cached-powers.h 3.0 KB

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  1. // Copyright 2010 the V8 project authors. All rights reserved.
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  27. #ifndef DOUBLE_CONVERSION_CACHED_POWERS_H_
  28. #define DOUBLE_CONVERSION_CACHED_POWERS_H_
  29. #include "diy-fp.h"
  30. namespace double_conversion {
  31. namespace PowersOfTenCache {
  32. // Not all powers of ten are cached. The decimal exponent of two neighboring
  33. // cached numbers will differ by kDecimalExponentDistance.
  34. static const int kDecimalExponentDistance = 8;
  35. static const int kMinDecimalExponent = -348;
  36. static const int kMaxDecimalExponent = 340;
  37. // Returns a cached power-of-ten with a binary exponent in the range
  38. // [min_exponent; max_exponent] (boundaries included).
  39. void GetCachedPowerForBinaryExponentRange(int min_exponent,
  40. int max_exponent,
  41. DiyFp* power,
  42. int* decimal_exponent);
  43. // Returns a cached power of ten x ~= 10^k such that
  44. // k <= decimal_exponent < k + kCachedPowersDecimalDistance.
  45. // The given decimal_exponent must satisfy
  46. // kMinDecimalExponent <= requested_exponent, and
  47. // requested_exponent < kMaxDecimalExponent + kDecimalExponentDistance.
  48. void GetCachedPowerForDecimalExponent(int requested_exponent,
  49. DiyFp* power,
  50. int* found_exponent);
  51. } // namespace PowersOfTenCache
  52. } // namespace double_conversion
  53. #endif // DOUBLE_CONVERSION_CACHED_POWERS_H_