1 // Copyright (c) 2020-2022 Uber Technologies, Inc.
2 //
3 // Permission is hereby granted, free of charge, to any person obtaining a copy
4 // of this software and associated documentation files (the "Software"), to deal
5 // in the Software without restriction, including without limitation the rights
6 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
7 // copies of the Software, and to permit persons to whom the Software is
8 // furnished to do so, subject to the following conditions:
9 //
10 // The above copyright notice and this permission notice shall be included in
11 // all copies or substantial portions of the Software.
12 //
13 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
18 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
19 // THE SOFTWARE.
20 21 package atomic
22 23 import (
24 "math"
25 "strconv"
26 )
27 28 //go:generate bin/gen-atomicwrapper -name=Float32 -type=float32 -wrapped=Uint32 -pack=math.Float32bits -unpack=math.Float32frombits -swap -json -imports math -file=float32.go
29 30 // Add atomically adds to the wrapped float32 and returns the new value.
31 func (f *Float32) Add(delta float32) float32 {
32 for {
33 old := f.Load()
34 new := old + delta
35 if f.CAS(old, new) {
36 return new
37 }
38 }
39 }
40 41 // Sub atomically subtracts from the wrapped float32 and returns the new value.
42 func (f *Float32) Sub(delta float32) float32 {
43 return f.Add(-delta)
44 }
45 46 // CAS is an atomic compare-and-swap for float32 values.
47 //
48 // Deprecated: Use CompareAndSwap
49 func (f *Float32) CAS(old, new float32) (swapped bool) {
50 return f.CompareAndSwap(old, new)
51 }
52 53 // CompareAndSwap is an atomic compare-and-swap for float32 values.
54 //
55 // Note: CompareAndSwap handles NaN incorrectly. NaN != NaN using Go's inbuilt operators
56 // but CompareAndSwap allows a stored NaN to compare equal to a passed in NaN.
57 // This avoids typical CompareAndSwap loops from blocking forever, e.g.,
58 //
59 // for {
60 // old := atom.Load()
61 // new = f(old)
62 // if atom.CompareAndSwap(old, new) {
63 // break
64 // }
65 // }
66 //
67 // If CompareAndSwap did not match NaN to match, then the above would loop forever.
68 func (f *Float32) CompareAndSwap(old, new float32) (swapped bool) {
69 return f.v.CompareAndSwap(math.Float32bits(old), math.Float32bits(new))
70 }
71 72 // String encodes the wrapped value as a string.
73 func (f *Float32) String() string {
74 // 'g' is the behavior for floats with %v.
75 return strconv.FormatFloat(float64(f.Load()), 'g', -1, 32)
76 }
77