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compiler-macros.h
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1 /****************************************************************************
2  *
3  * internal/compiler-macros.h
4  *
5  * Compiler-specific macro definitions used internally by FreeType.
6  *
7  * Copyright (C) 2020 by
8  * David Turner, Robert Wilhelm, and Werner Lemberg.
9  *
10  * This file is part of the FreeType project, and may only be used,
11  * modified, and distributed under the terms of the FreeType project
12  * license, LICENSE.TXT. By continuing to use, modify, or distribute
13  * this file you indicate that you have read the license and
14  * understand and accept it fully.
15  *
16  */
17 
18 #ifndef INTERNAL_COMPILER_MACROS_H_
19 #define INTERNAL_COMPILER_MACROS_H_
20 
21 #include <freetype/config/public-macros.h>
22 
24 
25  /* Fix compiler warning with sgi compiler. */
26 #if defined( __sgi ) && !defined( __GNUC__ )
27 # if defined( _COMPILER_VERSION ) && ( _COMPILER_VERSION >= 730 )
28 # pragma set woff 3505
29 # endif
30 #endif
31 
32  /* Fix compiler warning with sgi compiler. */
33 #if defined( __sgi ) && !defined( __GNUC__ )
34 # if defined( _COMPILER_VERSION ) && ( _COMPILER_VERSION >= 730 )
35 # pragma set woff 3505
36 # endif
37 #endif
38 
39  /*
40  * When defining a macro that expands to a non-trivial C statement, use
41  * FT_BEGIN_STMNT and FT_END_STMNT to enclose the macro's body. This
42  * ensures there are no surprises when the macro is invoked in conditional
43  * branches.
44  *
45  * Example:
46  *
47  * #define LOG( ... ) \
48  * FT_BEGIN_STMNT \
49  * if ( logging_enabled ) \
50  * log( __VA_ARGS__ ); \
51  * FT_END_STMNT
52  */
53 #define FT_BEGIN_STMNT do {
54 #define FT_END_STMNT } while ( 0 )
55 
56  /*
57  * FT_DUMMY_STMNT expands to an empty C statement. Useful for
58  * conditionally defined statement macros.
59  *
60  * Example:
61  *
62  * #ifdef BUILD_CONFIG_LOGGING
63  * #define LOG( ... ) \
64  * FT_BEGIN_STMNT \
65  * if ( logging_enabled ) \
66  * log( __VA_ARGS__ ); \
67  * FT_END_STMNT
68  * #else
69  * # define LOG( ... ) FT_DUMMY_STMNT
70  * #endif
71  */
72 #define FT_DUMMY_STMNT FT_BEGIN_STMNT FT_END_STMNT
73 
74 #ifdef _WIN64
75  /* only 64bit Windows uses the LLP64 data model, i.e., */
76  /* 32-bit integers, 64-bit pointers. */
77 #define FT_UINT_TO_POINTER( x ) (void *)(unsigned __int64)(x)
78 #else
79 #define FT_UINT_TO_POINTER( x ) (void *)(unsigned long)(x)
80 #endif
81 
82  /*
83  * Use `FT_TYPEOF( type )` to cast a value to `type`. This is useful to
84  * suppress signedness compilation warnings in macros.
85  *
86  * Example:
87  *
88  * #define PAD_( x, n ) ( (x) & ~FT_TYPEOF( x )( (n) - 1 ) )
89  *
90  * (The `typeof` condition is taken from gnulib's `intprops.h` header
91  * file.)
92  */
93 #if ( ( defined( __GNUC__ ) && __GNUC__ >= 2 ) || \
94  ( defined( __IBMC__ ) && __IBMC__ >= 1210 && \
95  defined( __IBM__TYPEOF__ ) ) || \
96  ( defined( __SUNPRO_C ) && __SUNPRO_C >= 0x5110 && !__STDC__ ) )
97 #define FT_TYPEOF( type ) ( __typeof__ ( type ) )
98 #else
99 #define FT_TYPEOF( type ) /* empty */
100 #endif
101 
102  /*
103  * Mark a function declaration as internal to the library. This ensures
104  * that it will not be exposed by default to client code, and helps
105  * generate smaller and faster code on ELF-based platforms. Place this
106  * before a function declaration.
107  */
108 
109  /* Visual C, mingw */
110 #if defined( _WIN32 )
111 #define FT_INTERNAL_FUNCTION_ATTRIBUTE /* empty */
112 
113  /* gcc, clang */
114 #elif ( defined( __GNUC__ ) && __GNUC__ >= 4 ) || defined( __clang__ )
115 #define FT_INTERNAL_FUNCTION_ATTRIBUTE \
116  __attribute__(( visibility( "hidden" ) ))
117 
118  /* Sun */
119 #elif defined( __SUNPRO_C ) && __SUNPRO_C >= 0x550
120 #define FT_INTERNAL_FUNCTION_ATTRIBUTE __hidden
121 
122 #else
123 #define FT_INTERNAL_FUNCTION_ATTRIBUTE /* empty */
124 #endif
125 
126  /*
127  * FreeType supports compilation of its C sources with a C++ compiler (in
128  * C++ mode); this introduces a number of subtle issues.
129  *
130  * The main one is that a C++ function declaration and its definition must
131  * have the same 'linkage'. Because all FreeType headers declare their
132  * functions with C linkage (i.e., within an `extern "C" { ... }` block
133  * due to the magic of FT_BEGIN_HEADER and FT_END_HEADER), their
134  * definition in FreeType sources should also be prefixed with `extern
135  * "C"` when compiled in C++ mode.
136  *
137  * The `FT_FUNCTION_DECLARATION` and `FT_FUNCTION_DEFINITION` macros are
138  * provided to deal with this case, as well as `FT_CALLBACK_DEF` and its
139  * siblings below.
140  */
141 
142  /*
143  * `FT_FUNCTION_DECLARATION( type )` can be used to write a C function
144  * declaration to ensure it will have C linkage when the library is built
145  * with a C++ compiler. The parameter is the function's return type, so a
146  * declaration would look like
147  *
148  * FT_FUNCTION_DECLARATION( int )
149  * foo( int x );
150  *
151  * NOTE: This requires that all uses are inside of `FT_BEGIN_HEADER ...
152  * FT_END_HEADER` blocks, which guarantees that the declarations have C
153  * linkage when the headers are included by C++ sources.
154  *
155  * NOTE: Do not use directly. Use `FT_LOCAL`, `FT_BASE`, and `FT_EXPORT`
156  * instead.
157  */
158 #define FT_FUNCTION_DECLARATION( x ) extern x
159 
160  /*
161  * Same as `FT_FUNCTION_DECLARATION`, but for function definitions instead.
162  *
163  * NOTE: Do not use directly. Use `FT_LOCAL_DEF`, `FT_BASE_DEF`, and
164  * `FT_EXPORT_DEF` instead.
165  */
166 #ifdef __cplusplus
167 #define FT_FUNCTION_DEFINITION( x ) extern "C" x
168 #else
169 #define FT_FUNCTION_DEFINITION( x ) x
170 #endif
171 
172  /*
173  * Use `FT_LOCAL` and `FT_LOCAL_DEF` to declare and define, respectively,
174  * an internal FreeType function that is only used by the sources of a
175  * single `src/module/` directory. This ensures that the functions are
176  * turned into static ones at build time, resulting in smaller and faster
177  * code.
178  */
179 #ifdef FT_MAKE_OPTION_SINGLE_OBJECT
180 
181 #define FT_LOCAL( x ) static x
182 #define FT_LOCAL_DEF( x ) static x
183 
184 #else
185 
186 #define FT_LOCAL( x ) FT_INTERNAL_FUNCTION_ATTRIBUTE \
187  FT_FUNCTION_DECLARATION( x )
188 #define FT_LOCAL_DEF( x ) FT_FUNCTION_DEFINITION( x )
189 
190 #endif /* FT_MAKE_OPTION_SINGLE_OBJECT */
191 
192  /*
193  * Use `FT_LOCAL_ARRAY` and `FT_LOCAL_ARRAY_DEF` to declare and define,
194  * respectively, a constant array that must be accessed from several
195  * sources in the same `src/module/` sub-directory, and which are internal
196  * to the library.
197  */
198 #define FT_LOCAL_ARRAY( x ) FT_INTERNAL_FUNCTION_ATTRIBUTE \
199  extern const x
200 #define FT_LOCAL_ARRAY_DEF( x ) FT_FUNCTION_DEFINITION( const x )
201 
202  /*
203  * `Use FT_BASE` and `FT_BASE_DEF` to declare and define, respectively, an
204  * internal library function that is used by more than a single module.
205  */
206 #define FT_BASE( x ) FT_INTERNAL_FUNCTION_ATTRIBUTE \
207  FT_FUNCTION_DECLARATION( x )
208 #define FT_BASE_DEF( x ) FT_FUNCTION_DEFINITION( x )
209 
210 
211  /*
212  * NOTE: Conditionally define `FT_EXPORT_VAR` due to its definition in
213  * `src/smooth/ftgrays.h` to make the header more portable.
214  */
215 #ifndef FT_EXPORT_VAR
216 #define FT_EXPORT_VAR( x ) FT_FUNCTION_DECLARATION( x )
217 #endif
218 
219  /* When compiling FreeType as a DLL or DSO with hidden visibility, */
220  /* some systems/compilers need a special attribute in front OR after */
221  /* the return type of function declarations. */
222  /* */
223  /* Two macros are used within the FreeType source code to define */
224  /* exported library functions: `FT_EXPORT` and `FT_EXPORT_DEF`. */
225  /* */
226  /* - `FT_EXPORT( return_type )` */
227  /* */
228  /* is used in a function declaration, as in */
229  /* */
230  /* ``` */
231  /* FT_EXPORT( FT_Error ) */
232  /* FT_Init_FreeType( FT_Library* alibrary ); */
233  /* ``` */
234  /* */
235  /* - `FT_EXPORT_DEF( return_type )` */
236  /* */
237  /* is used in a function definition, as in */
238  /* */
239  /* ``` */
240  /* FT_EXPORT_DEF( FT_Error ) */
241  /* FT_Init_FreeType( FT_Library* alibrary ) */
242  /* { */
243  /* ... some code ... */
244  /* return FT_Err_Ok; */
245  /* } */
246  /* ``` */
247  /* */
248  /* You can provide your own implementation of `FT_EXPORT` and */
249  /* `FT_EXPORT_DEF` here if you want. */
250  /* */
251  /* To export a variable, use `FT_EXPORT_VAR`. */
252  /* */
253 
254  /* See `freetype/config/compiler_macros.h` for the `FT_EXPORT` definition */
255 #define FT_EXPORT_DEF( x ) FT_FUNCTION_DEFINITION( x )
256 
257  /* The following macros are needed to compile the library with a */
258  /* C++ compiler and with 16bit compilers. */
259  /* */
260 
261  /* This is special. Within C++, you must specify `extern "C"` for */
262  /* functions which are used via function pointers, and you also */
263  /* must do that for structures which contain function pointers to */
264  /* assure C linkage -- it's not possible to have (local) anonymous */
265  /* functions which are accessed by (global) function pointers. */
266  /* */
267  /* */
268  /* FT_CALLBACK_DEF is used to _define_ a callback function, */
269  /* located in the same source code file as the structure that uses */
270  /* it. */
271  /* */
272  /* FT_BASE_CALLBACK and FT_BASE_CALLBACK_DEF are used to declare */
273  /* and define a callback function, respectively, in a similar way */
274  /* as FT_BASE and FT_BASE_DEF work. */
275  /* */
276  /* FT_CALLBACK_TABLE is used to _declare_ a constant variable that */
277  /* contains pointers to callback functions. */
278  /* */
279  /* FT_CALLBACK_TABLE_DEF is used to _define_ a constant variable */
280  /* that contains pointers to callback functions. */
281  /* */
282  /* */
283  /* Some 16bit compilers have to redefine these macros to insert */
284  /* the infamous `_cdecl` or `__fastcall` declarations. */
285  /* */
286 #ifdef __cplusplus
287 #define FT_CALLBACK_DEF( x ) extern "C" x
288 #else
289 #define FT_CALLBACK_DEF( x ) static x
290 #endif
291 
292 #define FT_BASE_CALLBACK( x ) FT_FUNCTION_DECLARATION( x )
293 #define FT_BASE_CALLBACK_DEF( x ) FT_FUNCTION_DEFINITION( x )
294 
295 #ifndef FT_CALLBACK_TABLE
296 #ifdef __cplusplus
297 #define FT_CALLBACK_TABLE extern "C"
298 #define FT_CALLBACK_TABLE_DEF extern "C"
299 #else
300 #define FT_CALLBACK_TABLE extern
301 #define FT_CALLBACK_TABLE_DEF /* nothing */
302 #endif
303 #endif /* FT_CALLBACK_TABLE */
304 
306 
307 #endif /* INTERNAL_COMPILER_MACROS_H_ */
#define FT_END_HEADER
Definition: ftheader.h:57