| 1 | // Copyright 2010 the V8 project authors. All rights reserved. |
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| 2 | // Redistribution and use in source and binary forms, with or without |
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| 3 | // modification, are permitted provided that the following conditions are |
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| 4 | // met: |
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| 5 | // |
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| 6 | // * Redistributions of source code must retain the above copyright |
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| 7 | // notice, this list of conditions and the following disclaimer. |
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| 8 | // * Redistributions in binary form must reproduce the above |
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| 9 | // copyright notice, this list of conditions and the following |
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| 10 | // disclaimer in the documentation and/or other materials provided |
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| 11 | // with the distribution. |
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| 12 | // * Neither the name of Google Inc. nor the names of its |
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| 13 | // contributors may be used to endorse or promote products derived |
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| 14 | // from this software without specific prior written permission. |
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| 15 | // |
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| 16 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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| 17 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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| 18 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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| 19 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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| 20 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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| 21 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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| 22 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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| 23 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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| 24 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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| 25 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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| 26 | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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| 27 | |
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| 28 | #ifndef DOUBLE_CONVERSION_FAST_DTOA_H_ |
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| 29 | #define DOUBLE_CONVERSION_FAST_DTOA_H_ |
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| 30 | |
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| 31 | #include <double-conversion/utils.h> |
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| 32 | |
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| 33 | namespace double_conversion { |
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| 34 | |
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| 35 | enum FastDtoaMode { |
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| 36 | // Computes the shortest representation of the given input. The returned |
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| 37 | // result will be the most accurate number of this length. Longer |
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| 38 | // representations might be more accurate. |
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| 39 | FAST_DTOA_SHORTEST, |
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| 40 | // Same as FAST_DTOA_SHORTEST but for single-precision floats. |
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| 41 | FAST_DTOA_SHORTEST_SINGLE, |
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| 42 | // Computes a representation where the precision (number of digits) is |
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| 43 | // given as input. The precision is independent of the decimal point. |
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| 44 | FAST_DTOA_PRECISION |
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| 45 | }; |
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| 46 | |
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| 47 | // FastDtoa will produce at most kFastDtoaMaximalLength digits. This does not |
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| 48 | // include the terminating '\0' character. |
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| 49 | static const int kFastDtoaMaximalLength = 17; |
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| 50 | // Same for single-precision numbers. |
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| 51 | static const int kFastDtoaMaximalSingleLength = 9; |
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| 52 | |
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| 53 | // Provides a decimal representation of v. |
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| 54 | // The result should be interpreted as buffer * 10^(point - length). |
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| 55 | // |
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| 56 | // Precondition: |
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| 57 | // * v must be a strictly positive finite double. |
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| 58 | // |
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| 59 | // Returns true if it succeeds, otherwise the result can not be trusted. |
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| 60 | // There will be *length digits inside the buffer followed by a null terminator. |
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| 61 | // If the function returns true and mode equals |
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| 62 | // - FAST_DTOA_SHORTEST, then |
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| 63 | // the parameter requested_digits is ignored. |
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| 64 | // The result satisfies |
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| 65 | // v == (double) (buffer * 10^(point - length)). |
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| 66 | // The digits in the buffer are the shortest representation possible. E.g. |
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| 67 | // if 0.099999999999 and 0.1 represent the same double then "1" is returned |
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| 68 | // with point = 0. |
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| 69 | // The last digit will be closest to the actual v. That is, even if several |
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| 70 | // digits might correctly yield 'v' when read again, the buffer will contain |
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| 71 | // the one closest to v. |
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| 72 | // - FAST_DTOA_PRECISION, then |
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| 73 | // the buffer contains requested_digits digits. |
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| 74 | // the difference v - (buffer * 10^(point-length)) is closest to zero for |
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| 75 | // all possible representations of requested_digits digits. |
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| 76 | // If there are two values that are equally close, then FastDtoa returns |
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| 77 | // false. |
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| 78 | // For both modes the buffer must be large enough to hold the result. |
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| 79 | bool FastDtoa(double d, |
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| 80 | FastDtoaMode mode, |
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| 81 | int requested_digits, |
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| 82 | Vector<char> buffer, |
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| 83 | int* length, |
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| 84 | int* decimal_point); |
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| 85 | |
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| 86 | } // namespace double_conversion |
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| 87 | |
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| 88 | #endif // DOUBLE_CONVERSION_FAST_DTOA_H_ |
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| 89 | |
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