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
11namespace v8 {
12namespace internal {
13
14class 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 v8::internal
41
42#endif  // V8_CACHED_POWERS_H_
43