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89 lines
4.0 KiB
C++
89 lines
4.0 KiB
C++
// Copyright 2010 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#ifndef DOUBLE_CONVERSION_FAST_DTOA_H_
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#define DOUBLE_CONVERSION_FAST_DTOA_H_
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#include "utils.h"
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namespace double_conversion {
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enum FastDtoaMode {
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// Computes the shortest representation of the given input. The returned
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// result will be the most accurate number of this length. Longer
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// representations might be more accurate.
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FAST_DTOA_SHORTEST,
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// Same as FAST_DTOA_SHORTEST but for single-precision floats.
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FAST_DTOA_SHORTEST_SINGLE,
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// Computes a representation where the precision (number of digits) is
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// given as input. The precision is independent of the decimal point.
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FAST_DTOA_PRECISION
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};
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// FastDtoa will produce at most kFastDtoaMaximalLength digits. This does not
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// include the terminating '\0' character.
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static const int kFastDtoaMaximalLength = 17;
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// Same for single-precision numbers.
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static const int kFastDtoaMaximalSingleLength = 9;
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// Provides a decimal representation of v.
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// The result should be interpreted as buffer * 10^(point - length).
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//
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// Precondition:
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// * v must be a strictly positive finite double.
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//
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// Returns true if it succeeds, otherwise the result can not be trusted.
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// There will be *length digits inside the buffer followed by a null terminator.
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// If the function returns true and mode equals
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// - FAST_DTOA_SHORTEST, then
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// the parameter requested_digits is ignored.
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// The result satisfies
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// v == (double) (buffer * 10^(point - length)).
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// The digits in the buffer are the shortest representation possible. E.g.
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// if 0.099999999999 and 0.1 represent the same double then "1" is returned
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// with point = 0.
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// The last digit will be closest to the actual v. That is, even if several
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// digits might correctly yield 'v' when read again, the buffer will contain
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// the one closest to v.
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// - FAST_DTOA_PRECISION, then
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// the buffer contains requested_digits digits.
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// the difference v - (buffer * 10^(point-length)) is closest to zero for
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// all possible representations of requested_digits digits.
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// If there are two values that are equally close, then FastDtoa returns
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// false.
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// For both modes the buffer must be large enough to hold the result.
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bool FastDtoa(double d,
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FastDtoaMode mode,
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int requested_digits,
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Vector<char> buffer,
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int* length,
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int* decimal_point);
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} // namespace double_conversion
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#endif // DOUBLE_CONVERSION_FAST_DTOA_H_
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