See readme.txt for a general introduction, copyright details, and information about how to install Allegro and link your program with it.
The available system ID codes will vary from one platform to another, but you will almost always want to pass SYSTEM_AUTODETECT. Alternatively, SYSTEM_NONE installs a stripped down version of Allegro that won't even try to touch your hardware or do anything platform specific: this can be useful for situations where you only want to manipulate memory bitmaps, such as the text mode datafile tools or the Windows GDI interfacing functions.
The `errno_ptr' and `atexit_ptr' parameters should point to the errno variable and atexit function from your libc: these are required because when Allegro is linked as a DLL, it doesn't have direct access to your local libc data. `atexit_ptr' may be NULL, in which case it is your responsibility to call allegro_exit() manually. Example:
      install_allegro(SYSTEM_AUTODETECT, &errno, atexit);Return value: This function returns zero on success and non-zero on failure (e.g. no system driver could be used). Note: in previous versions of Allegro this function would abort on error.
See also: allegro_init, allegro_exit, set_uformat, set_config_file.
See also: install_allegro, allegro_exit.
Examples using this: Available Allegro examples.
Note that after you call this function, other functions like destroy_bitmap() will most likely crash. This is a problem for C++ global destructors, which usually get called after atexit(), so don't put Allegro calls in them. You can write the destructor code in another method which you can manually call before your program exits, avoiding this problem.
See also: install_allegro, allegro_init, destroy_bitmap.
Examples using this: ex3d, exscn3d, exswitch, exxfade, exzbuf.
      int main(void)
      {
         allegro_init();
         /* more stuff goes here */
         ...
         return 0;
      }
      END_OF_MAIN()See also: Windows specifics, Unix specifics, MacOS X specifics, Differences between platforms.
Examples using this: Available Allegro examples.
      void abort_on_error(const char *message)
      {
         if (screen != NULL)
            set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
         allegro_message("%s.\nLast Allegro error `%s'\n",
                         message, allegro_error);
         exit(-1);
      }
      ...
         if (some_allegro_function() == ERROR_CODE)
            abort_on_error("Error calling some function!");See also: set_gfx_mode, install_sound.
Examples using this: Available Allegro examples.
      const int year = ALLEGRO_DATE / 10000;
      const int month = (ALLEGRO_DATE / 100) % 100;
      const int day = ALLEGRO_DATE % 100;
      allegro_message("Year %d, month %d, day %d\n",
         year, month, day);
      #define OSTYPE_LINUX       AL_ID('T','U','X',' ')See also: DAT_ID.
      /* Check if the current version is compatible with Allegro 4.2.0 */
      #if (MAKE_VERSION(4, 2, 0) <= MAKE_VERSION(ALLEGRO_VERSION, \
                         ALLEGRO_SUB_VERSION, ALLEGRO_WIP_VERSION))
         /* Allegro 4.2.0 compatibility */
      #else
         /* Work-around */
      #endifSee also: ALLEGRO_VERSION, ALLEGRO_SUB_VERSION, ALLEGRO_WIP_VERSION.
      OSTYPE_UNKNOWN    - unknown, or regular MSDOS
      OSTYPE_WIN3       - Windows 3.1 or earlier
      OSTYPE_WIN95      - Windows 95
      OSTYPE_WIN98      - Windows 98
      OSTYPE_WINME      - Windows ME
      OSTYPE_WINNT      - Windows NT
      OSTYPE_WIN2000    - Windows 2000
      OSTYPE_WINXP      - Windows XP
      OSTYPE_WIN2003    - Windows 2003
      OSTYPE_WINVISTA   - Windows Vista
      OSTYPE_OS2        - OS/2
      OSTYPE_WARP       - OS/2 Warp 3
      OSTYPE_DOSEMU     - Linux DOSEMU
      OSTYPE_OPENDOS    - Caldera OpenDOS
      OSTYPE_LINUX      - Linux
      OSTYPE_SUNOS      - SunOS/Solaris
      OSTYPE_FREEBSD    - FreeBSD
      OSTYPE_NETBSD     - NetBSD
      OSTYPE_IRIX       - IRIX
      OSTYPE_DARWIN     - Darwin
      OSTYPE_QNX        - QNX
      OSTYPE_UNIX       - Unknown Unix variant
      OSTYPE_BEOS       - BeOS
      OSTYPE_MACOS      - MacOS
      OSTYPE_MACOSX     - MacOS XSee also: allegro_init, os_version, os_multitasking.
See also: os_type, os_multitasking.
See also: os_type, os_version.
On platforms featuring a windowing system, it will bring up a blocking GUI message box. If there is no windowing system, it will try to print the string to a text console, attempting to work around codepage differences by reducing any accented characters to 7-bit ASCII approximations. Example:
      if (allegro_init() != 0)
         exit(1);
      if (init_my_data() != 0) {
         allegro_message("Sorry, missing game data!\n");
         exit(2);
      }See also: allegro_init, install_allegro, set_uformat.
Examples using this: Available Allegro examples.
      set_window_title("Allegro rules!");See also: set_close_button_callback, set_uformat.
Examples using this: exunicod.
This function should not generally attempt to exit the program or save any data itself. The function could be called at any time, and there is usually a risk of conflict with the main thread of the program. Instead, you should set a flag during this function, and test it on a regular basis in the main loop of the program.
Pass NULL as the `proc' argument to this function to disable the close button functionality, which is the default state.
Note that Allegro cannot intercept the close button of a DOS box in Windows.
Also note that the supplied callback is also called under MacOS X when the user hits Command-Q or selects "Quit" from the application menu. Example:
      volatile int close_button_pressed = FALSE;
      void close_button_handler(void)
      {
         close_button_pressed = TRUE;
      }
      END_OF_FUNCTION(close_button_handler)
      ...
      
      allegro_init();
      LOCK_FUNCTION(close_button_handler);
      set_close_button_callback(close_button_handler);
      ...
         
      while (!close_button_pressed)
         do_stuff();Return value: Returns zero on success and non-zero on failure (e.g. the feature is not supported by the platform).
See also: set_window_title.
Under some OSes, switching to a full screen graphics mode may automatically change the desktop color depth. You have, therefore, to call this function before setting any graphics mode in order to retrieve the real desktop color depth. Example:
      allegro_init();
      ...
      if ((depth = desktop_color_depth()) != 0) {
         set_color_depth(depth);
      }Return value: Returns the color depth or zero on platforms where this information is not available or does not apply.
See also: get_desktop_resolution, set_color_depth, set_gfx_mode.
Under some OSes, switching to a full screen graphics mode may automatically change the desktop resolution. You have, therefore, to call this function before setting any graphics mode in order to retrieve the real desktop resolution. Example:
      int width, height;
      
      allegro_init();
      ...
      if (get_desktop_resolution(&width, &height) == 0) {
         /* Got the resolution correctly */
      }Return value: Returns zero on success, or a negative number if this information is not available or does not apply, in which case the values stored in the variables you provided for `width' and `height' are undefined.
See also: desktop_color_depth, set_gfx_mode.
See also: cpu_vendor, cpu_family, cpu_model, cpu_capabilities, allegro_init.
See also: check_cpu, cpu_family, cpu_model, cpu_capabilities, allegro_init.
      CPU_FAMILY_UNKNOWN  - The type of processor is unknown
      CPU_FAMILY_I386     - The processor is an Intel-compatible 386
      CPU_FAMILY_I486     - The processor is an Intel-compatible 486
      CPU_FAMILY_I586     - The processor is a Pentium or equivalent
      CPU_FAMILY_I686     - The processor is a Pentium Pro, II, III
                            or equivalent
      CPU_FAMILY_ITANIUM  - The processor is an Itanium processor
      CPU_FAMILY_POWERPC  - The processor is a PowerPC processor
      CPU_FAMILY_EXTENDED - The processor type needs to be read
                            from the cpu_model
See also: check_cpu, cpu_vendor, cpu_model, cpu_capabilities, allegro_init.
      CPU_FAMILY_I586:
         CPU_MODEL_PENTIUM, CPU_MODEL_K5, CPU_MODEL_K6
      CPU_FAMILY_I686:
         CPU_MODEL_PENTIUMPRO, CPU_MODEL_PENTIUMII,
         CPU_MODEL_PENTIUMIIIKATMAI, CPU_MODEL_PENTIUMIIICOPPERMINE,
         CPU_MODEL_ATHLON, CPU_MODEL_DURON
      CPU_FAMILY_EXTENDED:
         CPU_MODEL_PENTIUMIV, CPU_MODEL_XEON,
         CPU_MODEL_ATHLON64, CPU_MODEL_OPTERON
      CPU_FAMILY_POWERPC:
         CPU_MODEL_POWERPC_x, for x=601-604, 620, 750, 7400, 7450
See also: check_cpu, cpu_vendor, cpu_family, cpu_capabilities, allegro_init.
      CPU_ID       - Indicates that the "cpuid" instruction is
                     available. If this is set, then all Allegro CPU
                     variables are 100% reliable, otherwise there
                     may be some mistakes.
      CPU_FPU      - An FPU is available.
      CPU_IA64     - Running on Intel 64 bit CPU
      CPU_AMD64    - Running on AMD 64 bit CPU
      CPU_MMX      - Intel MMX  instruction set is available.
      CPU_MMXPLUS  - Intel MMX+ instruction set is available.
      CPU_SSE      - Intel SSE  instruction set is available.
      CPU_SSE2     - Intel SSE2 instruction set is available.
      CPU_SSE3     - Intel SSE3 instruction set is available.
      CPU_3DNOW    - AMD 3DNow! instruction set is available.
      CPU_ENH3DNOW - AMD Enhanced 3DNow! instruction set is
                     available.
      CPU_CMOV     - Pentium Pro "cmov" instruction is available.
      if ((cpu_capabilities & (CPU_FPU | CPU_MMX)) ==
          (CPU_FPU | CPU_MMX)) {
         printf("CPU has both an FPU and MMX instructions!\n");
      }
See also: check_cpu, cpu_vendor, cpu_family, cpu_model, cpu_capabilities, allegro_init.