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 33 namespace v8 { 34 namespace internal { 35 36 class 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
