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 DOUBLE_CONVERSION_FAST_DTOA_H_ 29 #define DOUBLE_CONVERSION_FAST_DTOA_H_ 30 31 #include "utils.h" 32 33 namespace double_conversion { 34 35 enum FastDtoaMode { 36 // Computes the shortest representation of the given input. The returned 37 // result will be the most accurate number of this length. Longer 38 // representations might be more accurate. 39 FAST_DTOA_SHORTEST, 40 // Same as FAST_DTOA_SHORTEST but for single-precision floats. 41 FAST_DTOA_SHORTEST_SINGLE, 42 // Computes a representation where the precision (number of digits) is 43 // given as input. The precision is independent of the decimal point. 44 FAST_DTOA_PRECISION 45 }; 46 47 // FastDtoa will produce at most kFastDtoaMaximalLength digits. This does not 48 // include the terminating '\0' character. 49 static const int kFastDtoaMaximalLength = 17; 50 // Same for single-precision numbers. 51 static const int kFastDtoaMaximalSingleLength = 9; 52 53 // Provides a decimal representation of v. 54 // The result should be interpreted as buffer * 10^(point - length). 55 // 56 // Precondition: 57 // * v must be a strictly positive finite double. 58 // 59 // Returns true if it succeeds, otherwise the result can not be trusted. 60 // There will be *length digits inside the buffer followed by a null terminator. 61 // If the function returns true and mode equals 62 // - FAST_DTOA_SHORTEST, then 63 // the parameter requested_digits is ignored. 64 // The result satisfies 65 // v == (double) (buffer * 10^(point - length)). 66 // The digits in the buffer are the shortest representation possible. E.g. 67 // if 0.099999999999 and 0.1 represent the same double then "1" is returned 68 // with point = 0. 69 // The last digit will be closest to the actual v. That is, even if several 70 // digits might correctly yield 'v' when read again, the buffer will contain 71 // the one closest to v. 72 // - FAST_DTOA_PRECISION, then 73 // the buffer contains requested_digits digits. 74 // the difference v - (buffer * 10^(point-length)) is closest to zero for 75 // all possible representations of requested_digits digits. 76 // If there are two values that are equally close, then FastDtoa returns 77 // false. 78 // For both modes the buffer must be large enough to hold the result. 79 bool FastDtoa(double d, 80 FastDtoaMode mode, 81 int requested_digits, 82 Vector<char> buffer, 83 int* length, 84 int* decimal_point); 85 86 } // namespace double_conversion 87 88 #endif // DOUBLE_CONVERSION_FAST_DTOA_H_ 89