mfbt/double-conversion/fast-dtoa.h@97036ab72558 (annotated)
mfbt/double-conversion/fast-dtoa.h
Tue, 06 Jan 2015 21:39:09 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Tue, 06 Jan 2015 21:39:09 +0100
- branch
- TOR_BUG_9701
- changeset 8
- 97036ab72558
- permissions
- -rw-r--r--
Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.
| michael@0 | 1 | // Copyright 2010 the V8 project authors. All rights reserved. |
| michael@0 | 2 | // Redistribution and use in source and binary forms, with or without |
| michael@0 | 3 | // modification, are permitted provided that the following conditions are |
| michael@0 | 4 | // met: |
| michael@0 | 5 | // |
| michael@0 | 6 | // * Redistributions of source code must retain the above copyright |
| michael@0 | 7 | // notice, this list of conditions and the following disclaimer. |
| michael@0 | 8 | // * Redistributions in binary form must reproduce the above |
| michael@0 | 9 | // copyright notice, this list of conditions and the following |
| michael@0 | 10 | // disclaimer in the documentation and/or other materials provided |
| michael@0 | 11 | // with the distribution. |
| michael@0 | 12 | // * Neither the name of Google Inc. nor the names of its |
| michael@0 | 13 | // contributors may be used to endorse or promote products derived |
| michael@0 | 14 | // from this software without specific prior written permission. |
| michael@0 | 15 | // |
| michael@0 | 16 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| michael@0 | 17 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| michael@0 | 18 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| michael@0 | 19 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| michael@0 | 20 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| michael@0 | 21 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| michael@0 | 22 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| michael@0 | 23 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| michael@0 | 24 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| michael@0 | 25 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| michael@0 | 26 | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| michael@0 | 27 | |
| michael@0 | 28 | #ifndef DOUBLE_CONVERSION_FAST_DTOA_H_ |
| michael@0 | 29 | #define DOUBLE_CONVERSION_FAST_DTOA_H_ |
| michael@0 | 30 | |
| michael@0 | 31 | #include "utils.h" |
| michael@0 | 32 | |
| michael@0 | 33 | namespace double_conversion { |
| michael@0 | 34 | |
| michael@0 | 35 | enum FastDtoaMode { |
| michael@0 | 36 | // Computes the shortest representation of the given input. The returned |
| michael@0 | 37 | // result will be the most accurate number of this length. Longer |
| michael@0 | 38 | // representations might be more accurate. |
| michael@0 | 39 | FAST_DTOA_SHORTEST, |
| michael@0 | 40 | // Same as FAST_DTOA_SHORTEST but for single-precision floats. |
| michael@0 | 41 | FAST_DTOA_SHORTEST_SINGLE, |
| michael@0 | 42 | // Computes a representation where the precision (number of digits) is |
| michael@0 | 43 | // given as input. The precision is independent of the decimal point. |
| michael@0 | 44 | FAST_DTOA_PRECISION |
| michael@0 | 45 | }; |
| michael@0 | 46 | |
| michael@0 | 47 | // FastDtoa will produce at most kFastDtoaMaximalLength digits. This does not |
| michael@0 | 48 | // include the terminating '\0' character. |
| michael@0 | 49 | static const int kFastDtoaMaximalLength = 17; |
| michael@0 | 50 | // Same for single-precision numbers. |
| michael@0 | 51 | static const int kFastDtoaMaximalSingleLength = 9; |
| michael@0 | 52 | |
| michael@0 | 53 | // Provides a decimal representation of v. |
| michael@0 | 54 | // The result should be interpreted as buffer * 10^(point - length). |
| michael@0 | 55 | // |
| michael@0 | 56 | // Precondition: |
| michael@0 | 57 | // * v must be a strictly positive finite double. |
| michael@0 | 58 | // |
| michael@0 | 59 | // Returns true if it succeeds, otherwise the result can not be trusted. |
| michael@0 | 60 | // There will be *length digits inside the buffer followed by a null terminator. |
| michael@0 | 61 | // If the function returns true and mode equals |
| michael@0 | 62 | // - FAST_DTOA_SHORTEST, then |
| michael@0 | 63 | // the parameter requested_digits is ignored. |
| michael@0 | 64 | // The result satisfies |
| michael@0 | 65 | // v == (double) (buffer * 10^(point - length)). |
| michael@0 | 66 | // The digits in the buffer are the shortest representation possible. E.g. |
| michael@0 | 67 | // if 0.099999999999 and 0.1 represent the same double then "1" is returned |
| michael@0 | 68 | // with point = 0. |
| michael@0 | 69 | // The last digit will be closest to the actual v. That is, even if several |
| michael@0 | 70 | // digits might correctly yield 'v' when read again, the buffer will contain |
| michael@0 | 71 | // the one closest to v. |
| michael@0 | 72 | // - FAST_DTOA_PRECISION, then |
| michael@0 | 73 | // the buffer contains requested_digits digits. |
| michael@0 | 74 | // the difference v - (buffer * 10^(point-length)) is closest to zero for |
| michael@0 | 75 | // all possible representations of requested_digits digits. |
| michael@0 | 76 | // If there are two values that are equally close, then FastDtoa returns |
| michael@0 | 77 | // false. |
| michael@0 | 78 | // For both modes the buffer must be large enough to hold the result. |
| michael@0 | 79 | bool FastDtoa(double d, |
| michael@0 | 80 | FastDtoaMode mode, |
| michael@0 | 81 | int requested_digits, |
| michael@0 | 82 | Vector<char> buffer, |
| michael@0 | 83 | int* length, |
| michael@0 | 84 | int* decimal_point); |
| michael@0 | 85 | |
| michael@0 | 86 | } // namespace double_conversion |
| michael@0 | 87 | |
| michael@0 | 88 | #endif // DOUBLE_CONVERSION_FAST_DTOA_H_ |
