OLD | NEW |
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 |
11 // with the distribution. | 11 // with the distribution. |
12 // * Neither the name of Google Inc. nor the names of its | 12 // * Neither the name of Google Inc. nor the names of its |
13 // contributors may be used to endorse or promote products derived | 13 // contributors may be used to endorse or promote products derived |
14 // from this software without specific prior written permission. | 14 // from this software without specific prior written permission. |
15 // | 15 // |
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
27 | 27 |
28 #include "v8.h" | 28 #include "v8.h" |
29 | 29 |
30 #include "diy_fp.h" | 30 #include "diy-fp.h" |
31 | 31 |
32 namespace v8 { | 32 namespace v8 { |
33 namespace internal { | 33 namespace internal { |
34 | 34 |
35 void DiyFp::Multiply(const DiyFp& other) { | 35 void DiyFp::Multiply(const DiyFp& other) { |
36 // Simply "emulates" a 128 bit multiplication. | 36 // Simply "emulates" a 128 bit multiplication. |
37 // However: the resulting number only contains 64 bits. The least | 37 // However: the resulting number only contains 64 bits. The least |
38 // significant 64 bits are only used for rounding the most significant 64 | 38 // significant 64 bits are only used for rounding the most significant 64 |
39 // bits. | 39 // bits. |
40 const uint64_t kM32 = 0xFFFFFFFFu; | 40 const uint64_t kM32 = 0xFFFFFFFFu; |
41 uint64_t a = f_ >> 32; | 41 uint64_t a = f_ >> 32; |
42 uint64_t b = f_ & kM32; | 42 uint64_t b = f_ & kM32; |
43 uint64_t c = other.f_ >> 32; | 43 uint64_t c = other.f_ >> 32; |
44 uint64_t d = other.f_ & kM32; | 44 uint64_t d = other.f_ & kM32; |
45 uint64_t ac = a * c; | 45 uint64_t ac = a * c; |
46 uint64_t bc = b * c; | 46 uint64_t bc = b * c; |
47 uint64_t ad = a * d; | 47 uint64_t ad = a * d; |
48 uint64_t bd = b * d; | 48 uint64_t bd = b * d; |
49 uint64_t tmp = (bd >> 32) + (ad & kM32) + (bc & kM32); | 49 uint64_t tmp = (bd >> 32) + (ad & kM32) + (bc & kM32); |
50 // By adding 1U << 31 to tmp we round the final result. | 50 // By adding 1U << 31 to tmp we round the final result. |
51 // Halfway cases will be round up. | 51 // Halfway cases will be round up. |
52 tmp += 1U << 31; | 52 tmp += 1U << 31; |
53 uint64_t result_f = ac + (ad >> 32) + (bc >> 32) + (tmp >> 32); | 53 uint64_t result_f = ac + (ad >> 32) + (bc >> 32) + (tmp >> 32); |
54 e_ += other.e_ + 64; | 54 e_ += other.e_ + 64; |
55 f_ = result_f; | 55 f_ = result_f; |
56 } | 56 } |
57 | 57 |
58 } } // namespace v8::internal | 58 } } // namespace v8::internal |
OLD | NEW |