m_config.c

//
// Copyright(C) 1993-1996 Id Software, Inc.
// Copyright(C) 1993-2008 Raven Software
// Copyright(C) 2005-2014 Simon Howard
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// DESCRIPTION:
//    Configuration file interface.
//

#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "SDL_filesystem.h"

#include "config.h"

#include "doomkeys.h"
#include "doomtype.h"
#include "i_system.h"
#include "m_argv.h"
#include "m_config.h"
#include "m_misc.h"

#include "z_zone.h"

//
// DEFAULTS
//

// Location where all configuration data is stored -
// default.cfg, savegames, etc.

const char *configdir;

static char *autoload_path = "";

// Default filenames for configuration files.

static const char *default_main_config;
static const char *default_extra_config;

typedef enum {
    DEFAULT_INT,
    DEFAULT_INT_HEX,
    DEFAULT_STRING,
    DEFAULT_FLOAT,
    DEFAULT_KEY,
} default_type_t;

typedef struct {
    // Name of the variable
    const char *name;

    // Pointer to the location in memory of the variable
    union {
        int *i;
        char **s;
        float *f;
    } location;

    // Type of the variable
    default_type_t type;

    // If this is a key value, the original integer scancode we read from
    // the config file before translating it to the internal key value.
    // If zero, we didn't read this value from a config file.
    int untranslated;

    // The value we translated the scancode into when we read the
    // config file on startup.  If the variable value is different from
    // this, it has been changed and needs to be converted; otherwise,
    // use the 'untranslated' value.
    int original_translated;

    // If true, this config variable has been bound to a variable
    // and is being used.
    boolean bound;
} default_t;

typedef struct {
    default_t *defaults;
    int numdefaults;
    const char *filename;
} default_collection_t;

#define CONFIG_VARIABLE_GENERIC(name, type)                                                                           \
    {                                                                                                                 \
#name, {NULL }, type, 0, 0, false                                                                             \
    }

#define CONFIG_VARIABLE_KEY(name) CONFIG_VARIABLE_GENERIC(name, DEFAULT_KEY)
#define CONFIG_VARIABLE_INT(name) CONFIG_VARIABLE_GENERIC(name, DEFAULT_INT)
#define CONFIG_VARIABLE_INT_HEX(name) CONFIG_VARIABLE_GENERIC(name, DEFAULT_INT_HEX)
#define CONFIG_VARIABLE_FLOAT(name) CONFIG_VARIABLE_GENERIC(name, DEFAULT_FLOAT)
#define CONFIG_VARIABLE_STRING(name) CONFIG_VARIABLE_GENERIC(name, DEFAULT_STRING)

//! @begin_config_file default

static default_t doom_defaults_list[] = {
    //!
    // Mouse sensitivity.  This value is used to multiply input mouse
    // movement to control the effect of moving the mouse.
    //
    // The "normal" maximum value available for this through the
    // in-game options menu is 9. A value of 31 or greater will cause
    // the game to crash when entering the options menu.
    //

    CONFIG_VARIABLE_INT(mouse_sensitivity),

    //!
    // Volume of sound effects, range 0-15.
    //

    CONFIG_VARIABLE_INT(sfx_volume),

    //!
    // Volume of in-game music, range 0-15.
    //

    CONFIG_VARIABLE_INT(music_volume),

    //!
    // @game strife
    //
    // If non-zero, dialogue text is displayed over characters' pictures
    // when engaging actors who have voices.
    //

    CONFIG_VARIABLE_INT(show_talk),

    //!
    // @game strife
    //
    // Volume of voice sound effects, range 0-15.
    //

    CONFIG_VARIABLE_INT(voice_volume),

    //!
    // @game doom
    //
    // If non-zero, messages are displayed on the heads-up display
    // in the game ("picked up a clip", etc).  If zero, these messages
    // are not displayed.
    //

    CONFIG_VARIABLE_INT(show_messages),

    //!
    // Keyboard key to turn right.
    //

    CONFIG_VARIABLE_KEY(key_right),

    //!
    // Keyboard key to turn left.
    //

    CONFIG_VARIABLE_KEY(key_left),

    //!
    // Keyboard key to move forward.
    //

    CONFIG_VARIABLE_KEY(key_up),

    //!
    // Keyboard key to move backward.
    //

    CONFIG_VARIABLE_KEY(key_down),

    //!
    // Keyboard key to strafe left.
    //

    CONFIG_VARIABLE_KEY(key_strafeleft),

    //!
    // Keyboard key to strafe right.
    //

    CONFIG_VARIABLE_KEY(key_straferight),

    //!
    // @game strife
    //
    // Keyboard key to use health.
    //

    CONFIG_VARIABLE_KEY(key_useHealth),

    //!
    // @game hexen
    //
    // Keyboard key to jump.
    //

    CONFIG_VARIABLE_KEY(key_jump),

    //!
    // @game heretic hexen
    //
    // Keyboard key to fly upward.
    //

    CONFIG_VARIABLE_KEY(key_flyup),

    //!
    // @game heretic hexen
    //
    // Keyboard key to fly downwards.
    //

    CONFIG_VARIABLE_KEY(key_flydown),

    //!
    // @game heretic hexen
    //
    // Keyboard key to center flying.
    //

    CONFIG_VARIABLE_KEY(key_flycenter),

    //!
    // @game heretic hexen
    //
    // Keyboard key to look up.
    //

    CONFIG_VARIABLE_KEY(key_lookup),

    //!
    // @game heretic hexen
    //
    // Keyboard key to look down.
    //

    CONFIG_VARIABLE_KEY(key_lookdown),

    //!
    // @game heretic hexen
    //
    // Keyboard key to center the view.
    //

    CONFIG_VARIABLE_KEY(key_lookcenter),

    //!
    // @game strife
    //
    // Keyboard key to query inventory.
    //

    CONFIG_VARIABLE_KEY(key_invquery),

    //!
    // @game strife
    //
    // Keyboard key to display mission objective.
    //

    CONFIG_VARIABLE_KEY(key_mission),

    //!
    // @game strife
    //
    // Keyboard key to display inventory popup.
    //

    CONFIG_VARIABLE_KEY(key_invPop),

    //!
    // @game strife
    //
    // Keyboard key to display keys popup.
    //

    CONFIG_VARIABLE_KEY(key_invKey),

    //!
    // @game strife
    //
    // Keyboard key to jump to start of inventory.
    //

    CONFIG_VARIABLE_KEY(key_invHome),

    //!
    // @game strife
    //
    // Keyboard key to jump to end of inventory.
    //

    CONFIG_VARIABLE_KEY(key_invEnd),

    //!
    // @game heretic hexen
    //
    // Keyboard key to scroll left in the inventory.
    //

    CONFIG_VARIABLE_KEY(key_invleft),

    //!
    // @game heretic hexen
    //
    // Keyboard key to scroll right in the inventory.
    //

    CONFIG_VARIABLE_KEY(key_invright),

    //!
    // @game strife
    //
    // Keyboard key to scroll left in the inventory.
    //

    CONFIG_VARIABLE_KEY(key_invLeft),

    //!
    // @game strife
    //
    // Keyboard key to scroll right in the inventory.
    //

    CONFIG_VARIABLE_KEY(key_invRight),

    //!
    // @game heretic hexen
    //
    // Keyboard key to use the current item in the inventory.
    //

    CONFIG_VARIABLE_KEY(key_useartifact),

    //!
    // @game strife
    //
    // Keyboard key to use inventory item.
    //

    CONFIG_VARIABLE_KEY(key_invUse),

    //!
    // @game strife
    //
    // Keyboard key to drop an inventory item.
    //

    CONFIG_VARIABLE_KEY(key_invDrop),

    //!
    // @game strife
    //
    // Keyboard key to look up.
    //

    CONFIG_VARIABLE_KEY(key_lookUp),

    //!
    // @game strife
    //
    // Keyboard key to look down.
    //

    CONFIG_VARIABLE_KEY(key_lookDown),

    //!
    // Keyboard key to fire the currently selected weapon.
    //

    CONFIG_VARIABLE_KEY(key_fire),

    //!
    // Keyboard key to "use" an object, eg. a door or switch.
    //

    CONFIG_VARIABLE_KEY(key_use),

    //!
    // Keyboard key to turn on strafing.  When held down, pressing the
    // key to turn left or right causes the player to strafe left or
    // right instead.
    //

    CONFIG_VARIABLE_KEY(key_strafe),
    CONFIG_VARIABLE_KEY(key_strafe_alt),

    //!
    // Keyboard key to make the player run.
    //

    CONFIG_VARIABLE_KEY(key_speed),
    CONFIG_VARIABLE_KEY(key_speed_alt),

    //!
    // Keyboard key to go/exit fullscreen
    //

    CONFIG_VARIABLE_KEY(key_fullscreen),

    //!
    // If non-zero, mouse input is enabled.  If zero, mouse input is
    // disabled.
    //

    CONFIG_VARIABLE_INT(use_mouse),

    //!
    // Mouse button to fire the currently selected weapon.
    //

    CONFIG_VARIABLE_INT(mouseb_fire),

    //!
    // Mouse button to turn on strafing.  When held down, the player
    // will strafe left and right instead of turning left and right.
    //

    CONFIG_VARIABLE_INT(mouseb_strafe),

    //!
    // Mouse button to move forward.
    //

    CONFIG_VARIABLE_INT(mouseb_forward),

    //!
    // @game hexen strife
    //
    // Mouse button to jump.
    //

    CONFIG_VARIABLE_INT(mouseb_jump),

    //!
    // If non-zero, joystick input is enabled.
    //

    CONFIG_VARIABLE_INT(use_joystick),

    //!
    // Joystick virtual button that fires the current weapon.
    //

    CONFIG_VARIABLE_INT(joyb_fire),

    //!
    // Joystick virtual button that makes the player strafe while
    // held down.
    //

    CONFIG_VARIABLE_INT(joyb_strafe),

    //!
    // Joystick virtual button to "use" an object, eg. a door or switch.
    //

    CONFIG_VARIABLE_INT(joyb_use),

    //!
    // Joystick virtual button that makes the player run while held
    // down.
    //
    // If this has a value of 20 or greater, the player will always run,
    // even if use_joystick is 0.
    //

    CONFIG_VARIABLE_INT(joyb_speed),

    //!
    // @game hexen strife
    //
    // Joystick virtual button that makes the player jump.
    //

    CONFIG_VARIABLE_INT(joyb_jump),

    //!
    // @game doom heretic hexen
    //
    // Screen size, range 3-11.
    //
    // A value of 11 gives a full-screen view with the status bar not
    // displayed.  A value of 10 gives a full-screen view with the
    // status bar displayed.
    //

    CONFIG_VARIABLE_INT(screenblocks),

    //!
    // @game strife
    //
    // Screen size, range 3-11.
    //
    // A value of 11 gives a full-screen view with the status bar not
    // displayed.  A value of 10 gives a full-screen view with the
    // status bar displayed.
    //

    CONFIG_VARIABLE_INT(screensize),

    //!
    // @game doom
    //
    // Screen detail.  Zero gives normal "high detail" mode, while
    // a non-zero value gives "low detail" mode.
    //

    CONFIG_VARIABLE_INT(detaillevel),

    //!
    // Number of sounds that will be played simultaneously.
    //

    CONFIG_VARIABLE_INT(snd_channels),

    //!
    // Music output device.  A non-zero value gives MIDI sound output,
    // while a value of zero disables music.
    //

    CONFIG_VARIABLE_INT(snd_musicdevice),

    //!
    // Sound effects device.  A value of zero disables in-game sound
    // effects, a value of 1 enables PC speaker sound effects, while
    // a value in the range 2-9 enables the "normal" digital sound
    // effects.
    //

    CONFIG_VARIABLE_INT(snd_sfxdevice),

    //!
    // SoundBlaster I/O port. Unused.
    //

    CONFIG_VARIABLE_INT(snd_sbport),

    //!
    // SoundBlaster IRQ.  Unused.
    //

    CONFIG_VARIABLE_INT(snd_sbirq),

    //!
    // SoundBlaster DMA channel.  Unused.
    //

    CONFIG_VARIABLE_INT(snd_sbdma),

    //!
    // Output port to use for OPL MIDI playback.  Unused.
    //

    CONFIG_VARIABLE_INT(snd_mport),

    //!
    // Gamma correction level.  A value of zero disables gamma
    // correction, while a value in the range 1-4 gives increasing
    // levels of gamma correction.
    //

    CONFIG_VARIABLE_INT(usegamma),

    //!
    // @game hexen
    //
    // Directory in which to store savegames.
    //

    CONFIG_VARIABLE_STRING(savedir),

    //!
    // @game hexen
    //
    // Controls whether messages are displayed in the heads-up display.
    // If this has a non-zero value, messages are displayed.
    //

    CONFIG_VARIABLE_INT(messageson),

    //!
    // @game strife
    //
    // Name of background flat used by view border.
    //

    CONFIG_VARIABLE_STRING(back_flat),

    //!
    // @game strife
    //
    // Multiplayer nickname (?).
    //

    CONFIG_VARIABLE_STRING(nickname),

    //!
    // Multiplayer chat macro: message to send when alt+0 is pressed.
    //

    CONFIG_VARIABLE_STRING(chatmacro0),

    //!
    // Multiplayer chat macro: message to send when alt+1 is pressed.
    //

    CONFIG_VARIABLE_STRING(chatmacro1),

    //!
    // Multiplayer chat macro: message to send when alt+2 is pressed.
    //

    CONFIG_VARIABLE_STRING(chatmacro2),

    //!
    // Multiplayer chat macro: message to send when alt+3 is pressed.
    //

    CONFIG_VARIABLE_STRING(chatmacro3),

    //!
    // Multiplayer chat macro: message to send when alt+4 is pressed.
    //

    CONFIG_VARIABLE_STRING(chatmacro4),

    //!
    // Multiplayer chat macro: message to send when alt+5 is pressed.
    //

    CONFIG_VARIABLE_STRING(chatmacro5),

    //!
    // Multiplayer chat macro: message to send when alt+6 is pressed.
    //

    CONFIG_VARIABLE_STRING(chatmacro6),

    //!
    // Multiplayer chat macro: message to send when alt+7 is pressed.
    //

    CONFIG_VARIABLE_STRING(chatmacro7),

    //!
    // Multiplayer chat macro: message to send when alt+8 is pressed.
    //

    CONFIG_VARIABLE_STRING(chatmacro8),

    //!
    // Multiplayer chat macro: message to send when alt+9 is pressed.
    //

    CONFIG_VARIABLE_STRING(chatmacro9),

    //!
    // @game strife
    //
    // Serial port number to use for SERSETUP.EXE (unused).
    //

    CONFIG_VARIABLE_INT(comport),
};

static default_collection_t doom_defaults = {
    doom_defaults_list,
    arrlen(doom_defaults_list),
    NULL,
};

//! @begin_config_file extended

static default_t extra_defaults_list[] = {
    //!
    // Name of the SDL video driver to use.  If this is an empty string,
    // the default video driver is used.
    //

    CONFIG_VARIABLE_STRING(video_driver),

    //!
    // Position of the window on the screen when running in windowed
    // mode. Accepted values are: "" (empty string) - don't care,
    // "center" - place window at center of screen, "x,y" - place
    // window at the specified coordinates.
    //

    CONFIG_VARIABLE_STRING(window_position),

    //!
    // If non-zero, the game will run in full screen mode.  If zero,
    // the game will run in a window.
    //

    CONFIG_VARIABLE_INT(fullscreen),

    //!
    // Index of the display on which the game should run. This has no
    // effect if running in windowed mode (fullscreen=0) and
    // window_position is not set to "center".
    //

    CONFIG_VARIABLE_INT(video_display),

    //!
    // If non-zero, the screen will be stretched vertically to display
    // correctly on a square pixel video mode.
    //

    CONFIG_VARIABLE_INT(aspect_ratio_correct),

    //!
    // If non-zero, forces integer scales for resolution-independent rendering.
    //

    CONFIG_VARIABLE_INT(integer_scaling),

    // If non-zero, any pillar/letter boxes drawn around the game area
    // will "flash" when the game palette changes, simulating the VGA
    // "porch"

    CONFIG_VARIABLE_INT(vga_porch_flash),

    //!
    // Window width when running in windowed mode.
    //

    CONFIG_VARIABLE_INT(window_width),

    //!
    // Window height when running in windowed mode.
    //

    CONFIG_VARIABLE_INT(window_height),

    //!
    // Width for screen mode when running fullscreen.
    // If this and fullscreen_height are both set to zero, we run
    // fullscreen as a desktop window that covers the entire screen,
    // rather than ever switching screen modes. It should usually
    // be unnecessary to set this value.
    //

    CONFIG_VARIABLE_INT(fullscreen_width),

    //!
    // Height for screen mode when running fullscreen.
    // See documentation for fullscreen_width.
    //

    CONFIG_VARIABLE_INT(fullscreen_height),

    //!
    // If non-zero, force the use of a software renderer. For use on
    // systems lacking hardware acceleration.
    //

    CONFIG_VARIABLE_INT(force_software_renderer),

    //!
    // Maximum number of pixels to use for intermediate scaling buffer.
    // More pixels mean that the screen can be rendered more precisely,
    // but there are diminishing returns on quality. The default limits to
    // 16,000,000 pixels, which is enough to cover 4K monitor standards.

    CONFIG_VARIABLE_INT(max_scaling_buffer_pixels),

    //!
    // Number of milliseconds to wait on startup after the video mode
    // has been set, before the game will start.  This allows the
    // screen to settle on some monitors that do not display an image
    // for a brief interval after changing video modes.
    //

    CONFIG_VARIABLE_INT(startup_delay),

    //!
    // @game heretic hexen strife
    //
    // If non-zero, display the graphical startup screen.
    //

    CONFIG_VARIABLE_INT(graphical_startup),

    //!
    // @game doom heretic strife
    //
    // If non-zero, the ENDOOM text screen is displayed when exiting the
    // game. If zero, the ENDOOM screen is not displayed.
    //

    CONFIG_VARIABLE_INT(show_endoom),

    //!
    // @game doom strife
    //
    // If non-zero, a disk activity indicator is displayed when data is read
    // from disk. If zero, the disk activity indicator is not displayed.
    //

    CONFIG_VARIABLE_INT(show_diskicon),

    //!
    // If non-zero, save screenshots in PNG format. If zero, screenshots are
    // saved in PCX format, as Vanilla Doom does.
    //

    CONFIG_VARIABLE_INT(png_screenshots),

    //!
    // Sound output sample rate, in Hz.  Typical values to use are
    // 11025, 22050, 44100 and 48000.
    //

    CONFIG_VARIABLE_INT(snd_samplerate),

    //!
    // Maximum number of bytes to allocate for caching converted sound
    // effects in memory. If set to zero, there is no limit applied.
    //

    CONFIG_VARIABLE_INT(snd_cachesize),

    //!
    // Maximum size of the output sound buffer size in milliseconds.
    // Sound output is generated periodically in slices. Higher values
    // might be more efficient but will introduce latency to the
    // sound output. The default is 28ms (one slice per tic with the
    // 35fps timer).
    //

    CONFIG_VARIABLE_INT(snd_maxslicetime_ms),

    //!
    // If non-zero, sound effects will have their pitch varied up or
    // down by a random amount during play. If zero, sound effects
    // play back at their default pitch.
    //

    CONFIG_VARIABLE_INT(snd_pitchshift),

    //!
    // External command to invoke to perform MIDI playback. If set to
    // the empty string, SDL_mixer's internal MIDI playback is used.
    // This only has any effect when snd_musicdevice is set to General
    // MIDI output.
    //

    CONFIG_VARIABLE_STRING(snd_musiccmd),

    //!
    // Value to set for the DMXOPTION environment variable. If this contains
    // "-opl3", output for an OPL3 chip is generated when in OPL MIDI
    // playback mode.
    //

    CONFIG_VARIABLE_STRING(snd_dmxoption),

    //!
    // The I/O port to use to access the OPL chip.  Only relevant when
    // using native OPL music playback.
    //

    CONFIG_VARIABLE_INT_HEX(opl_io_port),

    //!
    // Controls whether libsamplerate support is used for performing
    // sample rate conversions of sound effects.  Support for this
    // must be compiled into the program.
    //
    // If zero, libsamplerate support is disabled.  If non-zero,
    // libsamplerate is enabled. Increasing values roughly correspond
    // to higher quality conversion; the higher the quality, the
    // slower the conversion process.  Linear conversion = 1;
    // Zero order hold = 2; Fast Sinc filter = 3; Medium quality
    // Sinc filter = 4; High quality Sinc filter = 5.
    //

    CONFIG_VARIABLE_INT(use_libsamplerate),

    //!
    // Scaling factor used by libsamplerate. This is used when converting
    // sounds internally back into integer form; normally it should not
    // be necessary to change it from the default value. The only time
    // it might be needed is if a PWAD file is loaded that contains very
    // loud sounds, in which case the conversion may cause sound clipping
    // and the scale factor should be reduced. The lower the value, the
    // quieter the sound effects become, so it should be set as high as is
    // possible without clipping occurring.

    CONFIG_VARIABLE_FLOAT(libsamplerate_scale),

    //!
    // Full path to a directory in which WAD files and dehacked patches
    // can be placed to be automatically loaded on startup. A subdirectory
    // of this directory matching the IWAD name is checked to find the
    // files to load.

    CONFIG_VARIABLE_STRING(autoload_path),

    //!
    // Full path to a directory containing configuration files for
    // substitute music packs. These packs contain high quality renderings
    // of game music to be played instead of using the system's built-in
    // MIDI playback.
    //

    CONFIG_VARIABLE_STRING(music_pack_path),

    //!
    // Full path to a Timidity configuration file to use for MIDI
    // playback. The file will be evaluated from the directory where
    // it is evaluated, so there is no need to add "dir" commands
    // into it.
    //

    CONFIG_VARIABLE_STRING(timidity_cfg_path),

    //!
    // Path to GUS patch files to use when operating in GUS emulation
    // mode.
    //

    CONFIG_VARIABLE_STRING(gus_patch_path),

    //!
    // Number of kilobytes of RAM to use in GUS emulation mode. Valid
    // values are 256, 512, 768 or 1024.
    //

    CONFIG_VARIABLE_INT(gus_ram_kb),

    //!
    // @game doom strife
    //
    // If non-zero, the Vanilla savegame limit is enforced; if the
    // savegame exceeds 180224 bytes in size, the game will exit with
    // an error.  If this has a value of zero, there is no limit to
    // the size of savegames.
    //

    CONFIG_VARIABLE_INT(vanilla_savegame_limit),

    //!
    // @game doom strife
    //
    // If non-zero, the Vanilla demo size limit is enforced; the game
    // exits with an error when a demo exceeds the demo size limit
    // (128KiB by default).  If this has a value of zero, there is no
    // limit to the size of demos.
    //

    CONFIG_VARIABLE_INT(vanilla_demo_limit),

    //!
    // If non-zero, the game behaves like Vanilla Doom, always assuming
    // an American keyboard mapping.  If this has a value of zero, the
    // native keyboard mapping of the keyboard is used.
    //

    CONFIG_VARIABLE_INT(vanilla_keyboard_mapping),

    //!
    // Name to use in network games for identification.  This is only
    // used on the "waiting" screen while waiting for the game to start.
    //

    CONFIG_VARIABLE_STRING(player_name),

    //!
    // If this is non-zero, the mouse will be "grabbed" when running
    // in windowed mode so that it can be used as an input device.
    // When running full screen, this has no effect.
    //

    CONFIG_VARIABLE_INT(grabmouse),

    //!
    // If non-zero, all vertical mouse movement is ignored.  This
    // emulates the behavior of the "novert" tool available under DOS
    // that performs the same function.
    //

    CONFIG_VARIABLE_INT(novert),

    //!
    // Mouse acceleration factor.  When the speed of mouse movement
    // exceeds the threshold value (mouse_threshold), the speed is
    // multiplied by this value.
    //

    CONFIG_VARIABLE_FLOAT(mouse_acceleration),

    //!
    // Mouse acceleration threshold.  When the speed of mouse movement
    // exceeds this threshold value, the speed is multiplied by an
    // acceleration factor (mouse_acceleration).
    //

    CONFIG_VARIABLE_INT(mouse_threshold),

    //!
    // Mouse button to strafe left.
    //

    CONFIG_VARIABLE_INT(mouseb_strafeleft),

    //!
    // Mouse button to strafe right.
    //

    CONFIG_VARIABLE_INT(mouseb_straferight),

    //!
    // Mouse button to turn left.
    //

    CONFIG_VARIABLE_INT(mouseb_turnleft),

    //!
    // Mouse button to turn right.
    //

    CONFIG_VARIABLE_INT(mouseb_turnright),

    //!
    // Mouse button to "use" an object, eg. a door or switch.
    //

    CONFIG_VARIABLE_INT(mouseb_use),

    //!
    // Mouse button to move backwards.
    //

    CONFIG_VARIABLE_INT(mouseb_backward),

    //!
    // Mouse button to cycle to the previous weapon.
    //

    CONFIG_VARIABLE_INT(mouseb_prevweapon),

    //!
    // Mouse button to cycle to the next weapon.
    //

    CONFIG_VARIABLE_INT(mouseb_nextweapon),

    //!
    // @game heretic
    //
    // Mouse button to move to the left in the inventory.
    //

    CONFIG_VARIABLE_INT(mouseb_invleft),

    //!
    // @game heretic
    //
    // Mouse button to move to the right in the inventory.
    //

    CONFIG_VARIABLE_INT(mouseb_invright),

    //!
    // If non-zero, double-clicking a mouse button acts like pressing
    // the "use" key to use an object in-game, eg. a door or switch.
    //

    CONFIG_VARIABLE_INT(dclick_use),

    //!
    // SDL GUID string indicating the joystick to use. An empty string
    // indicates that no joystick is configured.
    //

    CONFIG_VARIABLE_STRING(joystick_guid),

    //!
    // Index of SDL joystick to use; this is only used in the case where
    // multiple identical joystick devices are connected which have the
    // same GUID, to distinguish between devices.
    //

    CONFIG_VARIABLE_INT(joystick_index),

    //!
    // Joystick axis to use to for horizontal (X) movement.
    //

    CONFIG_VARIABLE_INT(joystick_x_axis),

    //!
    // If non-zero, movement on the horizontal joystick axis is inverted.
    //

    CONFIG_VARIABLE_INT(joystick_x_invert),

    //!
    // Joystick axis to use to for vertical (Y) movement.
    //

    CONFIG_VARIABLE_INT(joystick_y_axis),

    //!
    // If non-zero, movement on the vertical joystick axis is inverted.
    //

    CONFIG_VARIABLE_INT(joystick_y_invert),

    //!
    // Joystick axis to use to for strafing movement.
    //

    CONFIG_VARIABLE_INT(joystick_strafe_axis),

    //!
    // If non-zero, movement on the joystick axis used for strafing
    // is inverted.
    //

    CONFIG_VARIABLE_INT(joystick_strafe_invert),

    //!
    // Joystick axis to use to for looking up and down.
    //

    CONFIG_VARIABLE_INT(joystick_look_axis),

    //!
    // If non-zero, movement on the joystick axis used for looking
    // is inverted.
    //

    CONFIG_VARIABLE_INT(joystick_look_invert),

    //!
    // The physical joystick button that corresponds to joystick
    // virtual button #0.
    //

    CONFIG_VARIABLE_INT(joystick_physical_button0),

    //!
    // The physical joystick button that corresponds to joystick
    // virtual button #1.
    //

    CONFIG_VARIABLE_INT(joystick_physical_button1),

    //!
    // The physical joystick button that corresponds to joystick
    // virtual button #2.
    //

    CONFIG_VARIABLE_INT(joystick_physical_button2),

    //!
    // The physical joystick button that corresponds to joystick
    // virtual button #3.
    //

    CONFIG_VARIABLE_INT(joystick_physical_button3),

    //!
    // The physical joystick button that corresponds to joystick
    // virtual button #4.
    //

    CONFIG_VARIABLE_INT(joystick_physical_button4),

    //!
    // The physical joystick button that corresponds to joystick
    // virtual button #5.
    //

    CONFIG_VARIABLE_INT(joystick_physical_button5),

    //!
    // The physical joystick button that corresponds to joystick
    // virtual button #6.
    //

    CONFIG_VARIABLE_INT(joystick_physical_button6),

    //!
    // The physical joystick button that corresponds to joystick
    // virtual button #7.
    //

    CONFIG_VARIABLE_INT(joystick_physical_button7),

    //!
    // The physical joystick button that corresponds to joystick
    // virtual button #8.
    //

    CONFIG_VARIABLE_INT(joystick_physical_button8),

    //!
    // The physical joystick button that corresponds to joystick
    // virtual button #9.
    //

    CONFIG_VARIABLE_INT(joystick_physical_button9),

    //!
    // The physical joystick button that corresponds to joystick
    // virtual button #10.
    //

    CONFIG_VARIABLE_INT(joystick_physical_button10),

    //!
    // Joystick virtual button to make the player strafe left.
    //

    CONFIG_VARIABLE_INT(joyb_strafeleft),

    //!
    // Joystick virtual button to make the player strafe right.
    //

    CONFIG_VARIABLE_INT(joyb_straferight),

    //!
    // Joystick virtual button to activate the menu.
    //

    CONFIG_VARIABLE_INT(joyb_menu_activate),

    //!
    // Joystick virtual button to toggle the automap.
    //

    CONFIG_VARIABLE_INT(joyb_toggle_automap),

    //!
    // Joystick virtual button that cycles to the previous weapon.
    //

    CONFIG_VARIABLE_INT(joyb_prevweapon),

    //!
    // Joystick virtual button that cycles to the next weapon.
    //

    CONFIG_VARIABLE_INT(joyb_nextweapon),

    //!
    // Key to pause or unpause the game.
    //

    CONFIG_VARIABLE_KEY(key_pause),

    //!
    // Key that activates the menu when pressed.
    //

    CONFIG_VARIABLE_KEY(key_menu_activate),

    //!
    // Key that moves the cursor up on the menu.
    //

    CONFIG_VARIABLE_KEY(key_menu_up),

    //!
    // Key that moves the cursor down on the menu.
    //

    CONFIG_VARIABLE_KEY(key_menu_down),

    //!
    // Key that moves the currently selected slider on the menu left.
    //

    CONFIG_VARIABLE_KEY(key_menu_left),

    //!
    // Key that moves the currently selected slider on the menu right.
    //

    CONFIG_VARIABLE_KEY(key_menu_right),

    //!
    // Key to go back to the previous menu.
    //

    CONFIG_VARIABLE_KEY(key_menu_back),

    //!
    // Key to activate the currently selected menu item.
    //

    CONFIG_VARIABLE_KEY(key_menu_forward),

    //!
    // Key to answer 'yes' to a question in the menu.
    //

    CONFIG_VARIABLE_KEY(key_menu_confirm),

    //!
    // Key to answer 'no' to a question in the menu.
    //

    CONFIG_VARIABLE_KEY(key_menu_abort),

    //!
    // Keyboard shortcut to bring up the help screen.
    //

    CONFIG_VARIABLE_KEY(key_menu_help),

    //!
    // Keyboard shortcut to bring up the save game menu.
    //

    CONFIG_VARIABLE_KEY(key_menu_save),

    //!
    // Keyboard shortcut to bring up the load game menu.
    //

    CONFIG_VARIABLE_KEY(key_menu_load),

    //!
    // Keyboard shortcut to bring up the sound volume menu.
    //

    CONFIG_VARIABLE_KEY(key_menu_volume),

    //!
    // Keyboard shortcut to toggle the detail level.
    //

    CONFIG_VARIABLE_KEY(key_menu_detail),

    //!
    // Keyboard shortcut to quicksave the current game.
    //

    CONFIG_VARIABLE_KEY(key_menu_qsave),

    //!
    // Keyboard shortcut to end the game.
    //

    CONFIG_VARIABLE_KEY(key_menu_endgame),

    //!
    // Keyboard shortcut to toggle heads-up messages.
    //

    CONFIG_VARIABLE_KEY(key_menu_messages),

    //!
    // Keyboard shortcut to load the last quicksave.
    //

    CONFIG_VARIABLE_KEY(key_menu_qload),

    //!
    // Keyboard shortcut to quit the game.
    //

    CONFIG_VARIABLE_KEY(key_menu_quit),

    //!
    // Keyboard shortcut to toggle the gamma correction level.
    //

    CONFIG_VARIABLE_KEY(key_menu_gamma),

    //!
    // Keyboard shortcut to switch view in multiplayer.
    //

    CONFIG_VARIABLE_KEY(key_spy),

    //!
    // Keyboard shortcut to increase the screen size.
    //

    CONFIG_VARIABLE_KEY(key_menu_incscreen),

    //!
    // Keyboard shortcut to decrease the screen size.
    //

    CONFIG_VARIABLE_KEY(key_menu_decscreen),

    //!
    // Keyboard shortcut to save a screenshot.
    //

    CONFIG_VARIABLE_KEY(key_menu_screenshot),

    //!
    // Key to toggle the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_toggle),

    //!
    // Key to pan north when in the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_north),

    //!
    // Key to pan south when in the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_south),

    //!
    // Key to pan east when in the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_east),

    //!
    // Key to pan west when in the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_west),

    //!
    // Key to zoom in when in the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_zoomin),

    //!
    // Key to zoom out when in the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_zoomout),

    //!
    // Key to zoom out the maximum amount when in the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_maxzoom),

    //!
    // Key to toggle follow mode when in the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_follow),

    //!
    // Key to toggle the grid display when in the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_grid),

    //!
    // Key to set a mark when in the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_mark),

    //!
    // Key to clear all marks when in the map view.
    //

    CONFIG_VARIABLE_KEY(key_map_clearmark),

    //!
    // Key to select weapon 1.
    //

    CONFIG_VARIABLE_KEY(key_weapon1),

    //!
    // Key to select weapon 2.
    //

    CONFIG_VARIABLE_KEY(key_weapon2),

    //!
    // Key to select weapon 3.
    //

    CONFIG_VARIABLE_KEY(key_weapon3),

    //!
    // Key to select weapon 4.
    //

    CONFIG_VARIABLE_KEY(key_weapon4),

    //!
    // Key to select weapon 5.
    //

    CONFIG_VARIABLE_KEY(key_weapon5),

    //!
    // Key to select weapon 6.
    //

    CONFIG_VARIABLE_KEY(key_weapon6),

    //!
    // Key to select weapon 7.
    //

    CONFIG_VARIABLE_KEY(key_weapon7),

    //!
    // Key to select weapon 8.
    //

    CONFIG_VARIABLE_KEY(key_weapon8),

    //!
    // Key to cycle to the previous weapon.
    //

    CONFIG_VARIABLE_KEY(key_prevweapon),

    //!
    // Key to cycle to the next weapon.
    //

    CONFIG_VARIABLE_KEY(key_nextweapon),

    //!
    // @game heretic
    //
    // Key to use "quartz flask" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_quartz),

    //!
    // @game heretic
    //
    // Key to use "mystic urn" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_urn),

    //!
    // @game heretic
    //
    // Key to use "timebomb of the ancients" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_bomb),

    //!
    // @game heretic
    //
    // Key to use "tome of power" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_tome),

    //!
    // @game heretic
    //
    // Key to use "ring of invincibility" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_ring),

    //!
    // @game heretic
    //
    // Key to use "chaos device" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_chaosdevice),

    //!
    // @game heretic
    //
    // Key to use "shadowsphere" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_shadowsphere),

    //!
    // @game heretic
    //
    // Key to use "wings of wrath" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_wings),

    //!
    // @game heretic
    //
    // Key to use "torch" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_torch),

    //!
    // @game heretic
    //
    // Key to use "morph ovum" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_morph),

    //!
    // @game hexen
    //
    // Key to use one of each artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_all),

    //!
    // @game hexen
    //
    // Key to use "quartz flask" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_health),

    //!
    // @game hexen
    //
    // Key to use "flechette" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_poisonbag),

    //!
    // @game hexen
    //
    // Key to use "disc of repulsion" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_blastradius),

    //!
    // @game hexen
    //
    // Key to use "chaos device" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_teleport),

    //!
    // @game hexen
    //
    // Key to use "banishment device" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_teleportother),

    //!
    // @game hexen
    //
    // Key to use "porkalator" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_egg),

    //!
    // @game hexen
    //
    // Key to use "icon of the defender" artifact.
    //

    CONFIG_VARIABLE_KEY(key_arti_invulnerability),

    //!
    // Key to re-display last message.
    //

    CONFIG_VARIABLE_KEY(key_message_refresh),

    //!
    // Key to quit the game when recording a demo.
    //

    CONFIG_VARIABLE_KEY(key_demo_quit),

    //!
    // Key to send a message during multiplayer games.
    //

    CONFIG_VARIABLE_KEY(key_multi_msg),

    //!
    // Key to send a message to player 1 during multiplayer games.
    //

    CONFIG_VARIABLE_KEY(key_multi_msgplayer1),

    //!
    // Key to send a message to player 2 during multiplayer games.
    //

    CONFIG_VARIABLE_KEY(key_multi_msgplayer2),

    //!
    // Key to send a message to player 3 during multiplayer games.
    //

    CONFIG_VARIABLE_KEY(key_multi_msgplayer3),

    //!
    // Key to send a message to player 4 during multiplayer games.
    //

    CONFIG_VARIABLE_KEY(key_multi_msgplayer4),

    //!
    // @game hexen strife
    //
    // Key to send a message to player 5 during multiplayer games.
    //

    CONFIG_VARIABLE_KEY(key_multi_msgplayer5),

    //!
    // @game hexen strife
    //
    // Key to send a message to player 6 during multiplayer games.
    //

    CONFIG_VARIABLE_KEY(key_multi_msgplayer6),

    //!
    // @game hexen strife
    //
    // Key to send a message to player 7 during multiplayer games.
    //

    CONFIG_VARIABLE_KEY(key_multi_msgplayer7),

    //!
    // @game hexen strife
    //
    // Key to send a message to player 8 during multiplayer games.
    //

    CONFIG_VARIABLE_KEY(key_multi_msgplayer8),
};

static default_collection_t extra_defaults = {
    extra_defaults_list,
    arrlen(extra_defaults_list),
    NULL,
};

// Search a collection for a variable

static default_t *SearchCollection(default_collection_t *collection, const char *name)
{
    int i;

    for (i = 0; i < collection->numdefaults; ++i) {
        if (!strcmp(name, collection->defaults[i].name)) {
            return &collection->defaults[i];
        }
    }

    return NULL;
}

// Mapping from DOS keyboard scan code to internal key code (as defined
// in doomkey.h). I think I (fraggle) reused this from somewhere else
// but I can't find where. Anyway, notes:
//  * KEY_PAUSE is wrong - it's in the KEY_NUMLOCK spot. This shouldn't
//    matter in terms of Vanilla compatibility because neither of
//    those were valid for key bindings.
//  * There is no proper scan code for PrintScreen (on DOS machines it
//    sends an interrupt). So I added a fake scan code of 126 for it.
//    The presence of this is important so we can bind PrintScreen as
//    a screenshot key.
static const int scantokey[128] = {0,
                                   27,
                                   '1',
                                   '2',
                                   '3',
                                   '4',
                                   '5',
                                   '6',
                                   '7',
                                   '8',
                                   '9',
                                   '0',
                                   '-',
                                   '=',
                                   KEY_BACKSPACE,
                                   9,
                                   'q',
                                   'w',
                                   'e',
                                   'r',
                                   't',
                                   'y',
                                   'u',
                                   'i',
                                   'o',
                                   'p',
                                   '[',
                                   ']',
                                   13,
                                   KEY_RCTRL,
                                   'a',
                                   's',
                                   'd',
                                   'f',
                                   'g',
                                   'h',
                                   'j',
                                   'k',
                                   'l',
                                   ';',
                                   '\'',
                                   '`',
                                   KEY_RSHIFT,
                                   '\\',
                                   'z',
                                   'x',
                                   'c',
                                   'v',
                                   'b',
                                   'n',
                                   'm',
                                   ',',
                                   '.',
                                   '/',
                                   KEY_RSHIFT,
                                   KEYP_MULTIPLY,
                                   KEY_RALT,
                                   ' ',
                                   KEY_CAPSLOCK,
                                   KEY_F1,
                                   KEY_F2,
                                   KEY_F3,
                                   KEY_F4,
                                   KEY_F5,
                                   KEY_F6,
                                   KEY_F7,
                                   KEY_F8,
                                   KEY_F9,
                                   KEY_F10,
                                   /*KEY_NUMLOCK?*/ KEY_PAUSE,
                                   KEY_SCRLCK,
                                   KEY_HOME,
                                   KEY_UPARROW,
                                   KEY_PGUP,
                                   KEY_MINUS,
                                   KEY_LEFTARROW,
                                   KEYP_5,
                                   KEY_RIGHTARROW,
                                   KEYP_PLUS,
                                   KEY_END,
                                   KEY_DOWNARROW,
                                   KEY_PGDN,
                                   KEY_INS,
                                   KEY_DEL,
                                   0,
                                   0,
                                   0,
                                   KEY_F11,
                                   KEY_F12,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   0,
                                   KEY_PRTSCR,
                                   0};

static void SaveDefaultCollection(default_collection_t *collection)
{
    default_t *defaults;
    int i, v;
    FILE *f;

    f = fopen(collection->filename, "w");
    if (!f) return; // can't write the file, but don't complain

    defaults = collection->defaults;

    for (i = 0; i < collection->numdefaults; i++) {
        int chars_written;

        // Ignore unbound variables

        if (!defaults[i].bound) {
            continue;
        }

        // Print the name and line up all values at 30 characters

        chars_written = fprintf(f, "%s ", defaults[i].name);

        for (; chars_written < 30; ++chars_written)
            fprintf(f, " ");

        // Print the value

        switch (defaults[i].type) {
        case DEFAULT_KEY:

            // use the untranslated version if we can, to reduce
            // the possibility of screwing up the user's config
            // file

            v = *defaults[i].location.i;

            if (v == KEY_RSHIFT) {
                // Special case: for shift, force scan code for
                // right shift, as this is what Vanilla uses.
                // This overrides the change check below, to fix
                // configuration files made by old versions that
                // mistakenly used the scan code for left shift.

                v = 54;
            }
            else if (defaults[i].untranslated && v == defaults[i].original_translated) {
                // Has not been changed since the last time we
                // read the config file.

                v = defaults[i].untranslated;
            }
            else {
                // search for a reverse mapping back to a scancode
                // in the scantokey table

                int s;

                for (s = 0; s < 128; ++s) {
                    if (scantokey[s] == v) {
                        v = s;
                        break;
                    }
                }
            }

            fprintf(f, "%i", v);
            break;

        case DEFAULT_INT:
            fprintf(f, "%i", *defaults[i].location.i);
            break;

        case DEFAULT_INT_HEX:
            fprintf(f, "0x%x", *defaults[i].location.i);
            break;

        case DEFAULT_FLOAT:
            fprintf(f, "%f", *defaults[i].location.f);
            break;

        case DEFAULT_STRING:
            fprintf(f, "\"%s\"", *defaults[i].location.s);
            break;
        }

        fprintf(f, "\n");
    }

    fclose(f);
}

// Parses integer values in the configuration file

static int ParseIntParameter(const char *strparm)
{
    int parm;

    if (strparm[0] == '0' && strparm[1] == 'x')
        sscanf(strparm + 2, "%x", (unsigned int *)&parm);
    else
        sscanf(strparm, "%i", &parm);

    return parm;
}

static void SetVariable(default_t *def, const char *value)
{
    int intparm;

    // parameter found

    switch (def->type) {
    case DEFAULT_STRING:
        *def->location.s = M_StringDuplicate(value);
        break;

    case DEFAULT_INT:
    case DEFAULT_INT_HEX:
        *def->location.i = ParseIntParameter(value);
        break;

    case DEFAULT_KEY:

        // translate scancodes read from config
        // file (save the old value in untranslated)

        intparm = ParseIntParameter(value);
        def->untranslated = intparm;
        if (intparm >= 0 && intparm < 128) {
            intparm = scantokey[intparm];
        }
        else {
            intparm = 0;
        }

        def->original_translated = intparm;
        *def->location.i = intparm;
        break;

    case DEFAULT_FLOAT:
        *def->location.f = (float)atof(value);
        break;
    }
}

static void LoadDefaultCollection(default_collection_t *collection)
{
    FILE *f;
    default_t *def;
    char defname[80];
    char strparm[100];

    // read the file in, overriding any set defaults
    f = fopen(collection->filename, "r");

    if (f == NULL) {
        // File not opened, but don't complain.
        // It's probably just the first time they ran the game.

        return;
    }

    while (!feof(f)) {
        if (fscanf(f, "%79s %99[^\n]\n", defname, strparm) != 2) {
            // This line doesn't match

            continue;
        }

        // Find the setting in the list

        def = SearchCollection(collection, defname);

        if (def == NULL || !def->bound) {
            // Unknown variable?  Unbound variables are also treated
            // as unknown.

            continue;
        }

        // Strip off trailing non-printable characters (\r characters
        // from DOS text files)

        while (strlen(strparm) > 0 && !isprint(strparm[strlen(strparm) - 1])) {
            strparm[strlen(strparm) - 1] = '\0';
        }

        // Surrounded by quotes? If so, remove them.
        if (strlen(strparm) >= 2 && strparm[0] == '"' && strparm[strlen(strparm) - 1] == '"') {
            strparm[strlen(strparm) - 1] = '\0';
            memmove(strparm, strparm + 1, sizeof(strparm) - 1);
        }

        SetVariable(def, strparm);
    }

    fclose(f);
}

// Set the default filenames to use for configuration files.

void M_SetConfigFilenames(const char *main_config, const char *extra_config)
{
    default_main_config = main_config;
    default_extra_config = extra_config;
}

//
// M_SaveDefaults
//

void M_SaveDefaults(void)
{
    SaveDefaultCollection(&doom_defaults);
    SaveDefaultCollection(&extra_defaults);
}

//
// Save defaults to alternate filenames
//

void M_SaveDefaultsAlternate(const char *main, const char *extra)
{
    const char *orig_main;
    const char *orig_extra;

    // Temporarily change the filenames

    orig_main = doom_defaults.filename;
    orig_extra = extra_defaults.filename;

    doom_defaults.filename = main;
    extra_defaults.filename = extra;

    M_SaveDefaults();

    // Restore normal filenames

    doom_defaults.filename = orig_main;
    extra_defaults.filename = orig_extra;
}

//
// M_LoadDefaults
//

void M_LoadDefaults(void)
{
    int i;

    // This variable is a special snowflake for no good reason.
    M_BindStringVariable("autoload_path", &autoload_path);

    // check for a custom default file

    //!
    // @arg <file>
    // @vanilla
    //
    // Load main configuration from the specified file, instead of the
    // default.
    //

    i = M_CheckParmWithArgs("-config", 1);

    if (i) {
        doom_defaults.filename = myargv[i + 1];
        printf("	default file: %s\n", doom_defaults.filename);
    }
    else {
        doom_defaults.filename = M_StringJoin(configdir, default_main_config, NULL);
    }

    printf("saving config in %s\n", doom_defaults.filename);

    //!
    // @arg <file>
    //
    // Load additional configuration from the specified file, instead of
    // the default.
    //

    i = M_CheckParmWithArgs("-extraconfig", 1);

    if (i) {
        extra_defaults.filename = myargv[i + 1];
        printf("        extra configuration file: %s\n", extra_defaults.filename);
    }
    else {
        extra_defaults.filename = M_StringJoin(configdir, default_extra_config, NULL);
    }

    LoadDefaultCollection(&doom_defaults);
    LoadDefaultCollection(&extra_defaults);
}

// Get a configuration file variable by its name

static default_t *GetDefaultForName(const char *name)
{
    default_t *result;

    // Try the main list and the extras

    result = SearchCollection(&doom_defaults, name);

    if (result == NULL) {
        result = SearchCollection(&extra_defaults, name);
    }

    // Not found? Internal error.

    if (result == NULL) {
        I_Error("Unknown configuration variable: '%s'", name);
    }

    return result;
}

//
// Bind a variable to a given configuration file variable, by name.
//

void M_BindIntVariable(const char *name, int *location)
{
    default_t *variable;

    variable = GetDefaultForName(name);
    assert(variable->type == DEFAULT_INT || variable->type == DEFAULT_INT_HEX || variable->type == DEFAULT_KEY);

    variable->location.i = location;
    variable->bound = true;
}

void M_BindFloatVariable(const char *name, float *location)
{
    default_t *variable;

    variable = GetDefaultForName(name);
    assert(variable->type == DEFAULT_FLOAT);

    variable->location.f = location;
    variable->bound = true;
}

void M_BindStringVariable(const char *name, char **location)
{
    default_t *variable;

    variable = GetDefaultForName(name);
    assert(variable->type == DEFAULT_STRING);

    variable->location.s = location;
    variable->bound = true;
}

// Set the value of a particular variable; an API function for other
// parts of the program to assign values to config variables by name.

boolean M_SetVariable(const char *name, const char *value)
{
    default_t *variable;

    variable = GetDefaultForName(name);

    if (variable == NULL || !variable->bound) {
        return false;
    }

    SetVariable(variable, value);

    return true;
}

// Get the value of a variable.

int M_GetIntVariable(const char *name)
{
    default_t *variable;

    variable = GetDefaultForName(name);

    if (variable == NULL || !variable->bound || (variable->type != DEFAULT_INT && variable->type != DEFAULT_INT_HEX)) {
        return 0;
    }

    return *variable->location.i;
}

const char *M_GetStringVariable(const char *name)
{
    default_t *variable;

    variable = GetDefaultForName(name);

    if (variable == NULL || !variable->bound || variable->type != DEFAULT_STRING) {
        return NULL;
    }

    return *variable->location.s;
}

float M_GetFloatVariable(const char *name)
{
    default_t *variable;

    variable = GetDefaultForName(name);

    if (variable == NULL || !variable->bound || variable->type != DEFAULT_FLOAT) {
        return 0;
    }

    return *variable->location.f;
}

// Get the path to the default configuration dir to use, if NULL
// is passed to M_SetConfigDir.

static char *GetDefaultConfigDir(void)
{
#if !defined(_WIN32) || defined(_WIN32_WCE)

    // Configuration settings are stored in an OS-appropriate path
    // determined by SDL.  On typical Unix systems, this might be
    // ~/.local/share/chocolate-doom.  On Windows, we behave like
    // Vanilla Doom and save in the current directory.

    char *result;
    char *copy;

    result = SDL_GetPrefPath("", PACKAGE_TARNAME);
    if (result != NULL) {
        copy = M_StringDuplicate(result);
        SDL_free(result);
        return copy;
    }
#endif /* #ifndef _WIN32 */
    return M_StringDuplicate(exedir);
}

//
// SetConfigDir:
//
// Sets the location of the configuration directory, where configuration
// files are stored - default.cfg, chocolate-doom.cfg, savegames, etc.
//

void M_SetConfigDir(const char *dir)
{
    // Use the directory that was passed, or find the default.

    if (dir != NULL) {
        configdir = dir;
    }
    else {
        configdir = GetDefaultConfigDir();
    }

    if (strcmp(configdir, exedir) != 0) {
        printf("Using %s for configuration and saves\n", configdir);
    }

    // Make the directory if it doesn't already exist:

    M_MakeDirectory(configdir);
}

#define MUSIC_PACK_README                                                                                             \
    "Extract music packs into this directory in .flac or .ogg format;\n"                                              \
    "they will be automatically loaded based on filename to replace the\n"                                            \
    "in-game music with high quality versions.\n\n"                                                                   \
    "For more information check here:\n\n"                                                                            \
    "  <https://www.chocolate-doom.org/wiki/index.php/Digital_music_packs>\n\n"

// Set the value of music_pack_path if it is currently empty, and create
// the directory if necessary.
void M_SetMusicPackDir(void)
{
    const char *current_path;
    char *prefdir, *music_pack_path, *readme_path;

    current_path = M_GetStringVariable("music_pack_path");

    if (current_path != NULL && strlen(current_path) > 0) {
        return;
    }

    prefdir = SDL_GetPrefPath("", PACKAGE_TARNAME);
    music_pack_path = M_StringJoin(prefdir, "music-packs", NULL);

    M_MakeDirectory(prefdir);
    M_MakeDirectory(music_pack_path);
    M_SetVariable("music_pack_path", music_pack_path);

    // We write a README file with some basic instructions on how to use
    // the directory.
    readme_path = M_StringJoin(music_pack_path, DIR_SEPARATOR_S, "README.txt", NULL);
    M_WriteFile(readme_path, MUSIC_PACK_README, strlen(MUSIC_PACK_README));

    free(readme_path);
    free(music_pack_path);
    SDL_free(prefdir);
}

//
// Calculate the path to the directory to use to store save games.
// Creates the directory as necessary.
//

char *M_GetSaveGameDir(const char *iwadname)
{
    char *savegamedir;
    char *topdir;
    int p;

    //!
    // @arg <directory>
    //
    // Specify a path from which to load and save games. If the directory
    // does not exist then it will automatically be created.
    //

    p = M_CheckParmWithArgs("-savedir", 1);
    if (p) {
        savegamedir = myargv[p + 1];
        if (!M_FileExists(savegamedir)) {
            M_MakeDirectory(savegamedir);
        }

        // add separator at end just in case
        savegamedir = M_StringJoin(savegamedir, DIR_SEPARATOR_S, NULL);

        printf("Save directory changed to %s.\n", savegamedir);
    }
#ifdef _WIN32
    // In -cdrom mode, we write savegames to a specific directory
    // in addition to configs.

    else if (M_ParmExists("-cdrom")) {
        savegamedir = M_StringDuplicate(configdir);
    }
#endif
    // If not "doing" a configuration directory (Windows), don't "do"
    // a savegame directory, either.
    else if (!strcmp(configdir, exedir)) {
        savegamedir = M_StringDuplicate("");
    }
    else {
        // ~/.local/share/chocolate-doom/savegames

        topdir = M_StringJoin(configdir, "savegames", NULL);
        M_MakeDirectory(topdir);

        // eg. ~/.local/share/chocolate-doom/savegames/doom2.wad/

        savegamedir = M_StringJoin(topdir, DIR_SEPARATOR_S, iwadname, DIR_SEPARATOR_S, NULL);

        M_MakeDirectory(savegamedir);

        free(topdir);
    }

    return savegamedir;
}

//
// Calculate the path to the directory for autoloaded WADs/DEHs.
// Creates the directory as necessary.
//
char *M_GetAutoloadDir(const char *iwadname)
{
    char *result;

    if (autoload_path == NULL || strlen(autoload_path) == 0) {
        char *prefdir;
        prefdir = SDL_GetPrefPath("", PACKAGE_TARNAME);
        autoload_path = M_StringJoin(prefdir, "autoload", NULL);
        SDL_free(prefdir);
    }

    M_MakeDirectory(autoload_path);

    result = M_StringJoin(autoload_path, DIR_SEPARATOR_S, iwadname, NULL);
    M_MakeDirectory(result);

    // TODO: Add README file

    return result;
}