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atomicAdjustI386Impl.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 atomicAdjustI386Impl.I
10 * @author drose
11 * @date 2006-04-01
12 */
13
14/**
15 * Atomically increments the indicated variable.
16 */
17INLINE void AtomicAdjustI386Impl::
18inc(TVOLATILE AtomicAdjustI386Impl::Integer &var) {
19 assert((((size_t)&var) & (sizeof(Integer) - 1)) == 0);
20#ifdef _M_IX86
21 // Windows case
22 TVOLATILE Integer *var_ptr = &var;
23 __asm {
24 mov edx, var_ptr;
25 lock inc dword ptr [edx];
26 }
27#elif !defined(__EDG__)
28 // GCC case
29 __asm__ __volatile__("lock; incl %0"
30 :"=m" (var)
31 :"m" (&var));
32#endif // __EDG__
33}
34
35/**
36 * Atomically decrements the indicated variable and returns true if the new
37 * value is nonzero, false if it is zero.
38 */
39INLINE bool AtomicAdjustI386Impl::
40dec(TVOLATILE AtomicAdjustI386Impl::Integer &var) {
41 assert((((size_t)&var) & (sizeof(Integer) - 1)) == 0);
42 unsigned char c;
43#ifdef _M_IX86
44 // Windows case
45 TVOLATILE Integer *var_ptr = &var;
46 __asm {
47 mov edx, var_ptr;
48 lock dec dword ptr [edx];
49 sete c;
50 }
51#elif !defined(__EDG__)
52 // GCC case
53 __asm__ __volatile__("lock; decl %0; sete %1"
54 :"=m" (var), "=qm" (c)
55 :"m" (&var) : "memory");
56#endif // __EDG__
57 return (c == 0);
58}
59
60/**
61 * Atomically computes var += delta. It is legal for delta to be negative.
62 * Returns the result of the addition.
63 */
64INLINE AtomicAdjustI386Impl::Integer AtomicAdjustI386Impl::
65add(TVOLATILE AtomicAdjustI386Impl::Integer &var, AtomicAdjustI386Impl::Integer delta) {
66 assert((((size_t)&var) & (sizeof(Integer) - 1)) == 0);
67 Integer orig_value = var;
68 Integer new_value = orig_value + delta;
69 while (compare_and_exchange(var, orig_value, new_value) != orig_value) {
70 orig_value = var;
71 new_value = orig_value + delta;
72 }
73 return new_value;
74}
75
76/**
77 * Atomically changes the indicated variable and returns the original value.
78 */
79INLINE AtomicAdjustI386Impl::Integer AtomicAdjustI386Impl::
80set(TVOLATILE AtomicAdjustI386Impl::Integer &var,
81 AtomicAdjustI386Impl::Integer new_value) {
82 assert((((size_t)&var) & (sizeof(Integer) - 1)) == 0);
83 Integer orig_value = var;
84 var = new_value;
85 return orig_value;
86}
87
88/**
89 * Atomically retrieves the snapshot value of the indicated variable. This is
90 * the only guaranteed safe way to retrieve the value that other threads might
91 * be asynchronously setting, incrementing, or decrementing (via other
92 * AtomicAjust methods).
93 */
94INLINE AtomicAdjustI386Impl::Integer AtomicAdjustI386Impl::
95get(const TVOLATILE AtomicAdjustI386Impl::Integer &var) {
96 assert((((size_t)&var) & (sizeof(Integer) - 1)) == 0);
97 return var;
98}
99
100/**
101 * Atomically changes the indicated variable and returns the original value.
102 */
103INLINE AtomicAdjustI386Impl::Pointer AtomicAdjustI386Impl::
104set_ptr(TVOLATILE AtomicAdjustI386Impl::Pointer &var,
105 AtomicAdjustI386Impl::Pointer new_value) {
106 assert((((size_t)&var) & (sizeof(Pointer) - 1)) == 0);
107 Pointer orig_value = var;
108 var = new_value;
109 return orig_value;
110}
111
112/**
113 * Atomically retrieves the snapshot value of the indicated variable. This is
114 * the only guaranteed safe way to retrieve the value that other threads might
115 * be asynchronously setting, incrementing, or decrementing (via other
116 * AtomicAjust methods).
117 */
118INLINE AtomicAdjustI386Impl::Pointer AtomicAdjustI386Impl::
119get_ptr(const TVOLATILE AtomicAdjustI386Impl::Pointer &var) {
120 assert((((size_t)&var) & (sizeof(Pointer) - 1)) == 0);
121 return var;
122}
123
124/**
125 * Atomic compare and exchange.
126 *
127 * If mem is equal to old_value, store new_value in mem. In either case,
128 * return the original value of mem. The caller can test for success by
129 * comparing return_value == old_value.
130 *
131 * The atomic function expressed in pseudo-code:
132 *
133 * orig_value = mem; if (mem == old_value) { mem = new_value; } return
134 * orig_value;
135 *
136 */
137INLINE AtomicAdjustI386Impl::Integer AtomicAdjustI386Impl::
138compare_and_exchange(TVOLATILE AtomicAdjustI386Impl::Integer &mem,
139 AtomicAdjustI386Impl::Integer old_value,
140 AtomicAdjustI386Impl::Integer new_value) {
141 assert((((size_t)&mem) & (sizeof(Integer) - 1)) == 0);
142 Integer prev;
143#ifdef _M_IX86
144 // Windows case
145 TVOLATILE Integer *mem_ptr = &mem;
146 __asm {
147 mov edx, mem_ptr;
148 mov ecx, new_value;
149 mov eax, old_value;
150 lock cmpxchg dword ptr [edx], ecx;
151 mov prev, eax;
152 }
153#elif !defined(__EDG__)
154 // GCC case
155 __asm__ __volatile__("lock; cmpxchgl %1,%2"
156 : "=a"(prev)
157 : "r"(new_value), "m"(mem), "0"(old_value)
158 : "memory");
159#endif // __EDG__
160 return prev;
161}
162
163/**
164 * Atomic compare and exchange.
165 *
166 * As above, but works on pointers instead of integers.
167 */
168INLINE AtomicAdjustI386Impl::Pointer AtomicAdjustI386Impl::
169compare_and_exchange_ptr(TVOLATILE AtomicAdjustI386Impl::Pointer &mem,
170 AtomicAdjustI386Impl::Pointer old_value,
171 AtomicAdjustI386Impl::Pointer new_value) {
172 assert((((size_t)&mem) & (sizeof(Pointer) - 1)) == 0);
173 Pointer prev;
174#ifdef _M_IX86
175 // Windows case
176 TVOLATILE Pointer *mem_ptr = &mem;
177 __asm {
178 mov edx, mem_ptr;
179 mov ecx, new_value;
180 mov eax, old_value;
181 lock cmpxchg dword ptr [edx], ecx;
182 mov prev, eax;
183 }
184#elif !defined(__EDG__)
185 // GCC case
186 __asm__ __volatile__("lock; cmpxchgl %1,%2"
187 : "=a"(prev)
188 : "r"(new_value), "m"(mem), "0"(old_value)
189 : "memory");
190#endif // __EDG__
191 return prev;
192}