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 // Copyright 2011 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef V8_FAST_DTOA_H_ #define V8_FAST_DTOA_H_ namespace v8 { namespace internal { enum FastDtoaMode { // Computes the shortest representation of the given input. The returned // result will be the most accurate number of this length. Longer // representations might be more accurate. FAST_DTOA_SHORTEST, // Computes a representation where the precision (number of digits) is // given as input. The precision is independent of the decimal point. FAST_DTOA_PRECISION }; // FastDtoa will produce at most kFastDtoaMaximalLength digits. This does not // include the terminating '\0' character. const int kFastDtoaMaximalLength = 17; // Provides a decimal representation of v. // The result should be interpreted as buffer * 10^(point - length). // // Precondition: // * v must be a strictly positive finite double. // // Returns true if it succeeds, otherwise the result can not be trusted. // There will be *length digits inside the buffer followed by a null terminator. // If the function returns true and mode equals // - FAST_DTOA_SHORTEST, then // the parameter requested_digits is ignored. // The result satisfies // v == (double) (buffer * 10^(point - length)). // The digits in the buffer are the shortest representation possible. E.g. // if 0.099999999999 and 0.1 represent the same double then "1" is returned // with point = 0. // The last digit will be closest to the actual v. That is, even if several // digits might correctly yield 'v' when read again, the buffer will contain // the one closest to v. // - FAST_DTOA_PRECISION, then // the buffer contains requested_digits digits. // the difference v - (buffer * 10^(point-length)) is closest to zero for // all possible representations of requested_digits digits. // If there are two values that are equally close, then FastDtoa returns // false. // For both modes the buffer must be large enough to hold the result. bool FastDtoa(double d, FastDtoaMode mode, int requested_digits, Vector buffer, int* length, int* decimal_point); } } // namespace v8::internal #endif // V8_FAST_DTOA_H_