1 files changed, 111 insertions, 0 deletions
diff --git a/runtime/gc_map.h b/runtime/gc_map.h
new file mode 100644
index 0000000..473b39a
--- /dev/null
+++ b/runtime/gc_map.h
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_SRC_GC_MAP_H_
+#define ART_SRC_GC_MAP_H_
+
+#include <stdint.h>
+
+#include "base/logging.h"
+#include "base/macros.h"
+
+namespace art {
+
+// Lightweight wrapper for native PC offset to reference bit maps.
+class NativePcOffsetToReferenceMap {
+ public:
+  NativePcOffsetToReferenceMap(const uint8_t* data) : data_(data) {
+    CHECK(data_ != NULL);
+  }
+
+  // The number of entries in the table.
+  size_t NumEntries() const {
+    return data_[2] | (data_[3] << 8);
+  }
+
+  // Return address of bitmap encoding what are live references.
+  const uint8_t* GetBitMap(size_t index) const {
+    size_t entry_offset = index * EntryWidth();
+    return &Table()[entry_offset + NativeOffsetWidth()];
+  }
+
+  // Get the native PC encoded in the table at the given index.
+  uintptr_t GetNativePcOffset(size_t index) const {
+    size_t entry_offset = index * EntryWidth();
+    uintptr_t result = 0;
+    for (size_t i = 0; i < NativeOffsetWidth(); ++i) {
+      result |= Table()[entry_offset + i] << (i * 8);
+    }
+    return result;
+  }
+
+  // Does the given offset have an entry?
+  bool HasEntry(uintptr_t native_pc_offset) {
+    for (size_t i = 0; i < NumEntries(); ++i) {
+      if (GetNativePcOffset(i) == native_pc_offset) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  // Finds the bitmap associated with the native pc offset.
+  const uint8_t* FindBitMap(uintptr_t native_pc_offset) {
+    size_t num_entries = NumEntries();
+    size_t index = Hash(native_pc_offset) % num_entries;
+    size_t misses = 0;
+    while (GetNativePcOffset(index) != native_pc_offset) {
+      index = (index + 1) % num_entries;
+      misses++;
+      DCHECK_LT(misses, num_entries) << "Failed to find offset: " << native_pc_offset;
+    }
+    return GetBitMap(index);
+  }
+
+  static uint32_t Hash(uint32_t native_offset) {
+    uint32_t hash = native_offset;
+    hash ^= (hash >> 20) ^ (hash >> 12);
+    hash ^= (hash >> 7) ^ (hash >> 4);
+    return hash;
+  }
+
+  // The number of bytes used to encode registers.
+  size_t RegWidth() const {
+    return (static_cast<size_t>(data_[0]) | (static_cast<size_t>(data_[1]) << 8)) >> 3;
+  }
+
+ private:
+  // Skip the size information at the beginning of data.
+  const uint8_t* Table() const {
+    return data_ + 4;
+  }
+
+  // Number of bytes used to encode a native offset.
+  size_t NativeOffsetWidth() const {
+    return data_[0] & 7;
+  }
+
+  // The width of an entry in the table.
+  size_t EntryWidth() const {
+    return NativeOffsetWidth() + RegWidth();
+  }
+
+  const uint8_t* const data_;  // The header and table data
+};
+
+}  // namespace art
+
+#endif  // ART_SRC_GC_MAP_H_