1// Copyright 2010 the V8 project authors. All rights reserved.
2// Redistribution and use in source and binary forms, with or without
3// modification, are permitted provided that the following conditions are
4// met:
5//
6//     * Redistributions of source code must retain the above copyright
7//       notice, this list of conditions and the following disclaimer.
8//     * Redistributions in binary form must reproduce the above
9//       copyright notice, this list of conditions and the following
10//       disclaimer in the documentation and/or other materials provided
11//       with the distribution.
12//     * Neither the name of Google Inc. nor the names of its
13//       contributors may be used to endorse or promote products derived
14//       from this software without specific prior written permission.
15//
16// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
28#ifndef V8_CACHED_POWERS_H_
29#define V8_CACHED_POWERS_H_
30
31#include "diy-fp.h"
32
33namespace v8 {
34namespace internal {
35
36class PowersOfTenCache {
37 public:
38  // Not all powers of ten are cached. The decimal exponent of two neighboring
39  // cached numbers will differ by kDecimalExponentDistance.
40  static const int kDecimalExponentDistance;
41
42  static const int kMinDecimalExponent;
43  static const int kMaxDecimalExponent;
44
45  // Returns a cached power-of-ten with a binary exponent in the range
46  // [min_exponent; max_exponent] (boundaries included).
47  static void GetCachedPowerForBinaryExponentRange(int min_exponent,
48                                                   int max_exponent,
49                                                   DiyFp* power,
50                                                   int* decimal_exponent);
51
52  // Returns a cached power of ten x ~= 10^k such that
53  //   k <= decimal_exponent < k + kCachedPowersDecimalDistance.
54  // The given decimal_exponent must satisfy
55  //   kMinDecimalExponent <= requested_exponent, and
56  //   requested_exponent < kMaxDecimalExponent + kDecimalExponentDistance.
57  static void GetCachedPowerForDecimalExponent(int requested_exponent,
58                                               DiyFp* power,
59                                               int* found_exponent);
60};
61
62} }  // namespace v8::internal
63
64#endif  // V8_CACHED_POWERS_H_
65