mstarzinger@chromium.org | 1b3afd1 | 2011-11-29 14:28:56 +0000 | [diff] [blame] | 1 | // Copyright 2011 the V8 project authors. All rights reserved. |
whesse@chromium.org | cec079d | 2010-03-22 14:44:04 +0000 | [diff] [blame] | 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 | |
| 31 | namespace v8 { |
| 32 | namespace internal { |
| 33 | |
fschneider@chromium.org | c20610a | 2010-09-22 09:44:58 +0000 | [diff] [blame] | 34 | enum 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 | |
whesse@chromium.org | cec079d | 2010-03-22 14:44:04 +0000 | [diff] [blame] | 44 | // FastDtoa will produce at most kFastDtoaMaximalLength digits. This does not |
| 45 | // include the terminating '\0' character. |
mstarzinger@chromium.org | 1b3afd1 | 2011-11-29 14:28:56 +0000 | [diff] [blame] | 46 | const int kFastDtoaMaximalLength = 17; |
whesse@chromium.org | cec079d | 2010-03-22 14:44:04 +0000 | [diff] [blame] | 47 | |
| 48 | // Provides a decimal representation of v. |
fschneider@chromium.org | c20610a | 2010-09-22 09:44:58 +0000 | [diff] [blame] | 49 | // The result should be interpreted as buffer * 10^(point - length). |
| 50 | // |
| 51 | // Precondition: |
| 52 | // * v must be a strictly positive finite double. |
| 53 | // |
whesse@chromium.org | cec079d | 2010-03-22 14:44:04 +0000 | [diff] [blame] | 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. |
fschneider@chromium.org | c20610a | 2010-09-22 09:44:58 +0000 | [diff] [blame] | 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. |
kmillikin@chromium.org | 4111b80 | 2010-05-03 10:34:42 +0000 | [diff] [blame] | 74 | bool FastDtoa(double d, |
fschneider@chromium.org | c20610a | 2010-09-22 09:44:58 +0000 | [diff] [blame] | 75 | FastDtoaMode mode, |
| 76 | int requested_digits, |
kmillikin@chromium.org | 4111b80 | 2010-05-03 10:34:42 +0000 | [diff] [blame] | 77 | Vector<char> buffer, |
kmillikin@chromium.org | 4111b80 | 2010-05-03 10:34:42 +0000 | [diff] [blame] | 78 | int* length, |
fschneider@chromium.org | c20610a | 2010-09-22 09:44:58 +0000 | [diff] [blame] | 79 | int* decimal_point); |
whesse@chromium.org | cec079d | 2010-03-22 14:44:04 +0000 | [diff] [blame] | 80 | |
| 81 | } } // namespace v8::internal |
| 82 | |
| 83 | #endif // V8_FAST_DTOA_H_ |