Improve FF_SYMVER documentation
[libav.git] / libavutil / internal.h
1 /*
2 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file
23 * common internal API header
24 */
25
26 #ifndef AVUTIL_INTERNAL_H
27 #define AVUTIL_INTERNAL_H
28
29 #if !defined(DEBUG) && !defined(NDEBUG)
30 # define NDEBUG
31 #endif
32
33 #include <limits.h>
34 #include <stdint.h>
35 #include <stddef.h>
36 #include <assert.h>
37 #include "config.h"
38 #include "attributes.h"
39 #include "timer.h"
40
41 #ifndef attribute_align_arg
42 #if (!defined(__ICC) || __ICC > 1110) && AV_GCC_VERSION_AT_LEAST(4,2)
43 # define attribute_align_arg __attribute__((force_align_arg_pointer))
44 #else
45 # define attribute_align_arg
46 #endif
47 #endif
48
49
50 /**
51 * Mark a variable as used and prevent the compiler from optimizing it away.
52 * This is useful for asm that accesses varibles in ways that the compiler does not
53 * understand
54 */
55 #ifndef attribute_used
56 #if AV_GCC_VERSION_AT_LEAST(3,1)
57 # define attribute_used __attribute__((used))
58 #else
59 # define attribute_used
60 #endif
61 #endif
62
63 #ifndef INT16_MIN
64 #define INT16_MIN (-0x7fff - 1)
65 #endif
66
67 #ifndef INT16_MAX
68 #define INT16_MAX 0x7fff
69 #endif
70
71 #ifndef INT32_MIN
72 #define INT32_MIN (-0x7fffffff - 1)
73 #endif
74
75 #ifndef INT32_MAX
76 #define INT32_MAX 0x7fffffff
77 #endif
78
79 #ifndef UINT32_MAX
80 #define UINT32_MAX 0xffffffff
81 #endif
82
83 #ifndef INT64_MIN
84 #define INT64_MIN (-0x7fffffffffffffffLL - 1)
85 #endif
86
87 #ifndef INT64_MAX
88 #define INT64_MAX INT64_C(9223372036854775807)
89 #endif
90
91 #ifndef UINT64_MAX
92 #define UINT64_MAX UINT64_C(0xFFFFFFFFFFFFFFFF)
93 #endif
94
95 #ifndef INT_BIT
96 # define INT_BIT (CHAR_BIT * sizeof(int))
97 #endif
98
99 #ifndef offsetof
100 # define offsetof(T, F) ((unsigned int)((char *)&((T *)0)->F))
101 #endif
102
103 /* Use to export labels from asm. */
104 #define LABEL_MANGLE(a) EXTERN_PREFIX #a
105
106 // Use rip-relative addressing if compiling PIC code on x86-64.
107 #if ARCH_X86_64 && defined(PIC)
108 # define LOCAL_MANGLE(a) #a "(%%rip)"
109 #else
110 # define LOCAL_MANGLE(a) #a
111 #endif
112
113 #define MANGLE(a) EXTERN_PREFIX LOCAL_MANGLE(a)
114
115 /* debug stuff */
116
117 /* dprintf macros */
118 #ifdef DEBUG
119 # define dprintf(pctx, ...) av_log(pctx, AV_LOG_DEBUG, __VA_ARGS__)
120 #else
121 # define dprintf(pctx, ...)
122 #endif
123
124 #define av_abort() do { av_log(NULL, AV_LOG_ERROR, "Abort at %s:%d\n", __FILE__, __LINE__); abort(); } while (0)
125
126 /* math */
127
128 #if ARCH_X86
129 #define MASK_ABS(mask, level)\
130 __asm__ volatile(\
131 "cltd \n\t"\
132 "xorl %1, %0 \n\t"\
133 "subl %1, %0 \n\t"\
134 : "+a" (level), "=&d" (mask)\
135 );
136 #else
137 #define MASK_ABS(mask, level)\
138 mask = level >> 31;\
139 level = (level ^ mask) - mask;
140 #endif
141
142 /* avoid usage of dangerous/inappropriate system functions */
143 #undef malloc
144 #define malloc please_use_av_malloc
145 #undef free
146 #define free please_use_av_free
147 #undef realloc
148 #define realloc please_use_av_realloc
149 #undef time
150 #define time time_is_forbidden_due_to_security_issues
151 #undef rand
152 #define rand rand_is_forbidden_due_to_state_trashing_use_av_lfg_get
153 #undef srand
154 #define srand srand_is_forbidden_due_to_state_trashing_use_av_lfg_init
155 #undef random
156 #define random random_is_forbidden_due_to_state_trashing_use_av_lfg_get
157 #undef sprintf
158 #define sprintf sprintf_is_forbidden_due_to_security_issues_use_snprintf
159 #undef strcat
160 #define strcat strcat_is_forbidden_due_to_security_issues_use_av_strlcat
161 #undef exit
162 #define exit exit_is_forbidden
163 #ifndef LIBAVFORMAT_BUILD
164 #undef printf
165 #define printf please_use_av_log_instead_of_printf
166 #undef fprintf
167 #define fprintf please_use_av_log_instead_of_fprintf
168 #undef puts
169 #define puts please_use_av_log_instead_of_puts
170 #undef perror
171 #define perror please_use_av_log_instead_of_perror
172 #endif
173
174 #define FF_ALLOC_OR_GOTO(ctx, p, size, label)\
175 {\
176 p = av_malloc(size);\
177 if (p == NULL && (size) != 0) {\
178 av_log(ctx, AV_LOG_ERROR, "Cannot allocate memory.\n");\
179 goto label;\
180 }\
181 }
182
183 #define FF_ALLOCZ_OR_GOTO(ctx, p, size, label)\
184 {\
185 p = av_mallocz(size);\
186 if (p == NULL && (size) != 0) {\
187 av_log(ctx, AV_LOG_ERROR, "Cannot allocate memory.\n");\
188 goto label;\
189 }\
190 }
191
192 #include "libm.h"
193
194 /**
195 * Return NULL if CONFIG_SMALL is true, otherwise the argument
196 * without modification. Used to disable the definition of strings
197 * (for example AVCodec long_names).
198 */
199 #if CONFIG_SMALL
200 # define NULL_IF_CONFIG_SMALL(x) NULL
201 #else
202 # define NULL_IF_CONFIG_SMALL(x) x
203 #endif
204
205
206 /**
207 * Define a function with only the non-default version specified.
208 *
209 * On systems with ELF shared libraries, all symbols exported from
210 * FFmpeg libraries are tagged with the name and major version of the
211 * library to which they belong. If a function is moved from one
212 * library to another, a wrapper must be retained in the original
213 * location to preserve binary compatibility.
214 *
215 * Functions defined with this macro will never be used to resolve
216 * symbols by the build-time linker.
217 *
218 * @param type return type of function
219 * @param name name of function
220 * @param args argument list of function
221 * @param ver version tag to assign function
222 */
223 #if HAVE_SYMVER_ASM_LABEL
224 # define FF_SYMVER(type, name, args, ver) \
225 type ff_##name args __asm__ (EXTERN_PREFIX #name "@" ver); \
226 type ff_##name args
227 #elif HAVE_SYMVER_GNU_ASM
228 # define FF_SYMVER(type, name, args, ver) \
229 __asm__ (".symver ff_" #name "," EXTERN_PREFIX #name "@" ver); \
230 type ff_##name args; \
231 type ff_##name args
232 #endif
233
234 #endif /* AVUTIL_INTERNAL_H */