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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_BIGNUM_DTOA_H_ | 28 #ifndef DOUBLE_CONVERSION_BIGNUM_DTOA_H_ |
| 29 #define DOUBLE_CONVERSION_BIGNUM_DTOA_H_ | 29 #define DOUBLE_CONVERSION_BIGNUM_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 BignumDtoaMode { | 37 enum BignumDtoaMode { |
| 38 // Return the shortest correct representation. | 38 // Return the shortest correct representation. |
| 39 // For example the output of 0.299999999999999988897 is (the less accura
te but | 39 // For example the output of 0.299999999999999988897 is (the less accurate but |
| 40 // correct) 0.3. | 40 // correct) 0.3. |
| 41 BIGNUM_DTOA_SHORTEST, | 41 BIGNUM_DTOA_SHORTEST, |
| 42 // Return a fixed number of digits after the decimal point. | 42 // Return a fixed number of digits after the decimal point. |
| 43 // For instance fixed(0.1, 4) becomes 0.1000 | 43 // For instance fixed(0.1, 4) becomes 0.1000 |
| 44 // If the input number is big, the output will be big. | 44 // If the input number is big, the output will be big. |
| 45 BIGNUM_DTOA_FIXED, | 45 BIGNUM_DTOA_FIXED, |
| 46 // Return a fixed number of digits, no matter what the exponent is. | 46 // Return a fixed number of digits, no matter what the exponent is. |
| 47 BIGNUM_DTOA_PRECISION | 47 BIGNUM_DTOA_PRECISION |
| 48 }; | 48 }; |
| 49 | 49 |
| 50 // Converts the given double 'v' to ascii. | 50 // Converts the given double 'v' to ascii. |
| 51 // The result should be interpreted as buffer * 10^(point-length). | 51 // The result should be interpreted as buffer * 10^(point-length). |
| 52 // The buffer will be null-terminated. | 52 // The buffer will be null-terminated. |
| 53 // | 53 // |
| 54 // The input v must be > 0 and different from NaN, and Infinity. | 54 // The input v must be > 0 and different from NaN, and Infinity. |
| 55 // | 55 // |
| 56 // The output depends on the given mode: | 56 // The output depends on the given mode: |
| 57 // - SHORTEST: produce the least amount of digits for which the internal | 57 // - SHORTEST: produce the least amount of digits for which the internal |
| 58 // identity requirement is still satisfied. If the digits are printed | 58 // identity requirement is still satisfied. If the digits are printed |
| 59 // (together with the correct exponent) then reading this number will give | 59 // (together with the correct exponent) then reading this number will give |
| 60 // 'v' again. The buffer will choose the representation that is closest to | 60 // 'v' again. The buffer will choose the representation that is closest to |
| 61 // 'v'. If there are two at the same distance, than the number is round up
. | 61 // 'v'. If there are two at the same distance, than the number is round up. |
| 62 // In this mode the 'requested_digits' parameter is ignored. | 62 // In this mode the 'requested_digits' parameter is ignored. |
| 63 // - FIXED: produces digits necessary to print a given number with | 63 // - FIXED: produces digits necessary to print a given number with |
| 64 // 'requested_digits' digits after the decimal point. The produced digits | 64 // 'requested_digits' digits after the decimal point. The produced digits |
| 65 // might be too short in which case the caller has to fill the gaps with '
0's. | 65 // might be too short in which case the caller has to fill the gaps with '0's. |
| 66 // Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2. | 66 // Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2. |
| 67 // Halfway cases are rounded up. The call toFixed(0.15, 2) thus returns | 67 // Halfway cases are rounded up. The call toFixed(0.15, 2) thus returns |
| 68 // buffer="2", point=0. | 68 // buffer="2", point=0. |
| 69 // Note: the length of the returned buffer has no meaning wrt the signific
ance | 69 // Note: the length of the returned buffer has no meaning wrt the significance |
| 70 // of its digits. That is, just because it contains '0's does not mean tha
t | 70 // of its digits. That is, just because it contains '0's does not mean that |
| 71 // any other digit would not satisfy the internal identity requirement. | 71 // any other digit would not satisfy the internal identity requirement. |
| 72 // - PRECISION: produces 'requested_digits' where the first digit is not '0
'. | 72 // - PRECISION: produces 'requested_digits' where the first digit is not '0'. |
| 73 // Even though the length of produced digits usually equals | 73 // Even though the length of produced digits usually equals |
| 74 // 'requested_digits', the function is allowed to return fewer digits, in | 74 // 'requested_digits', the function is allowed to return fewer digits, in |
| 75 // which case the caller has to fill the missing digits with '0's. | 75 // which case the caller has to fill the missing digits with '0's. |
| 76 // Halfway cases are again rounded up. | 76 // Halfway cases are again rounded up. |
| 77 // 'BignumDtoa' expects the given buffer to be big enough to hold all digits | 77 // 'BignumDtoa' expects the given buffer to be big enough to hold all digits |
| 78 // and a terminating null-character. | 78 // and a terminating null-character. |
| 79 void BignumDtoa(double v, BignumDtoaMode mode, int requested_digits, | 79 void BignumDtoa(double v, |
| 80 Vector<char> buffer, int* length, int* point); | 80 BignumDtoaMode mode, |
| 81 int requested_digits, |
| 82 Vector<char> buffer, |
| 83 int* length, |
| 84 int* point); |
| 81 | 85 |
| 82 } // namespace double_conversion | 86 } // namespace double_conversion |
| 83 | 87 |
| 84 } // namespace WTF | 88 } // namespace WTF |
| 85 | 89 |
| 86 #endif // DOUBLE_CONVERSION_BIGNUM_DTOA_H_ | 90 #endif // DOUBLE_CONVERSION_BIGNUM_DTOA_H_ |
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