1// Copyright 2010 the V8 project authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#ifndef V8_BIGNUM_DTOA_H_ 6#define V8_BIGNUM_DTOA_H_ 7 8namespace v8 { 9namespace internal { 10 11enum BignumDtoaMode { 12 // Return the shortest correct representation. 13 // For example the output of 0.299999999999999988897 is (the less accurate but 14 // correct) 0.3. 15 BIGNUM_DTOA_SHORTEST, 16 // Return a fixed number of digits after the decimal point. 17 // For instance fixed(0.1, 4) becomes 0.1000 18 // If the input number is big, the output will be big. 19 BIGNUM_DTOA_FIXED, 20 // Return a fixed number of digits, no matter what the exponent is. 21 BIGNUM_DTOA_PRECISION 22}; 23 24// Converts the given double 'v' to ASCII. 25// The result should be interpreted as buffer * 10^(point-length). 26// The buffer will be null-terminated. 27// 28// The input v must be > 0 and different from NaN, and Infinity. 29// 30// The output depends on the given mode: 31// - SHORTEST: produce the least amount of digits for which the internal 32// identity requirement is still satisfied. If the digits are printed 33// (together with the correct exponent) then reading this number will give 34// 'v' again. The buffer will choose the representation that is closest to 35// 'v'. If there are two at the same distance, than the number is round up. 36// In this mode the 'requested_digits' parameter is ignored. 37// - FIXED: produces digits necessary to print a given number with 38// 'requested_digits' digits after the decimal point. The produced digits 39// might be too short in which case the caller has to fill the gaps with '0's. 40// Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2. 41// Halfway cases are rounded up. The call toFixed(0.15, 2) thus returns 42// buffer="2", point=0. 43// Note: the length of the returned buffer has no meaning wrt the significance 44// of its digits. That is, just because it contains '0's does not mean that 45// any other digit would not satisfy the internal identity requirement. 46// - PRECISION: produces 'requested_digits' where the first digit is not '0'. 47// Even though the length of produced digits usually equals 48// 'requested_digits', the function is allowed to return fewer digits, in 49// which case the caller has to fill the missing digits with '0's. 50// Halfway cases are again rounded up. 51// 'BignumDtoa' expects the given buffer to be big enough to hold all digits 52// and a terminating null-character. 53void BignumDtoa(double v, BignumDtoaMode mode, int requested_digits, 54 Vector<char> buffer, int* length, int* point); 55 56} } // namespace v8::internal 57 58#endif // V8_BIGNUM_DTOA_H_ 59