forked from mirror/brotli
230 lines
9.0 KiB
Go
230 lines
9.0 KiB
Go
package brotli
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/**
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* Opaque structure that holds encoder state.
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*
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* Allocated and initialized with ::BrotliEncoderCreateInstance.
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* Cleaned up and deallocated with ::BrotliEncoderDestroyInstance.
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*/
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/**
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* Sets the specified parameter to the given encoder instance.
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*
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* @param state encoder instance
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* @param param parameter to set
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* @param value new parameter value
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* @returns ::false if parameter is unrecognized, or value is invalid
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* @returns ::false if value of parameter can not be changed at current
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* encoder state (e.g. when encoding is started, window size might be
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* already encoded and therefore it is impossible to change it)
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* @returns ::true if value is accepted
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* @warning invalid values might be accepted in case they would not break
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* encoding process.
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*/
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/**
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* Creates an instance of ::BrotliEncoderState and initializes it.
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*
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* @p alloc_func and @p free_func @b MUST be both zero or both non-zero. In the
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* case they are both zero, default memory allocators are used. @p opaque is
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* passed to @p alloc_func and @p free_func when they are called. @p free_func
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* has to return without doing anything when asked to free a NULL pointer.
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*
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* @param alloc_func custom memory allocation function
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* @param free_func custom memory free function
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* @param opaque custom memory manager handle
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* @returns @c 0 if instance can not be allocated or initialized
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* @returns pointer to initialized ::BrotliEncoderState otherwise
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*/
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/**
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* Deinitializes and frees ::BrotliEncoderState instance.
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*
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* @param state decoder instance to be cleaned up and deallocated
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*/
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/**
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* Calculates the output size bound for the given @p input_size.
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*
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* @warning Result is only valid if quality is at least @c 2 and, in
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* case ::BrotliEncoderCompressStream was used, no flushes
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* (::BROTLI_OPERATION_FLUSH) were performed.
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*
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* @param input_size size of projected input
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* @returns @c 0 if result does not fit @c size_t
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*/
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/**
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* Performs one-shot memory-to-memory compression.
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*
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* Compresses the data in @p input_buffer into @p encoded_buffer, and sets
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* @p *encoded_size to the compressed length.
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*
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* @note If ::BrotliEncoderMaxCompressedSize(@p input_size) returns non-zero
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* value, then output is guaranteed to be no longer than that.
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*
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* @param quality quality parameter value, e.g. ::BROTLI_DEFAULT_QUALITY
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* @param lgwin lgwin parameter value, e.g. ::BROTLI_DEFAULT_WINDOW
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* @param mode mode parameter value, e.g. ::BROTLI_DEFAULT_MODE
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* @param input_size size of @p input_buffer
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* @param input_buffer input data buffer with at least @p input_size
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* addressable bytes
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* @param[in, out] encoded_size @b in: size of @p encoded_buffer; \n
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* @b out: length of compressed data written to
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* @p encoded_buffer, or @c 0 if compression fails
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* @param encoded_buffer compressed data destination buffer
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* @returns ::false in case of compression error
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* @returns ::false if output buffer is too small
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* @returns ::true otherwise
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*/
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/**
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* Compresses input stream to output stream.
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*
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* The values @p *available_in and @p *available_out must specify the number of
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* bytes addressable at @p *next_in and @p *next_out respectively.
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* When @p *available_out is @c 0, @p next_out is allowed to be @c NULL.
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*
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* After each call, @p *available_in will be decremented by the amount of input
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* bytes consumed, and the @p *next_in pointer will be incremented by that
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* amount. Similarly, @p *available_out will be decremented by the amount of
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* output bytes written, and the @p *next_out pointer will be incremented by
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* that amount.
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*
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* @p total_out, if it is not a null-pointer, will be set to the number
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* of bytes compressed since the last @p state initialization.
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*
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*
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*
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* Internally workflow consists of 3 tasks:
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* -# (optionally) copy input data to internal buffer
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* -# actually compress data and (optionally) store it to internal buffer
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* -# (optionally) copy compressed bytes from internal buffer to output stream
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*
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* Whenever all 3 tasks can't move forward anymore, or error occurs, this
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* method returns the control flow to caller.
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*
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* @p op is used to perform flush, finish the stream, or inject metadata block.
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* See ::BrotliEncoderOperation for more information.
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*
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* Flushing the stream means forcing encoding of all input passed to encoder and
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* completing the current output block, so it could be fully decoded by stream
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* decoder. To perform flush set @p op to ::BROTLI_OPERATION_FLUSH.
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* Under some circumstances (e.g. lack of output stream capacity) this operation
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* would require several calls to ::BrotliEncoderCompressStream. The method must
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* be called again until both input stream is depleted and encoder has no more
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* output (see ::BrotliEncoderHasMoreOutput) after the method is called.
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*
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* Finishing the stream means encoding of all input passed to encoder and
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* adding specific "final" marks, so stream decoder could determine that stream
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* is complete. To perform finish set @p op to ::BROTLI_OPERATION_FINISH.
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* Under some circumstances (e.g. lack of output stream capacity) this operation
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* would require several calls to ::BrotliEncoderCompressStream. The method must
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* be called again until both input stream is depleted and encoder has no more
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* output (see ::BrotliEncoderHasMoreOutput) after the method is called.
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*
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* @warning When flushing and finishing, @p op should not change until operation
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* is complete; input stream should not be swapped, reduced or
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* extended as well.
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*
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* @param state encoder instance
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* @param op requested operation
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* @param[in, out] available_in @b in: amount of available input; \n
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* @b out: amount of unused input
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* @param[in, out] next_in pointer to the next input byte
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* @param[in, out] available_out @b in: length of output buffer; \n
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* @b out: remaining size of output buffer
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* @param[in, out] next_out compressed output buffer cursor;
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* can be @c NULL if @p available_out is @c 0
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* @param[out] total_out number of bytes produced so far; can be @c NULL
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* @returns ::false if there was an error
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* @returns ::true otherwise
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*/
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/**
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* Checks if encoder instance reached the final state.
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*
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* @param state encoder instance
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* @returns ::true if encoder is in a state where it reached the end of
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* the input and produced all of the output
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* @returns ::false otherwise
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*/
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/**
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* Checks if encoder has more output.
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*
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* @param state encoder instance
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* @returns ::true, if encoder has some unconsumed output
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* @returns ::false otherwise
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*/
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/**
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* Acquires pointer to internal output buffer.
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*
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* This method is used to make language bindings easier and more efficient:
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* -# push data to ::BrotliEncoderCompressStream,
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* until ::BrotliEncoderHasMoreOutput returns BROTL_TRUE
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* -# use ::BrotliEncoderTakeOutput to peek bytes and copy to language-specific
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* entity
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*
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* Also this could be useful if there is an output stream that is able to
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* consume all the provided data (e.g. when data is saved to file system).
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*
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* @attention After every call to ::BrotliEncoderTakeOutput @p *size bytes of
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* output are considered consumed for all consecutive calls to the
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* instance methods; returned pointer becomes invalidated as well.
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*
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* @note Encoder output is not guaranteed to be contiguous. This means that
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* after the size-unrestricted call to ::BrotliEncoderTakeOutput,
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* immediate next call to ::BrotliEncoderTakeOutput may return more data.
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*
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* @param state encoder instance
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* @param[in, out] size @b in: number of bytes caller is ready to take, @c 0 if
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* any amount could be handled; \n
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* @b out: amount of data pointed by returned pointer and
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* considered consumed; \n
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* out value is never greater than in value, unless it is @c 0
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* @returns pointer to output data
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*/
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/**
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* Gets an encoder library version.
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*
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* Look at BROTLI_VERSION for more information.
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*/
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/* Copyright 2017 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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/* Parameters for the Brotli encoder with chosen quality levels. */
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type BrotliHasherParams struct {
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type_ int
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bucket_bits int
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block_bits int
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hash_len int
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num_last_distances_to_check int
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}
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type BrotliDistanceParams struct {
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distance_postfix_bits uint32
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num_direct_distance_codes uint32
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alphabet_size uint32
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max_distance uint
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}
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/* Encoding parameters */
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type BrotliEncoderParams struct {
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mode int
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quality int
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lgwin uint
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lgblock int
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size_hint uint
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disable_literal_context_modeling bool
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large_window bool
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hasher BrotliHasherParams
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dist BrotliDistanceParams
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dictionary BrotliEncoderDictionary
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}
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