mirror of
https://github.com/google/brotli.git
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a8f5813b84
Documentation: - add note that brotli is a "stream" format, not an archive-like - regenerate .1 with Pandoc Build: - drop legacy "BROTLI_BUILD_PORTABLE" option - drop "BROTLI_SANITIZED" definition Code: - c: comb includes - c/enc: extract encoder state into separate header - c/enc: drop designated q10 codepath - c/enc: dealing better with flushing of empty stream - fix MSVC compilation API: - py: use library version instead of one in version.h - c: add plugable API to report consumed input / produced output - c/java: support "lean" prepared dictionaries (without copy of source)
87 lines
3.5 KiB
C
87 lines
3.5 KiB
C
/* Copyright 2015 Google Inc. All Rights Reserved.
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Distributed under MIT license.
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See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
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*/
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/* Function for fast encoding of an input fragment, independently from the input
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history. This function uses one-pass processing: when we find a backward
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match, we immediately emit the corresponding command and literal codes to
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the bit stream. */
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#ifndef BROTLI_ENC_COMPRESS_FRAGMENT_H_
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#define BROTLI_ENC_COMPRESS_FRAGMENT_H_
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#include <brotli/types.h>
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#include "../common/constants.h"
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#include "../common/platform.h"
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#include "entropy_encode.h"
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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typedef struct BrotliOnePassArena {
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uint8_t lit_depth[256];
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uint16_t lit_bits[256];
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/* Command and distance prefix codes (each 64 symbols, stored back-to-back)
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used for the next block. The command prefix code is over a smaller alphabet
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with the following 64 symbols:
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0 - 15: insert length code 0, copy length code 0 - 15, same distance
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16 - 39: insert length code 0, copy length code 0 - 23
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40 - 63: insert length code 0 - 23, copy length code 0
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Note that symbols 16 and 40 represent the same code in the full alphabet,
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but we do not use either of them. */
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uint8_t cmd_depth[128];
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uint16_t cmd_bits[128];
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uint32_t cmd_histo[128];
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/* The compressed form of the command and distance prefix codes for the next
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block. */
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uint8_t cmd_code[512];
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size_t cmd_code_numbits;
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HuffmanTree tree[2 * BROTLI_NUM_LITERAL_SYMBOLS + 1];
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uint32_t histogram[256];
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uint8_t tmp_depth[BROTLI_NUM_COMMAND_SYMBOLS];
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uint16_t tmp_bits[64];
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} BrotliOnePassArena;
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/* Compresses "input" string to the "*storage" buffer as one or more complete
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meta-blocks, and updates the "*storage_ix" bit position.
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If "is_last" is 1, emits an additional empty last meta-block.
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"cmd_depth" and "cmd_bits" contain the command and distance prefix codes
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(see comment in encode.h) used for the encoding of this input fragment.
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If "is_last" is 0, they are updated to reflect the statistics
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of this input fragment, to be used for the encoding of the next fragment.
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"*cmd_code_numbits" is the number of bits of the compressed representation
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of the command and distance prefix codes, and "cmd_code" is an array of
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at least "(*cmd_code_numbits + 7) >> 3" size that contains the compressed
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command and distance prefix codes. If "is_last" is 0, these are also
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updated to represent the updated "cmd_depth" and "cmd_bits".
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REQUIRES: "input_size" is greater than zero, or "is_last" is 1.
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REQUIRES: "input_size" is less or equal to maximal metablock size (1 << 24).
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REQUIRES: All elements in "table[0..table_size-1]" are initialized to zero.
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REQUIRES: "table_size" is an odd (9, 11, 13, 15) power of two
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OUTPUT: maximal copy distance <= |input_size|
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OUTPUT: maximal copy distance <= BROTLI_MAX_BACKWARD_LIMIT(18) */
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BROTLI_INTERNAL void BrotliCompressFragmentFast(BrotliOnePassArena* s,
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const uint8_t* input,
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size_t input_size,
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BROTLI_BOOL is_last,
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int* table, size_t table_size,
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size_t* storage_ix,
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uint8_t* storage);
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#if defined(__cplusplus) || defined(c_plusplus)
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} /* extern "C" */
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#endif
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#endif /* BROTLI_ENC_COMPRESS_FRAGMENT_H_ */
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