FFmpeg
macros.h
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 /**
20  * @file
21  * @ingroup lavu
22  * Utility Preprocessor macros
23  */
24 
25 #ifndef AVUTIL_MACROS_H
26 #define AVUTIL_MACROS_H
27 
28 #include "libavutil/avconfig.h"
29 
30 #if AV_HAVE_BIGENDIAN
31 # define AV_NE(be, le) (be)
32 #else
33 # define AV_NE(be, le) (le)
34 #endif
35 
36 /**
37  * Comparator.
38  * For two numerical expressions x and y, gives 1 if x > y, -1 if x < y, and 0
39  * if x == y. This is useful for instance in a qsort comparator callback.
40  * Furthermore, compilers are able to optimize this to branchless code, and
41  * there is no risk of overflow with signed types.
42  * As with many macros, this evaluates its argument multiple times, it thus
43  * must not have a side-effect.
44  */
45 #define FFDIFFSIGN(x,y) (((x)>(y)) - ((x)<(y)))
46 
47 #define FFMAX(a,b) ((a) > (b) ? (a) : (b))
48 #define FFMAX3(a,b,c) FFMAX(FFMAX(a,b),c)
49 #define FFMIN(a,b) ((a) > (b) ? (b) : (a))
50 #define FFMIN3(a,b,c) FFMIN(FFMIN(a,b),c)
51 
52 #define FFSWAP(type,a,b) do{type SWAP_tmp= b; b= a; a= SWAP_tmp;}while(0)
53 #define FF_ARRAY_ELEMS(a) (sizeof(a) / sizeof((a)[0]))
54 
55 #define MKTAG(a,b,c,d) ((a) | ((b) << 8) | ((c) << 16) | ((unsigned)(d) << 24))
56 #define MKBETAG(a,b,c,d) ((d) | ((c) << 8) | ((b) << 16) | ((unsigned)(a) << 24))
57 
58 /**
59  * @addtogroup preproc_misc Preprocessor String Macros
60  *
61  * String manipulation macros
62  *
63  * @{
64  */
65 
66 #define AV_STRINGIFY(s) AV_TOSTRING(s)
67 #define AV_TOSTRING(s) #s
68 
69 #define AV_GLUE(a, b) a ## b
70 #define AV_JOIN(a, b) AV_GLUE(a, b)
71 
72 /**
73  * @}
74  */
75 
76 #define AV_PRAGMA(s) _Pragma(#s)
77 
78 #define FFALIGN(x, a) (((x)+(a)-1)&~((a)-1))
79 
80 #endif /* AVUTIL_MACROS_H */