1 files changed, 60 insertions, 0 deletions
diff --git a/libgo/runtime/mheapmap64.h b/libgo/runtime/mheapmap64.h
new file mode 100644
index 000000000..be304cb2e
--- /dev/null
+++ b/libgo/runtime/mheapmap64.h
@@ -0,0 +1,60 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Free(v) must be able to determine the MSpan containing v.
+// The MHeapMap is a 3-level radix tree mapping page numbers to MSpans.
+//
+// NOTE(rsc): On a 32-bit platform (= 20-bit page numbers),
+// we can swap in a 2-level radix tree.
+//
+// NOTE(rsc): We use a 3-level tree because tcmalloc does, but
+// having only three levels requires approximately 1 MB per node
+// in the tree, making the minimum map footprint 3 MB.
+// Using a 4-level tree would cut the minimum footprint to 256 kB.
+// On the other hand, it's just virtual address space: most of
+// the memory is never going to be touched, thus never paged in.
+
+typedef struct MHeapMapNode2 MHeapMapNode2;
+typedef struct MHeapMapNode3 MHeapMapNode3;
+
+enum
+{
+	// 64 bit address - 12 bit page size = 52 bits to map
+	MHeapMap_Level1Bits = 18,
+	MHeapMap_Level2Bits = 18,
+	MHeapMap_Level3Bits = 16,
+
+	MHeapMap_TotalBits =
+		MHeapMap_Level1Bits +
+		MHeapMap_Level2Bits +
+		MHeapMap_Level3Bits,
+
+	MHeapMap_Level1Mask = (1<<MHeapMap_Level1Bits) - 1,
+	MHeapMap_Level2Mask = (1<<MHeapMap_Level2Bits) - 1,
+	MHeapMap_Level3Mask = (1<<MHeapMap_Level3Bits) - 1,
+};
+
+struct MHeapMap
+{
+	void *(*allocator)(uintptr);
+	MHeapMapNode2 *p[1<<MHeapMap_Level1Bits];
+};
+
+struct MHeapMapNode2
+{
+	MHeapMapNode3 *p[1<<MHeapMap_Level2Bits];
+};
+
+struct MHeapMapNode3
+{
+	MSpan *s[1<<MHeapMap_Level3Bits];
+};
+
+void	runtime_MHeapMap_Init(MHeapMap *m, void *(*allocator)(uintptr));
+bool	runtime_MHeapMap_Preallocate(MHeapMap *m, PageID k, uintptr npages);
+MSpan*	runtime_MHeapMap_Get(MHeapMap *m, PageID k);
+MSpan*	runtime_MHeapMap_GetMaybe(MHeapMap *m, PageID k);
+void	runtime_MHeapMap_Set(MHeapMap *m, PageID k, MSpan *v);
+
+