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Issue 207823003: Rename A64 port to ARM64 port (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: retry Created 6 years, 9 months ago
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1 // Copyright 2013 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are
4 // met:
5 //
6 // * Redistributions of source code must retain the above copyright
7 // notice, this list of conditions and the following disclaimer.
8 // * Redistributions in binary form must reproduce the above
9 // copyright notice, this list of conditions and the following
10 // disclaimer in the documentation and/or other materials provided
11 // with the distribution.
12 // * Neither the name of Google Inc. nor the names of its
13 // contributors may be used to endorse or promote products derived
14 // from this software without specific prior written permission.
15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.
27
28 #if V8_TARGET_ARCH_A64
29
30 #include "a64/utils-a64.h"
31
32
33 namespace v8 {
34 namespace internal {
35
36 #define __ assm->
37
38
39 int CountLeadingZeros(uint64_t value, int width) {
40 // TODO(jbramley): Optimize this for A64 hosts.
41 ASSERT((width == 32) || (width == 64));
42 int count = 0;
43 uint64_t bit_test = 1UL << (width - 1);
44 while ((count < width) && ((bit_test & value) == 0)) {
45 count++;
46 bit_test >>= 1;
47 }
48 return count;
49 }
50
51
52 int CountLeadingSignBits(int64_t value, int width) {
53 // TODO(jbramley): Optimize this for A64 hosts.
54 ASSERT((width == 32) || (width == 64));
55 if (value >= 0) {
56 return CountLeadingZeros(value, width) - 1;
57 } else {
58 return CountLeadingZeros(~value, width) - 1;
59 }
60 }
61
62
63 int CountTrailingZeros(uint64_t value, int width) {
64 // TODO(jbramley): Optimize this for A64 hosts.
65 ASSERT((width == 32) || (width == 64));
66 int count = 0;
67 while ((count < width) && (((value >> count) & 1) == 0)) {
68 count++;
69 }
70 return count;
71 }
72
73
74 int CountSetBits(uint64_t value, int width) {
75 // TODO(jbramley): Would it be useful to allow other widths? The
76 // implementation already supports them.
77 ASSERT((width == 32) || (width == 64));
78
79 // Mask out unused bits to ensure that they are not counted.
80 value &= (0xffffffffffffffffUL >> (64-width));
81
82 // Add up the set bits.
83 // The algorithm works by adding pairs of bit fields together iteratively,
84 // where the size of each bit field doubles each time.
85 // An example for an 8-bit value:
86 // Bits: h g f e d c b a
87 // \ | \ | \ | \ |
88 // value = h+g f+e d+c b+a
89 // \ | \ |
90 // value = h+g+f+e d+c+b+a
91 // \ |
92 // value = h+g+f+e+d+c+b+a
93 value = ((value >> 1) & 0x5555555555555555) + (value & 0x5555555555555555);
94 value = ((value >> 2) & 0x3333333333333333) + (value & 0x3333333333333333);
95 value = ((value >> 4) & 0x0f0f0f0f0f0f0f0f) + (value & 0x0f0f0f0f0f0f0f0f);
96 value = ((value >> 8) & 0x00ff00ff00ff00ff) + (value & 0x00ff00ff00ff00ff);
97 value = ((value >> 16) & 0x0000ffff0000ffff) + (value & 0x0000ffff0000ffff);
98 value = ((value >> 32) & 0x00000000ffffffff) + (value & 0x00000000ffffffff);
99
100 return value;
101 }
102
103
104 int MaskToBit(uint64_t mask) {
105 ASSERT(CountSetBits(mask, 64) == 1);
106 return CountTrailingZeros(mask, 64);
107 }
108
109
110 } } // namespace v8::internal
111
112 #endif // V8_TARGET_ARCH_A64
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