// Copyright 2010 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef V8_BASE_NUMBERS_BIGNUM_DTOA_H_ #define V8_BASE_NUMBERS_BIGNUM_DTOA_H_ #include "src/base/vector.h" namespace v8 { namespace base { enum BignumDtoaMode { // Return the shortest correct representation. // For example the output of 0.299999999999999988897 is (the less accurate but // correct) 0.3. BIGNUM_DTOA_SHORTEST, // Return a fixed number of digits after the decimal point. // For instance fixed(0.1, 4) becomes 0.1000 // If the input number is big, the output will be big. BIGNUM_DTOA_FIXED, // Return a fixed number of digits, no matter what the exponent is. BIGNUM_DTOA_PRECISION }; // Converts the given double 'v' to ASCII. // The result should be interpreted as buffer * 10^(point-length). // The buffer will be null-terminated. // // The input v must be > 0 and different from NaN, and Infinity. // // The output depends on the given mode: // - SHORTEST: produce the least amount of digits for which the internal // identity requirement is still satisfied. If the digits are printed // (together with the correct exponent) then reading this number will give // 'v' again. The buffer will choose the representation that is closest to // 'v'. If there are two at the same distance, than the number is round up. // In this mode the 'requested_digits' parameter is ignored. // - FIXED: produces digits necessary to print a given number with // 'requested_digits' digits after the decimal point. The produced digits // might be too short in which case the caller has to fill the gaps with '0's. // Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2. // Halfway cases are rounded up. The call toFixed(0.15, 2) thus returns // buffer="2", point=0. // Note: the length of the returned buffer has no meaning wrt the significance // of its digits. That is, just because it contains '0's does not mean that // any other digit would not satisfy the internal identity requirement. // - PRECISION: produces 'requested_digits' where the first digit is not '0'. // Even though the length of produced digits usually equals // 'requested_digits', the function is allowed to return fewer digits, in // which case the caller has to fill the missing digits with '0's. // Halfway cases are again rounded up. // 'BignumDtoa' expects the given buffer to be big enough to hold all digits // and a terminating null-character. V8_BASE_EXPORT void BignumDtoa(double v, BignumDtoaMode mode, int requested_digits, Vector<char> buffer, int* length, int* point); } // namespace base } // namespace v8 #endif // V8_BASE_NUMBERS_BIGNUM_DTOA_H_