dtoa.cc 2.05 KB
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// Copyright 2011 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
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#include <cmath>
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#include "src/base/logging.h"
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#include "src/utils.h"
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#include "src/dtoa.h"
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#include "src/bignum-dtoa.h"
#include "src/double.h"
#include "src/fast-dtoa.h"
#include "src/fixed-dtoa.h"
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namespace v8 {
namespace internal {

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static BignumDtoaMode DtoaToBignumDtoaMode(DtoaMode dtoa_mode) {
  switch (dtoa_mode) {
    case DTOA_SHORTEST:  return BIGNUM_DTOA_SHORTEST;
    case DTOA_FIXED:     return BIGNUM_DTOA_FIXED;
    case DTOA_PRECISION: return BIGNUM_DTOA_PRECISION;
    default:
      UNREACHABLE();
      return BIGNUM_DTOA_SHORTEST;  // To silence compiler.
  }
}


void DoubleToAscii(double v, DtoaMode mode, int requested_digits,
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                   Vector<char> buffer, int* sign, int* length, int* point) {
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  DCHECK(!Double(v).IsSpecial());
  DCHECK(mode == DTOA_SHORTEST || requested_digits >= 0);
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  if (Double(v).Sign() < 0) {
    *sign = 1;
    v = -v;
  } else {
    *sign = 0;
  }

  if (v == 0) {
    buffer[0] = '0';
    buffer[1] = '\0';
    *length = 1;
    *point = 1;
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    return;
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  }

  if (mode == DTOA_PRECISION && requested_digits == 0) {
    buffer[0] = '\0';
    *length = 0;
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    return;
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  }

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  bool fast_worked;
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  switch (mode) {
    case DTOA_SHORTEST:
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      fast_worked = FastDtoa(v, FAST_DTOA_SHORTEST, 0, buffer, length, point);
      break;
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    case DTOA_FIXED:
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      fast_worked = FastFixedDtoa(v, requested_digits, buffer, length, point);
      break;
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    case DTOA_PRECISION:
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      fast_worked = FastDtoa(v, FAST_DTOA_PRECISION, requested_digits,
                             buffer, length, point);
      break;
    default:
      UNREACHABLE();
      fast_worked = false;
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  }
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  if (fast_worked) return;

  // If the fast dtoa didn't succeed use the slower bignum version.
  BignumDtoaMode bignum_mode = DtoaToBignumDtoaMode(mode);
  BignumDtoa(v, bignum_mode, requested_digits, buffer, length, point);
  buffer[*length] = '\0';
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}

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}  // namespace internal
}  // namespace v8