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      1 // Copyright 2011 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 #include <cmath>
      6 
      7 #include "include/v8stdint.h"
      8 #include "src/base/logging.h"
      9 #include "src/utils.h"
     10 
     11 #include "src/dtoa.h"
     12 
     13 #include "src/bignum-dtoa.h"
     14 #include "src/double.h"
     15 #include "src/fast-dtoa.h"
     16 #include "src/fixed-dtoa.h"
     17 
     18 namespace v8 {
     19 namespace internal {
     20 
     21 static BignumDtoaMode DtoaToBignumDtoaMode(DtoaMode dtoa_mode) {
     22   switch (dtoa_mode) {
     23     case DTOA_SHORTEST:  return BIGNUM_DTOA_SHORTEST;
     24     case DTOA_FIXED:     return BIGNUM_DTOA_FIXED;
     25     case DTOA_PRECISION: return BIGNUM_DTOA_PRECISION;
     26     default:
     27       UNREACHABLE();
     28       return BIGNUM_DTOA_SHORTEST;  // To silence compiler.
     29   }
     30 }
     31 
     32 
     33 void DoubleToAscii(double v, DtoaMode mode, int requested_digits,
     34                    Vector<char> buffer, int* sign, int* length, int* point) {
     35   DCHECK(!Double(v).IsSpecial());
     36   DCHECK(mode == DTOA_SHORTEST || requested_digits >= 0);
     37 
     38   if (Double(v).Sign() < 0) {
     39     *sign = 1;
     40     v = -v;
     41   } else {
     42     *sign = 0;
     43   }
     44 
     45   if (v == 0) {
     46     buffer[0] = '0';
     47     buffer[1] = '\0';
     48     *length = 1;
     49     *point = 1;
     50     return;
     51   }
     52 
     53   if (mode == DTOA_PRECISION && requested_digits == 0) {
     54     buffer[0] = '\0';
     55     *length = 0;
     56     return;
     57   }
     58 
     59   bool fast_worked;
     60   switch (mode) {
     61     case DTOA_SHORTEST:
     62       fast_worked = FastDtoa(v, FAST_DTOA_SHORTEST, 0, buffer, length, point);
     63       break;
     64     case DTOA_FIXED:
     65       fast_worked = FastFixedDtoa(v, requested_digits, buffer, length, point);
     66       break;
     67     case DTOA_PRECISION:
     68       fast_worked = FastDtoa(v, FAST_DTOA_PRECISION, requested_digits,
     69                              buffer, length, point);
     70       break;
     71     default:
     72       UNREACHABLE();
     73       fast_worked = false;
     74   }
     75   if (fast_worked) return;
     76 
     77   // If the fast dtoa didn't succeed use the slower bignum version.
     78   BignumDtoaMode bignum_mode = DtoaToBignumDtoaMode(mode);
     79   BignumDtoa(v, bignum_mode, requested_digits, buffer, length, point);
     80   buffer[*length] = '\0';
     81 }
     82 
     83 } }  // namespace v8::internal
     84