sgjesse@chromium.org | 720dc0b | 2010-05-10 09:25:39 +0000 | [diff] [blame] | 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 V8_DTOA_H_ |
| 29 | #define V8_DTOA_H_ |
| 30 | |
| 31 | namespace v8 { |
| 32 | namespace internal { |
| 33 | |
| 34 | enum DtoaMode { |
| 35 | // 0.9999999999999999 becomes 0.1 |
| 36 | DTOA_SHORTEST, |
| 37 | // Fixed number of digits after the decimal point. |
| 38 | // For instance fixed(0.1, 4) becomes 0.1000 |
| 39 | // If the input number is big, the output will be big. |
| 40 | DTOA_FIXED, |
| 41 | // Fixed number of digits (independent of the decimal point). |
| 42 | DTOA_PRECISION |
| 43 | }; |
| 44 | |
| 45 | // The maximal length of digits a double can have in base 10. |
| 46 | // Note that DoubleToAscii null-terminates its input. So the given buffer should |
| 47 | // be at least kBase10MaximalLength + 1 characters long. |
| 48 | static const int kBase10MaximalLength = 17; |
| 49 | |
| 50 | // Converts the given double 'v' to ascii. |
| 51 | // The result should be interpreted as buffer * 10^(point-length). |
| 52 | // |
| 53 | // The output depends on the given mode: |
| 54 | // - SHORTEST: produce the least amount of digits for which the internal |
| 55 | // identity requirement is still satisfied. If the digits are printed |
| 56 | // (together with the correct exponent) then reading this number will give |
| 57 | // 'v' again. The buffer will choose the representation that is closest to |
| 58 | // 'v'. If there are two at the same distance, than the one farther away |
| 59 | // from 0 is chosen (halfway cases - ending with 5 - are rounded up). |
| 60 | // In this mode the 'requested_digits' parameter is ignored. |
| 61 | // - FIXED: produces digits necessary to print a given number with |
| 62 | // 'requested_digits' digits after the decimal point. The produced digits |
| 63 | // might be too short in which case the caller has to fill the gaps with '0's. |
| 64 | // Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2. |
| 65 | // Halfway cases are rounded towards +/-Infinity (away from 0). The call |
| 66 | // toFixed(0.15, 2) thus returns buffer="2", point=0. |
| 67 | // The returned buffer may contain digits that would be truncated from the |
| 68 | // shortest representation of the input. |
| 69 | // - PRECISION: produces 'requested_digits' where the first digit is not '0'. |
| 70 | // Even though the length of produced digits usually equals |
| 71 | // 'requested_digits', the function is allowed to return fewer digits, in |
| 72 | // which case the caller has to fill the missing digits with '0's. |
| 73 | // Halfway cases are again rounded away from 0. |
| 74 | // 'DoubleToAscii' expects the given buffer to be big enough to hold all digits |
| 75 | // and a terminating null-character. |
| 76 | bool DoubleToAscii(double v, DtoaMode mode, int requested_digits, |
| 77 | Vector<char> buffer, int* sign, int* length, int* point); |
| 78 | |
| 79 | } } // namespace v8::internal |
| 80 | |
| 81 | #endif // V8_DTOA_H_ |