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atomicAdjustWin32Impl.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 atomicAdjustWin32Impl.I
10 * @author drose
11 * @date 2006-02-07
12 */
13
14/**
15 * Atomically increments the indicated variable.
16 */
17ALWAYS_INLINE void AtomicAdjustWin32Impl::
18inc(TVOLATILE AtomicAdjustWin32Impl::Integer &var) {
19 assert((((size_t)&var) & (sizeof(Integer) - 1)) == 0);
20#ifdef _WIN64
21 InterlockedIncrement64(&var);
22#else
23 InterlockedIncrement(&var);
24#endif // _WIN64
25}
26
27/**
28 * Atomically decrements the indicated variable and returns true if the new
29 * value is nonzero, false if it is zero.
30 */
31ALWAYS_INLINE bool AtomicAdjustWin32Impl::
32dec(TVOLATILE AtomicAdjustWin32Impl::Integer &var) {
33 assert((((size_t)&var) & (sizeof(Integer) - 1)) == 0);
34#ifdef _WIN64
35 return (InterlockedDecrement64(&var) != 0);
36#else
37 return (InterlockedDecrement(&var) != 0);
38#endif // _WIN64
39}
40
41/**
42 * Atomically computes var += delta. It is legal for delta to be negative.
43 * Returns the result of the addition.
44 */
45INLINE AtomicAdjustWin32Impl::Integer AtomicAdjustWin32Impl::
46add(TVOLATILE AtomicAdjustWin32Impl::Integer &var, AtomicAdjustWin32Impl::Integer delta) {
47 assert((((size_t)&var) & (sizeof(Integer) - 1)) == 0);
48#ifdef _WIN64
49 return InterlockedAdd64(&var, delta);
50#else
51 Integer orig_value = var;
52 Integer new_value = orig_value + delta;
53 while (compare_and_exchange(var, orig_value, new_value) != orig_value) {
54 orig_value = var;
55 new_value = orig_value + delta;
56 }
57 return new_value;
58#endif // _WIN64
59}
60
61/**
62 * Atomically changes the indicated variable and returns the original value.
63 */
64ALWAYS_INLINE AtomicAdjustWin32Impl::Integer AtomicAdjustWin32Impl::
65set(TVOLATILE AtomicAdjustWin32Impl::Integer &var,
66 AtomicAdjustWin32Impl::Integer new_value) {
67 assert((((size_t)&var) & (sizeof(Integer) - 1)) == 0);
68#ifdef _WIN64
69 return InterlockedExchange64(&var, new_value);
70#else
71 return InterlockedExchange(&var, new_value);
72#endif // _WIN64
73}
74
75/**
76 * Atomically retrieves the snapshot value of the indicated variable. This is
77 * the only guaranteed safe way to retrieve the value that other threads might
78 * be asynchronously setting, incrementing, or decrementing (via other
79 * AtomicAjust methods).
80 */
81ALWAYS_INLINE AtomicAdjustWin32Impl::Integer AtomicAdjustWin32Impl::
82get(const TVOLATILE AtomicAdjustWin32Impl::Integer &var) {
83 // On Intel platforms, word-aligned loads are atomic (if performed in a
84 // single instruction). We can't guarantee the compiler will generate a
85 // single instruction to load this value, but it certainly won't happen if
86 // its address isn't word-aligned, so make sure that's the case.
87 assert((((size_t)&var) & (sizeof(Integer) - 1)) == 0);
88 return var;
89}
90
91/**
92 * Atomically changes the indicated variable and returns the original value.
93 */
94ALWAYS_INLINE AtomicAdjustWin32Impl::Pointer AtomicAdjustWin32Impl::
95set_ptr(TVOLATILE AtomicAdjustWin32Impl::Pointer &var,
96 AtomicAdjustWin32Impl::Pointer new_value) {
97 assert((((size_t)&var) & (sizeof(Pointer) - 1)) == 0);
98 return InterlockedExchangePointer(&var, new_value);
99}
100
101/**
102 * Atomically retrieves the snapshot value of the indicated variable. This is
103 * the only guaranteed safe way to retrieve the value that other threads might
104 * be asynchronously setting, incrementing, or decrementing (via other
105 * AtomicAjust methods).
106 */
107ALWAYS_INLINE AtomicAdjustWin32Impl::Pointer AtomicAdjustWin32Impl::
108get_ptr(const TVOLATILE AtomicAdjustWin32Impl::Pointer &var) {
109 // As in get(), make sure the address is word-aligned.
110 assert((((size_t)&var) & (sizeof(Pointer) - 1)) == 0);
111 return var;
112}
113
114/**
115 * Atomic compare and exchange.
116 *
117 * If mem is equal to old_value, store new_value in mem. In either case,
118 * return the original value of mem. The caller can test for success by
119 * comparing return_value == old_value.
120 *
121 * The atomic function expressed in pseudo-code:
122 *
123 * orig_value = mem; if (mem == old_value) { mem = new_value; } return
124 * orig_value;
125 *
126 */
127INLINE AtomicAdjustWin32Impl::Integer AtomicAdjustWin32Impl::
128compare_and_exchange(TVOLATILE AtomicAdjustWin32Impl::Integer &mem,
129 AtomicAdjustWin32Impl::Integer old_value,
130 AtomicAdjustWin32Impl::Integer new_value) {
131 assert((((size_t)&mem) & (sizeof(Integer) - 1)) == 0);
132 // Note that the AtomicAdjust parameter order is different from Windows
133 // convention!
134#ifdef _WIN64
135 return InterlockedCompareExchange64((TVOLATILE LONGLONG *)&mem, new_value, old_value);
136#else
137 return InterlockedCompareExchange((TVOLATILE LONG *)&mem, new_value, old_value);
138#endif // _WIN64
139}
140
141/**
142 * Atomic compare and exchange.
143 *
144 * As above, but works on pointers instead of integers.
145 */
146INLINE AtomicAdjustWin32Impl::Pointer AtomicAdjustWin32Impl::
147compare_and_exchange_ptr(TVOLATILE AtomicAdjustWin32Impl::Pointer &mem,
148 AtomicAdjustWin32Impl::Pointer old_value,
149 AtomicAdjustWin32Impl::Pointer new_value) {
150 assert((((size_t)&mem) & (sizeof(Pointer) - 1)) == 0);
151 // Note that the AtomicAdjust parameter order is different from Windows
152 // convention!
153 return InterlockedCompareExchangePointer(&mem, new_value, old_value);
154}