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Unified Diff: tools/relocation_packer/src/packer.h

Issue 310483003: Add a host tool to pack R_ARM_RELATIVE relocations in libchrome.<ver>.so. (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Remove binary test data files, dcommit separately. Created 6 years, 6 months ago
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Index: tools/relocation_packer/src/packer.h
diff --git a/tools/relocation_packer/src/packer.h b/tools/relocation_packer/src/packer.h
new file mode 100644
index 0000000000000000000000000000000000000000..f0342cd078f5924658b187cb7b794d4452e1d510
--- /dev/null
+++ b/tools/relocation_packer/src/packer.h
@@ -0,0 +1,51 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Pack R_ARM_RELATIVE relocations into a more compact form.
+//
+// Applies two packing strategies. The first is run-length encoding, which
+// turns a large set of R_ARM_RELATIVE relocations into a much smaller set
+// of delta-count pairs, prefixed with a two-word header comprising the
+// count of pairs and the initial relocation offset. The second is LEB128
+// encoding, which compacts the result of run-length encoding.
+//
+// Once packed, data is prefixed by an identifier that allows for any later
+// versioning of packing strategies.
+//
+// A complete packed stream might look something like:
+//
+// "APR1" pairs init_offset count1 delta1 count2 delta2 ...
+// 41505231 f2b003 b08ac716 e001 04 01 10 ...
+
+#ifndef TOOLS_RELOCATION_PACKER_SRC_PACKER_H_
+#define TOOLS_RELOCATION_PACKER_SRC_PACKER_H_
+
+#include <stdint.h>
+#include <string.h>
+#include <vector>
+
+#include "elf.h"
+
+namespace relocation_packer {
+
+// A RelocationPacker packs vectors of R_ARM_RELATIVE relocations into more
+// compact forms, and unpacks them to reproduce the pre-packed data.
+class RelocationPacker {
+ public:
+ // Pack R_ARM_RELATIVE relocations into a more compact form.
+ // |relocations| is a vector of R_ARM_RELATIVE relocation structs.
+ // |packed| is the vector of packed bytes into which relocations are packed.
+ static void PackRelativeRelocations(const std::vector<Elf32_Rel>& relocations,
+ std::vector<uint8_t>* packed);
+
+ // Unpack R_ARM_RELATIVE relocations from their more compact form.
+ // |packed| is the vector of packed relocations.
+ // |relocations| is a vector of unpacked R_ARM_RELATIVE relocation structs.
+ static void UnpackRelativeRelocations(const std::vector<uint8_t>& packed,
+ std::vector<Elf32_Rel>* relocations);
+};
+
+} // namespace relocation_packer
+
+#endif // TOOLS_RELOCATION_PACKER_SRC_PACKER_H_
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