mirror of https://git.tukaani.org/xz.git
61 lines
2.3 KiB
C
61 lines
2.3 KiB
C
/**
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* \file lzma/alignment.h
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* \brief Calculating input and output alignment of filter chains
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*
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* \author Copyright (C) 1999-2006 Igor Pavlov
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* \author Copyright (C) 2007 Lasse Collin
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*/
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#ifndef LZMA_H_INTERNAL
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# error Never include this file directly. Use <lzma.h> instead.
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#endif
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/**
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* \brief Calculates the preferred alignment of the input data
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*
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* FIXME desc
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*/
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extern uint32_t lzma_alignment_input(
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const lzma_filter *filters, uint32_t guess);
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/**
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* \brief Calculates the alignment of the encoded output
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*
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* Knowing the alignment of the output data is useful e.g. in the Block
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* encoder which tries to align the Compressed Data field optimally.
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*
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* \param filters Pointer to lzma_filter array, whose last
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* member must have .id = LZMA_VLI_VALUE_UNKNOWN.
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* \param guess The value to return if the alignment of the output
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* is the same as the alignment of the input data.
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* If you want to always detect this special case,
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* this guess to zero; this function never returns
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* zero unless guess is zero.
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*
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* \return In most cases, a small positive integer is returned;
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* for optimal use, the encoded output of this filter
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* chain should start at on offset that is a multiple of
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* the returned integer value.
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*
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* If the alignment of the output is the same as the input
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* data (which this function cannot know), \a guess is
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* returned.
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*
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* If an error occurs (that is, unknown Filter IDs or filter
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* options), UINT32_MAX is returned.
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*/
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extern uint32_t lzma_alignment_output(
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const lzma_filter *filters, uint32_t guess);
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