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118 lines
2.8 KiB
C
118 lines
2.8 KiB
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file alignment.c
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/// \brief Calculates preferred alignments of different filters
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//
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// 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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///////////////////////////////////////////////////////////////////////////////
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#include "common.h"
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extern LZMA_API uint32_t
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lzma_alignment_input(const lzma_options_filter *filters, uint32_t guess)
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{
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for (size_t i = 0; filters[i].id != LZMA_VLI_VALUE_UNKNOWN; ++i) {
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switch (filters[i].id) {
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case LZMA_FILTER_COPY:
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case LZMA_FILTER_DELTA:
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// The same as the input, check the next filter.
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continue;
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case LZMA_FILTER_SUBBLOCK:
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if (filters[i].options == NULL)
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return LZMA_SUBBLOCK_ALIGNMENT_DEFAULT;
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else
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return ((const lzma_options_subblock *)(
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filters[i].options))->alignment;
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case LZMA_FILTER_X86:
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return 1;
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case LZMA_FILTER_ARMTHUMB:
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return 2;
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case LZMA_FILTER_POWERPC:
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case LZMA_FILTER_ARM:
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case LZMA_FILTER_SPARC:
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return 4;
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case LZMA_FILTER_IA64:
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return 16;
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case LZMA_FILTER_LZMA: {
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const lzma_options_lzma *lzma = filters[i].options;
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return 1 << MAX(lzma->pos_bits,
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lzma->literal_pos_bits);
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}
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default:
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return UINT32_MAX;
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}
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}
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return guess;
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}
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extern LZMA_API uint32_t
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lzma_alignment_output(const lzma_options_filter *filters, uint32_t guess)
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{
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// Check if there is only an implicit Copy filter.
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if (filters[0].id == LZMA_VLI_VALUE_UNKNOWN)
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return guess;
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// Find the last filter in the chain.
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size_t i = 0;
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while (filters[i + 1].id != LZMA_VLI_VALUE_UNKNOWN)
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++i;
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do {
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switch (filters[i].id) {
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case LZMA_FILTER_COPY:
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case LZMA_FILTER_DELTA:
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// It's the same as the input alignment, so
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// check the next filter.
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continue;
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case LZMA_FILTER_SUBBLOCK:
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if (filters[i].options == NULL)
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return LZMA_SUBBLOCK_ALIGNMENT_DEFAULT;
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else
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return ((const lzma_options_subblock *)(
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filters[i].options))->alignment;
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case LZMA_FILTER_X86:
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case LZMA_FILTER_LZMA:
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return 1;
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case LZMA_FILTER_ARMTHUMB:
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return 2;
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case LZMA_FILTER_POWERPC:
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case LZMA_FILTER_ARM:
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case LZMA_FILTER_SPARC:
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return 4;
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case LZMA_FILTER_IA64:
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return 16;
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default:
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return UINT32_MAX;
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}
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} while (i-- != 0);
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// If we get here, we have the same alignment as the input data.
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return guess;
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}
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