+    /* Write RLEMAX. */
+    BrotliWriteBits(1, 1, storage_ix, storage);
+    BrotliWriteBits(4, repeat_code - 1, storage_ix, storage);
+    histogram[repeat_code] = (uint32_t)num_types;
+    histogram[0] = 1;
+    for (i = context_bits; i < alphabet_size; ++i) {
+      histogram[i] = 1;
+    }
+    BuildAndStoreHuffmanTree(histogram, alphabet_size, tree,
+                             depths, bits, storage_ix, storage);
+    for (i = 0; i < num_types; ++i) {
+      size_t code = (i == 0 ? 0 : i + context_bits - 1);
+      BrotliWriteBits(depths[code], bits[code], storage_ix, storage);
+      BrotliWriteBits(
+          depths[repeat_code], bits[repeat_code], storage_ix, storage);
+      BrotliWriteBits(repeat_code, repeat_bits, storage_ix, storage);
+    }
+    /* Write IMTF (inverse-move-to-front) bit. */
+    BrotliWriteBits(1, 1, storage_ix, storage);
+  }
+}
+
+/* Manages the encoding of one block category (literal, command or distance). */
+typedef struct BlockEncoder {
+  size_t alphabet_size_;
+  size_t num_block_types_;
+  const uint8_t* block_types_;  /* Not owned. */
+  const uint32_t* block_lengths_;  /* Not owned. */
+  size_t num_blocks_;
+  BlockSplitCode block_split_code_;
+  size_t block_ix_;
+  size_t block_len_;
+  size_t entropy_ix_;
+  uint8_t* depths_;
+  uint16_t* bits_;
+} BlockEncoder;
+
+static void InitBlockEncoder(BlockEncoder* self, size_t alphabet_size,
+    size_t num_block_types, const uint8_t* block_types,
+    const uint32_t* block_lengths, const size_t num_blocks) {
+  self->alphabet_size_ = alphabet_size;
+  self->num_block_types_ = num_block_types;
+  self->block_types_ = block_types;
+  self->block_lengths_ = block_lengths;
+  self->num_blocks_ = num_blocks;
+  InitBlockTypeCodeCalculator(&self->block_split_code_.type_code_calculator);
+  self->block_ix_ = 0;
+  self->block_len_ = num_blocks == 0 ? 0 : block_lengths[0];
+  self->entropy_ix_ = 0;
+  self->depths_ = 0;
+  self->bits_ = 0;
+}
+
+static void CleanupBlockEncoder(MemoryManager* m, BlockEncoder* self) {
+  BROTLI_FREE(m, self->depths_);
+  BROTLI_FREE(m, self->bits_);
+}
+
+/* Creates entropy codes of block lengths and block types and stores them
+   to the bit stream. */
+static void BuildAndStoreBlockSwitchEntropyCodes(BlockEncoder* self,
+    HuffmanTree* tree, size_t* storage_ix, uint8_t* storage) {
+  BuildAndStoreBlockSplitCode(self->block_types_, self->block_lengths_,
+      self->num_blocks_, self->num_block_types_, tree, &self->block_split_code_,
+      storage_ix, storage);
+}
+
+/* Stores the next symbol with the entropy code of the current block type.
+   Updates the block type and block length at block boundaries. */
+static void StoreSymbol(BlockEncoder* self, size_t symbol, size_t* storage_ix,
+    uint8_t* storage) {
+  if (self->block_len_ == 0) {
+    size_t block_ix = ++self->block_ix_;
+    uint32_t block_len = self->block_lengths_[block_ix];
+    uint8_t block_type = self->block_types_[block_ix];
+    self->block_len_ = block_len;
+    self->entropy_ix_ = block_type * self->alphabet_size_;
+    StoreBlockSwitch(&self->block_split_code_, block_len, block_type, 0,
+        storage_ix, storage);
+  }
+  --self->block_len_;
+  {
+    size_t ix = self->entropy_ix_ + symbol;
+    BrotliWriteBits(self->depths_[ix], self->bits_[ix], storage_ix, storage);
+  }
+}
+
+/* Stores the next symbol with the entropy code of the current block type and
+   context value.
+   Updates the block type and block length at block boundaries. */
+static void StoreSymbolWithContext(BlockEncoder* self, size_t symbol,
+    size_t context, const uint32_t* context_map, size_t* storage_ix,
+    uint8_t* storage, const size_t context_bits) {
+  if (self->block_len_ == 0) {
+    size_t block_ix = ++self->block_ix_;
+    uint32_t block_len = self->block_lengths_[block_ix];
+    uint8_t block_type = self->block_types_[block_ix];
+    self->block_len_ = block_len;
+    self->entropy_ix_ = (size_t)block_type << context_bits;
+    StoreBlockSwitch(&self->block_split_code_, block_len, block_type, 0,
+        storage_ix, storage);
+  }
+  --self->block_len_;
+  {
+    size_t histo_ix = context_map[self->entropy_ix_ + context];
+    size_t ix = histo_ix * self->alphabet_size_ + symbol;
+    BrotliWriteBits(self->depths_[ix], self->bits_[ix], storage_ix, storage);
+  }
+}
+
+#define FN(X) X ## Literal
+/* NOLINTNEXTLINE(build/include) */
+#include "./block_encoder_inc.h"
+#undef FN
+
+#define FN(X) X ## Command
+/* NOLINTNEXTLINE(build/include) */
+#include "./block_encoder_inc.h"
+#undef FN
+
+#define FN(X) X ## Distance
+/* NOLINTNEXTLINE(build/include) */
+#include "./block_encoder_inc.h"
+#undef FN
+
+static void JumpToByteBoundary(size_t* storage_ix, uint8_t* storage) {
+  *storage_ix = (*storage_ix + 7u) & ~7u;
+  storage[*storage_ix >> 3] = 0;
+}
+
+void BrotliStoreMetaBlock(MemoryManager* m,
+                          const uint8_t* input,
+                          size_t start_pos,
+                          size_t length,
+                          size_t mask,
+                          uint8_t prev_byte,
+                          uint8_t prev_byte2,
+                          BROTLI_BOOL is_last,
+                          uint32_t num_direct_distance_codes,
+                          uint32_t distance_postfix_bits,
+                          ContextType literal_context_mode,
+                          const Command *commands,
+                          size_t n_commands,
+                          const MetaBlockSplit* mb,
+                          size_t *storage_ix,
+                          uint8_t *storage) {
+  size_t pos = start_pos;
+  size_t i;
+  size_t num_distance_codes =
+      BROTLI_NUM_DISTANCE_SHORT_CODES + num_direct_distance_codes +
+      (48u << distance_postfix_bits);
+  HuffmanTree* tree;
+  BlockEncoder literal_enc;
+  BlockEncoder command_enc;
+  BlockEncoder distance_enc;
+
+  StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage);
+
+  tree = BROTLI_ALLOC(m, HuffmanTree, MAX_HUFFMAN_TREE_SIZE);
+  if (BROTLI_IS_OOM(m)) return;
+  InitBlockEncoder(&literal_enc, 256, mb->literal_split.num_types,
+      mb->literal_split.types, mb->literal_split.lengths,
+      mb->literal_split.num_blocks);
+  InitBlockEncoder(&command_enc, BROTLI_NUM_COMMAND_SYMBOLS,
+      mb->command_split.num_types, mb->command_split.types,
+      mb->command_split.lengths, mb->command_split.num_blocks);
+  InitBlockEncoder(&distance_enc, num_distance_codes,
+      mb->distance_split.num_types, mb->distance_split.types,
+      mb->distance_split.lengths, mb->distance_split.num_blocks);
+
+  BuildAndStoreBlockSwitchEntropyCodes(&literal_enc, tree, storage_ix, storage);
+  BuildAndStoreBlockSwitchEntropyCodes(&command_enc, tree, storage_ix, storage);
+  BuildAndStoreBlockSwitchEntropyCodes(
+      &distance_enc, tree, storage_ix, storage);
+
+  BrotliWriteBits(2, distance_postfix_bits, storage_ix, storage);
+  BrotliWriteBits(4, num_direct_distance_codes >> distance_postfix_bits,
+                  storage_ix, storage);
+  for (i = 0; i < mb->literal_split.num_types; ++i) {
+    BrotliWriteBits(2, literal_context_mode, storage_ix, storage);
+  }
+
+  if (mb->literal_context_map_size == 0) {
+    StoreTrivialContextMap(mb->literal_histograms_size,
+        BROTLI_LITERAL_CONTEXT_BITS, tree, storage_ix, storage);
+  } else {
+    EncodeContextMap(m,
+        mb->literal_context_map, mb->literal_context_map_size,
+        mb->literal_histograms_size, tree, storage_ix, storage);
+    if (BROTLI_IS_OOM(m)) return;
+  }
+
+  if (mb->distance_context_map_size == 0) {
+    StoreTrivialContextMap(mb->distance_histograms_size,
+        BROTLI_DISTANCE_CONTEXT_BITS, tree, storage_ix, storage);
+  } else {
+    EncodeContextMap(m,
+        mb->distance_context_map, mb->distance_context_map_size,
+        mb->distance_histograms_size, tree, storage_ix, storage);
+    if (BROTLI_IS_OOM(m)) return;
+  }
+
+  BuildAndStoreEntropyCodesLiteral(m, &literal_enc, mb->literal_histograms,
+      mb->literal_histograms_size, tree, storage_ix, storage);
+  if (BROTLI_IS_OOM(m)) return;
+  BuildAndStoreEntropyCodesCommand(m, &command_enc, mb->command_histograms,
+      mb->command_histograms_size, tree, storage_ix, storage);
+  if (BROTLI_IS_OOM(m)) return;
+  BuildAndStoreEntropyCodesDistance(m, &distance_enc, mb->distance_histograms,
+      mb->distance_histograms_size, tree, storage_ix, storage);
+  if (BROTLI_IS_OOM(m)) return;
+  BROTLI_FREE(m, tree);
+
+  for (i = 0; i < n_commands; ++i) {
+    const Command cmd = commands[i];
+    size_t cmd_code = cmd.cmd_prefix_;
+    StoreSymbol(&command_enc, cmd_code, storage_ix, storage);
+    StoreCommandExtra(&cmd, storage_ix, storage);
+    if (mb->literal_context_map_size == 0) {
+      size_t j;
+      for (j = cmd.insert_len_; j != 0; --j) {
+        StoreSymbol(&literal_enc, input[pos & mask], storage_ix, storage);
+        ++pos;
+      }
+    } else {
+      size_t j;
+      for (j = cmd.insert_len_; j != 0; --j) {
+        size_t context = Context(prev_byte, prev_byte2, literal_context_mode);
+        uint8_t literal = input[pos & mask];
+        StoreSymbolWithContext(&literal_enc, literal, context,
+            mb->literal_context_map, storage_ix, storage,
+            BROTLI_LITERAL_CONTEXT_BITS);
+        prev_byte2 = prev_byte;
+        prev_byte = literal;
+        ++pos;
+      }
+    }
+    pos += CommandCopyLen(&cmd);
+    if (CommandCopyLen(&cmd)) {
+      prev_byte2 = input[(pos - 2) & mask];
+      prev_byte = input[(pos - 1) & mask];
+      if (cmd.cmd_prefix_ >= 128) {
+        size_t dist_code = cmd.dist_prefix_;
+        uint32_t distnumextra = cmd.dist_extra_ >> 24;
+        uint64_t distextra = cmd.dist_extra_ & 0xffffff;
+        if (mb->distance_context_map_size == 0) {
+          StoreSymbol(&distance_enc, dist_code, storage_ix, storage);
+        } else {
+          size_t context = CommandDistanceContext(&cmd);
+          StoreSymbolWithContext(&distance_enc, dist_code, context,
+              mb->distance_context_map, storage_ix, storage,
+              BROTLI_DISTANCE_CONTEXT_BITS);
+        }
+        BrotliWriteBits(distnumextra, distextra, storage_ix, storage);
+      }
+    }
+  }
+  CleanupBlockEncoder(m, &distance_enc);
+  CleanupBlockEncoder(m, &command_enc);
+  CleanupBlockEncoder(m, &literal_enc);
+  if (is_last) {
+    JumpToByteBoundary(storage_ix, storage);
+  }
+}
+
+static void BuildHistograms(const uint8_t* input,
+                            size_t start_pos,
+                            size_t mask,
+                            const Command *commands,
+                            size_t n_commands,
+                            HistogramLiteral* lit_histo,
+                            HistogramCommand* cmd_histo,
+                            HistogramDistance* dist_histo) {
+  size_t pos = start_pos;
+  size_t i;
+  for (i = 0; i < n_commands; ++i) {
+    const Command cmd = commands[i];
+    size_t j;
+    HistogramAddCommand(cmd_histo, cmd.cmd_prefix_);
+    for (j = cmd.insert_len_; j != 0; --j) {
+      HistogramAddLiteral(lit_histo, input[pos & mask]);
+      ++pos;
+    }
+    pos += CommandCopyLen(&cmd);
+    if (CommandCopyLen(&cmd) && cmd.cmd_prefix_ >= 128) {
+      HistogramAddDistance(dist_histo, cmd.dist_prefix_);
+    }
+  }
+}
+
+static void StoreDataWithHuffmanCodes(const uint8_t* input,
+                                      size_t start_pos,
+                                      size_t mask,
+                                      const Command *commands,
+                                      size_t n_commands,
+                                      const uint8_t* lit_depth,
+                                      const uint16_t* lit_bits,
+                                      const uint8_t* cmd_depth,
+                                      const uint16_t* cmd_bits,
+                                      const uint8_t* dist_depth,
+                                      const uint16_t* dist_bits,
+                                      size_t* storage_ix,
+                                      uint8_t* storage) {
+  size_t pos = start_pos;
+  size_t i;
+  for (i = 0; i < n_commands; ++i) {
+    const Command cmd = commands[i];
+    const size_t cmd_code = cmd.cmd_prefix_;
+    size_t j;
+    BrotliWriteBits(
+        cmd_depth[cmd_code], cmd_bits[cmd_code], storage_ix, storage);
+    StoreCommandExtra(&cmd, storage_ix, storage);
+    for (j = cmd.insert_len_; j != 0; --j) {
+      const uint8_t literal = input[pos & mask];
+      BrotliWriteBits(
+          lit_depth[literal], lit_bits[literal], storage_ix, storage);
+      ++pos;
+    }
+    pos += CommandCopyLen(&cmd);
+    if (CommandCopyLen(&cmd) && cmd.cmd_prefix_ >= 128) {
+      const size_t dist_code = cmd.dist_prefix_;
+      const uint32_t distnumextra = cmd.dist_extra_ >> 24;
+      const uint32_t distextra = cmd.dist_extra_ & 0xffffff;
+      BrotliWriteBits(dist_depth[dist_code], dist_bits[dist_code],
+                      storage_ix, storage);
+      BrotliWriteBits(distnumextra, distextra, storage_ix, storage);
+    }
+  }
+}
+
+void BrotliStoreMetaBlockTrivial(MemoryManager* m,
+                                 const uint8_t* input,
+                                 size_t start_pos,
+                                 size_t length,
+                                 size_t mask,
+                                 BROTLI_BOOL is_last,
+                                 const Command *commands,
+                                 size_t n_commands,
+                                 size_t *storage_ix,
+                                 uint8_t *storage) {
+  HistogramLiteral lit_histo;
+  HistogramCommand cmd_histo;
+  HistogramDistance dist_histo;
+  uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS];
+  uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS];
+  uint8_t cmd_depth[BROTLI_NUM_COMMAND_SYMBOLS];
+  uint16_t cmd_bits[BROTLI_NUM_COMMAND_SYMBOLS];
+  uint8_t dist_depth[SIMPLE_DISTANCE_ALPHABET_SIZE];
+  uint16_t dist_bits[SIMPLE_DISTANCE_ALPHABET_SIZE];
+  HuffmanTree* tree;
+
+  StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage);
+
+  HistogramClearLiteral(&lit_histo);
+  HistogramClearCommand(&cmd_histo);
+  HistogramClearDistance(&dist_histo);
+
+  BuildHistograms(input, start_pos, mask, commands, n_commands,
+                  &lit_histo, &cmd_histo, &dist_histo);
+
+  BrotliWriteBits(13, 0, storage_ix, storage);
+
+  tree = BROTLI_ALLOC(m, HuffmanTree, MAX_HUFFMAN_TREE_SIZE);
+  if (BROTLI_IS_OOM(m)) return;
+  BuildAndStoreHuffmanTree(lit_histo.data_, BROTLI_NUM_LITERAL_SYMBOLS, tree,
+                           lit_depth, lit_bits,
+                           storage_ix, storage);
+  BuildAndStoreHuffmanTree(cmd_histo.data_, BROTLI_NUM_COMMAND_SYMBOLS, tree,
+                           cmd_depth, cmd_bits,
+                           storage_ix, storage);
+  BuildAndStoreHuffmanTree(dist_histo.data_, SIMPLE_DISTANCE_ALPHABET_SIZE,
+                           tree,
+                           dist_depth, dist_bits,
+                           storage_ix, storage);
+  BROTLI_FREE(m, tree);
+  StoreDataWithHuffmanCodes(input, start_pos, mask, commands,
+                            n_commands, lit_depth, lit_bits,
+                            cmd_depth, cmd_bits,
+                            dist_depth, dist_bits,
+                            storage_ix, storage);
+  if (is_last) {
+    JumpToByteBoundary(storage_ix, storage);
+  }
+}
+
+void BrotliStoreMetaBlockFast(MemoryManager* m,
+                              const uint8_t* input,
+                              size_t start_pos,
+                              size_t length,
+                              size_t mask,
+                              BROTLI_BOOL is_last,
+                              const Command *commands,
+                              size_t n_commands,
+                              size_t *storage_ix,
+                              uint8_t *storage) {
+  StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage);
+
+  BrotliWriteBits(13, 0, storage_ix, storage);
+
+  if (n_commands <= 128) {
+    uint32_t histogram[BROTLI_NUM_LITERAL_SYMBOLS] = { 0 };
+    size_t pos = start_pos;
+    size_t num_literals = 0;
+    size_t i;
+    uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS];
+    uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS];
+    for (i = 0; i < n_commands; ++i) {
+      const Command cmd = commands[i];
+      size_t j;
+      for (j = cmd.insert_len_; j != 0; --j) {
+        ++histogram[input[pos & mask]];
+        ++pos;
+      }
+      num_literals += cmd.insert_len_;
+      pos += CommandCopyLen(&cmd);
+    }
+    BrotliBuildAndStoreHuffmanTreeFast(m, histogram, num_literals,
+                                       /* max_bits = */ 8,
+                                       lit_depth, lit_bits,
+                                       storage_ix, storage);
+    if (BROTLI_IS_OOM(m)) return;
+    StoreStaticCommandHuffmanTree(storage_ix, storage);
+    StoreStaticDistanceHuffmanTree(storage_ix, storage);
+    StoreDataWithHuffmanCodes(input, start_pos, mask, commands,
+                              n_commands, lit_depth, lit_bits,
+                              kStaticCommandCodeDepth,
+                              kStaticCommandCodeBits,
+                              kStaticDistanceCodeDepth,
+                              kStaticDistanceCodeBits,
+                              storage_ix, storage);
+  } else {
+    HistogramLiteral lit_histo;
+    HistogramCommand cmd_histo;
+    HistogramDistance dist_histo;
+    uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS];
+    uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS];
+    uint8_t cmd_depth[BROTLI_NUM_COMMAND_SYMBOLS];
+    uint16_t cmd_bits[BROTLI_NUM_COMMAND_SYMBOLS];
+    uint8_t dist_depth[SIMPLE_DISTANCE_ALPHABET_SIZE];
+    uint16_t dist_bits[SIMPLE_DISTANCE_ALPHABET_SIZE];
+    HistogramClearLiteral(&lit_histo);
+    HistogramClearCommand(&cmd_histo);
+    HistogramClearDistance(&dist_histo);
+    BuildHistograms(input, start_pos, mask, commands, n_commands,
+                    &lit_histo, &cmd_histo, &dist_histo);
+    BrotliBuildAndStoreHuffmanTreeFast(m, lit_histo.data_,
+                                       lit_histo.total_count_,
+                                       /* max_bits = */ 8,
+                                       lit_depth, lit_bits,
+                                       storage_ix, storage);
+    if (BROTLI_IS_OOM(m)) return;
+    BrotliBuildAndStoreHuffmanTreeFast(m, cmd_histo.data_,
+                                       cmd_histo.total_count_,
+                                       /* max_bits = */ 10,
+                                       cmd_depth, cmd_bits,
+                                       storage_ix, storage);
+    if (BROTLI_IS_OOM(m)) return;
+    BrotliBuildAndStoreHuffmanTreeFast(m, dist_histo.data_,
+                                       dist_histo.total_count_,
+                                       /* max_bits = */
+                                       SIMPLE_DISTANCE_ALPHABET_BITS,
+                                       dist_depth, dist_bits,
+                                       storage_ix, storage);
+    if (BROTLI_IS_OOM(m)) return;
+    StoreDataWithHuffmanCodes(input, start_pos, mask, commands,
+                              n_commands, lit_depth, lit_bits,
+                              cmd_depth, cmd_bits,
+                              dist_depth, dist_bits,
+                              storage_ix, storage);
+  }
+
+  if (is_last) {
+    JumpToByteBoundary(storage_ix, storage);
+  }
+}
+
+/* This is for storing uncompressed blocks (simple raw storage of
+   bytes-as-bytes). */
+void BrotliStoreUncompressedMetaBlock(BROTLI_BOOL is_final_block,
+                                      const uint8_t * BROTLI_RESTRICT input,
+                                      size_t position, size_t mask,
+                                      size_t len,
+                                      size_t * BROTLI_RESTRICT storage_ix,
+                                      uint8_t * BROTLI_RESTRICT storage) {
+  size_t masked_pos = position & mask;
+  BrotliStoreUncompressedMetaBlockHeader(len, storage_ix, storage);
+  JumpToByteBoundary(storage_ix, storage);
+
+  if (masked_pos + len > mask + 1) {
+    size_t len1 = mask + 1 - masked_pos;
+    memcpy(&storage[*storage_ix >> 3], &input[masked_pos], len1);
+    *storage_ix += len1 << 3;
+    len -= len1;
+    masked_pos = 0;
+  }
+  memcpy(&storage[*storage_ix >> 3], &input[masked_pos], len);
+  *storage_ix += len << 3;
+
+  /* We need to clear the next 4 bytes to continue to be
+     compatible with BrotliWriteBits. */
+  BrotliWriteBitsPrepareStorage(*storage_ix, storage);
+
+  /* Since the uncompressed block itself may not be the final block, add an
+     empty one after this. */
+  if (is_final_block) {
+    BrotliWriteBits(1, 1, storage_ix, storage);  /* islast */
+    BrotliWriteBits(1, 1, storage_ix, storage);  /* isempty */
+    JumpToByteBoundary(storage_ix, storage);
+  }
+}
+
+void BrotliStoreSyncMetaBlock(size_t* BROTLI_RESTRICT storage_ix,
+                              uint8_t* BROTLI_RESTRICT storage) {
+  /* Empty metadata meta-block bit pattern:
+       1 bit:  is_last (0)
+       2 bits: num nibbles (3)
+       1 bit:  reserved (0)
+       2 bits: metadata length bytes (0) */
+  BrotliWriteBits(6, 6, storage_ix, storage);
+  JumpToByteBoundary(storage_ix, storage);
+}
+
+
+#if defined(__cplusplus) || defined(c_plusplus)
+}  /* extern "C" */
+#endif