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/*

 * Mesa 3-D graphics library

 * Version:  7.1

 *

 * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included

 * in all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN

 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN

 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 */

/**

 * \file glapi_getproc.c

 *

 * Code for implementing glXGetProcAddress(), etc.

 * This was originally in glapi.c but refactored out.

 */

#include "glapi/glapi_priv.h"

#include "glapi/glapitable.h"

#define FIRST_DYNAMIC_OFFSET (sizeof(struct _glapi_table) / sizeof(void *))

/**********************************************************************

 * Static function management.

 */

#if !defined(DISPATCH_FUNCTION_SIZE)

# define NEED_FUNCTION_POINTER

#endif

#include "glapi/glprocs.h"

/**

 * Search the table of static entrypoint functions for the named function

 * and return the corresponding glprocs_table_t entry.

 */

static const glprocs_table_t *

get_static_proc( const char * n )

{

   GLuint i;

   for (i = 0; static_functions[i].Name_offset >= 0; i++) {

      const char *testName = gl_string_table + static_functions[i].Name_offset;

#ifdef MANGLE

      /* skip the prefix on the name */

      if (strcmp(testName, n + 1) == 0)

#else

      if (strcmp(testName, n) == 0)

#endif

      {

	 return &static_functions[i];

      }

   }

   return NULL;

}

/**

 * Return dispatch table offset of the named static (built-in) function.

 * Return -1 if function not found.

 */

static GLint

get_static_proc_offset(const char *funcName)

{

   const glprocs_table_t * const f = get_static_proc( funcName );

   if (f == NULL) {

      return -1;

   }

   return f->Offset;

}

/**

 * Return dispatch function address for the named static (built-in) function.

 * Return NULL if function not found.

 */

static _glapi_proc

get_static_proc_address(const char *funcName)

{

   const glprocs_table_t * const f = get_static_proc( funcName );

   if (f == NULL) {

      return NULL;

   }

#if defined(DISPATCH_FUNCTION_SIZE) && defined(GLX_INDIRECT_RENDERING)

   return (f->Address == NULL)

      ? get_entrypoint_address(f->Offset)

      : f->Address;

#elif defined(DISPATCH_FUNCTION_SIZE)

   return get_entrypoint_address(f->Offset);

#else

   return f->Address;

#endif

}

/**

 * Return the name of the function at the given offset in the dispatch

 * table.  For debugging only.

 */

static const char *

get_static_proc_name( GLuint offset )

{

   GLuint i;

   for (i = 0; static_functions[i].Name_offset >= 0; i++) {

      if (static_functions[i].Offset == offset) {

	 return gl_string_table + static_functions[i].Name_offset;

      }

   }

   return NULL;

}

/**********************************************************************

 * Extension function management.

 */

/**

 * Track information about a function added to the GL API.

 */

struct _glapi_function {

   /**

    * Name of the function.

    */

   const char * name;

   /**

    * Text string that describes the types of the parameters passed to the

    * named function.   Parameter types are converted to characters using the

    * following rules:

    *   - 'i' for \c GLint, \c GLuint, and \c GLenum

    *   - 'p' for any pointer type

    *   - 'f' for \c GLfloat and \c GLclampf

    *   - 'd' for \c GLdouble and \c GLclampd

    */

   const char * parameter_signature;

   /**

    * Offset in the dispatch table where the pointer to the real function is

    * located.  If the driver has not requested that the named function be

    * added to the dispatch table, this will have the value ~0.

    */

   unsigned dispatch_offset;

   /**

    * Pointer to the dispatch stub for the named function.

    *

    * \todo

    * The semantic of this field should be changed slightly.  Currently, it

    * is always expected to be non-\c NULL.  However, it would be better to

    * only allocate the entry-point stub when the application requests the

    * function via \c glXGetProcAddress.  This would save memory for all the

    * functions that the driver exports but that the application never wants

    * to call.

    */

   _glapi_proc dispatch_stub;

};

static struct _glapi_function ExtEntryTable[MAX_EXTENSION_FUNCS];

static GLuint NumExtEntryPoints = 0;

static struct _glapi_function *

get_extension_proc(const char *funcName)

{

   GLuint i;

   for (i = 0; i < NumExtEntryPoints; i++) {

      if (strcmp(ExtEntryTable[i].name, funcName) == 0) {

         return & ExtEntryTable[i];

      }

   }

   return NULL;

}

static GLint

get_extension_proc_offset(const char *funcName)

{

   const struct _glapi_function * const f = get_extension_proc( funcName );

   if (f == NULL) {

      return -1;

   }

   return f->dispatch_offset;

}

static _glapi_proc

get_extension_proc_address(const char *funcName)

{

   const struct _glapi_function * const f = get_extension_proc( funcName );

   if (f == NULL) {

      return NULL;

   }

   return f->dispatch_stub;

}

static const char *

get_extension_proc_name(GLuint offset)

{

   GLuint i;

   for (i = 0; i < NumExtEntryPoints; i++) {

      if (ExtEntryTable[i].dispatch_offset == offset) {

         return ExtEntryTable[i].name;

      }

   }

   return NULL;

}

/**

 * strdup() is actually not a standard ANSI C or POSIX routine.

 * Irix will not define it if ANSI mode is in effect.

 */

static char *

str_dup(const char *str)

{

   char *copy;

   copy = (char*) malloc(strlen(str) + 1);

   if (!copy)

      return NULL;

   strcpy(copy, str);

   return copy;

}

/**

 * Generate new entrypoint

 *

 * Use a temporary dispatch offset of ~0 (i.e. -1).  Later, when the driver

 * calls \c _glapi_add_dispatch we'll put in the proper offset.  If that

 * never happens, and the user calls this function, he'll segfault.  That's

 * what you get when you try calling a GL function that doesn't really exist.

 *

 * \param funcName  Name of the function to create an entry-point for.

 *

 * \sa _glapi_add_entrypoint

 */

static struct _glapi_function *

add_function_name( const char * funcName )

{

   struct _glapi_function * entry = NULL;

   _glapi_proc entrypoint = NULL;

   char * name_dup = NULL;

   if (NumExtEntryPoints >= MAX_EXTENSION_FUNCS)

      return NULL;

   if (funcName == NULL)

      return NULL;

   name_dup = str_dup(funcName);

   if (name_dup == NULL)

      return NULL;

   entrypoint = generate_entrypoint(~0);

   if (entrypoint == NULL) {

      free(name_dup);

      return NULL;

   }

   entry = & ExtEntryTable[NumExtEntryPoints];

   NumExtEntryPoints++;

   entry->name = name_dup;

   entry->parameter_signature = NULL;

   entry->dispatch_offset = ~0;

   entry->dispatch_stub = entrypoint;

   return entry;

}

static struct _glapi_function *

set_entry_info( struct _glapi_function * entry, const char * signature, unsigned offset )

{

   char * sig_dup = NULL;

   if (signature == NULL)

      return NULL;

   sig_dup = str_dup(signature);

   if (sig_dup == NULL)

      return NULL;

   fill_in_entrypoint_offset(entry->dispatch_stub, offset);

   entry->parameter_signature = sig_dup;

   entry->dispatch_offset = offset;

   return entry;

}

/**

 * Fill-in the dispatch stub for the named function.

 *

 * This function is intended to be called by a hardware driver.  When called,

 * a dispatch stub may be created created for the function.  A pointer to this

 * dispatch function will be returned by glXGetProcAddress.

 *

 * \param function_names       Array of pointers to function names that should

 *                             share a common dispatch offset.

 * \param parameter_signature  String representing the types of the parameters

 *                             passed to the named function.  Parameter types

 *                             are converted to characters using the following

 *                             rules:

 *                               - 'i' for \c GLint, \c GLuint, and \c GLenum

 *                               - 'p' for any pointer type

 *                               - 'f' for \c GLfloat and \c GLclampf

 *                               - 'd' for \c GLdouble and \c GLclampd

 *

 * \returns

 * The offset in the dispatch table of the named function.  A pointer to the

 * driver's implementation of the named function should be stored at

 * \c dispatch_table[\c offset].  Return -1 if error/problem.

 *

 * \sa glXGetProcAddress

 *

 * \warning

 * This function can only handle up to 8 names at a time.  As far as I know,

 * the maximum number of names ever associated with an existing GL function is

 * 4 (\c glPointParameterfSGIS, \c glPointParameterfEXT,

 * \c glPointParameterfARB, and \c glPointParameterf), so this should not be

 * too painful of a limitation.

 *

 * \todo

 * Determine whether or not \c parameter_signature should be allowed to be

 * \c NULL.  It doesn't seem like much of a hardship for drivers to have to

 * pass in an empty string.

 *

 * \todo

 * Determine if code should be added to reject function names that start with

 * 'glX'.

 *

 * \bug

 * Add code to compare \c parameter_signature with the parameter signature of

 * a static function.  In order to do that, we need to find a way to \b get

 * the parameter signature of a static function.

 */

int

_glapi_add_dispatch( const char * const * function_names,

		     const char * parameter_signature )

{

   static int next_dynamic_offset = FIRST_DYNAMIC_OFFSET;

   const char * const real_sig = (parameter_signature != NULL)

     ? parameter_signature : "";

   struct _glapi_function * entry[8];

   GLboolean is_static[8];

   unsigned i;

   int offset = ~0;

   init_glapi_relocs_once();

   (void) memset( is_static, 0, sizeof( is_static ) );

   (void) memset( entry, 0, sizeof( entry ) );

   /* Find the _single_ dispatch offset for all function names that already

    * exist (and have a dispatch offset).

    */

   for ( i = 0 ; function_names[i] != NULL ; i++ ) {

      const char * funcName = function_names[i];

      int static_offset;

      int extension_offset;

      if (funcName[0] != 'g' || funcName[1] != 'l')

         return -1;

      /* search built-in functions */

      static_offset = get_static_proc_offset(funcName);

      if (static_offset >= 0) {

	 is_static[i] = GL_TRUE;

	 /* FIXME: Make sure the parameter signatures match!  How do we get

	  * FIXME: the parameter signature for static functions?

	  */

	 if ( (offset != ~0) && (static_offset != offset) ) {

	    return -1;

	 }

	 offset = static_offset;

	 continue;

      }

      /* search added extension functions */

      entry[i] = get_extension_proc(funcName);

      if (entry[i] != NULL) {

	 extension_offset = entry[i]->dispatch_offset;

	 /* The offset may be ~0 if the function name was added by

	  * glXGetProcAddress but never filled in by the driver.

	  */

	 if (extension_offset == ~0) {

	    continue;

	 }

	 if (strcmp(real_sig, entry[i]->parameter_signature) != 0) {

	    return -1;

	 }

	 if ( (offset != ~0) && (extension_offset != offset) ) {

	    return -1;

	 }

	 offset = extension_offset;

      }

   }

   /* If all function names are either new (or with no dispatch offset),

    * allocate a new dispatch offset.

    */

   if (offset == ~0) {

      offset = next_dynamic_offset;

      next_dynamic_offset++;

   }

   /* Fill in the dispatch offset for the new function names (and those with

    * no dispatch offset).

    */

   for ( i = 0 ; function_names[i] != NULL ; i++ ) {

      if (is_static[i]) {

	 continue;

      }

      /* generate entrypoints for new function names */

      if (entry[i] == NULL) {

	 entry[i] = add_function_name( function_names[i] );

	 if (entry[i] == NULL) {

	    /* FIXME: Possible memory leak here. */

	    return -1;

	 }

      }

      if (entry[i]->dispatch_offset == ~0) {

	 set_entry_info( entry[i], real_sig, offset );

      }

   }

   return offset;

}

/**

 * Return offset of entrypoint for named function within dispatch table.

 */

GLint

_glapi_get_proc_offset(const char *funcName)

{

   GLint offset;

   /* search extension functions first */

   offset = get_extension_proc_offset(funcName);

   if (offset >= 0)

      return offset;

   /* search static functions */

   return get_static_proc_offset(funcName);

}

/**

 * Return pointer to the named function.  If the function name isn't found

 * in the name of static functions, try generating a new API entrypoint on

 * the fly with assembly language.

 */

_glapi_proc

_glapi_get_proc_address(const char *funcName)

{

   _glapi_proc func;

   struct _glapi_function * entry;

   init_glapi_relocs_once();

#ifdef MANGLE

   /* skip the prefix on the name */

   if (funcName[1] != 'g' || funcName[2] != 'l')

      return NULL;

#else

   if (funcName[0] != 'g' || funcName[1] != 'l')

      return NULL;

#endif

   /* search extension functions first */

   func = get_extension_proc_address(funcName);

   if (func)

      return func;

   /* search static functions */

   func = get_static_proc_address(funcName);

   if (func)

      return func;

   /* generate entrypoint, dispatch offset must be filled in by the driver */

   entry = add_function_name(funcName);

   if (entry == NULL)

      return NULL;

   return entry->dispatch_stub;

}

/**

 * Return the name of the function at the given dispatch offset.

 * This is only intended for debugging.

 */

const char *

_glapi_get_proc_name(GLuint offset)

{

   const char * n;

   /* search built-in functions */

   n = get_static_proc_name(offset);

   if ( n != NULL ) {

      return n;

   }

   /* search added extension functions */

   return get_extension_proc_name(offset);

}

/**********************************************************************

 * GL API table functions.

 */

/**

 * Return size of dispatch table struct as number of functions (or

 * slots).

 */

GLuint

_glapi_get_dispatch_table_size(void)

{

   /*

    * The dispatch table size (number of entries) is the size of the

    * _glapi_table struct plus the number of dynamic entries we can add.

    * The extra slots can be filled in by DRI drivers that register new

    * extension functions.

    */

   return FIRST_DYNAMIC_OFFSET + MAX_EXTENSION_FUNCS;

}

/**

 * Make sure there are no NULL pointers in the given dispatch table.

 * Intended for debugging purposes.

 */

void

_glapi_check_table_not_null(const struct _glapi_table *table)

{

#ifdef EXTRA_DEBUG /* set to DEBUG for extra DEBUG */

   const GLuint entries = _glapi_get_dispatch_table_size();

   const void **tab = (const void **) table;

   GLuint i;

   for (i = 1; i < entries; i++) {

      assert(tab[i]);

   }

#else

   (void) table;

#endif

}

/**

 * Do some spot checks to be sure that the dispatch table

 * slots are assigned correctly. For debugging only.

 */

void

_glapi_check_table(const struct _glapi_table *table)

{

#ifdef EXTRA_DEBUG /* set to DEBUG for extra DEBUG */

   {

      GLuint BeginOffset = _glapi_get_proc_offset("glBegin");

      char *BeginFunc = (char*) &table->Begin;

      GLuint offset = (BeginFunc - (char *) table) / sizeof(void *);

      assert(BeginOffset == offset);

   }

   {

      GLuint viewportOffset = _glapi_get_proc_offset("glViewport");

      char *viewportFunc = (char*) &table->Viewport;

      GLuint offset = (viewportFunc - (char *) table) / sizeof(void *);

      assert(viewportOffset == offset);

   }

   {

      GLuint VertexPointerOffset = _glapi_get_proc_offset("glVertexPointer");

      char *VertexPointerFunc = (char*) &table->VertexPointer;

      GLuint offset = (VertexPointerFunc - (char *) table) / sizeof(void *);

      assert(VertexPointerOffset == offset);

   }

   {

      GLuint ResetMinMaxOffset = _glapi_get_proc_offset("glResetMinmax");

      char *ResetMinMaxFunc = (char*) &table->ResetMinmax;

      GLuint offset = (ResetMinMaxFunc - (char *) table) / sizeof(void *);

      assert(ResetMinMaxOffset == offset);

   }

   {

      GLuint blendColorOffset = _glapi_get_proc_offset("glBlendColor");

      char *blendColorFunc = (char*) &table->BlendColor;

      GLuint offset = (blendColorFunc - (char *) table) / sizeof(void *);

      assert(blendColorOffset == offset);

   }

   {

      GLuint secondaryColor3fOffset = _glapi_get_proc_offset("glSecondaryColor3fEXT");

      char *secondaryColor3fFunc = (char*) &table->SecondaryColor3fEXT;

      GLuint offset = (secondaryColor3fFunc - (char *) table) / sizeof(void *);

      assert(secondaryColor3fOffset == offset);

   }

   {

      GLuint pointParameterivOffset = _glapi_get_proc_offset("glPointParameterivNV");

      char *pointParameterivFunc = (char*) &table->PointParameterivNV;

      GLuint offset = (pointParameterivFunc - (char *) table) / sizeof(void *);

      assert(pointParameterivOffset == offset);

   }

   {

      GLuint setFenceOffset = _glapi_get_proc_offset("glSetFenceNV");

      char *setFenceFunc = (char*) &table->SetFenceNV;

      GLuint offset = (setFenceFunc - (char *) table) / sizeof(void *);

      assert(setFenceOffset == offset);

   }

#else

   (void) table;

#endif

}