include/asterisk/inline_api.h

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 1999 - 2005, Digium, Inc.
   5  *
   6  * Kevin P. Fleming <kpfleming@digium.com>
   7  *
   8  * See http://www.asterisk.org for more information about
   9  * the Asterisk project. Please do not directly contact
  10  * any of the maintainers of this project for assistance;
  11  * the project provides a web site, mailing lists and IRC
  12  * channels for your use.
  13  *
  14  * This program is free software, distributed under the terms of
  15  * the GNU General Public License Version 2. See the LICENSE file
  16  * at the top of the source tree.
  17  */
  18
  19 #ifndef __ASTERISK_INLINEAPI_H
  20 #define __ASTERISK_INLINEAPI_H
  21
  22 /*! \file
  23  * \brief Inlinable API function macro
  24
  25   Small API functions that are candidates for inlining need to be specially
  26   declared and defined, to ensure that the 'right thing' always happens.
  27   For example:
  28         - there must _always_ be a non-inlined version of the function
  29         available for modules compiled out of the tree to link to
  30         - references to a function that cannot be inlined (for any
  31         reason that the compiler deems proper) must devolve into an
  32         'extern' reference, instead of 'static', so that multiple
  33         copies of the function body are not built in different modules
  34         - when LOW_MEMORY is defined, inlining should be disabled
  35         completely, even if the compiler is configured to support it
  36
  37   The AST_INLINE_API macro allows this to happen automatically, when
  38   used to define your function. Proper usage is as follows:
  39   - define your function one place, in a header file, using the macro
  40   to wrap the function (see strings.h or time.h for examples)
  41   - choose a module to 'host' the function body for non-inline
  42   usages, and in that module _only_, define AST_API_MODULE before
  43   including the header file
  44  */
  45
  46 #if !defined(LOW_MEMORY)
  47
  48 #if !defined(AST_API_MODULE)
  49 #define AST_INLINE_API(hdr, body) hdr; extern inline hdr body
  50 #else
  51 #define AST_INLINE_API(hdr, body) hdr; hdr body
  52 #endif
  53
  54 #else /* defined(LOW_MEMORY) */
  55
  56 #if !defined(AST_API_MODULE)
  57 #define AST_INLINE_API(hdr, body) hdr;
  58 #else
  59 #define AST_INLINE_API(hdr, body) hdr; hdr body
  60 #endif
  61
  62 #endif
  63
  64 #undef AST_API_MODULE
  65
  66 #endif /* __ASTERISK_INLINEAPI_H */