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| 1 // Copyright 2010 the V8 project authors. All rights reserved. | 1 // Copyright 2010 the V8 project authors. All rights reserved. |
| 2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
| 3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
| 4 // met: | 4 // met: |
| 5 // | 5 // |
| 6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
| 7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
| 8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
| 9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
| 10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
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| 27 | 27 |
| 28 #ifndef DOUBLE_CONVERSION_FAST_DTOA_H_ | 28 #ifndef DOUBLE_CONVERSION_FAST_DTOA_H_ |
| 29 #define DOUBLE_CONVERSION_FAST_DTOA_H_ | 29 #define DOUBLE_CONVERSION_FAST_DTOA_H_ |
| 30 | 30 |
| 31 #include "utils.h" | 31 #include "utils.h" |
| 32 | 32 |
| 33 namespace WTF { | 33 namespace WTF { |
| 34 | 34 |
| 35 namespace double_conversion { | 35 namespace double_conversion { |
| 36 | 36 |
| 37 enum FastDtoaMode { | 37 enum FastDtoaMode { |
| 38 // Computes the shortest representation of the given input. The returned | 38 // Computes the shortest representation of the given input. The returned |
| 39 // result will be the most accurate number of this length. Longer | 39 // result will be the most accurate number of this length. Longer |
| 40 // representations might be more accurate. | 40 // representations might be more accurate. |
| 41 FAST_DTOA_SHORTEST, | 41 FAST_DTOA_SHORTEST, |
| 42 // Computes a representation where the precision (number of digits) is | 42 // Computes a representation where the precision (number of digits) is |
| 43 // given as input. The precision is independent of the decimal point. | 43 // given as input. The precision is independent of the decimal point. |
| 44 FAST_DTOA_PRECISION | 44 FAST_DTOA_PRECISION |
| 45 }; | 45 }; |
| 46 | 46 |
| 47 // FastDtoa will produce at most kFastDtoaMaximalLength digits. This does no
t | 47 // FastDtoa will produce at most kFastDtoaMaximalLength digits. This does not |
| 48 // include the terminating '\0' character. | 48 // include the terminating '\0' character. |
| 49 static const int kFastDtoaMaximalLength = 17; | 49 static const int kFastDtoaMaximalLength = 17; |
| 50 | 50 |
| 51 // Provides a decimal representation of v. | 51 // Provides a decimal representation of v. |
| 52 // The result should be interpreted as buffer * 10^(point - length). | 52 // The result should be interpreted as buffer * 10^(point - length). |
| 53 // | 53 // |
| 54 // Precondition: | 54 // Precondition: |
| 55 // * v must be a strictly positive finite double. | 55 // * v must be a strictly positive finite double. |
| 56 // | 56 // |
| 57 // Returns true if it succeeds, otherwise the result can not be trusted. | 57 // Returns true if it succeeds, otherwise the result can not be trusted. |
| 58 // There will be *length digits inside the buffer followed by a null termina
tor. | 58 // There will be *length digits inside the buffer followed by a null terminator. |
| 59 // If the function returns true and mode equals | 59 // If the function returns true and mode equals |
| 60 // - FAST_DTOA_SHORTEST, then | 60 // - FAST_DTOA_SHORTEST, then |
| 61 // the parameter requested_digits is ignored. | 61 // the parameter requested_digits is ignored. |
| 62 // The result satisfies | 62 // The result satisfies |
| 63 // v == (double) (buffer * 10^(point - length)). | 63 // v == (double) (buffer * 10^(point - length)). |
| 64 // The digits in the buffer are the shortest representation possible. E.
g. | 64 // The digits in the buffer are the shortest representation possible. E.g. |
| 65 // if 0.099999999999 and 0.1 represent the same double then "1" is retur
ned | 65 // if 0.099999999999 and 0.1 represent the same double then "1" is returned |
| 66 // with point = 0. | 66 // with point = 0. |
| 67 // The last digit will be closest to the actual v. That is, even if seve
ral | 67 // The last digit will be closest to the actual v. That is, even if several |
| 68 // digits might correctly yield 'v' when read again, the buffer will con
tain | 68 // digits might correctly yield 'v' when read again, the buffer will contain |
| 69 // the one closest to v. | 69 // the one closest to v. |
| 70 // - FAST_DTOA_PRECISION, then | 70 // - FAST_DTOA_PRECISION, then |
| 71 // the buffer contains requested_digits digits. | 71 // the buffer contains requested_digits digits. |
| 72 // the difference v - (buffer * 10^(point-length)) is closest to zero fo
r | 72 // the difference v - (buffer * 10^(point-length)) is closest to zero for |
| 73 // all possible representations of requested_digits digits. | 73 // all possible representations of requested_digits digits. |
| 74 // If there are two values that are equally close, then FastDtoa returns | 74 // If there are two values that are equally close, then FastDtoa returns |
| 75 // false. | 75 // false. |
| 76 // For both modes the buffer must be large enough to hold the result. | 76 // For both modes the buffer must be large enough to hold the result. |
| 77 bool FastDtoa(double d, | 77 bool FastDtoa(double d, |
| 78 FastDtoaMode mode, | 78 FastDtoaMode mode, |
| 79 int requested_digits, | 79 int requested_digits, |
| 80 Vector<char> buffer, | 80 Vector<char> buffer, |
| 81 int* length, | 81 int* length, |
| 82 int* decimal_point); | 82 int* decimal_point); |
| 83 | 83 |
| 84 } // namespace double_conversion | 84 } // namespace double_conversion |
| 85 | 85 |
| 86 } // namespace WTF | 86 } // namespace WTF |
| 87 | 87 |
| 88 #endif // DOUBLE_CONVERSION_FAST_DTOA_H_ | 88 #endif // DOUBLE_CONVERSION_FAST_DTOA_H_ |
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