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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_ | |
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