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- //
- // Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
- //
- // Distributed under the Boost Software License, Version 1.0. (See accompanying
- // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- //
- // Official repository: https://github.com/boostorg/beast
- //
- // This is a derivative work based on Zlib, copyright below:
- /*
- Copyright (C) 1995-2013 Jean-loup Gailly and Mark Adler
- This software is provided 'as-is', without any express or implied
- warranty. In no event will the authors be held liable for any damages
- arising from the use of this software.
- Permission is granted to anyone to use this software for any purpose,
- including commercial applications, and to alter it and redistribute it
- freely, subject to the following restrictions:
- 1. The origin of this software must not be misrepresented; you must not
- claim that you wrote the original software. If you use this software
- in a product, an acknowledgment in the product documentation would be
- appreciated but is not required.
- 2. Altered source versions must be plainly marked as such, and must not be
- misrepresented as being the original software.
- 3. This notice may not be removed or altered from any source distribution.
- Jean-loup Gailly Mark Adler
- jloup@gzip.org madler@alumni.caltech.edu
- The data format used by the zlib library is described by RFCs (Request for
- Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950
- (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
- */
- #ifndef BOOST_BEAST_ZLIB_DETAIL_DEFLATE_STREAM_HPP
- #define BOOST_BEAST_ZLIB_DETAIL_DEFLATE_STREAM_HPP
- #include <boost/beast/zlib/error.hpp>
- #include <boost/beast/zlib/zlib.hpp>
- #include <boost/beast/zlib/detail/ranges.hpp>
- #include <boost/assert.hpp>
- #include <boost/config.hpp>
- #include <boost/optional.hpp>
- #include <boost/throw_exception.hpp>
- #include <cstdint>
- #include <cstdlib>
- #include <cstring>
- #include <memory>
- #include <stdexcept>
- #include <type_traits>
- namespace boost {
- namespace beast {
- namespace zlib {
- namespace detail {
- class deflate_stream
- {
- protected:
- // Upper limit on code length
- static std::uint8_t constexpr maxBits = 15;
- // Number of length codes, not counting the special END_BLOCK code
- static std::uint16_t constexpr lengthCodes = 29;
- // Number of literal bytes 0..255
- static std::uint16_t constexpr literals = 256;
- // Number of Literal or Length codes, including the END_BLOCK code
- static std::uint16_t constexpr lCodes = literals + 1 + lengthCodes;
- // Number of distance code lengths
- static std::uint16_t constexpr dCodes = 30;
- // Number of codes used to transfer the bit lengths
- static std::uint16_t constexpr blCodes = 19;
- // Number of distance codes
- static std::uint16_t constexpr distCodeLen = 512;
- // Size limit on bit length codes
- static std::uint8_t constexpr maxBlBits= 7;
- static std::uint16_t constexpr minMatch = 3;
- static std::uint16_t constexpr maxMatch = 258;
- // Can't change minMatch without also changing code, see original zlib
- BOOST_STATIC_ASSERT(minMatch == 3);
- // end of block literal code
- static std::uint16_t constexpr END_BLOCK = 256;
- // repeat previous bit length 3-6 times (2 bits of repeat count)
- static std::uint8_t constexpr REP_3_6 = 16;
- // repeat a zero length 3-10 times (3 bits of repeat count)
- static std::uint8_t constexpr REPZ_3_10 = 17;
- // repeat a zero length 11-138 times (7 bits of repeat count)
- static std::uint8_t constexpr REPZ_11_138 = 18;
- // The three kinds of block type
- static std::uint8_t constexpr STORED_BLOCK = 0;
- static std::uint8_t constexpr STATIC_TREES = 1;
- static std::uint8_t constexpr DYN_TREES = 2;
- // Maximum value for memLevel in deflateInit2
- static std::uint8_t constexpr max_mem_level = 9;
- // Default memLevel
- static std::uint8_t constexpr DEF_MEM_LEVEL = max_mem_level;
- /* Note: the deflate() code requires max_lazy >= minMatch and max_chain >= 4
- For deflate_fast() (levels <= 3) good is ignored and lazy has a different
- meaning.
- */
- // maximum heap size
- static std::uint16_t constexpr HEAP_SIZE = 2 * lCodes + 1;
- // size of bit buffer in bi_buf
- static std::uint8_t constexpr Buf_size = 16;
- // Matches of length 3 are discarded if their distance exceeds kTooFar
- static std::size_t constexpr kTooFar = 4096;
- /* Minimum amount of lookahead, except at the end of the input file.
- See deflate.c for comments about the minMatch+1.
- */
- static std::size_t constexpr kMinLookahead = maxMatch + minMatch+1;
- /* Number of bytes after end of data in window to initialize in order
- to avoid memory checker errors from longest match routines
- */
- static std::size_t constexpr kWinInit = maxMatch;
- // Describes a single value and its code string.
- struct ct_data
- {
- std::uint16_t fc; // frequency count or bit string
- std::uint16_t dl; // parent node in tree or length of bit string
- bool
- operator==(ct_data const& rhs) const
- {
- return fc == rhs.fc && dl == rhs.dl;
- }
- };
- struct static_desc
- {
- ct_data const* static_tree;// static tree or NULL
- std::uint8_t const* extra_bits; // extra bits for each code or NULL
- std::uint16_t extra_base; // base index for extra_bits
- std::uint16_t elems; // max number of elements in the tree
- std::uint8_t max_length; // max bit length for the codes
- };
- struct lut_type
- {
- // Number of extra bits for each length code
- std::uint8_t const extra_lbits[lengthCodes] = {
- 0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0
- };
- // Number of extra bits for each distance code
- std::uint8_t const extra_dbits[dCodes] = {
- 0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13
- };
- // Number of extra bits for each bit length code
- std::uint8_t const extra_blbits[blCodes] = {
- 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7
- };
- // The lengths of the bit length codes are sent in order
- // of decreasing probability, to avoid transmitting the
- // lengths for unused bit length codes.
- std::uint8_t const bl_order[blCodes] = {
- 16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15
- };
- ct_data ltree[lCodes + 2];
- ct_data dtree[dCodes];
- // Distance codes. The first 256 values correspond to the distances
- // 3 .. 258, the last 256 values correspond to the top 8 bits of
- // the 15 bit distances.
- std::uint8_t dist_code[distCodeLen];
- std::uint8_t length_code[maxMatch-minMatch+1];
- std::uint8_t base_length[lengthCodes];
- std::uint16_t base_dist[dCodes];
- static_desc l_desc = {
- ltree, extra_lbits, literals+1, lCodes, maxBits
- };
- static_desc d_desc = {
- dtree, extra_dbits, 0, dCodes, maxBits
- };
- static_desc bl_desc =
- {
- nullptr, extra_blbits, 0, blCodes, maxBlBits
- };
- };
- struct tree_desc
- {
- ct_data *dyn_tree; /* the dynamic tree */
- int max_code; /* largest code with non zero frequency */
- static_desc const* stat_desc; /* the corresponding static tree */
- };
- enum block_state
- {
- need_more, /* block not completed, need more input or more output */
- block_done, /* block flush performed */
- finish_started, /* finish started, need only more output at next deflate */
- finish_done /* finish done, accept no more input or output */
- };
- // VFALCO This might not be needed, e.g. for zip/gzip
- enum StreamStatus
- {
- EXTRA_STATE = 69,
- NAME_STATE = 73,
- COMMENT_STATE = 91,
- HCRC_STATE = 103,
- BUSY_STATE = 113,
- FINISH_STATE = 666
- };
- /* A std::uint16_t is an index in the character window. We use short instead of int to
- * save space in the various tables. IPos is used only for parameter passing.
- */
- using IPos = unsigned;
- using self = deflate_stream;
- typedef block_state(self::*compress_func)(z_params& zs, Flush flush);
- //--------------------------------------------------------------------------
- lut_type const& lut_;
- bool inited_ = false;
- std::size_t buf_size_;
- std::unique_ptr<std::uint8_t[]> buf_;
- int status_; // as the name implies
- Byte* pending_buf_; // output still pending
- std::uint32_t
- pending_buf_size_; // size of pending_buf
- Byte* pending_out_; // next pending byte to output to the stream
- uInt pending_; // nb of bytes in the pending buffer
- boost::optional<Flush>
- last_flush_; // value of flush param for previous deflate call
- uInt w_size_; // LZ77 window size (32K by default)
- uInt w_bits_; // log2(w_size) (8..16)
- uInt w_mask_; // w_size - 1
- /* Sliding window. Input bytes are read into the second half of the window,
- and move to the first half later to keep a dictionary of at least wSize
- bytes. With this organization, matches are limited to a distance of
- wSize-maxMatch bytes, but this ensures that IO is always
- performed with a length multiple of the block size. Also, it limits
- the window size to 64K.
- To do: use the user input buffer as sliding window.
- */
- Byte *window_ = nullptr;
- /* Actual size of window: 2*wSize, except when the user input buffer
- is directly used as sliding window.
- */
- std::uint32_t window_size_;
- /* Link to older string with same hash index. To limit the size of this
- array to 64K, this link is maintained only for the last 32K strings.
- An index in this array is thus a window index modulo 32K.
- */
- std::uint16_t* prev_;
- std::uint16_t* head_; // Heads of the hash chains or 0
- uInt ins_h_; // hash index of string to be inserted
- uInt hash_size_; // number of elements in hash table
- uInt hash_bits_; // log2(hash_size)
- uInt hash_mask_; // hash_size-1
- /* Number of bits by which ins_h must be shifted at each input
- step. It must be such that after minMatch steps,
- the oldest byte no longer takes part in the hash key, that is:
- hash_shift * minMatch >= hash_bits
- */
- uInt hash_shift_;
- /* Window position at the beginning of the current output block.
- Gets negative when the window is moved backwards.
- */
- long block_start_;
- uInt match_length_; // length of best match
- IPos prev_match_; // previous match
- int match_available_; // set if previous match exists
- uInt strstart_; // start of string to insert
- uInt match_start_; // start of matching string
- uInt lookahead_; // number of valid bytes ahead in window
- /* Length of the best match at previous step. Matches not greater
- than this are discarded. This is used in the lazy match evaluation.
- */
- uInt prev_length_;
- /* To speed up deflation, hash chains are never searched beyond
- this length. A higher limit improves compression ratio but
- degrades the speed.
- */
- uInt max_chain_length_;
- /* Attempt to find a better match only when the current match is strictly
- smaller than this value. This mechanism is used only for compression
- levels >= 4.
- OR Insert new strings in the hash table only if the match length is not
- greater than this length. This saves time but degrades compression.
- used only for compression levels <= 3.
- */
- uInt max_lazy_match_;
- int level_; // compression level (1..9)
- Strategy strategy_; // favor or force Huffman coding
- // Use a faster search when the previous match is longer than this
- uInt good_match_;
- int nice_match_; // Stop searching when current match exceeds this
- ct_data dyn_ltree_[
- HEAP_SIZE]; // literal and length tree
- ct_data dyn_dtree_[
- 2*dCodes+1]; // distance tree
- ct_data bl_tree_[
- 2*blCodes+1]; // Huffman tree for bit lengths
- tree_desc l_desc_; // desc. for literal tree
- tree_desc d_desc_; // desc. for distance tree
- tree_desc bl_desc_; // desc. for bit length tree
- // number of codes at each bit length for an optimal tree
- std::uint16_t bl_count_[maxBits+1];
- // Index within the heap array of least frequent node in the Huffman tree
- static std::size_t constexpr kSmallest = 1;
- /* The sons of heap[n] are heap[2*n] and heap[2*n+1].
- heap[0] is not used. The same heap array is used to build all trees.
- */
- int heap_[2*lCodes+1]; // heap used to build the Huffman trees
- int heap_len_; // number of elements in the heap
- int heap_max_; // element of largest frequency
- // Depth of each subtree used as tie breaker for trees of equal frequency
- std::uint8_t depth_[2*lCodes+1];
- std::uint8_t *l_buf_; // buffer for literals or lengths
- /* Size of match buffer for literals/lengths.
- There are 4 reasons for limiting lit_bufsize to 64K:
- - frequencies can be kept in 16 bit counters
- - if compression is not successful for the first block, all input
- data is still in the window so we can still emit a stored block even
- when input comes from standard input. (This can also be done for
- all blocks if lit_bufsize is not greater than 32K.)
- - if compression is not successful for a file smaller than 64K, we can
- even emit a stored file instead of a stored block (saving 5 bytes).
- This is applicable only for zip (not gzip or zlib).
- - creating new Huffman trees less frequently may not provide fast
- adaptation to changes in the input data statistics. (Take for
- example a binary file with poorly compressible code followed by
- a highly compressible string table.) Smaller buffer sizes give
- fast adaptation but have of course the overhead of transmitting
- trees more frequently.
- - I can't count above 4
- */
- uInt lit_bufsize_;
- uInt last_lit_; // running index in l_buf_
- /* Buffer for distances. To simplify the code, d_buf_ and l_buf_
- have the same number of elements. To use different lengths, an
- extra flag array would be necessary.
- */
- std::uint16_t* d_buf_;
- std::uint32_t opt_len_; // bit length of current block with optimal trees
- std::uint32_t static_len_; // bit length of current block with static trees
- uInt matches_; // number of string matches in current block
- uInt insert_; // bytes at end of window left to insert
- /* Output buffer.
- Bits are inserted starting at the bottom (least significant bits).
- */
- std::uint16_t bi_buf_;
- /* Number of valid bits in bi_buf._ All bits above the last valid
- bit are always zero.
- */
- int bi_valid_;
- /* High water mark offset in window for initialized bytes -- bytes
- above this are set to zero in order to avoid memory check warnings
- when longest match routines access bytes past the input. This is
- then updated to the new high water mark.
- */
- std::uint32_t high_water_;
- //--------------------------------------------------------------------------
- deflate_stream()
- : lut_(get_lut())
- {
- }
- /* In order to simplify the code, particularly on 16 bit machines, match
- distances are limited to MAX_DIST instead of WSIZE.
- */
- std::size_t
- max_dist() const
- {
- return w_size_ - kMinLookahead;
- }
- void
- put_byte(std::uint8_t c)
- {
- pending_buf_[pending_++] = c;
- }
- void
- put_short(std::uint16_t w)
- {
- put_byte(w & 0xff);
- put_byte(w >> 8);
- }
- /* Send a value on a given number of bits.
- IN assertion: length <= 16 and value fits in length bits.
- */
- void
- send_bits(int value, int length)
- {
- if(bi_valid_ > (int)Buf_size - length)
- {
- bi_buf_ |= (std::uint16_t)value << bi_valid_;
- put_short(bi_buf_);
- bi_buf_ = (std::uint16_t)value >> (Buf_size - bi_valid_);
- bi_valid_ += length - Buf_size;
- }
- else
- {
- bi_buf_ |= (std::uint16_t)(value) << bi_valid_;
- bi_valid_ += length;
- }
- }
- // Send a code of the given tree
- void
- send_code(int value, ct_data const* tree)
- {
- send_bits(tree[value].fc, tree[value].dl);
- }
- /* Mapping from a distance to a distance code. dist is the
- distance - 1 and must not have side effects. _dist_code[256]
- and _dist_code[257] are never used.
- */
- std::uint8_t
- d_code(unsigned dist)
- {
- if(dist < 256)
- return lut_.dist_code[dist];
- return lut_.dist_code[256+(dist>>7)];
- }
- /* Update a hash value with the given input byte
- IN assertion: all calls to to update_hash are made with
- consecutive input characters, so that a running hash
- key can be computed from the previous key instead of
- complete recalculation each time.
- */
- void
- update_hash(uInt& h, std::uint8_t c)
- {
- h = ((h << hash_shift_) ^ c) & hash_mask_;
- }
- /* Initialize the hash table (avoiding 64K overflow for 16
- bit systems). prev[] will be initialized on the fly.
- */
- void
- clear_hash()
- {
- head_[hash_size_-1] = 0;
- std::memset((Byte *)head_, 0,
- (unsigned)(hash_size_-1)*sizeof(*head_));
- }
- /* Compares two subtrees, using the tree depth as tie breaker
- when the subtrees have equal frequency. This minimizes the
- worst case length.
- */
- bool
- smaller(ct_data const* tree, int n, int m)
- {
- return tree[n].fc < tree[m].fc ||
- (tree[n].fc == tree[m].fc &&
- depth_[n] <= depth_[m]);
- }
- /* Insert string str in the dictionary and set match_head to the
- previous head of the hash chain (the most recent string with
- same hash key). Return the previous length of the hash chain.
- If this file is compiled with -DFASTEST, the compression level
- is forced to 1, and no hash chains are maintained.
- IN assertion: all calls to to INSERT_STRING are made with
- consecutive input characters and the first minMatch
- bytes of str are valid (except for the last minMatch-1
- bytes of the input file).
- */
- void
- insert_string(IPos& hash_head)
- {
- update_hash(ins_h_, window_[strstart_ + (minMatch-1)]);
- hash_head = prev_[strstart_ & w_mask_] = head_[ins_h_];
- head_[ins_h_] = (std::uint16_t)strstart_;
- }
- //--------------------------------------------------------------------------
- /* Values for max_lazy_match, good_match and max_chain_length, depending on
- * the desired pack level (0..9). The values given below have been tuned to
- * exclude worst case performance for pathological files. Better values may be
- * found for specific files.
- */
- struct config
- {
- std::uint16_t good_length; /* reduce lazy search above this match length */
- std::uint16_t max_lazy; /* do not perform lazy search above this match length */
- std::uint16_t nice_length; /* quit search above this match length */
- std::uint16_t max_chain;
- compress_func func;
- config(
- std::uint16_t good_length_,
- std::uint16_t max_lazy_,
- std::uint16_t nice_length_,
- std::uint16_t max_chain_,
- compress_func func_)
- : good_length(good_length_)
- , max_lazy(max_lazy_)
- , nice_length(nice_length_)
- , max_chain(max_chain_)
- , func(func_)
- {
- }
- };
- static
- config
- get_config(std::size_t level)
- {
- switch(level)
- {
- // good lazy nice chain
- case 0: return { 0, 0, 0, 0, &self::deflate_stored}; // store only
- case 1: return { 4, 4, 8, 4, &self::deflate_fast}; // max speed, no lazy matches
- case 2: return { 4, 5, 16, 8, &self::deflate_fast};
- case 3: return { 4, 6, 32, 32, &self::deflate_fast};
- case 4: return { 4, 4, 16, 16, &self::deflate_slow}; // lazy matches
- case 5: return { 8, 16, 32, 32, &self::deflate_slow};
- case 6: return { 8, 16, 128, 128, &self::deflate_slow};
- case 7: return { 8, 32, 128, 256, &self::deflate_slow};
- case 8: return { 32, 128, 258, 1024, &self::deflate_slow};
- default:
- case 9: return { 32, 258, 258, 4096, &self::deflate_slow}; // max compression
- }
- }
- void
- maybe_init()
- {
- if(! inited_)
- init();
- }
- template<class Unsigned>
- static
- Unsigned
- bi_reverse(Unsigned code, unsigned len);
- BOOST_BEAST_DECL
- static
- void
- gen_codes(ct_data *tree, int max_code, std::uint16_t *bl_count);
- BOOST_BEAST_DECL
- static
- lut_type const&
- get_lut();
- BOOST_BEAST_DECL void doReset (int level, int windowBits, int memLevel, Strategy strategy);
- BOOST_BEAST_DECL void doReset ();
- BOOST_BEAST_DECL void doClear ();
- BOOST_BEAST_DECL std::size_t doUpperBound (std::size_t sourceLen) const;
- BOOST_BEAST_DECL void doTune (int good_length, int max_lazy, int nice_length, int max_chain);
- BOOST_BEAST_DECL void doParams (z_params& zs, int level, Strategy strategy, error_code& ec);
- BOOST_BEAST_DECL void doWrite (z_params& zs, boost::optional<Flush> flush, error_code& ec);
- BOOST_BEAST_DECL void doDictionary (Byte const* dict, uInt dictLength, error_code& ec);
- BOOST_BEAST_DECL void doPrime (int bits, int value, error_code& ec);
- BOOST_BEAST_DECL void doPending (unsigned* value, int* bits);
- BOOST_BEAST_DECL void init ();
- BOOST_BEAST_DECL void lm_init ();
- BOOST_BEAST_DECL void init_block ();
- BOOST_BEAST_DECL void pqdownheap (ct_data const* tree, int k);
- BOOST_BEAST_DECL void pqremove (ct_data const* tree, int& top);
- BOOST_BEAST_DECL void gen_bitlen (tree_desc *desc);
- BOOST_BEAST_DECL void build_tree (tree_desc *desc);
- BOOST_BEAST_DECL void scan_tree (ct_data *tree, int max_code);
- BOOST_BEAST_DECL void send_tree (ct_data *tree, int max_code);
- BOOST_BEAST_DECL int build_bl_tree ();
- BOOST_BEAST_DECL void send_all_trees (int lcodes, int dcodes, int blcodes);
- BOOST_BEAST_DECL void compress_block (ct_data const* ltree, ct_data const* dtree);
- BOOST_BEAST_DECL int detect_data_type ();
- BOOST_BEAST_DECL void bi_windup ();
- BOOST_BEAST_DECL void bi_flush ();
- BOOST_BEAST_DECL void copy_block (char *buf, unsigned len, int header);
- BOOST_BEAST_DECL void tr_init ();
- BOOST_BEAST_DECL void tr_align ();
- BOOST_BEAST_DECL void tr_flush_bits ();
- BOOST_BEAST_DECL void tr_stored_block (char *bu, std::uint32_t stored_len, int last);
- BOOST_BEAST_DECL void tr_tally_dist (std::uint16_t dist, std::uint8_t len, bool& flush);
- BOOST_BEAST_DECL void tr_tally_lit (std::uint8_t c, bool& flush);
- BOOST_BEAST_DECL void tr_flush_block (z_params& zs, char *buf, std::uint32_t stored_len, int last);
- BOOST_BEAST_DECL void fill_window (z_params& zs);
- BOOST_BEAST_DECL void flush_pending (z_params& zs);
- BOOST_BEAST_DECL void flush_block (z_params& zs, bool last);
- BOOST_BEAST_DECL int read_buf (z_params& zs, Byte *buf, unsigned size);
- BOOST_BEAST_DECL uInt longest_match (IPos cur_match);
- BOOST_BEAST_DECL block_state f_stored (z_params& zs, Flush flush);
- BOOST_BEAST_DECL block_state f_fast (z_params& zs, Flush flush);
- BOOST_BEAST_DECL block_state f_slow (z_params& zs, Flush flush);
- BOOST_BEAST_DECL block_state f_rle (z_params& zs, Flush flush);
- BOOST_BEAST_DECL block_state f_huff (z_params& zs, Flush flush);
- block_state
- deflate_stored(z_params& zs, Flush flush)
- {
- return f_stored(zs, flush);
- }
- block_state
- deflate_fast(z_params& zs, Flush flush)
- {
- return f_fast(zs, flush);
- }
- block_state
- deflate_slow(z_params& zs, Flush flush)
- {
- return f_slow(zs, flush);
- }
- block_state
- deflate_rle(z_params& zs, Flush flush)
- {
- return f_rle(zs, flush);
- }
- block_state
- deflate_huff(z_params& zs, Flush flush)
- {
- return f_huff(zs, flush);
- }
- };
- //--------------------------------------------------------------------------
- // Reverse the first len bits of a code
- template<class Unsigned>
- Unsigned
- deflate_stream::
- bi_reverse(Unsigned code, unsigned len)
- {
- BOOST_STATIC_ASSERT(std::is_unsigned<Unsigned>::value);
- BOOST_ASSERT(len <= 8 * sizeof(unsigned));
- Unsigned res = 0;
- do
- {
- res |= code & 1;
- code >>= 1;
- res <<= 1;
- }
- while(--len > 0);
- return res >> 1;
- }
- } // detail
- } // zlib
- } // beast
- } // boost
- #ifdef BOOST_BEAST_HEADER_ONLY
- #include <boost/beast/zlib/detail/deflate_stream.ipp>
- #endif
- #endif
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