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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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96 return result; | 96 return result; |
97 } | 97 } |
98 } | 98 } |
99 | 99 |
100 bool IsZero() const { | 100 bool IsZero() const { |
101 return high_bits_ == 0 && low_bits_ == 0; | 101 return high_bits_ == 0 && low_bits_ == 0; |
102 } | 102 } |
103 | 103 |
104 int BitAt(int position) { | 104 int BitAt(int position) { |
105 if (position >= 64) { | 105 if (position >= 64) { |
106 return (high_bits_ >> (position - 64)) & 1; | 106 return static_cast<int>(high_bits_ >> (position - 64)) & 1; |
107 } else { | 107 } else { |
108 return (low_bits_ >> position) & 1; | 108 return static_cast<int>(low_bits_ >> position) & 1; |
109 } | 109 } |
110 } | 110 } |
111 | 111 |
112 private: | 112 private: |
113 static const uint64_t kMask32 = 0xFFFFFFFF; | 113 static const uint64_t kMask32 = 0xFFFFFFFF; |
114 // Value == (high_bits_ << 64) + low_bits_ | 114 // Value == (high_bits_ << 64) + low_bits_ |
115 uint64_t high_bits_; | 115 uint64_t high_bits_; |
116 uint64_t low_bits_; | 116 uint64_t low_bits_; |
117 }; | 117 }; |
118 | 118 |
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139 buffer[(*length) + number_length] = '0' + digit; | 139 buffer[(*length) + number_length] = '0' + digit; |
140 number_length++; | 140 number_length++; |
141 } | 141 } |
142 // Exchange the digits. | 142 // Exchange the digits. |
143 int i = *length; | 143 int i = *length; |
144 int j = *length + number_length - 1; | 144 int j = *length + number_length - 1; |
145 while (i < j) { | 145 while (i < j) { |
146 char tmp = buffer[i]; | 146 char tmp = buffer[i]; |
147 buffer[i] = buffer[j]; | 147 buffer[i] = buffer[j]; |
148 buffer[j] = tmp; | 148 buffer[j] = tmp; |
149 i++; j--; | 149 i++; |
| 150 j--; |
150 } | 151 } |
151 *length += number_length; | 152 *length += number_length; |
152 } | 153 } |
153 | 154 |
154 | 155 |
155 static void FillDigits64FixedLength(uint64_t number, int requested_length, | 156 static void FillDigits64FixedLength(uint64_t number, int requested_length, |
156 Vector<char> buffer, int* length) { | 157 Vector<char> buffer, int* length) { |
157 const uint32_t kTen7 = 10000000; | 158 const uint32_t kTen7 = 10000000; |
158 // For efficiency cut the number into 3 uint32_t parts, and print those. | 159 // For efficiency cut the number into 3 uint32_t parts, and print those. |
159 uint32_t part2 = number % kTen7; | 160 uint32_t part2 = static_cast<uint32_t>(number % kTen7); |
160 number /= kTen7; | 161 number /= kTen7; |
161 uint32_t part1 = number % kTen7; | 162 uint32_t part1 = static_cast<uint32_t>(number % kTen7); |
162 uint32_t part0 = number / kTen7; | 163 uint32_t part0 = static_cast<uint32_t>(number / kTen7); |
163 | 164 |
164 FillDigits32FixedLength(part0, 3, buffer, length); | 165 FillDigits32FixedLength(part0, 3, buffer, length); |
165 FillDigits32FixedLength(part1, 7, buffer, length); | 166 FillDigits32FixedLength(part1, 7, buffer, length); |
166 FillDigits32FixedLength(part2, 7, buffer, length); | 167 FillDigits32FixedLength(part2, 7, buffer, length); |
167 } | 168 } |
168 | 169 |
169 | 170 |
170 static void FillDigits64(uint64_t number, Vector<char> buffer, int* length) { | 171 static void FillDigits64(uint64_t number, Vector<char> buffer, int* length) { |
171 const uint32_t kTen7 = 10000000; | 172 const uint32_t kTen7 = 10000000; |
172 // For efficiency cut the number into 3 uint32_t parts, and print those. | 173 // For efficiency cut the number into 3 uint32_t parts, and print those. |
173 uint32_t part2 = number % kTen7; | 174 uint32_t part2 = static_cast<uint32_t>(number % kTen7); |
174 number /= kTen7; | 175 number /= kTen7; |
175 uint32_t part1 = number % kTen7; | 176 uint32_t part1 = static_cast<uint32_t>(number % kTen7); |
176 uint32_t part0 = number / kTen7; | 177 uint32_t part0 = static_cast<uint32_t>(number / kTen7); |
177 | 178 |
178 if (part0 != 0) { | 179 if (part0 != 0) { |
179 FillDigits32(part0, buffer, length); | 180 FillDigits32(part0, buffer, length); |
180 FillDigits32FixedLength(part1, 7, buffer, length); | 181 FillDigits32FixedLength(part1, 7, buffer, length); |
181 FillDigits32FixedLength(part2, 7, buffer, length); | 182 FillDigits32FixedLength(part2, 7, buffer, length); |
182 } else if (part1 != 0) { | 183 } else if (part1 != 0) { |
183 FillDigits32(part1, buffer, length); | 184 FillDigits32(part1, buffer, length); |
184 FillDigits32FixedLength(part2, 7, buffer, length); | 185 FillDigits32FixedLength(part2, 7, buffer, length); |
185 } else { | 186 } else { |
186 FillDigits32(part2, buffer, length); | 187 FillDigits32(part2, buffer, length); |
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242 int point = -exponent; | 243 int point = -exponent; |
243 for (int i = 0; i < fractional_count; ++i) { | 244 for (int i = 0; i < fractional_count; ++i) { |
244 if (fractionals == 0) break; | 245 if (fractionals == 0) break; |
245 // Instead of multiplying by 10 we multiply by 5 and adjust the point | 246 // Instead of multiplying by 10 we multiply by 5 and adjust the point |
246 // location. This way the fractionals variable will not overflow. | 247 // location. This way the fractionals variable will not overflow. |
247 // Invariant at the beginning of the loop: fractionals < 2^point. | 248 // Invariant at the beginning of the loop: fractionals < 2^point. |
248 // Initially we have: point <= 64 and fractionals < 2^56 | 249 // Initially we have: point <= 64 and fractionals < 2^56 |
249 // After each iteration the point is decremented by one. | 250 // After each iteration the point is decremented by one. |
250 // Note that 5^3 = 125 < 128 = 2^7. | 251 // Note that 5^3 = 125 < 128 = 2^7. |
251 // Therefore three iterations of this loop will not overflow fractionals | 252 // Therefore three iterations of this loop will not overflow fractionals |
252 // (even without the subtraction at the end of the loop body). At this tim
e | 253 // (even without the subtraction at the end of the loop body). At this |
253 // point will satisfy point <= 61 and therefore fractionals < 2^point and | 254 // time point will satisfy point <= 61 and therefore fractionals < 2^point |
254 // any further multiplication of fractionals by 5 will not overflow. | 255 // and any further multiplication of fractionals by 5 will not overflow. |
255 fractionals *= 5; | 256 fractionals *= 5; |
256 point--; | 257 point--; |
257 int digit = static_cast<int>(fractionals >> point); | 258 int digit = static_cast<int>(fractionals >> point); |
258 buffer[*length] = '0' + digit; | 259 buffer[*length] = '0' + digit; |
259 (*length)++; | 260 (*length)++; |
260 fractionals -= static_cast<uint64_t>(digit) << point; | 261 fractionals -= static_cast<uint64_t>(digit) << point; |
261 } | 262 } |
262 // If the first bit after the point is set we have to round up. | 263 // If the first bit after the point is set we have to round up. |
263 if (((fractionals >> (point - 1)) & 1) == 1) { | 264 if (((fractionals >> (point - 1)) & 1) == 1) { |
264 RoundUp(buffer, length, decimal_point); | 265 RoundUp(buffer, length, decimal_point); |
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331 // We know that v = significand * 2^exponent. | 332 // We know that v = significand * 2^exponent. |
332 // And the exponent > 11. | 333 // And the exponent > 11. |
333 // We simplify the task by dividing v by 10^17. | 334 // We simplify the task by dividing v by 10^17. |
334 // The quotient delivers the first digits, and the remainder fits into a 64 | 335 // The quotient delivers the first digits, and the remainder fits into a 64 |
335 // bit number. | 336 // bit number. |
336 // Dividing by 10^17 is equivalent to dividing by 5^17*2^17. | 337 // Dividing by 10^17 is equivalent to dividing by 5^17*2^17. |
337 const uint64_t kFive17 = V8_2PART_UINT64_C(0xB1, A2BC2EC5); // 5^17 | 338 const uint64_t kFive17 = V8_2PART_UINT64_C(0xB1, A2BC2EC5); // 5^17 |
338 uint64_t divisor = kFive17; | 339 uint64_t divisor = kFive17; |
339 int divisor_power = 17; | 340 int divisor_power = 17; |
340 uint64_t dividend = significand; | 341 uint64_t dividend = significand; |
341 uint64_t quotient; | 342 uint32_t quotient; |
342 uint64_t remainder; | 343 uint64_t remainder; |
343 // Let v = f * 2^e with f == significand and e == exponent. | 344 // Let v = f * 2^e with f == significand and e == exponent. |
344 // Then need q (quotient) and r (remainder) as follows: | 345 // Then need q (quotient) and r (remainder) as follows: |
345 // v = q * 10^17 + r | 346 // v = q * 10^17 + r |
346 // f * 2^e = q * 10^17 + r | 347 // f * 2^e = q * 10^17 + r |
347 // f * 2^e = q * 5^17 * 2^17 + r | 348 // f * 2^e = q * 5^17 * 2^17 + r |
348 // If e > 17 then | 349 // If e > 17 then |
349 // f * 2^(e-17) = q * 5^17 + r/2^17 | 350 // f * 2^(e-17) = q * 5^17 + r/2^17 |
350 // else | 351 // else |
351 // f = q * 5^17 * 2^(17-e) + r/2^e | 352 // f = q * 5^17 * 2^(17-e) + r/2^e |
352 if (exponent > divisor_power) { | 353 if (exponent > divisor_power) { |
353 // We only allow exponents of up to 20 and therefore (17 - e) <= 3 | 354 // We only allow exponents of up to 20 and therefore (17 - e) <= 3 |
354 dividend <<= exponent - divisor_power; | 355 dividend <<= exponent - divisor_power; |
355 quotient = dividend / divisor; | 356 quotient = static_cast<uint32_t>(dividend / divisor); |
356 remainder = (dividend % divisor) << divisor_power; | 357 remainder = (dividend % divisor) << divisor_power; |
357 } else { | 358 } else { |
358 divisor <<= divisor_power - exponent; | 359 divisor <<= divisor_power - exponent; |
359 quotient = dividend / divisor; | 360 quotient = static_cast<uint32_t>(dividend / divisor); |
360 remainder = (dividend % divisor) << exponent; | 361 remainder = (dividend % divisor) << exponent; |
361 } | 362 } |
362 FillDigits32(quotient, buffer, length); | 363 FillDigits32(quotient, buffer, length); |
363 FillDigits64FixedLength(remainder, divisor_power, buffer, length); | 364 FillDigits64FixedLength(remainder, divisor_power, buffer, length); |
364 *decimal_point = *length; | 365 *decimal_point = *length; |
365 } else if (exponent >= 0) { | 366 } else if (exponent >= 0) { |
366 // 0 <= exponent <= 11 | 367 // 0 <= exponent <= 11 |
367 significand <<= exponent; | 368 significand <<= exponent; |
368 FillDigits64(significand, buffer, length); | 369 FillDigits64(significand, buffer, length); |
369 *decimal_point = *length; | 370 *decimal_point = *length; |
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395 buffer[*length] = '\0'; | 396 buffer[*length] = '\0'; |
396 if ((*length) == 0) { | 397 if ((*length) == 0) { |
397 // The string is empty and the decimal_point thus has no importance. Mimick | 398 // The string is empty and the decimal_point thus has no importance. Mimick |
398 // Gay's dtoa and and set it to -fractional_count. | 399 // Gay's dtoa and and set it to -fractional_count. |
399 *decimal_point = -fractional_count; | 400 *decimal_point = -fractional_count; |
400 } | 401 } |
401 return true; | 402 return true; |
402 } | 403 } |
403 | 404 |
404 } } // namespace v8::internal | 405 } } // namespace v8::internal |
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