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// Copyright 2011 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_NUMBERS_DTOA_H_
#define V8_NUMBERS_DTOA_H_
#include "src/utils/vector.h"
namespace v8 {
namespace internal {
enum DtoaMode {
// Return the shortest correct representation.
// For example the output of 0.299999999999999988897 is (the less accurate but
// correct) 0.3.
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.
DTOA_FIXED,
// Return a fixed number of digits, no matter what the exponent is.
DTOA_PRECISION
};
// The maximal length of digits a double can have in base 10.
// Note that DoubleToAscii null-terminates its input. So the given buffer should
// be at least kBase10MaximalLength + 1 characters long.
const int kBase10MaximalLength = 17;
// Converts the given double 'v' to ASCII.
// The result should be interpreted as buffer * 10^(point-length).
//
// 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 one farther away
// from 0 is chosen (halfway cases - ending with 5 - are rounded 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 towards +/-Infinity (away from 0). The call
// toFixed(0.15, 2) thus returns buffer="2", point=0.
// The returned buffer may contain digits that would be truncated from the
// shortest representation of the input.
// - 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 away from 0.
// 'DoubleToAscii' expects the given buffer to be big enough to hold all digits
// and a terminating null-character. In SHORTEST-mode it expects a buffer of
// at least kBase10MaximalLength + 1. Otherwise, the size of the output is
// limited to requested_digits digits plus the null terminator.
V8_EXPORT_PRIVATE void DoubleToAscii(double v, DtoaMode mode,
int requested_digits, Vector<char> buffer,
int* sign, int* length, int* point);
} // namespace internal
} // namespace v8
#endif // V8_NUMBERS_DTOA_H_