Provide BitField64 utility class.

src/utils.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 224 matching lines @@
 inline int StrLength(const char* string) {
   size_t length = strlen(string);
   ASSERT(length == static_cast<size_t>(static_cast<int>(length)));
   return static_cast<int>(length);
 }
 
 
 // ----------------------------------------------------------------------------
 // BitField is a help template for encoding and decode bitfield with
 // unsigned content.
-template<class T, int shift, int size>
-class BitField {
+
+template<class T, int shift, int size, class U>
+class BitFieldBase {
  public:
-  // A uint32_t mask of bit field.  To use all bits of a uint32 in a
-  // bitfield without compiler warnings we have to compute 2^32 without
-  // using a shift count of 32.
-  static const uint32_t kMask = ((1U << shift) << size) - (1U << shift);
-  static const uint32_t kShift = shift;
-  static const uint32_t kSize = size;
+  // A type U mask of bit field.  To use all bits of a type U of x bits
+  // in a bitfield without compiler warnings we have to compute 2^x
+  // without using a shift count of x in the computation.
+  static const U kOne = static_cast<U>(1U);
+  static const U kMask = ((kOne << shift) << size) - (kOne << shift);
+  static const U kShift = shift;
+  static const U kSize = size;
 
   // Value for the field with all bits set.
   static const T kMax = static_cast<T>((1U << size) - 1);
 
   // Tells whether the provided value fits into the bit field.
   static bool is_valid(T value) {
-    return (static_cast<uint32_t>(value) & ~static_cast<uint32_t>(kMax)) == 0;
+    return (static_cast<U>(value) & ~static_cast<U>(kMax)) == 0;
   }
 
-  // Returns a uint32_t with the bit field value encoded.
-  static uint32_t encode(T value) {
+  // Returns a type U with the bit field value encoded.
+  static U encode(T value) {
     ASSERT(is_valid(value));
-    return static_cast<uint32_t>(value) << shift;
+    return static_cast<U>(value) << shift;
   }
 
-  // Returns a uint32_t with the bit field value updated.
-  static uint32_t update(uint32_t previous, T value) {
+  // Returns a type U with the bit field value updated.
+  static U update(U previous, T value) {
     return (previous & ~kMask) | encode(value);
   }
 
   // Extracts the bit field from the value.
-  static T decode(uint32_t value) {
+  static T decode(U value) {
     return static_cast<T>((value & kMask) >> shift);
   }
 };
 
 
+template<class T, int shift, int size>
+class BitField : public BitFieldBase<T, shift, size, uint32_t> { };
+
+
+template<class T, int shift, int size>
+class BitField64 : public BitFieldBase<T, shift, size, uint64_t> { };
+
+
 // ----------------------------------------------------------------------------
 // Hash function.
 
 static const uint32_t kZeroHashSeed = 0;
 
 // Thomas Wang, Integer Hash Functions.
 // http://www.concentric.net/~Ttwang/tech/inthash.htm
 inline uint32_t ComputeIntegerHash(uint32_t key, uint32_t seed) {
   uint32_t hash = key;
   hash = hash ^ seed;
@@ skipping 800 matching lines @@
 
   // Every compiled stub starts with this id.
   static const int kStubEntryId = 5;
 
   int id_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_UTILS_H_