ff7da410106a39d981556cd13d0905d2a2d662b8
[babeltrace.git] / src / common / macros.h
1 #ifndef _BABELTRACE_INTERNAL_H
2 #define _BABELTRACE_INTERNAL_H
3
4 /*
5 * Copyright 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE.
24 */
25
26
27 #define bt_max_t(type, a, b) \
28 ((type) (a) > (type) (b) ? (type) (a) : (type) (b))
29
30 /*
31 * BT_HIDDEN: set the hidden attribute for internal functions
32 * On Windows, symbols are local unless explicitly exported,
33 * see https://gcc.gnu.org/wiki/Visibility
34 */
35 #if defined(_WIN32) || defined(__CYGWIN__)
36 #define BT_HIDDEN
37 #else
38 #define BT_HIDDEN __attribute__((visibility("hidden")))
39 #endif
40
41 /*
42 * Yield `ref`'s value while setting `ref` to NULL.
43 *
44 * This can be used to give a strong reference to a callee:
45 *
46 * add_foo_to_list(list, BT_MOVE_REF(foo));
47 *
48 * or in a simple assignment:
49 *
50 * my_struct->foo = BT_MOVE_REF(foo);
51 *
52 * When moving a reference in a function call, the reference is given to the
53 * callee even if that function call fails, so make sure the called function
54 * is written accordingly.
55 */
56
57 #define BT_MOVE_REF(ref) \
58 ({ \
59 typeof(ref) _ref = ref; \
60 ref = NULL; \
61 _ref; \
62 })
63
64 #endif
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