1 files changed, 118 insertions, 0 deletions
diff --git a/src/liblzma/common/alignment.c b/src/liblzma/common/alignment.c
new file mode 100644
index 00000000..2d468fe5
--- /dev/null
+++ b/src/liblzma/common/alignment.c
@@ -0,0 +1,118 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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;
+}