Allegro Manual: Configuration routines

# Configuration routines

- config_is_hooked — Tells if a config section has custom hooks.
- flush_config_file — Flushes the current config file to disk.
- free_config_entries — Frees memory allocated for config entry lists.
- get_config_argv — Reads a token list from the configuration file.
- get_config_float — Retrieves a float from the configuration file.
- get_config_hex — Retrieves a hexadecimal value from the configuration file.
- get_config_id — Retrieves a driver ID from a configuration file.
- get_config_int — Retrieves an integer from the configuration file.
- get_config_string — Retrieves a string from the configuration file.
- get_config_text — Returns a string translated to the current language.
- hook_config_section — Hooks a configuration file section with custom handlers.
- list_config_entries — Lists the names of all entries in a config section
- list_config_sections — Lists the names of all sections available in the current configuration.
- override_config_data — Specifies a block of data containing config overrides.
- override_config_file — Specifies a file containing config overrides.
- pop_config_state — Pops a previously pushed configuration state.
- push_config_state — Pushes the current configuration state.
- reload_config_texts — Reloads translated strings returned by get_config_text().
- set_config_data — Sets a block of configuration data.
- set_config_file — Sets the configuration file.
- set_config_float — Writes a float in the configuration file.
- set_config_hex — Writes a hexadecimal integer in the configuration file.
- set_config_id — Writes a driver ID in the configuration file.
- set_config_int — Writes an integer in the configuration file.
- set_config_string — Writes a string in the configuration file.

Various parts of Allegro, such as the sound routines and the load_joystick_data() function, require some configuration information. This data is stored in text files as a collection of ``variable=value'` lines, along with comments that begin with a `#' character and continue to the end of the line. The configuration file may optionally be divided into sections, which begin with a ``[sectionname]'` line. Each section has a unique namespace, to prevent variable name conflicts, but any variables that aren't in a section are considered to belong to all the sections simultaneously.

Note that variable and section names cannot contain spaces.

By default the configuration data is read from a file called ``allegro.cfg'`, which can be located either in the same directory as the program executable, or the directory pointed to by the ALLEGRO environment variable. Under Unix, it also checks for `~/allegro.cfg', `~/.allegrorc', ``/etc/allegro.cfg'`, and ``/etc/allegrorc'`, in that order; under BeOS only the last two are also checked. MacOS X also checks in the Contents/Resources directory of the application bundle, if any, before doing the checks above.

If you don't like this approach, you can specify any filename you like, or use a block of binary configuration data provided by your program (which could for example be loaded from a datafile). You can also extend the paths searched for allegro resources with set_allegro_resource_path().

You can store whatever custom information you like in the config file, along with the standard variables that are used by Allegro (see below). Allegro comes with a setup directory where you can find configuration programs. The standalone setup program is likely to be of interest to final users. It allows any user to create an ``allegro.cfg'` file without the need to touch a text editor and enter values by hand. It also provides a few basic tests like sound playing for sound card testing. You are welcome to include the setup program with your game, either as is or with modified graphics to fit better your game.

void set_config_file(const char *filename);
Sets the configuration file to be used by all subsequent config functions. (Allegro will not search for this file in other locations as it does with allegro.cfg at the time of initialization.)

All pointers returned by previous calls to get_config_string() and other related functions are invalidated when you call this function! You can call this function before install_allegro() to change the configuration file, but after set_uformat() if you want to use a text encoding format other than the default.

> See also: set_config_data, override_config_file, push_config_state, set_uformat, Standard config variables, set_config_string, get_config_string.

> Examples using this: exconfig.

void set_config_data(const char *data, int length);
Specifies a block of data to be used by all subsequent config functions, which you have already loaded from disk (eg. as part of some more complicated format of your own, or in a grabber datafile). This routine makes a copy of the information, so you can safely free the data after calling it.

> See also: set_config_file, override_config_data, push_config_state, Standard config variables, set_config_string, get_config_string.

void override_config_file(const char *filename);
Specifies a file containing config overrides. These settings will be used in addition to the parameters in the main config file, and where a variable is present in both files this version will take priority. This can be used by application programmers to override some of the config settings from their code, while still leaving the main config file free for the end user to customise. For example, you could specify a particular sample frequency and IBK instrument file, but the user could still use an ``allegro.cfg'` file to specify the port settings and irq numbers.

The override config file will not only take precedence when reading, but will also be used for storing values. When you are done with using the override config file, you can call override_config_file with a NULL parameter, so config data will be directly read from the current config file again.

Note: The override file is completely independent from the current configuration. You can e.g. call set_config_file, and the override file will still be active. Also the flush_config_file function will only affect the current config file (which can be changed with set_config_file), never the overriding one specified with this function. The modified override config is written back to disk whenever you call override_config_file.

Example:

>           override_config_file("my.cfg");
>           /* This will read from my.cfg, and if it doesn't find a
>            * setting, will read from the current config file instead.
>            */
>           language = get_config_string("system", "language", NULL);
>           /* This will always write to my.cfg, no matter if the
>            * settings is already present or not.
>            */
>           set_config_string("system", "language", "RU");
>           /* This forces the changed setting to be written back to
>            * disk. Else it is written back at the next call to
>            * override_config_file, or when Allegro shuts down.
>            */
>           override_config_file(NULL);

Note that this function and override_config_data() are mutually exclusive, i.e. calling one will cancel the effects of the other.

> See also: override_config_data, set_config_file.

void override_config_data(const char *data, int length);
Version of override_config_file() which uses a block of data that has already been read into memory. The length of the block has to be specified in bytes. Example:

>           /* Force German as system language, Spanish keyboard map. */
>           const char *override_data = "[system]\n"
>              "language=DE\n"
>              "keyboard=ES";
>           override_config_data(override_data, ustrsize(override_data));

Note that this function and override_config_file() are mutually exclusive, i.e. calling one will cancel the effects of the other.

> See also: override_config_file, set_config_data.

void push_config_state();
Pushes the current configuration state (filename, variable values, etc). onto an internal stack, allowing you to select some other config source and later restore the current settings by calling pop_config_state(). This function is mostly intended for internal use by other library functions, for example when you specify a config filename to the save_joystick_data() function, it pushes the config state before switching to the file you specified.

> See also: pop_config_state, set_config_file, save_joystick_data.

> Examples using this: exconfig.

void pop_config_state();
Pops a configuration state previously stored by push_config_state(), replacing the current config source with it.

> See also: push_config_state.

> Examples using this: exconfig.

void flush_config_file();
Writes the current config file to disk if the contents have changed since it was loaded or since the latest call to the function.

> See also: set_config_file, override_config_file, push_config_state.

void reload_config_texts(const char *new_language);
Reloads the translated strings returned by get_config_text(). This is useful to switch to another language in your program at runtime. If you want to modify the ``[system]'` language configuration variable yourself, or you have switched configuration files, you will want to pass NULL to just reload whatever language is currently selected. Or you can pass a string containing the two letter code of the language you desire to switch to, and the function will modify the language variable. After you call this function, the previously returned pointers of get_config_text() will be invalid. Example:

>           ...
>           /* The user selects French from a language choice menu. */
>           reload_config_texts("FR");

> See also: get_config_text, get_config_string, Standard config variables.

void hook_config_section(const char *section, int (*intgetter)(const char *name, int def), const char *(*stringgetter)(const char *name, const char *def), void (*stringsetter)(const char *name, const char *value));
Takes control of the specified config file section, so that your hook functions will be used to manipulate it instead of the normal disk file access. If both the getter and setter functions are NULL, a currently present hook will be unhooked. Hooked functions have the highest priority. If a section is hooked, the hook will always be called, so you can also hook a '#' section: even override_config_file() cannot override a hooked section. Example:

>           int decode_encrypted_int(const char *name, int def)
>           {
>              ...
>           }

>           const char *decode_encrypted_string(const char *name, const char *def)
>           {
>              ...
>           }

>           void encode_plaintext_string(const char *name, const char *value)
>           {
>              ...
>           }

>           int main(int argc, char *argv[])
>           {
>              ...
>              /* Make it harder for users to tinker with the high scores. */
>              hook_config_section("high_scores", decode_encrypted_int,
>                 decode_encrypted_string, encode_plaintext_string);
>              ...
>           } END_OF_MAIN()

> See also: config_is_hooked.

int config_is_hooked(const char *section);
Returns TRUE if the specified config section has been hooked. Example:

>           if (config_is_hooked("high_scores")) {
>              hook_config_section("high_scores, NULL, NULL, NULL);
>           }

> See also: hook_config_section.

const char *get_config_string(const char *section, const char *name, const char *def);
Retrieves a string variable from the current config file. The section name may be set to NULL to read variables from the root of the file, or used to control which set of parameters (eg. sound or joystick) you are interested in reading. Example:

>           const char *lang = get_config_string("system", "language", "EN");

Return value: Returns a pointer to the constant string found in the configuration file. If the named variable cannot be found, or its entry in the config file is empty, the value of ``def'` is returned.

> See also: set_config_file, set_config_string, get_config_argv, get_config_float, get_config_hex, get_config_int, get_config_id, get_config_text.

> Examples using this: exconfig.

int get_config_int(const char *section, const char *name, int def);
Reads an integer variable from the current config file. See the comments about get_config_string().

> See also: set_config_file, set_config_int, get_config_string, get_config_argv, get_config_float, get_config_hex, get_config_id.

> Examples using this: exconfig.

int get_config_hex(const char *section, const char *name, int def);
Reads an integer variable from the current config file, in hexadecimal format. See the comments about get_config_string().

> See also: set_config_file, set_config_hex, get_config_string, get_config_argv, get_config_float, get_config_int, get_config_id.

float get_config_float(const char *section, const char *name, float def);
Reads a floating point variable from the current config file. See the comments about get_config_string().

> See also: set_config_file, set_config_float, get_config_string, get_config_argv, get_config_hex, get_config_int, get_config_id.

int get_config_id(const char *section, const char *name, int def);
Reads a 4-letter driver ID variable from the current config file. See the comments about get_config_string().

> See also: set_config_file, set_config_id, get_config_string, get_config_argv, get_config_float, get_config_hex, get_config_int.

char **get_config_argv(const char *section, const char *name, int *argc);
Reads a token list (words separated by spaces) from the current config file. The token list is stored in a temporary buffer that will be clobbered by the next call to get_config_argv(), so the data should not be expected to persist.

Return value: Returns an argv style argument list and sets ``argc'` to the number of retrieved tokens. If the variable is not present, returns NULL and sets argc to zero.

> See also: set_config_file, get_config_string, get_config_float, get_config_hex, get_config_int, get_config_id.

> Examples using this: exconfig.

const char *get_config_text(const char *msg);
This function is primarily intended for use by internal library code, but it may perhaps be helpful to application programmers as well. It uses the ``language.dat'` or ``XXtext.cfg'` files (where XX is a language code) to look up a translated version of the parameter in the currently selected language.

This is basically the same thing as calling get_config_string() with ``[language]'` as the section, ``msg'` as the variable name, and ``msg'` as the default value, but it contains some special code to handle Unicode format conversions. The ``msg'` parameter is always given in ASCII format, but the returned string will be converted into the current text encoding, with memory being allocated as required, so you can assume that this pointer will persist without having to manually allocate storage space for each string.

Note that if you are planning on distributing your game on the Unix platform there is a special issue with how to deal with the ``language.dat'` file. Read section "Files shared by Allegro" of the chapter "Unix specifics" to learn more about this.

Return value: Returns a suitable translation if one can be found or a copy of the parameter if nothing else is available.

> See also: get_config_string, reload_config_texts, Standard config variables.

void set_config_string(const char *section, const char *name, const char *val);
Writes a string variable to the current config file, replacing any existing value it may have, or removes the variable if ``val'` is NULL. The section name may be set to NULL to write the variable to the root of the file, or used to control which section the variable is inserted into. The altered file will be cached in memory, and not actually written to disk until you call allegro_exit(). Note that you can only write to files in this way, so the function will have no effect if the current config source was specified with set_config_data() rather than set_config_file().

As a special case, variable or section names that begin with a '#' character are treated specially and will not be read from or written to the disk. Addon packages can use this to store version info or other status information into the config module, from where it can be read with the get_config_string() function.

> See also: set_config_file, get_config_string, set_config_float, set_config_hex, set_config_int, set_config_id.

void set_config_int(const char *section, const char *name, int val);
Writes an integer variable to the current config file. See the comments about set_config_string().

> See also: set_config_file, get_config_int, set_config_string, set_config_float, set_config_hex, set_config_id.

void set_config_hex(const char *section, const char *name, int val);
Writes an integer variable to the current config file, in hexadecimal format. See the comments about set_config_string().

> See also: set_config_file, get_config_hex, set_config_string, set_config_float, set_config_int, set_config_id.

void set_config_float(const char *section, const char *name, float val);
Writes a floating point variable to the current config file. See the comments about set_config_string().

> See also: set_config_file, get_config_float, set_config_string, set_config_hex, set_config_int, set_config_id.

void set_config_id(const char *section, const char *name, int val);
Writes a 4-letter driver ID variable to the current config file. See the comments about set_config_string().

> See also: set_config_file, get_config_id, set_config_string, set_config_float, set_config_hex, set_config_int.

int list_config_entries(const char *section, const char ***names);
This function can be used to get a list of all entries in the given config section. The names parameter is a pointer to an array of strings. If it points to a NULL pointer, the list will be allocated, else it will be re-allocated. You should free the list again with free_config_entries if you don't need it anymore, or you can pass it again to list_config_entries and the memory will be re-used. See the following example for how you can use it, it will print out the complete contents of the current configuration:

>        int i, n;
>        char const **sections = NULL;
>        char const **entries = NULL;

>        /* List all entries not in any section. */
>        n = list_config_entries(NULL, &entries);
>        for (i = 0; i < n; i++)
>           printf(" %s=\"%s\"\n", entries[i], get_config_string(
>                  NULL, entries[i], "-"));

>        /* List all sections (and entries in them). */
>        n = list_config_sections(&sections);
>        /* loop through all section names */
>        for (i = 0; i < n; i++)
>        {
>           int j, m;
>           printf("%s\n", sections[i]);
>           m = list_config_entries(sections[i], &entries);
>           /* loop through all entries in the section */
>           for (j = 0; j < m; j++)
>           {
>               printf(" %s=\"%s\"\n", entries[j], get_config_string(
>                  sections[i], entries[j], "-"));
>           }
>        }
>        /* It is enough to free the arrays once at the end. */
>        free_config_entries(&sections);
>        free_config_entries(&entries);

Return value: Returns the number of valid strings in the names array.

> See also: set_config_file, get_config_string, list_config_sections, free_config_entries.

int list_config_sections(const char ***names);
The names parameter is a pointer to an array of strings. If it points to a NULL pointer, the list will be allocated, else it will be re-allocated. After the function returns, it will contain the names of all sections in the current configuration. Use free_config_entries to free the allocated memory again. See list_config_entries for more information and an example how to use it.

Return value: Returns the number of valid strings in the names array.

> See also: list_config_entries, set_config_file, get_config_string, free_config_entries.

int free_config_entries(const char ***names);

Once you are done with the string arrays filled in by list_config_entries and list_config_sections, you can free them again with this function. The passed array pointer will be set to NULL, and you directly can pass the same pointer again to list_config_entries or list_config_sections later - but you also could pass them again without freeing first, since the memory is re-allocated when the pointer is not NULL.

See list_config_entries for an example of how to use it.

> See also: list_config_entries, list_config_sections.

## Standard config variables

Allegro uses these standard variables from the configuration file:

- [system]
  Section containing general purpose variables:
  - system = x
    Specifies which system driver to use. This is currently only useful on Linux, for choosing between the X-Windows ("XWIN") or console ("LNXC") modes.
  - keyboard = x
    Specifies which keyboard layout to use. The parameter is the name of a keyboard mapping file produced by the keyconf utility, and can either be a fully qualified file path or a base name like ``us'` or ``uk'`. If the latter, Allegro will look first for a separate config file with that name (eg. ``uk.cfg'`) and then for an object with that name in the ``keyboard.dat'` file (eg. ``UK_CFG'`). The config file or ``keyboard.dat'` file can be stored in the same directory as the program, or in the location pointed to by the ALLEGRO environment variable. Look in the ``keyboard.dat'` file to see what mappings are currently available.
  - language = x
    Specifies which language file to use for error messages and other bits of system text. The parameter is the name of a translation file, and can either be a fully qualified file path or a base name like ``en'` or ``es'`. If the latter, Allegro will look first for a separate config file with a name in the form ``entext.cfg'`, and then for an object with that name in the ``language.dat'` file (eg. ``ENTEXT_CFG'`). The config file or ``language.dat'` file can be stored in the same directory as the program, or in the location pointed to by the ALLEGRO environment variable. Look in the ``language.dat'` file to see which mappings are currently available. If there is none for your language, you can create it using the English one as model, and even send it to the Allegro development team to include it in future releases.
  - disable_screensaver = x
    Specifies whether to disable the screensaver: 0 to never disable it, 1 to disable it in fullscreen mode only and 2 to always disable it. Default is 1.
  - menu_opening_delay = x
    Sets how long the menus take to auto-open. The time is given in milliseconds (default is ``300'`). Specifying `-1' will disable the auto-opening feature.
  - XInitThreads = x
    If this is set to 0, the X11 port will not call XInitThreads. This can have slight performance advantages and was required on some broken X11 servers, but it makes Allegro incompatible with other X11 libraries like Mesa.
- [graphics]
  Section containing graphics configuration information, using the variables:
  - gfx_card = x
    Specifies which graphics driver to use when the program requests GFX_AUTODETECT. Multiple possible drivers can be suggested with extra lines in the form `gfx_card1 = x', `gfx_card2 = x', etc, or you can specify different drivers for each mode and color depth with variables in the form `gfx_card_24bpp = x', `gfx_card_640x480x16 = x', etc.
  - gfx_cardw = x
    Specifies which graphics driver to use when the program requests GFX_AUTODETECT_WINDOWED. This variable functions exactly like gfx_card in all other respects. If it is not set, Allegro will look for the gfx_card variable.
  - disable_vsync = x
    Specifies whether to disable synchronization with the vertical blank when page-flipping (yes or no). Disabling synchronization may increase the frame rate on slow systems, at the expense of introducing flicker on fast systems.
  - vbeaf_driver = x
    DOS and Linux only: specifies where to look for the VBE/AF driver (vbeaf.drv). If this variable is not set, Allegro will look in the same directory as the program, and then fall back on the standard locations (``c:\'` for DOS, ``/usr/local/lib'`, ``/usr/lib'`, ``/lib'`, and ``/'` for Linux, or the directory specified with the VBEAF_PATH environment variable).
  - framebuffer = x
    Linux only: specifies what device file to use for the fbcon driver. If this variable is not set, Allegro checks the FRAMEBUFFER environment variable, and then defaults to ``/dev/fb0'`.
  - force_centering = x
    Unix/X11 only: specifies whether to force window centering in fullscreen mode when the XWFS driver is used (yes or no). Enabling this setting may cause some artifacts to appear on KDE desktops.
  - disable_direct_updating = x
    Windows only: specifies whether to disable direct updating when the GFX_DIRECTX_WIN driver is used in color conversion mode (yes or no). Direct updating can cause artifacts to be left on the desktop when the window is moved or minimized; disabling it results in a significant performance loss.
- [mouse]
  Section containing mouse configuration information, using the variables:
  - mouse = x
    Mouse driver type. Available DOS drivers are:

    >           MICK - mickey mode driver (normally the best)
    >           I33  - int 0x33 callback driver
    >           POLL - timer polling (for use under NT)

    Linux console mouse drivers are:

    >           MS   - Microsoft serial mouse
    >           IMS  - Microsoft serial mouse with Intellimouse extension
    >           LPS2 - PS2 mouse
    >           LIPS - PS2 mouse with Intellimouse extension
    >           GPMD - GPM repeater data (Mouse Systems protocol)
    >           EV   - Event interfaces (EVDEV)

  - num_buttons = x
    Sets the number of mouse buttons viewed by Allegro. You don't normally need to set this variable because Allegro will autodetect it. You can only use it to restrict the set of actual mouse buttons to zero or positive values, negative values will be ignored.
  - emulate_three = x
    Sets whether to emulate a third mouse button by detecting chords of the left and right buttons (yes or no). Defaults to no.
  - mouse_device = x
    Linux only: specifies the name of the mouse device file (eg. ``/dev/mouse'`).
  - ev_absolute = x
    Linux only: specifies the mode for the default EV input: 0 - relative mode: pointer position changes if the input moves, 1 - absolute mode: pointer position is the input position. If unspecified, the mode is relative. If the device supports several tools (such as a graphic tablet), the default input is the mouse. If the device has only one tool (e.g. a normal mouse) the default input is this tool. All additional tools work in absolute mode.
  - ev_min_x = x
    ev_max_x = x
    ev_min_y = x
    ev_max_y = x
    ev_min_z = x
    ev_max_z = x
    Linux only: for absolute EV inputs, minimum and maximum value. By default this information is autodetected. If you want to use only part of a tablet, you need to set the entries for X and Y axis by hand.
  - ev_abs_to_rel_x = x
    ev_abs_to_rel_y = x
    ev_abs_to_rel_z = x
    Linux only: scaling factor for tablet mouse speed. Defaults to 1. This is used only when the input sends absolute events (tablet, joystick, etc.) and the cursor should behave like a mouse. If you are using a mouse on a tablet, you need to set these entries for X and Y axis (try numbers between 1 and 40).
  - mouse_accel_factor = x
    Windows only: specifies the mouse acceleration factor. Defaults to 1. Set it to 0 in order to disable mouse acceleration. 2 accelerates twice as much as 1.
- [sound]
  Section containing sound configuration information, using the variables:
  - digi_card = x
    Sets the driver to use for playing digital samples.
  - midi_card = x
    Sets the driver to use for MIDI music.
  - digi_input_card = x
    Sets the driver to use for digital sample input.
  - midi_input_card = x
    Sets the driver to use for MIDI data input.
  - digi_voices = x
    Specifies the minimum number of voices to reserve for use by the digital sound driver. How many are possible depends on the driver.
  - midi_voices = x
    Specifies the minimum number of voices to reserve for use by the MIDI sound driver. How many are possible depends on the driver.
  - digi_volume = x
    Sets the volume for digital sample playback, from 0 to 255.
  - midi_volume = x
    Sets the volume for midi music playback, from 0 to 255.
  - quality = x
    Controls the sound quality vs. performance tradeoff for the sample mixing code. This can be set to any of the values:

    >           0 - fast mixing of 8-bit data into 16-bit buffers
    >           1 - true 16-bit mixing (requires a 16-bit stereo sound card)
    >           2 - interpolated 16-bit mixing

  - flip_pan = x
    Toggling this between 0 and 1 reverses the left/right panning of samples, which might be needed because some SB cards get the stereo image the wrong way round.
  - sound_freq = x
    DOS, Unix and BeOS: sets the sample frequency. With the SB driver, possible rates are 11906 (any), 16129 (any), 22727 (SB 2.0 and above), and 45454 (only on SB 2.0 or SB16, not the stereo SB Pro driver). On the ESS Audiodrive, possible rates are 11363, 17046, 22729, or 44194. On the Ensoniq Soundscape, possible rates are 11025, 16000, 22050, or 48000. On the Windows Sound System, possible rates are 11025, 22050, 44100, or 48000. Don't worry if you set some other number by mistake: Allegro will automatically round it to the closest supported frequency.
  - sound_bits = x
    Unix and BeOS: sets the preferred number of bits (8 or 16).
  - sound_stereo = x
    Unix and BeOS: selects mono or stereo output (0 or 1).
  - sound_port = x
    DOS only: sets the sound card port address (this is usually 220).
  - sound_dma = x
    DOS only: sets the sound card DMA channel (this is usually 1).
  - sound_irq = x
    DOS only: sets the sound card IRQ number (this is usually 7).
  - fm_port = x
    DOS only: sets the port address of the OPL synth (this is usually 388).
  - mpu_port = x
    DOS only: sets the port address of the MPU-401 MIDI interface (this is usually 330).
  - mpu_irq = x
    DOS only: sets the IRQ for the MPU-401 (this is usually the same as sound_irq).
  - ibk_file = x
    DOS only: specifies the name of a .IBK file which will be used to replace the standard Adlib patch set.
  - ibk_drum_file = x
    DOS only: specifies the name of a .IBK file which will be used to replace the standard set of Adlib percussion patches.
  - oss_driver = x
    Unix only: sets the OSS device driver name. Usually ``/dev/dsp'` or ``/dev/audio'`, but could be a particular device (e.g. ``/dev/dsp2'`).
  - oss_numfrags = x
    oss_fragsize = x
    Unix only: sets number of OSS driver fragments (buffers) and size of each buffer in samples. Buffers are filled with data in the interrupts where interval between subsequent interrupts is not less than 10 ms. If hardware can play all information from buffers faster than 10 ms, then there will be clicks, when hardware have played all data and library has not prepared new data yet. On the other hand, if it takes too long for device driver to play data from all buffers, then there will be delays between action which triggers sound and sound itself.
  - oss_midi_driver = x
    Unix only: sets the OSS MIDI device name. Usually ``/dev/sequencer'`.
  - oss_mixer_driver = x
    Unix only: sets the OSS mixer device name. Usually ``/dev/mixer'`.
  - esd_server = x
    Unix only: where to find the ESD (Enlightened Sound Daemon) server.
  - alsa_card = x
    alsa_pcmdevice = x
    Unix only: card number and PCM device for the ALSA 0.5 sound driver.
  - alsa_device = x
    Unix only: device name for the ALSA 0.9 sound driver. The format is <driver>[:<card>,<device>], for example: `hw:0,1'.
  - alsa_mixer_device = x
    Unix only: mixer device name for the ALSA 0.9 sound driver. The default is "default".
  - alsa_mixer_elem = x
    Unix only: mixer element name for the ALSA 0.9 driver. The default is PCM.
  - alsa_numfrags = x
    Unix only: number of ALSA driver fragments (buffers).
  - alsa_fragsize = x
    Unix only: size of each ALSA fragment, in samples.
  - alsa_rawmidi_card = x
    Unix only: card number and device for the ALSA 0.5 midi driver.
  - alsa_rawmidi_device = x
    Unix only: device for the ALSA 0.5 midi driver or device name for the ALSA 0.9 midi driver (see alsa_device for the format).
  - jack_client_name = x
    Sets the name with which Allegro should identify itself to the Jack audio server.
  - jack_buffer_size = x
    Forces a buffer size for the transfer buffer from Allegro's mixer to Jack.
  - be_midi_quality = x
    BeOS only: system MIDI synthesizer instruments quality. 0 uses low quality 8-bit 11 kHz samples, 1 uses 16-bit 22 kHz samples.
  - be_midi_freq = x
    BeOS only: MIDI sample mixing frequency in Hz. Can be 11025, 22050 or 44100.
  - be_midi_interpolation = x
    BeOS only: specifies the MIDI samples interpolation method. 0 doesn't interpolate, it's fast but has the worst quality; 1 does a fast interpolation with better performances, but it's a bit slower than the previous method; 2 does a linear interpolation between samples, it is the slowest method but gives the best performances.
  - be_midi_reverb = x
    BeOS only: reverberation intensity, from 0 to 5. 0 disables it, 5 is the strongest one.
  - ca_midi_quality = x
    MacOS X only: CoreAudio MIDI synthesizer rendering quality, from 0 to 127. Higher qualities sound better but increase the CPU work load.
  - ca_midi_reverb = x
    MacOS X only: CoreAudio MIDI synthesizer reverberation intensity, from 0 to 5. 0 equals to a small room (low reverb), 5 to a plate (high reverb).
  - patches = x
    Specifies where to find the sample set for the DIGMID driver. This can either be a Gravis style directory containing a collection of .pat files and a ``default.cfg'` index, or an Allegro datafile produced by the pat2dat utility. If this variable is not set, Allegro will look either for a ``default.cfg'` or ``patches.dat'` file in the same directory as the program, the directory pointed to by the ALLEGRO environment variable, and the standard GUS directory pointed to by the ULTRASND environment variable.
- [midimap]
  If you are using the SB MIDI output or MPU-401 drivers with an external synthesiser that is not General MIDI compatible, you can use the midimap section of the config file to specify a patch mapping table for converting GM patch numbers into whatever bank and program change messages will select the appropriate sound on your synth. This is a real piece of self-indulgence. I have a Yamaha TG500, which has some great sounds but no GM patch set, and I just had to make it work somehow... This section consists of a set of lines in the form:
  - p<n> = bank0 bank1 prog pitch
    With this statement, n is the GM program change number (1-128), bank0 and bank1 are the two bank change messages to send to your synth (on controllers #0 and #32), prog is the program change message to send to your synth, and pitch is the number of semitones to shift everything that is played with that sound. Setting the bank change numbers to -1 will prevent them from being sent. For example, the line:

    >           p36 = 0 34 9 12

    specifies that whenever GM program 36 (which happens to be a fretless bass) is selected, Allegro should send a bank change message #0 with a parameter of 0, a bank change message #32 with a parameter of 34, a program change with a parameter of 9, and then should shift everything up by an octave.
- [joystick]
  Section containing joystick configuration information, using the variables:
  - joytype = x
    Specifies which joystick driver to use when the program requests JOY_TYPE_AUTODETECT.
  - joystick_device = x
    BeOS and Linux only: specifies the name of the joystick device to be used (as reported in the system joystick preferences under BeOS). The first device found is used by default. If you want to specify the device for each joystick, use variables of the form joystick_device_n, where n is the joystick number.
  - throttle_axis = x
    Linux only: sets the axis number the throttle is located at. This variable will be used for every detected joystick. If you want to specify the axis number for each joystick individually, use variables of the form throttle_axis_n, where n is the joystick number.

> See also: set_config_file, set_config_string, get_config_string.

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