1 // Avisynth C Interface Version 0.20
2 // Copyright 2003 Kevin Atkinson
3
4 // This program is free software; you can redistribute it and/or modify
5 // it under the terms of the GNU General Public License as published by
6 // the Free Software Foundation; either version 2 of the License, or
7 // (at your option) any later version.
8 //
9 // This program 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
12 // GNU General Public License for more details.
13 //
14 // You should have received a copy of the GNU General Public License
15 // along with this program; if not, write to the Free Software
16 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA, or visit
17 // http://www.gnu.org/copyleft/gpl.html .
18 //
19 // As a special exception, I give you permission to link to the
20 // Avisynth C interface with independent modules that communicate with
21 // the Avisynth C interface solely through the interfaces defined in
22 // avisynth_c.h, regardless of the license terms of these independent
23 // modules, and to copy and distribute the resulting combined work
24 // under terms of your choice, provided that every copy of the
25 // combined work is accompanied by a complete copy of the source code
26 // of the Avisynth C interface and Avisynth itself (with the version
27 // used to produce the combined work), being distributed under the
28 // terms of the GNU General Public License plus this exception. An
29 // independent module is a module which is not derived from or based
30 // on Avisynth C Interface, such as 3rd-party filters, import and
31 // export plugins, or graphical user interfaces.
32
33 #ifndef AVS_ALIGNMENT_H
34 #define AVS_ALIGNMENT_H
35
36 // Functions and macros to help work with alignment requirements.
37
38 // Tells if a number is a power of two.
39 #define IS_POWER2(n) ((n) && !((n) & ((n) - 1)))
40
41 // Tells if the pointer "ptr" is aligned to "align" bytes.
42 #define IS_PTR_ALIGNED(ptr, align) (((uintptr_t)ptr & ((uintptr_t)(align-1))) == 0)
43
44 // Rounds up the number "n" to the next greater multiple of "align"
45 #define ALIGN_NUMBER(n, align) (((n) + (align)-1) & (~((align)-1)))
46
47 // Rounds up the pointer address "ptr" to the next greater multiple of "align"
48 #define ALIGN_POINTER(ptr, align) (((uintptr_t)(ptr) + (align)-1) & (~(uintptr_t)((align)-1)))
49
50 #ifdef __cplusplus
51
52 #include <cassert>
53 #include <cstdlib>
54 #include <cstdint>
55 #include <avs/config.h>
56
57 #if defined(MSVC)
58 // needed for VS2013, otherwise C++11 'alignas' works
59 #define avs_alignas(x) __declspec(align(x))
60 #else
61 // assumes C++11 support
62 #define avs_alignas(x) alignas(x)
63 #endif
64
65 template<typename T>
IsPtrAligned(T * ptr,size_t align)66 static bool IsPtrAligned(T* ptr, size_t align)
67 {
68 assert(IS_POWER2(align));
69 return (bool)IS_PTR_ALIGNED(ptr, align);
70 }
71
72 template<typename T>
AlignNumber(T n,T align)73 static T AlignNumber(T n, T align)
74 {
75 assert(IS_POWER2(align));
76 return ALIGN_NUMBER(n, align);
77 }
78
79 template<typename T>
AlignPointer(T * ptr,size_t align)80 static T* AlignPointer(T* ptr, size_t align)
81 {
82 assert(IS_POWER2(align));
83 return (T*)ALIGN_POINTER(ptr, align);
84 }
85
86 extern "C"
87 {
88 #else
89 #include <stdlib.h>
90 #endif // __cplusplus
91
92 // Returns a new buffer that is at least the size "nbytes".
93 // The buffer will be aligned to "align" bytes.
94 // Returns NULL on error. On successful allocation,
95 // the returned buffer must be freed using "avs_free".
avs_malloc(size_t nbytes,size_t align)96 inline void* avs_malloc(size_t nbytes, size_t align)
97 {
98 if (!IS_POWER2(align))
99 return NULL;
100
101 size_t offset = sizeof(void*) + align - 1;
102
103 void *orig = malloc(nbytes + offset);
104 if (orig == NULL)
105 return NULL;
106
107 void **aligned = (void**)(((uintptr_t)orig + (uintptr_t)offset) & (~(uintptr_t)(align-1)));
108 aligned[-1] = orig;
109 return aligned;
110 }
111
112 // Buffers allocated using "avs_malloc" must be freed
113 // using "avs_free" instead of "free".
avs_free(void * ptr)114 inline void avs_free(void *ptr)
115 {
116 // Mirroring free()'s semantic requires us to accept NULLs
117 if (ptr == NULL)
118 return;
119
120 free(((void**)ptr)[-1]);
121 }
122
123 #ifdef __cplusplus
124 } // extern "C"
125
126 // The point of these undef's is to force using the template functions
127 // if we are in C++ mode. For C, the user can rely only on the macros.
128 #undef IS_PTR_ALIGNED
129 #undef ALIGN_NUMBER
130 #undef ALIGN_POINTER
131
132 #endif // __cplusplus
133
134 #endif //AVS_ALIGNMENT_H
135