mirror of
https://github.com/google/brotli.git
synced 2024-11-09 21:50:07 +00:00
35e69fc7cf
* New feature: "Large Window Brotli" By setting special encoder/decoder flag it is now possible to extend LZ-window up to 30 bits; though produced stream will not be RFC7932 compliant. Added new dictionary generator - "DSH". It combines speed of "Sieve" and quality of "DM". Plus utilities to prepare train corpora (remove unique strings). Improved compression ratio: now two sub-blocks could be stitched: the last copy command could be extended to span the next sub-block. Fixed compression ineffectiveness caused by floating numbers rounding and wrong cost heuristic. Other C changes: - combined / moved `context.h` to `common` - moved transforms to `common` - unified some aspects of code formatting - added an abstraction for encoder (static) dictionary - moved default allocator/deallocator functions to `common` brotli CLI: - window size is auto-adjusted if not specified explicitly Java: - added "eager" decoding both to JNI wrapper and pure decoder - huge speed-up of `DictionaryData` initialization * Add dictionaryless compressed dictionary * Fix `sources.lst` * Fix `sources.lst` and add a note that `libtool` is also required. * Update setup.py * Fix `EagerStreamTest` * Fix BUILD file * Add missing `libdivsufsort` dependency * Fix "unused parameter" warning.
416 lines
14 KiB
Groff
416 lines
14 KiB
Groff
.TH "decode.h" 3 "Thu Feb 22 2018" "Brotli" \" -*- nroff -*-
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.ad l
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.nh
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.SH NAME
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decode.h \- API for Brotli decompression\&.
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.SH SYNOPSIS
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.br
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.PP
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.SS "Macros"
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.in +1c
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.ti -1c
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.RI "#define \fBBROTLI_DECODER_ERROR_CODES_LIST\fP(BROTLI_ERROR_CODE, SEPARATOR) "
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.br
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.RI "\fITemplate that evaluates items of \fBBrotliDecoderErrorCode\fP\&. \fP"
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.ti -1c
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.RI "#define \fBBROTLI_LAST_ERROR_CODE\fP BROTLI_DECODER_ERROR_UNREACHABLE"
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.br
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.RI "\fIThe value of the last error code, negative integer\&. \fP"
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.in -1c
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.SS "Typedefs"
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.in +1c
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.ti -1c
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.RI "typedef enum \fBBrotliDecoderParameter\fP \fBBrotliDecoderParameter\fP"
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.br
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.RI "\fIOptions to be used with \fBBrotliDecoderSetParameter\fP\&. \fP"
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.ti -1c
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.RI "typedef struct BrotliDecoderStateStruct \fBBrotliDecoderState\fP"
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.br
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.RI "\fIOpaque structure that holds decoder state\&. \fP"
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.in -1c
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.SS "Enumerations"
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.SS "Functions"
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.in +1c
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.ti -1c
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.RI "\fBBrotliDecoderState\fP * \fBBrotliDecoderCreateInstance\fP (\fBbrotli_alloc_func\fP alloc_func, \fBbrotli_free_func\fP free_func, void *opaque)"
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.br
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.RI "\fICreates an instance of \fBBrotliDecoderState\fP and initializes it\&. \fP"
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.ti -1c
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.RI "\fBBrotliDecoderResult\fP \fBBrotliDecoderDecompress\fP (size_t encoded_size, const uint8_t encoded_buffer[encoded_size], size_t *decoded_size, uint8_t decoded_buffer[*decoded_size])"
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.br
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.RI "\fIPerforms one-shot memory-to-memory decompression\&. \fP"
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.ti -1c
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.RI "\fBBrotliDecoderResult\fP \fBBrotliDecoderDecompressStream\fP (\fBBrotliDecoderState\fP *state, size_t *available_in, const uint8_t **next_in, size_t *available_out, uint8_t **next_out, size_t *total_out)"
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.br
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.RI "\fIDecompresses the input stream to the output stream\&. \fP"
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.ti -1c
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.RI "void \fBBrotliDecoderDestroyInstance\fP (\fBBrotliDecoderState\fP *state)"
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.br
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.RI "\fIDeinitializes and frees \fBBrotliDecoderState\fP instance\&. \fP"
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.ti -1c
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.RI "const char * \fBBrotliDecoderErrorString\fP (\fBBrotliDecoderErrorCode\fP c)"
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.br
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.RI "\fIConverts error code to a c-string\&. \fP"
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.ti -1c
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.RI "\fBBrotliDecoderErrorCode\fP \fBBrotliDecoderGetErrorCode\fP (const \fBBrotliDecoderState\fP *state)"
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.br
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.RI "\fIAcquires a detailed error code\&. \fP"
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.ti -1c
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.RI "\fBBROTLI_BOOL\fP \fBBrotliDecoderHasMoreOutput\fP (const \fBBrotliDecoderState\fP *state)"
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.br
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.RI "\fIChecks if decoder has more output\&. \fP"
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.ti -1c
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.RI "\fBBROTLI_BOOL\fP \fBBrotliDecoderIsFinished\fP (const \fBBrotliDecoderState\fP *state)"
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.br
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.RI "\fIChecks if decoder instance reached the final state\&. \fP"
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.ti -1c
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.RI "\fBBROTLI_BOOL\fP \fBBrotliDecoderIsUsed\fP (const \fBBrotliDecoderState\fP *state)"
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.br
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.RI "\fIChecks if instance has already consumed input\&. \fP"
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.ti -1c
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.RI "\fBBROTLI_BOOL\fP \fBBrotliDecoderSetParameter\fP (\fBBrotliDecoderState\fP *state, \fBBrotliDecoderParameter\fP param, uint32_t value)"
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.br
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.RI "\fISets the specified parameter to the given decoder instance\&. \fP"
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.ti -1c
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.RI "const uint8_t * \fBBrotliDecoderTakeOutput\fP (\fBBrotliDecoderState\fP *state, size_t *size)"
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.br
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.RI "\fIAcquires pointer to internal output buffer\&. \fP"
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.ti -1c
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.RI "uint32_t \fBBrotliDecoderVersion\fP (void)"
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.br
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.RI "\fIGets a decoder library version\&. \fP"
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.in -1c
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.SH "Detailed Description"
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.PP
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API for Brotli decompression\&.
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.SH "Macro Definition Documentation"
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.PP
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.SS "#define BROTLI_DECODER_ERROR_CODES_LIST(BROTLI_ERROR_CODE, SEPARATOR)"
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.PP
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Template that evaluates items of \fBBrotliDecoderErrorCode\fP\&. Example:
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.PP
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.nf
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// Log Brotli error code\&.
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switch (brotliDecoderErrorCode) {
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#define CASE_(PREFIX, NAME, CODE) \
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case BROTLI_DECODER ## PREFIX ## NAME: \
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LOG(INFO) << "error code:" << #NAME; \
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break;
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#define NEWLINE_
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BROTLI_DECODER_ERROR_CODES_LIST(CASE_, NEWLINE_)
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#undef CASE_
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#undef NEWLINE_
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default: LOG(FATAL) << "unknown brotli error code";
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}
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.fi
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.PP
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.SS "#define BROTLI_LAST_ERROR_CODE BROTLI_DECODER_ERROR_UNREACHABLE"
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.PP
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The value of the last error code, negative integer\&. All other error code values are in the range from \fBBROTLI_LAST_ERROR_CODE\fP to \fC-1\fP\&. There are also 4 other possible non-error codes \fC0\fP \&.\&. \fC3\fP in \fBBrotliDecoderErrorCode\fP enumeration\&.
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.SH "Typedef Documentation"
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.PP
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.SS "typedef enum \fBBrotliDecoderParameter\fP \fBBrotliDecoderParameter\fP"
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.PP
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Options to be used with \fBBrotliDecoderSetParameter\fP\&.
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.SS "typedef struct BrotliDecoderStateStruct \fBBrotliDecoderState\fP"
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.PP
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Opaque structure that holds decoder state\&. Allocated and initialized with \fBBrotliDecoderCreateInstance\fP\&. Cleaned up and deallocated with \fBBrotliDecoderDestroyInstance\fP\&.
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.SH "Enumeration Type Documentation"
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.PP
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.SS "enum \fBBrotliDecoderErrorCode\fP"
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.PP
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Error code for detailed logging / production debugging\&. See \fBBrotliDecoderGetErrorCode\fP and \fBBROTLI_LAST_ERROR_CODE\fP\&.
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.SS "enum \fBBrotliDecoderParameter\fP"
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.PP
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Options to be used with \fBBrotliDecoderSetParameter\fP\&.
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.PP
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\fBEnumerator\fP
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.in +1c
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.TP
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\fB\fIBROTLI_DECODER_PARAM_DISABLE_RING_BUFFER_REALLOCATION \fP\fP
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Disable 'canny' ring buffer allocation strategy\&. Ring buffer is allocated according to window size, despite the real size of the content\&.
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.TP
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\fB\fIBROTLI_DECODER_PARAM_LARGE_WINDOW \fP\fP
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Flag that determines if 'Large Window Brotli' is used\&.
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.SS "enum \fBBrotliDecoderResult\fP"
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.PP
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Result type for \fBBrotliDecoderDecompress\fP and \fBBrotliDecoderDecompressStream\fP functions\&.
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.PP
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\fBEnumerator\fP
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.in +1c
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.TP
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\fB\fIBROTLI_DECODER_RESULT_ERROR \fP\fP
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Decoding error, e\&.g\&. corrupted input or memory allocation problem\&.
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.TP
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\fB\fIBROTLI_DECODER_RESULT_SUCCESS \fP\fP
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Decoding successfully completed\&.
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.TP
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\fB\fIBROTLI_DECODER_RESULT_NEEDS_MORE_INPUT \fP\fP
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Partially done; should be called again with more input\&.
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.TP
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\fB\fIBROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT \fP\fP
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Partially done; should be called again with more output\&.
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.SH "Function Documentation"
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.PP
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.SS "\fBBrotliDecoderState\fP* BrotliDecoderCreateInstance (\fBbrotli_alloc_func\fP alloc_func, \fBbrotli_free_func\fP free_func, void * opaque)"
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.PP
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Creates an instance of \fBBrotliDecoderState\fP and initializes it\&. The instance can be used once for decoding and should then be destroyed with \fBBrotliDecoderDestroyInstance\fP, it cannot be reused for a new decoding session\&.
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.PP
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\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\&. \fCfree_func\fP has to return without doing anything when asked to free a NULL pointer\&.
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.PP
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\fBParameters:\fP
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.RS 4
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\fIalloc_func\fP custom memory allocation function
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.br
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\fIfree_func\fP custom memory free function
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.br
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\fIopaque\fP custom memory manager handle
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.RE
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.PP
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\fBReturns:\fP
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.RS 4
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\fC0\fP if instance can not be allocated or initialized
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.PP
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pointer to initialized \fBBrotliDecoderState\fP otherwise
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.RE
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.PP
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.SS "\fBBrotliDecoderResult\fP BrotliDecoderDecompress (size_t encoded_size, const uint8_t encoded_buffer[encoded_size], size_t * decoded_size, uint8_t decoded_buffer[*decoded_size])"
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.PP
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Performs one-shot memory-to-memory decompression\&. Decompresses the data in \fCencoded_buffer\fP into \fCdecoded_buffer\fP, and sets \fC*decoded_size\fP to the decompressed length\&.
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.PP
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\fBParameters:\fP
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.RS 4
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\fIencoded_size\fP size of \fCencoded_buffer\fP
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.br
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\fIencoded_buffer\fP compressed data buffer with at least \fCencoded_size\fP addressable bytes
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.br
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\fIdecoded_size\fP \fBin:\fP size of \fCdecoded_buffer\fP;
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.br
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\fBout:\fP length of decompressed data written to \fCdecoded_buffer\fP
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.br
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\fIdecoded_buffer\fP decompressed data destination buffer
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.RE
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.PP
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\fBReturns:\fP
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.RS 4
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\fBBROTLI_DECODER_RESULT_ERROR\fP if input is corrupted, memory allocation failed, or \fCdecoded_buffer\fP is not large enough;
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.PP
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\fBBROTLI_DECODER_RESULT_SUCCESS\fP otherwise
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.RE
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.PP
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.SS "\fBBrotliDecoderResult\fP BrotliDecoderDecompressStream (\fBBrotliDecoderState\fP * state, size_t * available_in, const uint8_t ** next_in, size_t * available_out, uint8_t ** next_out, size_t * total_out)"
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.PP
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Decompresses the input stream to the 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\&.
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.PP
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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\&.
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.PP
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\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\&.
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.PP
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\fBNote:\fP
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.RS 4
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Input is never overconsumed, so \fCnext_in\fP and \fCavailable_in\fP could be passed to the next consumer after decoding is complete\&.
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.RE
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.PP
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\fBParameters:\fP
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.RS 4
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\fIstate\fP decoder instance
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.br
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\fIavailable_in\fP \fBin:\fP amount of available input;
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.br
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\fBout:\fP amount of unused input
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.br
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\fInext_in\fP pointer to the next compressed byte
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.br
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\fIavailable_out\fP \fBin:\fP length of output buffer;
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.br
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\fBout:\fP remaining size of output buffer
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.br
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\fInext_out\fP output buffer cursor; can be \fCNULL\fP if \fCavailable_out\fP is \fC0\fP
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.br
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\fItotal_out\fP number of bytes decompressed so far; can be \fCNULL\fP
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.RE
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.PP
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\fBReturns:\fP
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.RS 4
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\fBBROTLI_DECODER_RESULT_ERROR\fP if input is corrupted, memory allocation failed, arguments were invalid, etc\&.; use \fBBrotliDecoderGetErrorCode\fP to get detailed error code
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.PP
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\fBBROTLI_DECODER_RESULT_NEEDS_MORE_INPUT\fP decoding is blocked until more input data is provided
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.PP
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\fBBROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT\fP decoding is blocked until more output space is provided
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.PP
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\fBBROTLI_DECODER_RESULT_SUCCESS\fP decoding is finished, no more input might be consumed and no more output will be produced
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.RE
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.PP
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.SS "void BrotliDecoderDestroyInstance (\fBBrotliDecoderState\fP * state)"
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.PP
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Deinitializes and frees \fBBrotliDecoderState\fP instance\&.
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.PP
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\fBParameters:\fP
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.RS 4
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\fIstate\fP decoder instance to be cleaned up and deallocated
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.RE
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.PP
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.SS "\fBBrotliDecoderErrorCode\fP BrotliDecoderGetErrorCode (const \fBBrotliDecoderState\fP * state)"
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.PP
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Acquires a detailed error code\&. Should be used only after \fBBrotliDecoderDecompressStream\fP returns \fBBROTLI_DECODER_RESULT_ERROR\fP\&.
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.PP
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See also \fBBrotliDecoderErrorString\fP
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.PP
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\fBParameters:\fP
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.RS 4
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\fIstate\fP decoder instance
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.RE
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.PP
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\fBReturns:\fP
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.RS 4
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last saved error code
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.RE
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.PP
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.SS "\fBBROTLI_BOOL\fP BrotliDecoderHasMoreOutput (const \fBBrotliDecoderState\fP * state)"
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.PP
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Checks if decoder has more output\&.
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.PP
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\fBParameters:\fP
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.RS 4
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\fIstate\fP decoder instance
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.RE
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.PP
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\fBReturns:\fP
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.RS 4
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\fBBROTLI_TRUE\fP, if decoder has some unconsumed output
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.PP
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\fBBROTLI_FALSE\fP otherwise
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.RE
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.PP
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.SS "\fBBROTLI_BOOL\fP BrotliDecoderIsFinished (const \fBBrotliDecoderState\fP * state)"
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.PP
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Checks if decoder instance reached the final state\&.
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.PP
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\fBParameters:\fP
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.RS 4
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\fIstate\fP decoder instance
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.RE
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.PP
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\fBReturns:\fP
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.RS 4
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\fBBROTLI_TRUE\fP if decoder is in a state where it reached the end of the input and produced all of the output
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.PP
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\fBBROTLI_FALSE\fP otherwise
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.RE
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.PP
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.SS "\fBBROTLI_BOOL\fP BrotliDecoderIsUsed (const \fBBrotliDecoderState\fP * state)"
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.PP
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Checks if instance has already consumed input\&. Instance that returns \fBBROTLI_FALSE\fP is considered 'fresh' and could be reused\&.
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.PP
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\fBParameters:\fP
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.RS 4
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\fIstate\fP decoder instance
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.RE
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.PP
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\fBReturns:\fP
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.RS 4
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\fBBROTLI_TRUE\fP if decoder has already used some input bytes
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.PP
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\fBBROTLI_FALSE\fP otherwise
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.RE
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.PP
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.SS "\fBBROTLI_BOOL\fP BrotliDecoderSetParameter (\fBBrotliDecoderState\fP * state, \fBBrotliDecoderParameter\fP param, uint32_t value)"
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.PP
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Sets the specified parameter to the given decoder instance\&.
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.PP
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\fBParameters:\fP
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.RS 4
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\fIstate\fP decoder instance
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.br
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\fIparam\fP parameter to set
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.br
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\fIvalue\fP new parameter value
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.RE
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.PP
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\fBReturns:\fP
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.RS 4
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\fBBROTLI_FALSE\fP if parameter is unrecognized, or value is invalid
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.PP
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\fBBROTLI_TRUE\fP if value is accepted
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.RE
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.PP
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.SS "const uint8_t* BrotliDecoderTakeOutput (\fBBrotliDecoderState\fP * state, size_t * size)"
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.PP
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Acquires pointer to internal output buffer\&. This method is used to make language bindings easier and more efficient:
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.IP "1." 4
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push data to \fBBrotliDecoderDecompressStream\fP, until \fBBROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT\fP is reported
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.IP "2." 4
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use \fBBrotliDecoderTakeOutput\fP to peek bytes and copy to language-specific entity
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.PP
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.PP
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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)\&.
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.PP
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\fBAttention:\fP
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.RS 4
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After every call to \fBBrotliDecoderTakeOutput\fP \fC*size\fP bytes of output are considered consumed for all consecutive calls to the instance methods; returned pointer becomes invalidated as well\&.
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.RE
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.PP
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\fBNote:\fP
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.RS 4
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Decoder output is not guaranteed to be contiguous\&. This means that after the size-unrestricted call to \fBBrotliDecoderTakeOutput\fP, immediate next call to \fBBrotliDecoderTakeOutput\fP may return more data\&.
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.RE
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.PP
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\fBParameters:\fP
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.RS 4
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\fIstate\fP decoder instance
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.br
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\fIsize\fP \fBin:\fP number of bytes caller is ready to take, \fC0\fP if any amount could be handled;
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.br
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\fBout:\fP amount of data pointed by returned pointer and considered consumed;
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.br
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out value is never greater than in value, unless it is \fC0\fP
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.RE
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.PP
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\fBReturns:\fP
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.RS 4
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pointer to output data
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.RE
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.PP
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.SS "uint32_t BrotliDecoderVersion (void)"
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.PP
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Gets a decoder library version\&. Look at BROTLI_VERSION for more information\&.
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.SH "Author"
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.PP
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Generated automatically by Doxygen for Brotli from the source code\&.
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