. Added files needed for the forthcoming module management.

 Notes:

   Plugins are now called modules, because we will be able to compile
   them either as a dynamic plugin, or within the program. And, more
   important, I can commit this without having to break the vlc :)

   I tried to be as clear as possible in my comments, please tell me
   if a few prototypes still have an unclear beahaviour.

   Current features:
    . none, files haven't even been added to the Makefile yet.

   Future features:
    . dynamic loading (done)
    . built-in modules (still to do)
    . automatic unloading of plugins (done)
    . dynamic configuration (still to do)
    . automatic choosing of the most appropriate plugin for a given
       task (still to do but well prepared)

include/modules.h

+/*****************************************************************************
+ * modules.h : Module management functions.
+ *****************************************************************************
+ * Copyright (C) 2001 VideoLAN
+ *
+ * Authors: Samuel Hocevar <sam@zoy.org>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ *****************************************************************************/
+
+/* Number of tries before we unload an unused module */
+#define MODULE_HIDE_DELAY 10
+
+/* The module handle type. */
+#ifdef SYS_BEOS
+typedef int     module_handle_t;
+#else
+typedef void *  module_handle_t;
+#endif
+
+/*****************************************************************************
+ * Configuration structure
+ *****************************************************************************/
+typedef struct module_config_s
+{
+    int         i_type;                         /* Configuration widget type */
+    char *      psz_text;        /* Text commenting or describing the widget */
+    char *      psz_name;                                   /* Variable name */
+    void *      p_getlist;          /* Function to call to get a choice list */
+    void *      p_change;        /* Function to call when commiting a change */
+} module_config_t;
+
+/*****************************************************************************
+ * Bank and module description structures
+ *****************************************************************************/
+
+/* The main module structure */
+typedef struct module_s
+{
+    boolean_t           b_builtin;  /* Set to true if the module is built in */
+
+    module_handle_t     handle;      /* Unique handle to refer to the module */
+    char *              psz_filename;                     /* Module filename */
+
+    char *              psz_name;                    /* Module _unique_ name */
+    char *              psz_longname;             /* Module descriptive name */
+    char *              psz_version;                       /* Module version */
+
+    int                 i_usage;                        /* Reference counter */
+    int                 i_unused_delay;    /* Delay until module is unloaded */
+
+    struct module_s *   next;                                 /* Next module */
+    struct module_s *   prev;                             /* Previous module */
+
+    u32                 i_capabilities;                   /* Capability list */
+
+    module_config_t *   p_config;    /* Module configuration structure table */
+
+} module_t;
+
+/* The module bank structure */
+typedef struct module_bank_s
+{
+    module_t *          first; /* First module of the bank */
+
+    vlc_mutex_t         lock;  /* Global lock -- you can't imagine how awful it
+                                  is to design thread-safe linked lists. */
+} module_bank_t;
+
+/*****************************************************************************
+ * Stuff for handling dynamic modules
+ *****************************************************************************/
+
+/* Function to load a dynamic module, returns 0 if successful. */
+static __inline__ int
+module_load( char * psz_filename, module_handle_t * handle )
+{
+#ifdef SYS_BEOS
+    *handle = load_add_on( psz_filename );
+    return( *handle >= 0 );
+#else
+    *handle = dlopen( psz_filename, RTLD_NOW | RTLD_GLOBAL );
+    return( *handle != NULL );
+#endif
+}
+
+/* Unload a dynamic module. */
+static __inline__ void
+module_unload( module_handle_t handle )
+{
+#ifdef SYS_BEOS
+    unload_add_on( handle );
+#else
+    dlclose( handle );
+#endif
+    return;
+}
+
+/* Get a given symbol from a module. */
+static __inline__ void *
+module_getsymbol( module_handle_t handle, char * psz_function )
+{
+#ifdef SYS_BEOS
+    void * p_symbol;
+    get_image_symbol( handle, psz_function, B_SYMBOL_TYPE_TEXT, &p_symbol );
+    return( p_symbol );
+#else
+    return( dlsym( handle, psz_function ) );
+#endif
+}
+
+/* Wrapper to dlerror() for systems that don't have it. */
+static __inline__ char *
+module_error( void )
+{
+#ifdef SYS_BEOS
+    return( "failed" );
+#else
+    return( dlerror() );
+#endif
+}
+
+/*****************************************************************************
+ * Exported functions.
+ *****************************************************************************/
+module_bank_t * module_InitBank     ( void );
+int             module_DestroyBank  ( module_bank_t * p_bank );
+int             module_ResetBank    ( module_bank_t * p_bank );
+void            module_ManageBank   ( module_bank_t * p_bank );
+
+int module_Need    ( module_t * p_module );
+int module_Unneed  ( module_t * p_module );
+

include/modules_config.h

+/*****************************************************************************
+ * modules_config.h : Module configuration tools.
+ *****************************************************************************
+ * Copyright (C) 2001 VideoLAN
+ *
+ * Authors: Samuel Hocevar <sam@zoy.org>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Module capabilities.
+ *****************************************************************************/
+#define MODULE_CAPABILITY_NULL     0       /* The Module can't do anything */
+#define MODULE_CAPABILITY_INTF     1<<0    /* Interface */
+#define MODULE_CAPABILITY_INPUT    1<<1    /* Input */
+#define MODULE_CAPABILITY_DECAPS   1<<2    /* Decaps */
+#define MODULE_CAPABILITY_ADEC     1<<3    /* Audio decoder */
+#define MODULE_CAPABILITY_VDEC     1<<4    /* Video decoder */
+#define MODULE_CAPABILITY_AOUT     1<<5    /* Audio output */
+#define MODULE_CAPABILITY_VOUT     1<<6    /* Video output */
+#define MODULE_CAPABILITY_YUV      1<<7    /* YUV colorspace conversion */
+#define MODULE_CAPABILITY_AFX      1<<8    /* Audio effects */
+#define MODULE_CAPABILITY_VFX      1<<9    /* Video effects */
+
+/*****************************************************************************
+ * Macros used to build the configuration structure.
+ *****************************************************************************/
+
+/* Mandatory first and last parts of the structure */
+#define MODULE_CONFIG_ITEM_START       0x01    /* The main window */
+#define MODULE_CONFIG_ITEM_END         0x00    /* End of the window */
+
+/* Configuration widgets */
+#define MODULE_CONFIG_ITEM_PANE        0x02    /* A notebook pane */
+#define MODULE_CONFIG_ITEM_FRAME       0x03    /* A frame */
+#define MODULE_CONFIG_ITEM_COMMENT     0x04    /* A comment text */
+#define MODULE_CONFIG_ITEM_STRING      0x05    /* A string */
+#define MODULE_CONFIG_ITEM_FILE        0x06    /* A file selector */
+#define MODULE_CONFIG_ITEM_CHECK       0x07    /* A checkbox */
+#define MODULE_CONFIG_ITEM_CHOOSE      0x08    /* A choose box */
+#define MODULE_CONFIG_ITEM_RADIO       0x09    /* A radio box */
+#define MODULE_CONFIG_ITEM_SCALE       0x0a    /* A horizontal ruler */
+#define MODULE_CONFIG_ITEM_SPIN        0x0b    /* A numerical selector */
+

include/modules_inner.h

+/*****************************************************************************
+ * modules_inner.h : Macros used from within a module.
+ *****************************************************************************
+ * Copyright (C) 2001 VideoLAN
+ *
+ * Authors: Samuel Hocevar <sam@zoy.org>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Check that we are within a module.
+ *****************************************************************************/
+#ifndef MODULE_NAME
+#  error "You must define MODULE_NAME before using modules_inner.h !"
+#endif
+
+/*****************************************************************************
+ * Add a few defines. You do not want to read this section. Really.
+ *****************************************************************************/
+
+/* Explanation:
+ *
+ * if user has #defined MODULE_NAME foo, then we will need:
+ * #define MODULE_STRING "foo"
+ * #define MODULE_VAR(blah) "VLC_MODULE_foo_blah"
+ *
+ * and, if BUILTIN is set, we will also need:
+ * #define InitModule foo_InitModule
+ * #define ActivateModule foo_ActivateModule
+ * #define DeactivateModule foo_DeactivateModule
+ *
+ * this can't easily be done with the C preprocessor, thus a few ugly hacks.
+ */
+
+/* I can't believe I need to do this to change  foo  to  "foo"  */
+#define UGLY_KLUDGE(z) NASTY_CROCK(z)
+#define NASTY_CROCK(z) #z
+/* And I need to do _this_ to change  foo bar  to  foo_bar  ! */
+#define AWFUL_BRITTLE(y,z) CRUDE_HACK(y,z)
+#define CRUDE_HACK(y,z) y##_##z
+
+/* Also, I need to do this to change  blah  to  "VLC_MODULE_foo_blah"  */
+#define MODULE_STRING UGLY_KLUDGE(MODULE_NAME)
+#define MODULE_VAR(z) "VLC_MODULE_" UGLY_KLUDGE(MODULE_NAME) "_" #z
+
+/* If the module is built-in, then we need to define foo_InitModule instead
+ * of InitModule. Same for Activate- and DeactivateModule. */
+#ifdef BUILTIN
+#  define InitModule AWFUL_BRITTLE(MODULE_NAME,InitModule)
+#  define ActivateModule AWFUL_BRITTLE(MODULE_NAME,ActivateModule)
+#  define DeactivateModule AWFUL_BRITTLE(MODULE_NAME,DeactivateModule)
+#endif
+
+/*****************************************************************************
+ * Macros used to build the configuration structure.
+ *****************************************************************************/
+#define MODULE_CONFIG_START( text ) \
+static module_config_t p_config[] = { \
+    { MODULE_CONFIG_ITEM_START, text, NULL, NULL, NULL },
+
+#define MODULE_CONFIG_END   \
+    { MODULE_CONFIG_ITEM_END, NULL, NULL, NULL, NULL } \
+};
+
+#define ADD_FRAME( text ) \
+    { MODULE_CONFIG_ITEM_FRAME, text, NULL, NULL, NULL },
+#define ADD_PANE( text ) \
+    { MODULE_CONFIG_ITEM_PANE, text, NULL, NULL, NULL },
+#define ADD_COMMENT( text ) \
+    { MODULE_CONFIG_ITEM_COMMENT, text, NULL, NULL, NULL },
+#define ADD_STRING( text, name, p_update ) \
+    { MODULE_CONFIG_ITEM_STRING, text, name, NULL, p_update },
+#define ADD_FILE( text, name, p_update ) \
+    { MODULE_CONFIG_ITEM_FILE, text, name, NULL, p_update },
+#define ADD_CHECK( text, name, p_update ) \
+    { MODULE_CONFIG_ITEM_CHECK, text, name, NULL, p_update },
+#define ADD_CHOOSE( text, name, p_getlist, p_update ) \
+    { MODULE_CONFIG_ITEM_CHOOSE, text, name, p_getlist, p_update },
+#define ADD_RADIO( text, name, p_getlist, p_update ) \
+    { MODULE_CONFIG_ITEM_RADIO, text, name, p_getlist, p_update },
+#define ADD_SCALE( text, name, p_getlist, p_update ) \
+    { MODULE_CONFIG_ITEM_SCALE, text, name, p_getlist, p_update },
+#define ADD_SPIN( text, name, p_getlist, p_update ) \
+    { MODULE_CONFIG_ITEM_SPIN, text, name, p_getlist, p_update },
+