.TH "encode.h" 3 "Wed Sep 20 2017" "Brotli" \" -*- nroff -*- .ad l .nh .SH NAME encode.h \- API for Brotli compression\&. .SH SYNOPSIS .br .PP .SS "Macros" .in +1c .ti -1c .RI "#define \fBBROTLI_DEFAULT_MODE\fP \fBBROTLI_MODE_GENERIC\fP" .br .RI "\fIDefault value for \fBBROTLI_PARAM_MODE\fP parameter\&. \fP" .ti -1c .RI "#define \fBBROTLI_DEFAULT_QUALITY\fP 11" .br .RI "\fIDefault value for \fBBROTLI_PARAM_QUALITY\fP parameter\&. \fP" .ti -1c .RI "#define \fBBROTLI_DEFAULT_WINDOW\fP 22" .br .RI "\fIDefault value for \fBBROTLI_PARAM_LGWIN\fP parameter\&. \fP" .ti -1c .RI "#define \fBBROTLI_MAX_INPUT_BLOCK_BITS\fP 24" .br .RI "\fIMaximal value for \fBBROTLI_PARAM_LGBLOCK\fP parameter\&. \fP" .ti -1c .RI "#define \fBBROTLI_MAX_QUALITY\fP 11" .br .RI "\fIMaximal value for \fBBROTLI_PARAM_QUALITY\fP parameter\&. \fP" .ti -1c .RI "#define \fBBROTLI_MAX_WINDOW_BITS\fP 24" .br .RI "\fIMaximal value for \fBBROTLI_PARAM_LGWIN\fP parameter\&. \fP" .ti -1c .RI "#define \fBBROTLI_MIN_INPUT_BLOCK_BITS\fP 16" .br .RI "\fIMinimal value for \fBBROTLI_PARAM_LGBLOCK\fP parameter\&. \fP" .ti -1c .RI "#define \fBBROTLI_MIN_QUALITY\fP 0" .br .RI "\fIMinimal value for \fBBROTLI_PARAM_QUALITY\fP parameter\&. \fP" .ti -1c .RI "#define \fBBROTLI_MIN_WINDOW_BITS\fP 10" .br .RI "\fIMinimal value for \fBBROTLI_PARAM_LGWIN\fP parameter\&. \fP" .in -1c .SS "Typedefs" .in +1c .ti -1c .RI "typedef enum \fBBrotliEncoderMode\fP \fBBrotliEncoderMode\fP" .br .RI "\fIOptions for \fBBROTLI_PARAM_MODE\fP parameter\&. \fP" .ti -1c .RI "typedef enum \fBBrotliEncoderOperation\fP \fBBrotliEncoderOperation\fP" .br .RI "\fIOperations that can be performed by streaming encoder\&. \fP" .ti -1c .RI "typedef enum \fBBrotliEncoderParameter\fP \fBBrotliEncoderParameter\fP" .br .RI "\fIOptions to be used with \fBBrotliEncoderSetParameter\fP\&. \fP" .ti -1c .RI "typedef struct BrotliEncoderStateStruct \fBBrotliEncoderState\fP" .br .RI "\fIOpaque structure that holds encoder state\&. \fP" .in -1c .SS "Enumerations" .SS "Functions" .in +1c .ti -1c .RI "\fBBROTLI_BOOL\fP \fBBrotliEncoderCompress\fP (int quality, int lgwin, \fBBrotliEncoderMode\fP mode, size_t input_size, const uint8_t input_buffer[input_size], size_t *encoded_size, uint8_t encoded_buffer[*encoded_size])" .br .RI "\fIPerforms one-shot memory-to-memory compression\&. \fP" .ti -1c .RI "\fBBROTLI_BOOL\fP \fBBrotliEncoderCompressStream\fP (\fBBrotliEncoderState\fP *state, \fBBrotliEncoderOperation\fP op, size_t *available_in, const uint8_t **next_in, size_t *available_out, uint8_t **next_out, size_t *total_out)" .br .RI "\fICompresses input stream to output stream\&. \fP" .ti -1c .RI "\fBBrotliEncoderState\fP * \fBBrotliEncoderCreateInstance\fP (\fBbrotli_alloc_func\fP alloc_func, \fBbrotli_free_func\fP free_func, void *opaque)" .br .RI "\fICreates an instance of \fBBrotliEncoderState\fP and initializes it\&. \fP" .ti -1c .RI "void \fBBrotliEncoderDestroyInstance\fP (\fBBrotliEncoderState\fP *state)" .br .RI "\fIDeinitializes and frees \fBBrotliEncoderState\fP instance\&. \fP" .ti -1c .RI "\fBBROTLI_BOOL\fP \fBBrotliEncoderHasMoreOutput\fP (\fBBrotliEncoderState\fP *state)" .br .RI "\fIChecks if encoder has more output\&. \fP" .ti -1c .RI "\fBBROTLI_BOOL\fP \fBBrotliEncoderIsFinished\fP (\fBBrotliEncoderState\fP *state)" .br .RI "\fIChecks if encoder instance reached the final state\&. \fP" .ti -1c .RI "size_t \fBBrotliEncoderMaxCompressedSize\fP (size_t input_size)" .br .RI "\fICalculates the output size bound for the given \fCinput_size\fP\&. \fP" .ti -1c .RI "\fBBROTLI_BOOL\fP \fBBrotliEncoderSetParameter\fP (\fBBrotliEncoderState\fP *state, \fBBrotliEncoderParameter\fP param, uint32_t value)" .br .RI "\fISets the specified parameter to the given encoder instance\&. \fP" .ti -1c .RI "const uint8_t * \fBBrotliEncoderTakeOutput\fP (\fBBrotliEncoderState\fP *state, size_t *size)" .br .RI "\fIAcquires pointer to internal output buffer\&. \fP" .ti -1c .RI "uint32_t \fBBrotliEncoderVersion\fP (void)" .br .RI "\fIGets an encoder library version\&. \fP" .in -1c .SH "Detailed Description" .PP API for Brotli compression\&. .SH "Macro Definition Documentation" .PP .SS "#define BROTLI_DEFAULT_MODE \fBBROTLI_MODE_GENERIC\fP" .PP Default value for \fBBROTLI_PARAM_MODE\fP parameter\&. .SS "#define BROTLI_DEFAULT_QUALITY 11" .PP Default value for \fBBROTLI_PARAM_QUALITY\fP parameter\&. .SS "#define BROTLI_DEFAULT_WINDOW 22" .PP Default value for \fBBROTLI_PARAM_LGWIN\fP parameter\&. .SS "#define BROTLI_MAX_INPUT_BLOCK_BITS 24" .PP Maximal value for \fBBROTLI_PARAM_LGBLOCK\fP parameter\&. .SS "#define BROTLI_MAX_QUALITY 11" .PP Maximal value for \fBBROTLI_PARAM_QUALITY\fP parameter\&. .SS "#define BROTLI_MAX_WINDOW_BITS 24" .PP Maximal value for \fBBROTLI_PARAM_LGWIN\fP parameter\&. .PP \fBNote:\fP .RS 4 equal to \fCBROTLI_MAX_DISTANCE_BITS\fP constant\&. .RE .PP .SS "#define BROTLI_MIN_INPUT_BLOCK_BITS 16" .PP Minimal value for \fBBROTLI_PARAM_LGBLOCK\fP parameter\&. .SS "#define BROTLI_MIN_QUALITY 0" .PP Minimal value for \fBBROTLI_PARAM_QUALITY\fP parameter\&. .SS "#define BROTLI_MIN_WINDOW_BITS 10" .PP Minimal value for \fBBROTLI_PARAM_LGWIN\fP parameter\&. .SH "Typedef Documentation" .PP .SS "typedef enum \fBBrotliEncoderMode\fP \fBBrotliEncoderMode\fP" .PP Options for \fBBROTLI_PARAM_MODE\fP parameter\&. .SS "typedef enum \fBBrotliEncoderOperation\fP \fBBrotliEncoderOperation\fP" .PP Operations that can be performed by streaming encoder\&. .SS "typedef enum \fBBrotliEncoderParameter\fP \fBBrotliEncoderParameter\fP" .PP Options to be used with \fBBrotliEncoderSetParameter\fP\&. .SS "typedef struct BrotliEncoderStateStruct \fBBrotliEncoderState\fP" .PP Opaque structure that holds encoder state\&. Allocated and initialized with \fBBrotliEncoderCreateInstance\fP\&. Cleaned up and deallocated with \fBBrotliEncoderDestroyInstance\fP\&. .SH "Enumeration Type Documentation" .PP .SS "enum \fBBrotliEncoderMode\fP" .PP Options for \fBBROTLI_PARAM_MODE\fP parameter\&. .PP \fBEnumerator\fP .in +1c .TP \fB\fIBROTLI_MODE_GENERIC \fP\fP Default compression mode\&. In this mode compressor does not know anything in advance about the properties of the input\&. .TP \fB\fIBROTLI_MODE_TEXT \fP\fP Compression mode for UTF-8 formatted text input\&. .TP \fB\fIBROTLI_MODE_FONT \fP\fP Compression mode used in WOFF 2\&.0\&. .SS "enum \fBBrotliEncoderOperation\fP" .PP Operations that can be performed by streaming encoder\&. .PP \fBEnumerator\fP .in +1c .TP \fB\fIBROTLI_OPERATION_PROCESS \fP\fP Process input\&. Encoder may postpone producing output, until it has processed enough input\&. .TP \fB\fIBROTLI_OPERATION_FLUSH \fP\fP 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 \fBBROTLI_OPERATION_FLUSH\fP operation until \fCavailable_in\fP becomes \fC0\fP, and \fBBrotliEncoderHasMoreOutput\fP returns \fBBROTLI_FALSE\fP\&. If output is acquired via \fBBrotliEncoderTakeOutput\fP, then operation should be repeated after output buffer is drained\&. .PP \fBWarning:\fP .RS 4 Until flush is complete, client \fBSHOULD\fP \fBNOT\fP swap, reduce or extend input stream\&. .RE .PP When flush is complete, output data will be sufficient for decoder to reproduce all the given input\&. .TP \fB\fIBROTLI_OPERATION_FINISH \fP\fP 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 \fBBROTLI_OPERATION_FINISH\fP operation until \fCavailable_in\fP becomes \fC0\fP, and \fBBrotliEncoderHasMoreOutput\fP returns \fBBROTLI_FALSE\fP\&. If output is acquired via \fBBrotliEncoderTakeOutput\fP, then operation should be repeated after output buffer is drained\&. .PP \fBWarning:\fP .RS 4 Until finalization is complete, client \fBSHOULD\fP \fBNOT\fP swap, reduce or extend input stream\&. .RE .PP Helper function \fBBrotliEncoderIsFinished\fP checks if stream is finalized and output fully dumped\&. .PP Adding more input data to finalized stream is impossible\&. .TP \fB\fIBROTLI_OPERATION_EMIT_METADATA \fP\fP 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\&. .PP \fBNote:\fP .RS 4 Encoder may emit empty metadata blocks internally, to pad encoded stream to byte boundary\&. .RE .PP \fBWarning:\fP .RS 4 Until emitting metadata is complete client \fBSHOULD\fP \fBNOT\fP swap, reduce or extend input stream\&. .PP The whole content of input buffer is considered to be the content of metadata block\&. Do \fBNOT\fP \fIappend\fP metadata to input stream, before it is depleted with other operations\&. .RE .PP Stream is soft-flushed before metadata block is emitted\&. Metadata block \fBMUST\fP be no longer than than 16MiB\&. .SS "enum \fBBrotliEncoderParameter\fP" .PP Options to be used with \fBBrotliEncoderSetParameter\fP\&. .PP \fBEnumerator\fP .in +1c .TP \fB\fIBROTLI_PARAM_MODE \fP\fP Tune encoder for specific input\&. \fBBrotliEncoderMode\fP enumerates all available values\&. .TP \fB\fIBROTLI_PARAM_QUALITY \fP\fP The main compression speed-density lever\&. The higher the quality, the slower the compression\&. Range is from \fBBROTLI_MIN_QUALITY\fP to \fBBROTLI_MAX_QUALITY\fP\&. .TP \fB\fIBROTLI_PARAM_LGWIN \fP\fP Recommended sliding LZ77 window size\&. Encoder may reduce this value, e\&.g\&. if input is much smaller than window size\&. .PP Window size is \fC(1 << value) - 16\fP\&. .PP Range is from \fBBROTLI_MIN_WINDOW_BITS\fP to \fBBROTLI_MAX_WINDOW_BITS\fP\&. .TP \fB\fIBROTLI_PARAM_LGBLOCK \fP\fP Recommended input block size\&. Encoder may reduce this value, e\&.g\&. if input is much smaller than input block size\&. .PP Range is from \fBBROTLI_MIN_INPUT_BLOCK_BITS\fP to \fBBROTLI_MAX_INPUT_BLOCK_BITS\fP\&. .PP \fBNote:\fP .RS 4 Bigger input block size allows better compression, but consumes more memory\&. .br The rough formula of memory used for temporary input storage is \fC3 << lgBlock\fP\&. .RE .PP .TP \fB\fIBROTLI_PARAM_DISABLE_LITERAL_CONTEXT_MODELING \fP\fP Flag that affects usage of 'literal context modeling' format feature\&. This flag is a 'decoding-speed vs compression ratio' trade-off\&. .TP \fB\fIBROTLI_PARAM_SIZE_HINT \fP\fP Estimated total input size for all \fBBrotliEncoderCompressStream\fP calls\&. The default value is 0, which means that the total input size is unknown\&. .SH "Function Documentation" .PP .SS "\fBBROTLI_BOOL\fP BrotliEncoderCompress (int quality, int lgwin, \fBBrotliEncoderMode\fP mode, size_t input_size, const uint8_t input_buffer[input_size], size_t * encoded_size, uint8_t encoded_buffer[*encoded_size])" .PP Performs one-shot memory-to-memory compression\&. Compresses the data in \fCinput_buffer\fP into \fCencoded_buffer\fP, and sets \fC*encoded_size\fP to the compressed length\&. .PP \fBNote:\fP .RS 4 If \fBBrotliEncoderMaxCompressedSize\fP(\fCinput_size\fP) returns non-zero value, then output is guaranteed to be no longer than that\&. .RE .PP \fBParameters:\fP .RS 4 \fIquality\fP quality parameter value, e\&.g\&. \fBBROTLI_DEFAULT_QUALITY\fP .br \fIlgwin\fP lgwin parameter value, e\&.g\&. \fBBROTLI_DEFAULT_WINDOW\fP .br \fImode\fP mode parameter value, e\&.g\&. \fBBROTLI_DEFAULT_MODE\fP .br \fIinput_size\fP size of \fCinput_buffer\fP .br \fIinput_buffer\fP input data buffer with at least \fCinput_size\fP addressable bytes .br \fIencoded_size\fP \fBin:\fP size of \fCencoded_buffer\fP; .br \fBout:\fP length of compressed data written to \fCencoded_buffer\fP, or \fC0\fP if compression fails .br \fIencoded_buffer\fP compressed data destination buffer .RE .PP \fBReturns:\fP .RS 4 \fBBROTLI_FALSE\fP in case of compression error .PP \fBBROTLI_FALSE\fP if output buffer is too small .PP \fBBROTLI_TRUE\fP otherwise .RE .PP .SS "\fBBROTLI_BOOL\fP BrotliEncoderCompressStream (\fBBrotliEncoderState\fP * state, \fBBrotliEncoderOperation\fP op, size_t * available_in, const uint8_t ** next_in, size_t * available_out, uint8_t ** next_out, size_t * total_out)" .PP Compresses input stream to output stream\&. The values \fC*available_in\fP and \fC*available_out\fP must specify the number of bytes addressable at \fC*next_in\fP and \fC*next_out\fP respectively\&. When \fC*available_out\fP is \fC0\fP, \fCnext_out\fP is allowed to be \fCNULL\fP\&. .PP After each call, \fC*available_in\fP will be decremented by the amount of input bytes consumed, and the \fC*next_in\fP pointer will be incremented by that amount\&. Similarly, \fC*available_out\fP will be decremented by the amount of output bytes written, and the \fC*next_out\fP pointer will be incremented by that amount\&. .PP \fCtotal_out\fP, if it is not a null-pointer, will be set to the number of bytes decompressed since the last \fCstate\fP initialization\&. .PP Internally workflow consists of 3 tasks: .IP "1." 4 (optionally) copy input data to internal buffer .IP "2." 4 actually compress data and (optionally) store it to internal buffer .IP "3." 4 (optionally) copy compressed bytes from internal buffer to output stream .PP .PP Whenever all 3 tasks can't move forward anymore, or error occurs, this method returns the control flow to caller\&. .PP \fCop\fP is used to perform flush, finish the stream, or inject metadata block\&. See \fBBrotliEncoderOperation\fP for more information\&. .PP 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 \fCop\fP to \fBBROTLI_OPERATION_FLUSH\fP\&. Under some circumstances (e\&.g\&. lack of output stream capacity) this operation would require several calls to \fBBrotliEncoderCompressStream\fP\&. The method must be called again until both input stream is depleted and encoder has no more output (see \fBBrotliEncoderHasMoreOutput\fP) after the method is called\&. .PP 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 \fCop\fP to \fBBROTLI_OPERATION_FINISH\fP\&. Under some circumstances (e\&.g\&. lack of output stream capacity) this operation would require several calls to \fBBrotliEncoderCompressStream\fP\&. The method must be called again until both input stream is depleted and encoder has no more output (see \fBBrotliEncoderHasMoreOutput\fP) after the method is called\&. .PP \fBWarning:\fP .RS 4 When flushing and finishing, \fCop\fP should not change until operation is complete; input stream should not be swapped, reduced or extended as well\&. .RE .PP \fBParameters:\fP .RS 4 \fIstate\fP encoder instance .br \fIop\fP requested operation .br \fIavailable_in\fP \fBin:\fP amount of available input; .br \fBout:\fP amount of unused input .br \fInext_in\fP pointer to the next input byte .br \fIavailable_out\fP \fBin:\fP length of output buffer; .br \fBout:\fP remaining size of output buffer .br \fInext_out\fP compressed output buffer cursor; can be \fCNULL\fP if \fCavailable_out\fP is \fC0\fP .br \fItotal_out\fP number of bytes produced so far; can be \fCNULL\fP .RE .PP \fBReturns:\fP .RS 4 \fBBROTLI_FALSE\fP if there was an error .PP \fBBROTLI_TRUE\fP otherwise .RE .PP .SS "\fBBrotliEncoderState\fP* BrotliEncoderCreateInstance (\fBbrotli_alloc_func\fP alloc_func, \fBbrotli_free_func\fP free_func, void * opaque)" .PP Creates an instance of \fBBrotliEncoderState\fP and initializes it\&. \fCalloc_func\fP and \fCfree_func\fP \fBMUST\fP be both zero or both non-zero\&. In the case they are both zero, default memory allocators are used\&. \fCopaque\fP is passed to \fCalloc_func\fP and \fCfree_func\fP when they are called\&. .PP \fBParameters:\fP .RS 4 \fIalloc_func\fP custom memory allocation function .br \fIfree_func\fP custom memory fee function .br \fIopaque\fP custom memory manager handle .RE .PP \fBReturns:\fP .RS 4 \fC0\fP if instance can not be allocated or initialized .PP pointer to initialized \fBBrotliEncoderState\fP otherwise .RE .PP .SS "void BrotliEncoderDestroyInstance (\fBBrotliEncoderState\fP * state)" .PP Deinitializes and frees \fBBrotliEncoderState\fP instance\&. .PP \fBParameters:\fP .RS 4 \fIstate\fP decoder instance to be cleaned up and deallocated .RE .PP .SS "\fBBROTLI_BOOL\fP BrotliEncoderHasMoreOutput (\fBBrotliEncoderState\fP * state)" .PP Checks if encoder has more output\&. .PP \fBParameters:\fP .RS 4 \fIstate\fP encoder instance .RE .PP \fBReturns:\fP .RS 4 \fBBROTLI_TRUE\fP, if encoder has some unconsumed output .PP \fBBROTLI_FALSE\fP otherwise .RE .PP .SS "\fBBROTLI_BOOL\fP BrotliEncoderIsFinished (\fBBrotliEncoderState\fP * state)" .PP Checks if encoder instance reached the final state\&. .PP \fBParameters:\fP .RS 4 \fIstate\fP encoder instance .RE .PP \fBReturns:\fP .RS 4 \fBBROTLI_TRUE\fP if encoder is in a state where it reached the end of the input and produced all of the output .PP \fBBROTLI_FALSE\fP otherwise .RE .PP .SS "size_t BrotliEncoderMaxCompressedSize (size_t input_size)" .PP Calculates the output size bound for the given \fCinput_size\fP\&. .PP \fBWarning:\fP .RS 4 Result is not applicable to \fBBrotliEncoderCompressStream\fP output, because every 'flush' adds extra overhead bytes, and some encoder settings (e\&.g\&. quality \fC0\fP and \fC1\fP) might imply a 'soft flush' after every chunk of input\&. .RE .PP \fBParameters:\fP .RS 4 \fIinput_size\fP size of projected input .RE .PP \fBReturns:\fP .RS 4 \fC0\fP if result does not fit \fCsize_t\fP .RE .PP .SS "\fBBROTLI_BOOL\fP BrotliEncoderSetParameter (\fBBrotliEncoderState\fP * state, \fBBrotliEncoderParameter\fP param, uint32_t value)" .PP Sets the specified parameter to the given encoder instance\&. .PP \fBParameters:\fP .RS 4 \fIstate\fP encoder instance .br \fIparam\fP parameter to set .br \fIvalue\fP new parameter value .RE .PP \fBReturns:\fP .RS 4 \fBBROTLI_FALSE\fP if parameter is unrecognized, or value is invalid .PP \fBBROTLI_FALSE\fP 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) .PP \fBBROTLI_TRUE\fP if value is accepted .RE .PP \fBWarning:\fP .RS 4 invalid values might be accepted in case they would not break encoding process\&. .RE .PP .SS "const uint8_t* BrotliEncoderTakeOutput (\fBBrotliEncoderState\fP * state, size_t * size)" .PP Acquires pointer to internal output buffer\&. This method is used to make language bindings easier and more efficient: .IP "1." 4 push data to \fBBrotliEncoderCompressStream\fP, until \fBBrotliEncoderHasMoreOutput\fP returns BROTL_TRUE .IP "2." 4 use \fBBrotliEncoderTakeOutput\fP to peek bytes and copy to language-specific entity .PP .PP 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)\&. .PP \fBAttention:\fP .RS 4 After every call to \fBBrotliEncoderTakeOutput\fP \fC*size\fP bytes of output are considered consumed for all consecutive calls to the instance methods; returned pointer becomes invalidated as well\&. .RE .PP \fBNote:\fP .RS 4 Encoder output is not guaranteed to be contiguous\&. This means that after the size-unrestricted call to \fBBrotliEncoderTakeOutput\fP, immediate next call to \fBBrotliEncoderTakeOutput\fP may return more data\&. .RE .PP \fBParameters:\fP .RS 4 \fIstate\fP encoder instance .br \fIsize\fP \fBin:\fP number of bytes caller is ready to take, \fC0\fP if any amount could be handled; .br \fBout:\fP amount of data pointed by returned pointer and considered consumed; .br out value is never greater than in value, unless it is \fC0\fP .RE .PP \fBReturns:\fP .RS 4 pointer to output data .RE .PP .SS "uint32_t BrotliEncoderVersion (void)" .PP Gets an encoder library version\&. Look at BROTLI_VERSION for more information\&. .SH "Author" .PP Generated automatically by Doxygen for Brotli from the source code\&.