1 // Copyright 2010 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef V8_CACHED_POWERS_H_
6 #define V8_CACHED_POWERS_H_
7 
8 #include "src/base/logging.h"
9 #include "src/diy-fp.h"
10 
11 namespace v8 {
12 namespace internal {
13 
14 class PowersOfTenCache {
15  public:
16   // Not all powers of ten are cached. The decimal exponent of two neighboring
17   // cached numbers will differ by kDecimalExponentDistance.
18   static const int kDecimalExponentDistance;
19 
20   static const int kMinDecimalExponent;
21   static const int kMaxDecimalExponent;
22 
23   // Returns a cached power-of-ten with a binary exponent in the range
24   // [min_exponent; max_exponent] (boundaries included).
25   static void GetCachedPowerForBinaryExponentRange(int min_exponent,
26                                                    int max_exponent,
27                                                    DiyFp* power,
28                                                    int* decimal_exponent);
29 
30   // Returns a cached power of ten x ~= 10^k such that
31   //   k <= decimal_exponent < k + kCachedPowersDecimalDistance.
32   // The given decimal_exponent must satisfy
33   //   kMinDecimalExponent <= requested_exponent, and
34   //   requested_exponent < kMaxDecimalExponent + kDecimalExponentDistance.
35   static void GetCachedPowerForDecimalExponent(int requested_exponent,
36                                                DiyFp* power,
37                                                int* found_exponent);
38 };
39 
40 }  // namespace internal
41 }  // namespace v8
42 
43 #endif  // V8_CACHED_POWERS_H_
44