1// Copyright 2011 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_FAST_DTOA_H_ 29#define V8_FAST_DTOA_H_ 30 31namespace v8 { 32namespace internal { 33 34enum FastDtoaMode { 35 // Computes the shortest representation of the given input. The returned 36 // result will be the most accurate number of this length. Longer 37 // representations might be more accurate. 38 FAST_DTOA_SHORTEST, 39 // Computes a representation where the precision (number of digits) is 40 // given as input. The precision is independent of the decimal point. 41 FAST_DTOA_PRECISION 42}; 43 44// FastDtoa will produce at most kFastDtoaMaximalLength digits. This does not 45// include the terminating '\0' character. 46const int kFastDtoaMaximalLength = 17; 47 48// Provides a decimal representation of v. 49// The result should be interpreted as buffer * 10^(point - length). 50// 51// Precondition: 52// * v must be a strictly positive finite double. 53// 54// Returns true if it succeeds, otherwise the result can not be trusted. 55// There will be *length digits inside the buffer followed by a null terminator. 56// If the function returns true and mode equals 57// - FAST_DTOA_SHORTEST, then 58// the parameter requested_digits is ignored. 59// The result satisfies 60// v == (double) (buffer * 10^(point - length)). 61// The digits in the buffer are the shortest representation possible. E.g. 62// if 0.099999999999 and 0.1 represent the same double then "1" is returned 63// with point = 0. 64// The last digit will be closest to the actual v. That is, even if several 65// digits might correctly yield 'v' when read again, the buffer will contain 66// the one closest to v. 67// - FAST_DTOA_PRECISION, then 68// the buffer contains requested_digits digits. 69// the difference v - (buffer * 10^(point-length)) is closest to zero for 70// all possible representations of requested_digits digits. 71// If there are two values that are equally close, then FastDtoa returns 72// false. 73// For both modes the buffer must be large enough to hold the result. 74bool FastDtoa(double d, 75 FastDtoaMode mode, 76 int requested_digits, 77 Vector<char> buffer, 78 int* length, 79 int* decimal_point); 80 81} } // namespace v8::internal 82 83#endif // V8_FAST_DTOA_H_ 84