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/* Copyright 2013 Google Inc. All Rights Reserved.
Distributed under MIT license.
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/
/**
* @file
* API for Brotli compression.
*/
#ifndef BROTLI_ENC_ENCODE_H_
#define BROTLI_ENC_ENCODE_H_
#include <brotli/port.h>
#include <brotli/types.h>
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
/** Minimal value for ::BROTLI_PARAM_LGWIN parameter. */
#define BROTLI_MIN_WINDOW_BITS 10
/**
* Maximal value for ::BROTLI_PARAM_LGWIN parameter.
*
* @note equal to @c BROTLI_MAX_DISTANCE_BITS constant.
*/
#define BROTLI_MAX_WINDOW_BITS 24
/**
* Maximal value for ::BROTLI_PARAM_LGWIN parameter
* in "Large Window Brotli" (32-bit).
*/
#define BROTLI_LARGE_MAX_WINDOW_BITS 30
/** Minimal value for ::BROTLI_PARAM_LGBLOCK parameter. */
#define BROTLI_MIN_INPUT_BLOCK_BITS 16
/** Maximal value for ::BROTLI_PARAM_LGBLOCK parameter. */
#define BROTLI_MAX_INPUT_BLOCK_BITS 24
/** Minimal value for ::BROTLI_PARAM_QUALITY parameter. */
#define BROTLI_MIN_QUALITY 0
/** Maximal value for ::BROTLI_PARAM_QUALITY parameter. */
#define BROTLI_MAX_QUALITY 11
/** Options for ::BROTLI_PARAM_MODE parameter. */
typedef enum BrotliEncoderMode {
/**
* Default compression mode.
*
* In this mode compressor does not know anything in advance about the
* properties of the input.
*/
BROTLI_MODE_GENERIC = 0,
/** Compression mode for UTF-8 formatted text input. */
BROTLI_MODE_TEXT = 1,
/** Compression mode used in WOFF 2.0. */
BROTLI_MODE_FONT = 2
} BrotliEncoderMode;
/** Default value for ::BROTLI_PARAM_QUALITY parameter. */
#define BROTLI_DEFAULT_QUALITY 11
/** Default value for ::BROTLI_PARAM_LGWIN parameter. */
#define BROTLI_DEFAULT_WINDOW 22
/** Default value for ::BROTLI_PARAM_MODE parameter. */
#define BROTLI_DEFAULT_MODE BROTLI_MODE_GENERIC
/** Operations that can be performed by streaming encoder. */
typedef enum BrotliEncoderOperation {
/**
* Process input.
*
* Encoder may postpone producing output, until it has processed enough input.
*/
BROTLI_OPERATION_PROCESS = 0,
/**
* Produce output for all processed input.
*
* Actual flush is performed when input stream is depleted and there is enough
* space in output stream. This means that client should repeat
* ::BROTLI_OPERATION_FLUSH operation until @p available_in becomes @c 0, and
* ::BrotliEncoderHasMoreOutput returns ::BROTLI_FALSE. If output is acquired
* via ::BrotliEncoderTakeOutput, then operation should be repeated after
* output buffer is drained.
*
* @warning Until flush is complete, client @b SHOULD @b NOT swap,
* reduce or extend input stream.
*
* When flush is complete, output data will be sufficient for decoder to
* reproduce all the given input.
*/
BROTLI_OPERATION_FLUSH = 1,
/**
* Finalize the stream.
*
* Actual finalization is performed when input stream is depleted and there is
* enough space in output stream. This means that client should repeat
* ::BROTLI_OPERATION_FINISH operation until @p available_in becomes @c 0, and
* ::BrotliEncoderHasMoreOutput returns ::BROTLI_FALSE. If output is acquired
* via ::BrotliEncoderTakeOutput, then operation should be repeated after
* output buffer is drained.
*
* @warning Until finalization is complete, client @b SHOULD @b NOT swap,
* reduce or extend input stream.
*
* Helper function ::BrotliEncoderIsFinished checks if stream is finalized and
* output fully dumped.
*
* Adding more input data to finalized stream is impossible.
*/
BROTLI_OPERATION_FINISH = 2,
/**
* Emit metadata block to stream.
*
* Metadata is opaque to Brotli: neither encoder, nor decoder processes this
* data or relies on it. It may be used to pass some extra information from
* encoder client to decoder client without interfering with main data stream.
*
* @note Encoder may emit empty metadata blocks internally, to pad encoded
* stream to byte boundary.
*
* @warning Until emitting metadata is complete client @b SHOULD @b NOT swap,
* reduce or extend input stream.
*
* @warning The whole content of input buffer is considered to be the content
* of metadata block. Do @b NOT @e append metadata to input stream,
* before it is depleted with other operations.
*
* Stream is soft-flushed before metadata block is emitted. Metadata block
* @b MUST be no longer than than 16MiB.
*/
BROTLI_OPERATION_EMIT_METADATA = 3
} BrotliEncoderOperation;
/** Options to be used with ::BrotliEncoderSetParameter. */
typedef enum BrotliEncoderParameter {
/**
* Tune encoder for specific input.
*
* ::BrotliEncoderMode enumerates all available values.
*/
BROTLI_PARAM_MODE = 0,
/**
* The main compression speed-density lever.
*
* The higher the quality, the slower the compression. Range is
* from ::BROTLI_MIN_QUALITY to ::BROTLI_MAX_QUALITY.
*/
BROTLI_PARAM_QUALITY = 1,
/**
* Recommended sliding LZ77 window size.
*
* Encoder may reduce this value, e.g. if input is much smaller than
* window size.
*
* Window size is `(1 << value) - 16`.
*
* Range is from ::BROTLI_MIN_WINDOW_BITS to ::BROTLI_MAX_WINDOW_BITS.
*/
BROTLI_PARAM_LGWIN = 2,
/**
* Recommended input block size.
*
* Encoder may reduce this value, e.g. if input is much smaller than input
* block size.
*
* Range is from ::BROTLI_MIN_INPUT_BLOCK_BITS to
* ::BROTLI_MAX_INPUT_BLOCK_BITS.
*
* @note Bigger input block size allows better compression, but consumes more
* memory. \n The rough formula of memory used for temporary input
* storage is `3 << lgBlock`.
*/
BROTLI_PARAM_LGBLOCK = 3,
/**
* Flag that affects usage of "literal context modeling" format feature.
*
* This flag is a "decoding-speed vs compression ratio" trade-off.
*/
BROTLI_PARAM_DISABLE_LITERAL_CONTEXT_MODELING = 4,
/**
* Estimated total input size for all ::BrotliEncoderCompressStream calls.
*
* The default value is 0, which means that the total input size is unknown.
*/
BROTLI_PARAM_SIZE_HINT = 5,
/**
* Flag that determines if "Large Window Brotli" is used.
*/
BROTLI_PARAM_LARGE_WINDOW = 6,
/**
* Recommended number of postfix bits (NPOSTFIX).
*
* Encoder may change this value.
*
* Range is from 0 to ::BROTLI_MAX_NPOSTFIX.
*/
BROTLI_PARAM_NPOSTFIX = 7,
/**
* Recommended number of direct distance codes (NDIRECT).
*
* Encoder may change this value.
*
* Range is from 0 to (15 << NPOSTFIX) in steps of (1 << NPOSTFIX).
*/
BROTLI_PARAM_NDIRECT = 8,
/**
* Number of bytes of input stream already processed by a different instance.
*
* @note It is important to configure all the encoder instances with same
* parameters (except this one) in order to allow all the encoded parts
* obey the same restrictions implied by header.
*
* If offset is not 0, then stream header is omitted.
* In any case output start is byte aligned, so for proper streams stitching
* "predecessor" stream must be flushed.
*
* Range is not artificially limited, but all the values greater or equal to
* maximal window size have the same effect. Values greater than 2**30 are not
* allowed.
*/
BROTLI_PARAM_STREAM_OFFSET = 9
} BrotliEncoderParameter;
/**
* Opaque structure that holds encoder state.
*
* Allocated and initialized with ::BrotliEncoderCreateInstance.
* Cleaned up and deallocated with ::BrotliEncoderDestroyInstance.
*/
typedef struct BrotliEncoderStateStruct BrotliEncoderState;
/**
* Sets the specified parameter to the given encoder instance.
*
* @param state encoder instance
* @param param parameter to set
* @param value new parameter value
* @returns ::BROTLI_FALSE if parameter is unrecognized, or value is invalid
* @returns ::BROTLI_FALSE if value of parameter can not be changed at current
* encoder state (e.g. when encoding is started, window size might be
* already encoded and therefore it is impossible to change it)
* @returns ::BROTLI_TRUE if value is accepted
* @warning invalid values might be accepted in case they would not break
* encoding process.
*/
BROTLI_ENC_API BROTLI_BOOL BrotliEncoderSetParameter(
BrotliEncoderState* state, BrotliEncoderParameter param, uint32_t value);
/**
* Creates an instance of ::BrotliEncoderState and initializes it.
*
* @p alloc_func and @p free_func @b MUST be both zero or both non-zero. In the
* case they are both zero, default memory allocators are used. @p opaque is
* passed to @p alloc_func and @p free_func when they are called. @p free_func
* has to return without doing anything when asked to free a NULL pointer.
*
* @param alloc_func custom memory allocation function
* @param free_func custom memory free function
* @param opaque custom memory manager handle
* @returns @c 0 if instance can not be allocated or initialized
* @returns pointer to initialized ::BrotliEncoderState otherwise
*/
BROTLI_ENC_API BrotliEncoderState* BrotliEncoderCreateInstance(
brotli_alloc_func alloc_func, brotli_free_func free_func, void* opaque);
/**
* Deinitializes and frees ::BrotliEncoderState instance.
*
* @param state decoder instance to be cleaned up and deallocated
*/
BROTLI_ENC_API void BrotliEncoderDestroyInstance(BrotliEncoderState* state);
/**
* Calculates the output size bound for the given @p input_size.
*
* @warning Result is only valid if quality is at least @c 2 and, in
* case ::BrotliEncoderCompressStream was used, no flushes
* (::BROTLI_OPERATION_FLUSH) were performed.
*
* @param input_size size of projected input
* @returns @c 0 if result does not fit @c size_t
*/
BROTLI_ENC_API size_t BrotliEncoderMaxCompressedSize(size_t input_size);
/**
* Performs one-shot memory-to-memory compression.
*
* Compresses the data in @p input_buffer into @p encoded_buffer, and sets
* @p *encoded_size to the compressed length.
*
* @note If ::BrotliEncoderMaxCompressedSize(@p input_size) returns non-zero
* value, then output is guaranteed to be no longer than that.
*
* @note If @p lgwin is greater than ::BROTLI_MAX_WINDOW_BITS then resulting
* stream might be incompatible with RFC 7932; to decode such streams,
* decoder should be configured with
* ::BROTLI_DECODER_PARAM_LARGE_WINDOW = @c 1
*
* @param quality quality parameter value, e.g. ::BROTLI_DEFAULT_QUALITY
* @param lgwin lgwin parameter value, e.g. ::BROTLI_DEFAULT_WINDOW
* @param mode mode parameter value, e.g. ::BROTLI_DEFAULT_MODE
* @param input_size size of @p input_buffer
* @param input_buffer input data buffer with at least @p input_size
* addressable bytes
* @param[in, out] encoded_size @b in: size of @p encoded_buffer; \n
* @b out: length of compressed data written to
* @p encoded_buffer, or @c 0 if compression fails
* @param encoded_buffer compressed data destination buffer
* @returns ::BROTLI_FALSE in case of compression error
* @returns ::BROTLI_FALSE if output buffer is too small
* @returns ::BROTLI_TRUE otherwise
*/
BROTLI_ENC_API BROTLI_BOOL BrotliEncoderCompress(
int quality, int lgwin, BrotliEncoderMode mode, size_t input_size,
const uint8_t input_buffer[BROTLI_ARRAY_PARAM(input_size)],
size_t* encoded_size,
uint8_t encoded_buffer[BROTLI_ARRAY_PARAM(*encoded_size)]);
/**
* Compresses input stream to output stream.
*
* The values @p *available_in and @p *available_out must specify the number of
* bytes addressable at @p *next_in and @p *next_out respectively.
* When @p *available_out is @c 0, @p next_out is allowed to be @c NULL.
*
* After each call, @p *available_in will be decremented by the amount of input
* bytes consumed, and the @p *next_in pointer will be incremented by that
* amount. Similarly, @p *available_out will be decremented by the amount of
* output bytes written, and the @p *next_out pointer will be incremented by
* that amount.
*
* @p total_out, if it is not a null-pointer, will be set to the number
* of bytes compressed since the last @p state initialization.
*
*
*
* Internally workflow consists of 3 tasks:
* -# (optionally) copy input data to internal buffer
* -# actually compress data and (optionally) store it to internal buffer
* -# (optionally) copy compressed bytes from internal buffer to output stream
*
* Whenever all 3 tasks can't move forward anymore, or error occurs, this
* method returns the control flow to caller.
*
* @p op is used to perform flush, finish the stream, or inject metadata block.
* See ::BrotliEncoderOperation for more information.
*
* Flushing the stream means forcing encoding of all input passed to encoder and
* completing the current output block, so it could be fully decoded by stream
* decoder. To perform flush set @p op to ::BROTLI_OPERATION_FLUSH.
* Under some circumstances (e.g. lack of output stream capacity) this operation
* would require several calls to ::BrotliEncoderCompressStream. The method must
* be called again until both input stream is depleted and encoder has no more
* output (see ::BrotliEncoderHasMoreOutput) after the method is called.
*
* Finishing the stream means encoding of all input passed to encoder and
* adding specific "final" marks, so stream decoder could determine that stream
* is complete. To perform finish set @p op to ::BROTLI_OPERATION_FINISH.
* Under some circumstances (e.g. lack of output stream capacity) this operation
* would require several calls to ::BrotliEncoderCompressStream. The method must
* be called again until both input stream is depleted and encoder has no more
* output (see ::BrotliEncoderHasMoreOutput) after the method is called.
*
* @warning When flushing and finishing, @p op should not change until operation
* is complete; input stream should not be swapped, reduced or
* extended as well.
*
* @param state encoder instance
* @param op requested operation
* @param[in, out] available_in @b in: amount of available input; \n
* @b out: amount of unused input
* @param[in, out] next_in pointer to the next input byte
* @param[in, out] available_out @b in: length of output buffer; \n
* @b out: remaining size of output buffer
* @param[in, out] next_out compressed output buffer cursor;
* can be @c NULL if @p available_out is @c 0
* @param[out] total_out number of bytes produced so far; can be @c NULL
* @returns ::BROTLI_FALSE if there was an error
* @returns ::BROTLI_TRUE otherwise
*/
BROTLI_ENC_API BROTLI_BOOL BrotliEncoderCompressStream(
BrotliEncoderState* state, BrotliEncoderOperation op, size_t* available_in,
const uint8_t** next_in, size_t* available_out, uint8_t** next_out,
size_t* total_out);
/**
* Checks if encoder instance reached the final state.
*
* @param state encoder instance
* @returns ::BROTLI_TRUE if encoder is in a state where it reached the end of
* the input and produced all of the output
* @returns ::BROTLI_FALSE otherwise
*/
BROTLI_ENC_API BROTLI_BOOL BrotliEncoderIsFinished(BrotliEncoderState* state);
/**
* Checks if encoder has more output.
*
* @param state encoder instance
* @returns ::BROTLI_TRUE, if encoder has some unconsumed output
* @returns ::BROTLI_FALSE otherwise
*/
BROTLI_ENC_API BROTLI_BOOL BrotliEncoderHasMoreOutput(
BrotliEncoderState* state);
/**
* Acquires pointer to internal output buffer.
*
* This method is used to make language bindings easier and more efficient:
* -# push data to ::BrotliEncoderCompressStream,
* until ::BrotliEncoderHasMoreOutput returns BROTL_TRUE
* -# use ::BrotliEncoderTakeOutput to peek bytes and copy to language-specific
* entity
*
* Also this could be useful if there is an output stream that is able to
* consume all the provided data (e.g. when data is saved to file system).
*
* @attention After every call to ::BrotliEncoderTakeOutput @p *size bytes of
* output are considered consumed for all consecutive calls to the
* instance methods; returned pointer becomes invalidated as well.
*
* @note Encoder output is not guaranteed to be contiguous. This means that
* after the size-unrestricted call to ::BrotliEncoderTakeOutput,
* immediate next call to ::BrotliEncoderTakeOutput may return more data.
*
* @param state encoder instance
* @param[in, out] size @b in: number of bytes caller is ready to take, @c 0 if
* any amount could be handled; \n
* @b out: amount of data pointed by returned pointer and
* considered consumed; \n
* out value is never greater than in value, unless it is @c 0
* @returns pointer to output data
*/
BROTLI_ENC_API const uint8_t* BrotliEncoderTakeOutput(
BrotliEncoderState* state, size_t* size);
/**
* Gets an encoder library version.
*
* Look at BROTLI_VERSION for more information.
*/
BROTLI_ENC_API uint32_t BrotliEncoderVersion(void);
#if defined(__cplusplus) || defined(c_plusplus)
} /* extern "C" */
#endif
#endif /* BROTLI_ENC_ENCODE_H_ */
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