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
8#include "src/vector.h"
9
10namespace v8 {
11namespace internal {
12
13enum BignumDtoaMode {
14 // Return the shortest correct representation.
15 // For example the output of 0.299999999999999988897 is (the less accurate but
16 // correct) 0.3.
17 BIGNUM_DTOA_SHORTEST,
18 // Return a fixed number of digits after the decimal point.
19 // For instance fixed(0.1, 4) becomes 0.1000
20 // If the input number is big, the output will be big.
21 BIGNUM_DTOA_FIXED,
22 // Return a fixed number of digits, no matter what the exponent is.
23 BIGNUM_DTOA_PRECISION
24};
25
26// Converts the given double 'v' to ASCII.
27// The result should be interpreted as buffer * 10^(point-length).
28// The buffer will be null-terminated.
29//
30// The input v must be > 0 and different from NaN, and Infinity.
31//
32// The output depends on the given mode:
33// - SHORTEST: produce the least amount of digits for which the internal
34// identity requirement is still satisfied. If the digits are printed
35// (together with the correct exponent) then reading this number will give
36// 'v' again. The buffer will choose the representation that is closest to
37// 'v'. If there are two at the same distance, than the number is round up.
38// In this mode the 'requested_digits' parameter is ignored.
39// - FIXED: produces digits necessary to print a given number with
40// 'requested_digits' digits after the decimal point. The produced digits
41// might be too short in which case the caller has to fill the gaps with '0's.
42// Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2.
43// Halfway cases are rounded up. The call toFixed(0.15, 2) thus returns
44// buffer="2", point=0.
45// Note: the length of the returned buffer has no meaning wrt the significance
46// of its digits. That is, just because it contains '0's does not mean that
47// any other digit would not satisfy the internal identity requirement.
48// - PRECISION: produces 'requested_digits' where the first digit is not '0'.
49// Even though the length of produced digits usually equals
50// 'requested_digits', the function is allowed to return fewer digits, in
51// which case the caller has to fill the missing digits with '0's.
52// Halfway cases are again rounded up.
53// 'BignumDtoa' expects the given buffer to be big enough to hold all digits
54// and a terminating null-character.
55V8_EXPORT_PRIVATE void BignumDtoa(double v, BignumDtoaMode mode,
56 int requested_digits, Vector<char> buffer,
57 int* length, int* point);
58
59} // namespace internal
60} // namespace v8
61
62#endif // V8_BIGNUM_DTOA_H_
63