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atomicAdjustGccImpl.I
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1/**
2 * PANDA 3D SOFTWARE
3 * Copyright (c) Carnegie Mellon University. All rights reserved.
4 *
5 * All use of this software is subject to the terms of the revised BSD
6 * license. You should have received a copy of this license along
7 * with this source code in a file named "LICENSE."
8 *
9 * @file atomicAdjustGccImpl.I
10 * @author rdb
11 * @date 2014-07-04
12 */
13
14/**
15 * Atomically increments the indicated variable.
16 */
17INLINE void AtomicAdjustGccImpl::
18inc(TVOLATILE AtomicAdjustGccImpl::Integer &var) {
19 __atomic_fetch_add(&var, 1, __ATOMIC_SEQ_CST);
20}
21
22/**
23 * Atomically decrements the indicated variable and returns true if the new
24 * value is nonzero, false if it is zero.
25 */
26INLINE bool AtomicAdjustGccImpl::
27dec(TVOLATILE AtomicAdjustGccImpl::Integer &var) {
28 return (__atomic_sub_fetch(&var, 1, __ATOMIC_SEQ_CST) != 0);
29}
30
31/**
32 * Atomically computes var += delta. It is legal for delta to be negative.
33 * Returns the result of the addition.
34 */
35INLINE AtomicAdjustGccImpl::Integer AtomicAdjustGccImpl::
36add(TVOLATILE AtomicAdjustGccImpl::Integer &var,
37 AtomicAdjustGccImpl::Integer delta) {
38 return __atomic_add_fetch(&var, delta, __ATOMIC_SEQ_CST);
39}
40
41/**
42 * Atomically changes the indicated variable and returns the original value.
43 */
44INLINE AtomicAdjustGccImpl::Integer AtomicAdjustGccImpl::
45set(TVOLATILE AtomicAdjustGccImpl::Integer &var,
46 AtomicAdjustGccImpl::Integer new_value) {
47
48 return __atomic_exchange_n(&var, new_value, __ATOMIC_SEQ_CST);
49}
50
51/**
52 * Atomically retrieves the snapshot value of the indicated variable. This is
53 * the only guaranteed safe way to retrieve the value that other threads might
54 * be asynchronously setting, incrementing, or decrementing (via other
55 * AtomicAjust methods).
56 */
57INLINE AtomicAdjustGccImpl::Integer AtomicAdjustGccImpl::
58get(const TVOLATILE AtomicAdjustGccImpl::Integer &var) {
59 return __atomic_load_n(&var, __ATOMIC_SEQ_CST);
60}
61
62/**
63 * Atomically changes the indicated variable and returns the original value.
64 */
65INLINE AtomicAdjustGccImpl::Pointer AtomicAdjustGccImpl::
66set_ptr(TVOLATILE AtomicAdjustGccImpl::Pointer &var,
67 AtomicAdjustGccImpl::Pointer new_value) {
68
69 return __atomic_exchange_n(&var, new_value, __ATOMIC_SEQ_CST);
70}
71
72/**
73 * Atomically retrieves the snapshot value of the indicated variable. This is
74 * the only guaranteed safe way to retrieve the value that other threads might
75 * be asynchronously setting, incrementing, or decrementing (via other
76 * AtomicAjust methods).
77 */
78INLINE AtomicAdjustGccImpl::Pointer AtomicAdjustGccImpl::
79get_ptr(const TVOLATILE AtomicAdjustGccImpl::Pointer &var) {
80 return __atomic_load_n(&var, __ATOMIC_SEQ_CST);
81}
82
83/**
84 * Atomic compare and exchange.
85 *
86 * If mem is equal to old_value, store new_value in mem. In either case,
87 * return the original value of mem. The caller can test for success by
88 * comparing return_value == old_value.
89 *
90 * The atomic function expressed in pseudo-code:
91 *
92 * orig_value = mem; if (mem == old_value) { mem = new_value; } return
93 * orig_value;
94 *
95 */
96INLINE AtomicAdjustGccImpl::Integer AtomicAdjustGccImpl::
97compare_and_exchange(TVOLATILE AtomicAdjustGccImpl::Integer &mem,
98 AtomicAdjustGccImpl::Integer old_value,
99 AtomicAdjustGccImpl::Integer new_value) {
100
101 __atomic_compare_exchange_n(&mem, &old_value, new_value, false,
102 __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
103 return old_value;
104}
105
106/**
107 * Atomic compare and exchange.
108 *
109 * As above, but works on pointers instead of integers.
110 */
111INLINE AtomicAdjustGccImpl::Pointer AtomicAdjustGccImpl::
112compare_and_exchange_ptr(TVOLATILE AtomicAdjustGccImpl::Pointer &mem,
113 AtomicAdjustGccImpl::Pointer old_value,
114 AtomicAdjustGccImpl::Pointer new_value) {
115
116 __atomic_compare_exchange_n(&mem, &old_value, new_value, false,
117 __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
118 return old_value;
119}