1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
|
/*
* Copyright (c) 2012, Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef SaturatedArithmetic_h
#define SaturatedArithmetic_h
#include "wtf/CPU.h"
#include <limits>
#include <stdint.h>
#if CPU(ARM) && COMPILER(GCC) && __OPTIMIZE__
// If we're building ARM on GCC we replace the C++ versions with some
// native ARM assembly for speed.
#include "wtf/asm/SaturatedArithmeticARM.h"
#else
ALWAYS_INLINE int32_t saturatedAddition(int32_t a, int32_t b)
{
uint32_t ua = a;
uint32_t ub = b;
uint32_t result = ua + ub;
// Can only overflow if the signed bit of the two values match. If the
// signed bit of the result and one of the values differ it overflowed.
if (~(ua ^ ub) & (result ^ ua) & (1 << 31))
return std::numeric_limits<int>::max() + (ua >> 31);
return result;
}
ALWAYS_INLINE int32_t saturatedSubtraction(int32_t a, int32_t b)
{
uint32_t ua = a;
uint32_t ub = b;
uint32_t result = ua - ub;
// Can only overflow if the signed bit of the two input values differ. If
// the signed bit of the result and the first value differ it overflowed.
if ((ua ^ ub) & (result ^ ua) & (1 << 31))
return std::numeric_limits<int>::max() + (ua >> 31);
return result;
}
inline int getMaxSaturatedSetResultForTesting(int FractionalShift)
{
// For C version the set function maxes out to max int, this differs from
// the ARM asm version, see SaturatedArithmetiARM.h for the equivalent asm
// version.
return std::numeric_limits<int>::max();
}
inline int getMinSaturatedSetResultForTesting(int FractionalShift)
{
return std::numeric_limits<int>::min();
}
ALWAYS_INLINE int saturatedSet(int value, int FractionalShift)
{
const int intMaxForLayoutUnit =
std::numeric_limits<int>::max() >> FractionalShift;
const int intMinForLayoutUnit =
std::numeric_limits<int>::min() >> FractionalShift;
if (value > intMaxForLayoutUnit)
return std::numeric_limits<int>::max();
if (value < intMinForLayoutUnit)
return std::numeric_limits<int>::min();
return value << FractionalShift;
}
ALWAYS_INLINE int saturatedSet(unsigned value, int FractionalShift)
{
const unsigned intMaxForLayoutUnit =
std::numeric_limits<int>::max() >> FractionalShift;
if (value >= intMaxForLayoutUnit)
return std::numeric_limits<int>::max();
return value << FractionalShift;
}
#endif // CPU(ARM) && COMPILER(GCC)
#endif // SaturatedArithmetic_h
|
