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authorLasse Collin <lasse.collin@tukaani.org>2007-12-09 00:42:33 +0200
committerLasse Collin <lasse.collin@tukaani.org>2007-12-09 00:42:33 +0200
commit5d018dc03549c1ee4958364712fb0c94e1bf2741 (patch)
tree1b211911fb33fddb3f04b77f99e81df23623ffc4 /src/liblzma/common/alignment.c
downloadxz-5d018dc03549c1ee4958364712fb0c94e1bf2741.tar.xz
Imported to git.
Diffstat (limited to 'src/liblzma/common/alignment.c')
-rw-r--r--src/liblzma/common/alignment.c118
1 files changed, 118 insertions, 0 deletions
diff --git a/src/liblzma/common/alignment.c b/src/liblzma/common/alignment.c
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+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file alignment.c
+/// \brief Calculates preferred alignments of different filters
+//
+// Copyright (C) 2007 Lasse Collin
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// Lesser General Public License for more details.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "common.h"
+
+
+extern LZMA_API uint32_t
+lzma_alignment_input(const lzma_options_filter *filters, uint32_t guess)
+{
+ for (size_t i = 0; filters[i].id != LZMA_VLI_VALUE_UNKNOWN; ++i) {
+ switch (filters[i].id) {
+ case LZMA_FILTER_COPY:
+ case LZMA_FILTER_DELTA:
+ // The same as the input, check the next filter.
+ continue;
+
+ case LZMA_FILTER_SUBBLOCK:
+ if (filters[i].options == NULL)
+ return LZMA_SUBBLOCK_ALIGNMENT_DEFAULT;
+ else
+ return ((const lzma_options_subblock *)(
+ filters[i].options))->alignment;
+
+ case LZMA_FILTER_X86:
+ return 1;
+
+ case LZMA_FILTER_ARMTHUMB:
+ return 2;
+
+ case LZMA_FILTER_POWERPC:
+ case LZMA_FILTER_ARM:
+ case LZMA_FILTER_SPARC:
+ return 4;
+
+ case LZMA_FILTER_IA64:
+ return 16;
+
+ case LZMA_FILTER_LZMA: {
+ const lzma_options_lzma *lzma = filters[i].options;
+ return 1 << MAX(lzma->pos_bits,
+ lzma->literal_pos_bits);
+ }
+
+ default:
+ return UINT32_MAX;
+ }
+ }
+
+ return guess;
+}
+
+
+extern LZMA_API uint32_t
+lzma_alignment_output(const lzma_options_filter *filters, uint32_t guess)
+{
+ // Check if there is only an implicit Copy filter.
+ if (filters[0].id == LZMA_VLI_VALUE_UNKNOWN)
+ return guess;
+
+ // Find the last filter in the chain.
+ size_t i = 0;
+ while (filters[i + 1].id != LZMA_VLI_VALUE_UNKNOWN)
+ ++i;
+
+ do {
+ switch (filters[i].id) {
+ case LZMA_FILTER_COPY:
+ case LZMA_FILTER_DELTA:
+ // It's the same as the input alignment, so
+ // check the next filter.
+ continue;
+
+ case LZMA_FILTER_SUBBLOCK:
+ if (filters[i].options == NULL)
+ return LZMA_SUBBLOCK_ALIGNMENT_DEFAULT;
+ else
+ return ((const lzma_options_subblock *)(
+ filters[i].options))->alignment;
+
+ case LZMA_FILTER_X86:
+ case LZMA_FILTER_LZMA:
+ return 1;
+
+ case LZMA_FILTER_ARMTHUMB:
+ return 2;
+
+ case LZMA_FILTER_POWERPC:
+ case LZMA_FILTER_ARM:
+ case LZMA_FILTER_SPARC:
+ return 4;
+
+ case LZMA_FILTER_IA64:
+ return 16;
+
+ default:
+ return UINT32_MAX;
+ }
+ } while (i-- != 0);
+
+ // If we get here, we have the same alignment as the input data.
+ return guess;
+}