CSE2410 Fall 2014 Bounce

// 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_FAST_DTOA_H_

#define V8_FAST_DTOA_H_

namespace v8 {

namespace internal {

enum FastDtoaMode {

  // Computes the shortest representation of the given input. The returned

  // result will be the most accurate number of this length. Longer

  // representations might be more accurate.

  FAST_DTOA_SHORTEST,

  // Computes a representation where the precision (number of digits) is

  // given as input. The precision is independent of the decimal point.

  FAST_DTOA_PRECISION

};

// FastDtoa will produce at most kFastDtoaMaximalLength digits. This does not

// include the terminating '\0' character.

const int kFastDtoaMaximalLength = 17;

// Provides a decimal representation of v.

// The result should be interpreted as buffer * 10^(point - length).

//

// Precondition:

//   * v must be a strictly positive finite double.

//

// Returns true if it succeeds, otherwise the result can not be trusted.

// There will be *length digits inside the buffer followed by a null terminator.

// If the function returns true and mode equals

//   - FAST_DTOA_SHORTEST, then

//     the parameter requested_digits is ignored.

//     The result satisfies

//         v == (double) (buffer * 10^(point - length)).

//     The digits in the buffer are the shortest representation possible. E.g.

//     if 0.099999999999 and 0.1 represent the same double then "1" is returned

//     with point = 0.

//     The last digit will be closest to the actual v. That is, even if several

//     digits might correctly yield 'v' when read again, the buffer will contain

//     the one closest to v.

//   - FAST_DTOA_PRECISION, then

//     the buffer contains requested_digits digits.

//     the difference v - (buffer * 10^(point-length)) is closest to zero for

//     all possible representations of requested_digits digits.

//     If there are two values that are equally close, then FastDtoa returns

//     false.

// For both modes the buffer must be large enough to hold the result.

bool FastDtoa(double d,

              FastDtoaMode mode,

              int requested_digits,

              Vector<char> buffer,

              int* length,

              int* decimal_point);

} }  // namespace v8::internal

#endif  // V8_FAST_DTOA_H_