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Side by Side Diff: third_party/WebKit/Source/wtf/asm/SaturatedArithmeticARM.h

Issue 1436153002: Apply clang-format with Chromium-style without column limit. (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Created 5 years, 1 month ago
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1 // Copyright 2014 The Chromium Authors. All rights reserved. 1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #ifndef SaturatedArithmeticARM_h 5 #ifndef SaturatedArithmeticARM_h
6 #define SaturatedArithmeticARM_h 6 #define SaturatedArithmeticARM_h
7 7
8 #include "wtf/CPU.h" 8 #include "wtf/CPU.h"
9 #include <limits> 9 #include <limits>
10 #include <stdint.h> 10 #include <stdint.h>
11 11
12 ALWAYS_INLINE int32_t saturatedAddition(int32_t a, int32_t b) 12 ALWAYS_INLINE int32_t saturatedAddition(int32_t a, int32_t b) {
13 { 13 int32_t result;
14 int32_t result;
15 14
16 asm("qadd %[output],%[first],%[second]" 15 asm("qadd %[output],%[first],%[second]"
17 : [output] "=r" (result) 16 : [output] "=r"(result)
18 : [first] "r" (a), 17 : [first] "r"(a),
19 [second] "r" (b)); 18 [second] "r"(b));
20 19
21 return result; 20 return result;
22 } 21 }
23 22
24 ALWAYS_INLINE int32_t saturatedSubtraction(int32_t a, int32_t b) 23 ALWAYS_INLINE int32_t saturatedSubtraction(int32_t a, int32_t b) {
25 { 24 int32_t result;
26 int32_t result;
27 25
28 asm("qsub %[output],%[first],%[second]" 26 asm("qsub %[output],%[first],%[second]"
29 : [output] "=r" (result) 27 : [output] "=r"(result)
30 : [first] "r" (a), 28 : [first] "r"(a),
31 [second] "r" (b)); 29 [second] "r"(b));
32 30
33 return result; 31 return result;
34 } 32 }
35 33
36 inline int getMaxSaturatedSetResultForTesting(int FractionalShift) 34 inline int getMaxSaturatedSetResultForTesting(int FractionalShift) {
37 { 35 // For ARM Asm version the set function maxes out to the biggest
38 // For ARM Asm version the set function maxes out to the biggest 36 // possible integer part with the fractional part zero'd out.
39 // possible integer part with the fractional part zero'd out. 37 // e.g. 0x7fffffc0.
40 // e.g. 0x7fffffc0. 38 return std::numeric_limits<int>::max() & ~((1 << FractionalShift) - 1);
41 return std::numeric_limits<int>::max() & ~((1 << FractionalShift)-1);
42 } 39 }
43 40
44 inline int getMinSaturatedSetResultForTesting(int FractionalShift) 41 inline int getMinSaturatedSetResultForTesting(int FractionalShift) {
45 { 42 return std::numeric_limits<int>::min();
46 return std::numeric_limits<int>::min();
47 } 43 }
48 44
49 ALWAYS_INLINE int saturatedSet(int value, int FractionalShift) 45 ALWAYS_INLINE int saturatedSet(int value, int FractionalShift) {
50 { 46 // Figure out how many bits are left for storing the integer part of
51 // Figure out how many bits are left for storing the integer part of 47 // the fixed point number, and saturate our input to that
52 // the fixed point number, and saturate our input to that 48 const int saturate = 32 - FractionalShift;
53 const int saturate = 32 - FractionalShift;
54 49
55 int result; 50 int result;
56 51
57 // The following ARM code will Saturate the passed value to the number of 52 // The following ARM code will Saturate the passed value to the number of
58 // bits used for the whole part of the fixed point representation, then 53 // bits used for the whole part of the fixed point representation, then
59 // shift it up into place. This will result in the low <FractionShift> bits 54 // shift it up into place. This will result in the low <FractionShift> bits
60 // all being 0's. When the value saturates this gives a different result 55 // all being 0's. When the value saturates this gives a different result
61 // to from the C++ case; in the C++ code a saturated value has all the low 56 // to from the C++ case; in the C++ code a saturated value has all the low
62 // bits set to 1 (for a +ve number at least). This cannot be done rapidly 57 // bits set to 1 (for a +ve number at least). This cannot be done rapidly
63 // in ARM ... we live with the difference, for the sake of speed. 58 // in ARM ... we live with the difference, for the sake of speed.
64 59
65 asm("ssat %[output],%[saturate],%[value]\n\t" 60 asm(
66 "lsl %[output],%[shift]" 61 "ssat %[output],%[saturate],%[value]\n\t"
67 : [output] "=r" (result) 62 "lsl %[output],%[shift]"
68 : [value] "r" (value), 63 : [output] "=r"(result)
69 [saturate] "n" (saturate), 64 : [value] "r"(value),
70 [shift] "n" (FractionalShift)); 65 [saturate] "n"(saturate),
66 [shift] "n"(FractionalShift));
71 67
72 return result; 68 return result;
73 } 69 }
74 70
71 ALWAYS_INLINE int saturatedSet(unsigned value, int FractionalShift) {
72 // Here we are being passed an unsigned value to saturate,
73 // even though the result is returned as a signed integer. The ARM
74 // instruction for unsigned saturation therefore needs to be given one
75 // less bit (i.e. the sign bit) for the saturation to work correctly; hence
76 // the '31' below.
77 const int saturate = 31 - FractionalShift;
75 78
76 ALWAYS_INLINE int saturatedSet(unsigned value, int FractionalShift) 79 // The following ARM code will Saturate the passed value to the number of
77 { 80 // bits used for the whole part of the fixed point representation, then
78 // Here we are being passed an unsigned value to saturate, 81 // shift it up into place. This will result in the low <FractionShift> bits
79 // even though the result is returned as a signed integer. The ARM 82 // all being 0's. When the value saturates this gives a different result
80 // instruction for unsigned saturation therefore needs to be given one 83 // to from the C++ case; in the C++ code a saturated value has all the low
81 // less bit (i.e. the sign bit) for the saturation to work correctly; hence 84 // bits set to 1. This cannot be done rapidly in ARM, so we live with the
82 // the '31' below. 85 // difference, for the sake of speed.
83 const int saturate = 31 - FractionalShift;
84 86
85 // The following ARM code will Saturate the passed value to the number of 87 int result;
86 // bits used for the whole part of the fixed point representation, then
87 // shift it up into place. This will result in the low <FractionShift> bits
88 // all being 0's. When the value saturates this gives a different result
89 // to from the C++ case; in the C++ code a saturated value has all the low
90 // bits set to 1. This cannot be done rapidly in ARM, so we live with the
91 // difference, for the sake of speed.
92 88
93 int result; 89 asm(
90 "usat %[output],%[saturate],%[value]\n\t"
91 "lsl %[output],%[shift]"
92 : [output] "=r"(result)
93 : [value] "r"(value),
94 [saturate] "n"(saturate),
95 [shift] "n"(FractionalShift));
94 96
95 asm("usat %[output],%[saturate],%[value]\n\t" 97 return result;
96 "lsl %[output],%[shift]"
97 : [output] "=r" (result)
98 : [value] "r" (value),
99 [saturate] "n" (saturate),
100 [shift] "n" (FractionalShift));
101
102 return result;
103 } 98 }
104 99
105 #endif // SaturatedArithmeticARM_h 100 #endif // SaturatedArithmeticARM_h
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