1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
|
/*
* Copyright © 2015 Samsung Electronics Co., Ltd
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#ifndef WESTON_HELPERS_H
#define WESTON_HELPERS_H
#ifdef __cplusplus
extern "C" {
#endif
/**
* @file
* Simple misc helper macros.
*/
/**
* Compile-time computation of number of items in a hardcoded array.
*
* @param a the array being measured.
* @return the number of items hardcoded into the array.
*/
#ifndef ARRAY_LENGTH
#define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
#endif
/**
* Returns the smaller of two values.
*
* @param x the first item to compare.
* @param y the second item to compare.
* @return the value that evaluates to lesser than the other.
*/
#ifndef MIN
#define MIN(x,y) (((x) < (y)) ? (x) : (y))
#endif
/**
* Returns the bigger of two values.
*
* @param x the first item to compare.
* @param y the second item to compare.
* @return the value that evaluates to more than the other.
*/
#ifndef MAX
#define MAX(x,y) (((x) > (y)) ? (x) : (y))
#endif
/**
* Returns a pointer to the containing struct of a given member item.
*
* To demonstrate, the following example retrieves a pointer to
* `example_container` given only its `destroy_listener` member:
*
* @code
* struct example_container {
* struct wl_listener destroy_listener;
* // other members...
* };
*
* void example_container_destroy(struct wl_listener *listener, void *data)
* {
* struct example_container *ctr;
*
* ctr = wl_container_of(listener, ctr, destroy_listener);
* // destroy ctr...
* }
* @endcode
*
* @param ptr A valid pointer to the contained item.
*
* @param type A pointer to the type of content that the list item
* stores. Type does not need be a valid pointer; a null or
* an uninitialised pointer will suffice.
*
* @param member The named location of ptr within the sample type.
*
* @return The container for the specified pointer.
*/
#ifndef container_of
#define container_of(ptr, type, member) ({ \
const __typeof__( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})
#endif
/**
* Build-time static assertion support
*
* A build-time equivalent to assert(), will generate a compilation error
* if the supplied condition does not evaluate true.
*
* The following example demonstrates use of static_assert to ensure that
* arrays which are supposed to mirror each other have a consistent
* size.
*
* This is only a fallback definition; support must be provided by the
* compiler itself.
*
* @code
* int small[4];
* long expanded[4];
*
* static_assert(ARRAY_LENGTH(small) == ARRAY_LENGTH(expanded),
* "size mismatch between small and expanded arrays");
* for (i = 0; i < ARRAY_LENGTH(small); i++)
* expanded[i] = small[4];
* @endcode
*
* @param cond Expression to check for truth
* @param msg Message to print on failure
*/
#ifndef static_assert
# ifdef _Static_assert
# define static_assert(cond, msg) _Static_assert(cond, msg)
# else
# define static_assert(cond, msg)
# endif
#endif
#ifdef __cplusplus
}
#endif
#endif /* WESTON_HELPERS_H */
|
