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1 // Copyright 2014 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 "src/base/bits.h"
6 
7 #include <limits>
8 
9 #include "src/base/logging.h"
10 
11 namespace v8 {
12 namespace base {
13 namespace bits {
14 
RoundUpToPowerOfTwo32(uint32_t value)15 uint32_t RoundUpToPowerOfTwo32(uint32_t value) {
16   DCHECK_LE(value, 0x80000000u);
17   value = value - 1;
18   value = value | (value >> 1);
19   value = value | (value >> 2);
20   value = value | (value >> 4);
21   value = value | (value >> 8);
22   value = value | (value >> 16);
23   return value + 1;
24 }
25 
26 
SignedMulHigh32(int32_t lhs,int32_t rhs)27 int32_t SignedMulHigh32(int32_t lhs, int32_t rhs) {
28   int64_t const value = static_cast<int64_t>(lhs) * static_cast<int64_t>(rhs);
29   return bit_cast<int32_t, uint32_t>(bit_cast<uint64_t>(value) >> 32u);
30 }
31 
32 
SignedMulHighAndAdd32(int32_t lhs,int32_t rhs,int32_t acc)33 int32_t SignedMulHighAndAdd32(int32_t lhs, int32_t rhs, int32_t acc) {
34   return bit_cast<int32_t>(bit_cast<uint32_t>(acc) +
35                            bit_cast<uint32_t>(SignedMulHigh32(lhs, rhs)));
36 }
37 
38 
SignedDiv32(int32_t lhs,int32_t rhs)39 int32_t SignedDiv32(int32_t lhs, int32_t rhs) {
40   if (rhs == 0) return 0;
41   if (rhs == -1) return -lhs;
42   return lhs / rhs;
43 }
44 
45 
SignedMod32(int32_t lhs,int32_t rhs)46 int32_t SignedMod32(int32_t lhs, int32_t rhs) {
47   if (rhs == 0 || rhs == -1) return 0;
48   return lhs % rhs;
49 }
50 
51 }  // namespace bits
52 }  // namespace base
53 }  // namespace v8
54