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1 // Copyright 2010 the V8 project authors. All rights reserved. | 1 // Copyright 2010 the V8 project authors. All rights reserved. |
2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
4 // met: | 4 // met: |
5 // | 5 // |
6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
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145 ASSERT(0 <= digit && digit <= 9); | 145 ASSERT(0 <= digit && digit <= 9); |
146 result = 10 * result + digit; | 146 result = 10 * result + digit; |
147 } | 147 } |
148 return result; | 148 return result; |
149 } | 149 } |
150 | 150 |
151 | 151 |
152 static bool DoubleStrtod(Vector<const char> trimmed, | 152 static bool DoubleStrtod(Vector<const char> trimmed, |
153 int exponent, | 153 int exponent, |
154 double* result) { | 154 double* result) { |
155 #if defined(V8_TARGET_ARCH_IA32) && !defined(WIN32) | 155 #if (defined(V8_TARGET_ARCH_IA32) || defined(USE_SIMULATOR)) && !defined(WIN32) |
156 // On x86 the floating-point stack can be 64 or 80 bits wide. If it is | 156 // On x86 the floating-point stack can be 64 or 80 bits wide. If it is |
157 // 80 bits wide (as is the case on Linux) then double-rounding occurs and the | 157 // 80 bits wide (as is the case on Linux) then double-rounding occurs and the |
158 // result is not accurate. | 158 // result is not accurate. |
159 // We know that Windows32 uses 64 bits and is therefore accurate. | 159 // We know that Windows32 uses 64 bits and is therefore accurate. |
| 160 // Note that the ARM simulator is compiled for 32bits. It therefore exhibits |
| 161 // the same problem. |
160 return false; | 162 return false; |
161 #endif | 163 #endif |
162 if (trimmed.length() <= kMaxExactDoubleIntegerDecimalDigits) { | 164 if (trimmed.length() <= kMaxExactDoubleIntegerDecimalDigits) { |
163 // The trimmed input fits into a double. | 165 // The trimmed input fits into a double. |
164 // If the 10^exponent (resp. 10^-exponent) fits into a double too then we | 166 // If the 10^exponent (resp. 10^-exponent) fits into a double too then we |
165 // can compute the result-double simply by multiplying (resp. dividing) the | 167 // can compute the result-double simply by multiplying (resp. dividing) the |
166 // two numbers. | 168 // two numbers. |
167 // This is possible because IEEE guarantees that floating-point operations | 169 // This is possible because IEEE guarantees that floating-point operations |
168 // return the best possible approximation. | 170 // return the best possible approximation. |
169 if (exponent < 0 && -exponent < kExactPowersOfTenSize) { | 171 if (exponent < 0 && -exponent < kExactPowersOfTenSize) { |
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203 if (exponent + trimmed.length() - 1 >= kMaxDecimalPower) return V8_INFINITY; | 205 if (exponent + trimmed.length() - 1 >= kMaxDecimalPower) return V8_INFINITY; |
204 if (exponent + trimmed.length() <= kMinDecimalPower) return 0.0; | 206 if (exponent + trimmed.length() <= kMinDecimalPower) return 0.0; |
205 double result; | 207 double result; |
206 if (DoubleStrtod(trimmed, exponent, &result)) { | 208 if (DoubleStrtod(trimmed, exponent, &result)) { |
207 return result; | 209 return result; |
208 } | 210 } |
209 return old_strtod(trimmed, exponent); | 211 return old_strtod(trimmed, exponent); |
210 } | 212 } |
211 | 213 |
212 } } // namespace v8::internal | 214 } } // namespace v8::internal |
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