Edit

IABSD.fr/xenocara/xserver/glx/glapi.c

Branch :

  • Show log

    Commit

  • Author : matthieu
    Date : 2010-07-27 19:02:24
    Hash : 95d684a0
    Message : Update to xserver 1.8. Tested by many. Ok oga@, todd@.

  • xserver/glx/glapi.c
  • /*
     * Mesa 3-D graphics library
     * Version:  6.5
     *
     * Copyright (C) 1999-2006  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.
     */
    
    
    /*
     * This file manages the OpenGL API dispatch layer.
     * The dispatch table (struct _glapi_table) is basically just a list
     * of function pointers.
     * There are functions to set/get the current dispatch table for the
     * current thread and to manage registration/dispatch of dynamically
     * added extension functions.
     *
     * It's intended that this file and the other glapi*.[ch] files are
     * flexible enough to be reused in several places:  XFree86, DRI-
     * based libGL.so, and perhaps the SGI SI.
     *
     * NOTE: There are no dependencies on Mesa in this code.
     *
     * Versions (API changes):
     *   2000/02/23  - original version for Mesa 3.3 and XFree86 4.0
     *   2001/01/16  - added dispatch override feature for Mesa 3.5
     *   2002/06/28  - added _glapi_set_warning_func(), Mesa 4.1.
     *   2002/10/01  - _glapi_get_proc_address() will now generate new entrypoints
     *                 itself (using offset ~0).  _glapi_add_entrypoint() can be
     *                 called afterward and it'll fill in the correct dispatch
     *                 offset.  This allows DRI libGL to avoid probing for DRI
     *                 drivers!  No changes to the public glapi interface.
     */
    
    
    
    #ifdef HAVE_DIX_CONFIG_H
    
    #include <dix-config.h>
    #include <X11/Xfuncproto.h>
    #define PUBLIC _X_EXPORT
    
    #else
    
    #include "glheader.h"
    
    #endif
    
    #include <stdlib.h>
    #include <string.h>
    #ifdef DEBUG
    #include <assert.h>
    #endif
    
    #include "glapi.h"
    #include "glapioffsets.h"
    #include "glapitable.h"
    
    /***** BEGIN NO-OP DISPATCH *****/
    
    static GLboolean WarnFlag = GL_FALSE;
    static _glapi_warning_func warning_func;
    
    #if defined(PTHREADS) || defined(GLX_USE_TLS)
    static void init_glapi_relocs(void);
    #endif
    
    static _glapi_proc generate_entrypoint(GLuint functionOffset);
    static void fill_in_entrypoint_offset(_glapi_proc entrypoint, GLuint offset);
    
    /*
     * Enable/disable printing of warning messages.
     */
    PUBLIC void
    _glapi_noop_enable_warnings(GLboolean enable)
    {
       WarnFlag = enable;
    }
    
    /*
     * Register a callback function for reporting errors.
     */
    PUBLIC void
    _glapi_set_warning_func( _glapi_warning_func func )
    {
       warning_func = func;
    }
    
    static GLboolean
    warn(void)
    {
       if ((WarnFlag || getenv("MESA_DEBUG") || getenv("LIBGL_DEBUG"))
           && warning_func) {
          return GL_TRUE;
       }
       else {
          return GL_FALSE;
       }
    }
    
    #if defined(__GNUC__) && (__GNUC__ > 2)
    #define possibly_unused __attribute((unused))
    #else
    #define possibly_unused
    #endif
    
    #define KEYWORD1 static
    #define KEYWORD1_ALT static
    #define KEYWORD2 GLAPIENTRY possibly_unused
    #define NAME(func)  NoOp##func
    
    #define F NULL
    
    #define DISPATCH(func, args, msg)					      \
       if (warn()) {							      \
          warning_func(NULL, "GL User Error: called without context: %s", #func); \
       }
    
    #define RETURN_DISPATCH(func, args, msg)				      \
       if (warn()) {							      \
          warning_func(NULL, "GL User Error: called without context: %s", #func); \
       }									      \
       return 0
    
    #define DISPATCH_TABLE_NAME __glapi_noop_table
    #define UNUSED_TABLE_NAME __unused_noop_functions
    
    #define TABLE_ENTRY(name) (_glapi_proc) NoOp##name
    
    static GLint NoOpUnused(void)
    {
       if (warn()) {
          warning_func(NULL, "GL User Error: calling extension function without a current context\n");
       }
       return 0;
    }
    
    #include "glapitemp.h"
    
    /***** END NO-OP DISPATCH *****/
    
    
    
    /**
     * \name Current dispatch and current context control variables
     *
     * Depending on whether or not multithreading is support, and the type of
     * support available, several variables are used to store the current context
     * pointer and the current dispatch table pointer.  In the non-threaded case,
     * the variables \c _glapi_Dispatch and \c _glapi_Context are used for this
     * purpose.
     *
     * In the "normal" threaded case, the variables \c _glapi_Dispatch and
     * \c _glapi_Context will be \c NULL if an application is detected as being
     * multithreaded.  Single-threaded applications will use \c _glapi_Dispatch
     * and \c _glapi_Context just like the case without any threading support.
     * When \c _glapi_Dispatch and \c _glapi_Context are \c NULL, the thread state
     * data \c _gl_DispatchTSD and \c ContextTSD are used.  Drivers and the
     * static dispatch functions access these variables via \c _glapi_get_dispatch
     * and \c _glapi_get_context.
     *
     * There is a race condition in setting \c _glapi_Dispatch to \c NULL.  It is
     * possible for the original thread to be setting it at the same instant a new
     * thread, perhaps running on a different processor, is clearing it.  Because
     * of that, \c ThreadSafe, which can only ever be changed to \c GL_TRUE, is
     * used to determine whether or not the application is multithreaded.
     * 
     * In the TLS case, the variables \c _glapi_Dispatch and \c _glapi_Context are
     * hardcoded to \c NULL.  Instead the TLS variables \c _glapi_tls_Dispatch and
     * \c _glapi_tls_Context are used.  Having \c _glapi_Dispatch and
     * \c _glapi_Context be hardcoded to \c NULL maintains binary compatability
     * between TLS enabled loaders and non-TLS DRI drivers.
     */
    /*@{*/
    #if defined(GLX_USE_TLS)
    
    PUBLIC __thread struct _glapi_table * _glapi_tls_Dispatch
        __attribute__((tls_model("initial-exec")))
        = (struct _glapi_table *) __glapi_noop_table;
    
    PUBLIC __thread void * _glapi_tls_Context
        __attribute__((tls_model("initial-exec")));
    
    PUBLIC const struct _glapi_table *_glapi_Dispatch = NULL;
    PUBLIC const void *_glapi_Context = NULL;
    
    #else
    
    #if defined(THREADS)
    
    static GLboolean ThreadSafe = GL_FALSE;  /**< In thread-safe mode? */
    _glthread_TSD _gl_DispatchTSD;           /**< Per-thread dispatch pointer */
    static _glthread_TSD ContextTSD;         /**< Per-thread context pointer */
    
    #if defined(WIN32_THREADS)
    void FreeTSD(_glthread_TSD *p);
    void FreeAllTSD(void)
    {
       FreeTSD(&_gl_DispatchTSD);
       FreeTSD(&ContextTSD);
    }
    #endif /* defined(WIN32_THREADS) */
    
    #endif /* defined(THREADS) */
    
    PUBLIC struct _glapi_table *_glapi_Dispatch = 
      (struct _glapi_table *) __glapi_noop_table;
    PUBLIC void *_glapi_Context = NULL;
    
    #endif /* defined(GLX_USE_TLS) */
    /*@}*/
    
    
    /**
     * 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;
    }
    
    
    
    /**
     * We should call this periodically from a function such as glXMakeCurrent
     * in order to test if multiple threads are being used.
     */
    PUBLIC void
    _glapi_check_multithread(void)
    {
    #if defined(THREADS) && !defined(GLX_USE_TLS)
       if (!ThreadSafe) {
          static unsigned long knownID;
          static GLboolean firstCall = GL_TRUE;
          if (firstCall) {
             knownID = _glthread_GetID();
             firstCall = GL_FALSE;
          }
          else if (knownID != _glthread_GetID()) {
             ThreadSafe = GL_TRUE;
             _glapi_set_dispatch(NULL);
             _glapi_set_context(NULL);
          }
       }
       else if (!_glapi_get_dispatch()) {
          /* make sure that this thread's dispatch pointer isn't null */
          _glapi_set_dispatch(NULL);
       }
    #endif
    }
    
    
    
    /**
     * Set the current context pointer for this thread.
     * The context pointer is an opaque type which should be cast to
     * void from the real context pointer type.
     */
    PUBLIC void
    _glapi_set_context(void *context)
    {
       (void) __unused_noop_functions; /* silence a warning */
    #if defined(GLX_USE_TLS)
       _glapi_tls_Context = context;
    #elif defined(THREADS)
       _glthread_SetTSD(&ContextTSD, context);
       _glapi_Context = (ThreadSafe) ? NULL : context;
    #else
       _glapi_Context = context;
    #endif
    }
    
    
    
    /**
     * Get the current context pointer for this thread.
     * The context pointer is an opaque type which should be cast from
     * void to the real context pointer type.
     */
    PUBLIC void *
    _glapi_get_context(void)
    {
    #if defined(GLX_USE_TLS)
       return _glapi_tls_Context;
    #elif defined(THREADS)
       if (ThreadSafe) {
          return _glthread_GetTSD(&ContextTSD);
       }
       else {
          return _glapi_Context;
       }
    #else
       return _glapi_Context;
    #endif
    }
    
    
    
    /**
     * Set the global or per-thread dispatch table pointer.
     * If the dispatch parameter is NULL we'll plug in the no-op dispatch
     * table (__glapi_noop_table).
     */
    PUBLIC void
    _glapi_set_dispatch(struct _glapi_table *dispatch)
    {
    #if defined(PTHREADS) || defined(GLX_USE_TLS)
       static pthread_once_t once_control = PTHREAD_ONCE_INIT;
       pthread_once( & once_control, init_glapi_relocs );
    #endif
    
       if (!dispatch) {
          /* use the no-op functions */
          dispatch = (struct _glapi_table *) __glapi_noop_table;
       }
    #ifdef DEBUG
       else {
          _glapi_check_table(dispatch);
       }
    #endif
    
    #if defined(GLX_USE_TLS)
       _glapi_tls_Dispatch = dispatch;
    #elif defined(THREADS)
       _glthread_SetTSD(&_gl_DispatchTSD, (void *) dispatch);
       _glapi_Dispatch = (ThreadSafe) ? NULL : dispatch;
    #else /*THREADS*/
       _glapi_Dispatch = dispatch;
    #endif /*THREADS*/
    }
    
    
    
    /**
     * Return pointer to current dispatch table for calling thread.
     */
    PUBLIC struct _glapi_table *
    _glapi_get_dispatch(void)
    {
       struct _glapi_table * api;
    #if defined(GLX_USE_TLS)
       api = _glapi_tls_Dispatch;
    #elif defined(THREADS)
       api = (ThreadSafe)
         ? (struct _glapi_table *) _glthread_GetTSD(&_gl_DispatchTSD)
         : _glapi_Dispatch;
    #else
       api = _glapi_Dispatch;
    #endif
       return api;
    }
    
    
    
    /***
     *** The rest of this file is pretty much concerned with GetProcAddress
     *** functionality.
     ***/
    
    #if defined(USE_X64_64_ASM) && defined(GLX_USE_TLS)
    # define DISPATCH_FUNCTION_SIZE  16
    #elif defined(USE_X86_ASM)
    # if defined(THREADS) && !defined(GLX_USE_TLS)
    #  define DISPATCH_FUNCTION_SIZE  32
    # else
    #  define DISPATCH_FUNCTION_SIZE  16
    # endif
    #endif
    
    #if !defined(DISPATCH_FUNCTION_SIZE) && !defined(XFree86Server) && !defined(XGLServer)
    # define NEED_FUNCTION_POINTER
    #endif
    
    /* The code in this file is auto-generated with Python */
    #include "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 *
    find_entry( 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;
          if (strcmp(testName, n) == 0) {
    	 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 = find_entry( funcName );
       if (f) {
          return f->Offset;
       }
       return -1;
    }
    
    
    #if !defined(XFree86Server) && !defined(XGLServer)
    #ifdef USE_X86_ASM
    
    #if defined( GLX_USE_TLS )
    extern       GLubyte gl_dispatch_functions_start[];
    extern       GLubyte gl_dispatch_functions_end[];
    #else
    extern const GLubyte gl_dispatch_functions_start[];
    #endif
    
    #endif /* USE_X86_ASM */
    
    
    /**
     * 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 = find_entry( funcName );
       if (f) {
    #if defined(DISPATCH_FUNCTION_SIZE) && defined(GLX_INDIRECT_RENDERING)
          return (f->Address == NULL)
    	 ? (_glapi_proc) (gl_dispatch_functions_start
    			  + (DISPATCH_FUNCTION_SIZE * f->Offset))
             : f->Address;
    #elif defined(DISPATCH_FUNCTION_SIZE)
          return (_glapi_proc) (gl_dispatch_functions_start 
                                + (DISPATCH_FUNCTION_SIZE * f->Offset));
    #else
          return f->Address;
    #endif
       }
       else {
          return NULL;
       }
    }
    
    #endif /* !defined(XFree86Server) && !defined(XGLServer) */
    
    
    
    /**
     * 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.
     */
    
    /*
     * Number of extension functions which we can dynamically add at runtime.
     */
    #define MAX_EXTENSION_FUNCS 300
    
    
    /*
     * 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.
     */
    #define DISPATCH_TABLE_SIZE (sizeof(struct _glapi_table) / sizeof(void *) + MAX_EXTENSION_FUNCS)
    
    
    /**
     * 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;
    
    #ifdef USE_SPARC_ASM
    extern void __glapi_sparc_icache_flush(unsigned int *);
    #endif
    
    /**
     * Generate a dispatch function (entrypoint) which jumps through
     * the given slot number (offset) in the current dispatch table.
     * We need assembly language in order to accomplish this.
     */
    static _glapi_proc
    generate_entrypoint(GLuint functionOffset)
    {
    #if defined(USE_X86_ASM)
       /* 32 is chosen as something of a magic offset.  For x86, the dispatch
        * at offset 32 is the first one where the offset in the
        * "jmp OFFSET*4(%eax)" can't be encoded in a single byte.
        */
       const GLubyte * const template_func = gl_dispatch_functions_start 
         + (DISPATCH_FUNCTION_SIZE * 32);
       GLubyte * const code = (GLubyte *) malloc(DISPATCH_FUNCTION_SIZE);
    
    
       if ( code != NULL ) {
          (void) memcpy(code, template_func, DISPATCH_FUNCTION_SIZE);
          fill_in_entrypoint_offset( (_glapi_proc) code, functionOffset );
       }
    
       return (_glapi_proc) code;
    #elif defined(USE_SPARC_ASM)
    
    #ifdef __arch64__
       static const unsigned int insn_template[] = {
    	   0x05000000,	/* sethi	%uhi(_glapi_Dispatch), %g2	*/
    	   0x03000000,	/* sethi	%hi(_glapi_Dispatch), %g1	*/
    	   0x8410a000,	/* or		%g2, %ulo(_glapi_Dispatch), %g2	*/
    	   0x82106000,	/* or		%g1, %lo(_glapi_Dispatch), %g1	*/
    	   0x8528b020,	/* sllx		%g2, 32, %g2			*/
    	   0xc2584002,	/* ldx		[%g1 + %g2], %g1		*/
    	   0x05000000,	/* sethi	%hi(8 * glapioffset), %g2	*/
    	   0x8410a000,	/* or		%g2, %lo(8 * glapioffset), %g2	*/
    	   0xc6584002,	/* ldx		[%g1 + %g2], %g3		*/
    	   0x81c0c000,	/* jmpl		%g3, %g0			*/
    	   0x01000000	/*  nop						*/
       };
    #else
       static const unsigned int insn_template[] = {
    	   0x03000000,	/* sethi	%hi(_glapi_Dispatch), %g1	  */
    	   0xc2006000,	/* ld		[%g1 + %lo(_glapi_Dispatch)], %g1 */
    	   0xc6006000,	/* ld		[%g1 + %lo(4*glapioffset)], %g3	  */
    	   0x81c0c000,	/* jmpl		%g3, %g0			  */
    	   0x01000000	/*  nop						  */
       };
    #endif /* __arch64__ */
       unsigned int *code = (unsigned int *) malloc(sizeof(insn_template));
       unsigned long glapi_addr = (unsigned long) &_glapi_Dispatch;
       if (code) {
          memcpy(code, insn_template, sizeof(insn_template));
    
    #ifdef __arch64__
          code[0] |= (glapi_addr >> (32 + 10));
          code[1] |= ((glapi_addr & 0xffffffff) >> 10);
          __glapi_sparc_icache_flush(&code[0]);
          code[2] |= ((glapi_addr >> 32) & ((1 << 10) - 1));
          code[3] |= (glapi_addr & ((1 << 10) - 1));
          __glapi_sparc_icache_flush(&code[2]);
          code[6] |= ((functionOffset * 8) >> 10);
          code[7] |= ((functionOffset * 8) & ((1 << 10) - 1));
          __glapi_sparc_icache_flush(&code[6]);
    #else
          code[0] |= (glapi_addr >> 10);
          code[1] |= (glapi_addr & ((1 << 10) - 1));
          __glapi_sparc_icache_flush(&code[0]);
          code[2] |= (functionOffset * 4);
          __glapi_sparc_icache_flush(&code[2]);
    #endif /* __arch64__ */
       }
       return (_glapi_proc) code;
    #else
       (void) functionOffset;
       return NULL;
    #endif /* USE_*_ASM */
    }
    
    
    /**
     * This function inserts a new dispatch offset into the assembly language
     * stub that was generated with the preceeding function.
     */
    static void
    fill_in_entrypoint_offset(_glapi_proc entrypoint, GLuint offset)
    {
    #if defined(USE_X86_ASM)
       GLubyte * const code = (GLubyte *) entrypoint;
    
    #if DISPATCH_FUNCTION_SIZE == 32
       *((unsigned int *)(code + 11)) = 4 * offset;
       *((unsigned int *)(code + 22)) = 4 * offset;
    #elif DISPATCH_FUNCTION_SIZE == 16 && defined( GLX_USE_TLS )
       *((unsigned int *)(code +  8)) = 4 * offset;
    #elif DISPATCH_FUNCTION_SIZE == 16
       *((unsigned int *)(code +  7)) = 4 * offset;
    #else
    # error Invalid DISPATCH_FUNCTION_SIZE!
    #endif
    
    #elif defined(USE_SPARC_ASM)
    
       /* XXX this hasn't been tested! */
       unsigned int *code = (unsigned int *) entrypoint;
    #ifdef __arch64__
       code[6] = 0x05000000;  /* sethi	%hi(8 * glapioffset), %g2	*/
       code[7] = 0x8410a000;  /* or		%g2, %lo(8 * glapioffset), %g2	*/
       code[6] |= ((offset * 8) >> 10);
       code[7] |= ((offset * 8) & ((1 << 10) - 1));
       __glapi_sparc_icache_flush(&code[6]);
    #else /* __arch64__ */
       code[2] = 0xc6006000;  /* ld		[%g1 + %lo(4*glapioffset)], %g3	  */
       code[2] |= (offset * 4);
       __glapi_sparc_icache_flush(&code[2]);
    #endif /* __arch64__ */
    
    #else
    
       /* an unimplemented architecture */
       (void) entrypoint;
       (void) offset;
    
    #endif /* USE_*_ASM */
    }
    
    
    /**
     * 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;
       
       if (NumExtEntryPoints < MAX_EXTENSION_FUNCS) {
          _glapi_proc entrypoint = generate_entrypoint(~0);
          if (entrypoint != NULL) {
    	 entry = & ExtEntryTable[NumExtEntryPoints];
    
    	 ExtEntryTable[NumExtEntryPoints].name = str_dup(funcName);
    	 ExtEntryTable[NumExtEntryPoints].parameter_signature = NULL;
    	 ExtEntryTable[NumExtEntryPoints].dispatch_offset = ~0;
    	 ExtEntryTable[NumExtEntryPoints].dispatch_stub = entrypoint;
    	 NumExtEntryPoints++;
          }
       }
    
       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].
     *
     * \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.
     */
    
    PUBLIC int
    _glapi_add_dispatch( const char * const * function_names,
    		     const char * parameter_signature )
    {
       static int next_dynamic_offset = _gloffset_FIRST_DYNAMIC;
       const char * const real_sig = (parameter_signature != NULL)
         ? parameter_signature : "";
       struct _glapi_function * entry[8];
       GLboolean is_static[8];
       unsigned i;
       unsigned j;
       int offset = ~0;
       int new_offset;
    
    
       (void) memset( is_static, 0, sizeof( is_static ) );
       (void) memset( entry, 0, sizeof( entry ) );
    
       for ( i = 0 ; function_names[i] != NULL ; i++ ) {
          /* Do some trivial validation on the name of the function.
           */
    
          if (!function_names[i] || function_names[i][0] != 'g' || function_names[i][1] != 'l')
    	return GL_FALSE;
       
          /* Determine if the named function already exists.  If the function does
           * exist, it must have the same parameter signature as the function
           * being added.
           */
    
          new_offset = get_static_proc_offset(function_names[i]);
          if (new_offset >= 0) {
    	 /* FIXME: Make sure the parameter signatures match!  How do we get
    	  * FIXME: the parameter signature for static functions?
    	  */
    
    	 if ( (offset != ~0) && (new_offset != offset) ) {
    	    return -1;
    	 }
    
    	 is_static[i] = GL_TRUE;
    	 offset = new_offset;
          }
       
       
          for ( j = 0 ; j < NumExtEntryPoints ; j++ ) {
    	 if (strcmp(ExtEntryTable[j].name, function_names[i]) == 0) {
    	    /* The offset may be ~0 if the function name was added by
    	     * glXGetProcAddress but never filled in by the driver.
    	     */
    
    	    if (ExtEntryTable[j].dispatch_offset != ~0) {
    	       if (strcmp(real_sig, ExtEntryTable[j].parameter_signature) 
    		   != 0) {
    		  return -1;
    	       }
    
    	       if ( (offset != ~0) && (ExtEntryTable[j].dispatch_offset != offset) ) {
    		  return -1;
    	       }
    
    	       offset = ExtEntryTable[j].dispatch_offset;
    	    }
    	    
    	    entry[i] = & ExtEntryTable[j];
    	    break;
    	 }
          }
       }
    
       if (offset == ~0) {
          offset = next_dynamic_offset;
          next_dynamic_offset++;
       }
    
       for ( i = 0 ; function_names[i] != NULL ; i++ ) {
          if (! is_static[i] ) {
    	 if (entry[i] == NULL) {
    	    entry[i] = add_function_name( function_names[i] );
    	    if (entry[i] == NULL) {
    	       /* FIXME: Possible memory leak here.
    		*/
    	       return -1;
    	    }
    	 }
    
    	 entry[i]->parameter_signature = str_dup(real_sig);
    	 fill_in_entrypoint_offset(entry[i]->dispatch_stub, offset);
    	 entry[i]->dispatch_offset = offset;
          }
       }
       
       return offset;
    }
    
    
    /**
     * Return offset of entrypoint for named function within dispatch table.
     */
    PUBLIC GLint
    _glapi_get_proc_offset(const char *funcName)
    {
       /* search extension functions first */
       GLuint i;
       for (i = 0; i < NumExtEntryPoints; i++) {
          if (strcmp(ExtEntryTable[i].name, funcName) == 0) {
             return ExtEntryTable[i].dispatch_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)
    {
       struct _glapi_function * entry;
       GLuint i;
    
    #ifdef MANGLE
       if (funcName[0] != 'm' || funcName[1] != 'g' || funcName[2] != 'l')
          return NULL;
    #else
       if (funcName[0] != 'g' || funcName[1] != 'l')
          return NULL;
    #endif
    
       /* search extension functions first */
       for (i = 0; i < NumExtEntryPoints; i++) {
          if (strcmp(ExtEntryTable[i].name, funcName) == 0) {
             return ExtEntryTable[i].dispatch_stub;
          }
       }
    
    #if !defined( XFree86Server ) && !defined( XGLServer )
       /* search static functions */
       {
          const _glapi_proc func = get_static_proc_address(funcName);
          if (func)
             return func;
       }
    #endif /* !defined( XFree86Server ) */
    
       entry = add_function_name(funcName);
       return (entry == NULL) ? NULL : 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)
    {
       GLuint i;
       const char * n;
    
       /* search built-in functions */
       n = get_static_proc_name(offset);
       if ( n != NULL ) {
          return n;
       }
    
       /* search added extension functions */
       for (i = 0; i < NumExtEntryPoints; i++) {
          if (ExtEntryTable[i].dispatch_offset == offset) {
             return ExtEntryTable[i].name;
          }
       }
       return NULL;
    }
    
    
    
    /**
     * Return size of dispatch table struct as number of functions (or
     * slots).
     */
    PUBLIC GLuint
    _glapi_get_dispatch_table_size(void)
    {
       return DISPATCH_TABLE_SIZE;
    }
    
    
    
    /**
     * Make sure there are no NULL pointers in the given dispatch table.
     * Intended for debugging purposes.
     */
    void
    _glapi_check_table(const struct _glapi_table *table)
    {
    #ifdef 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]);
       }
    
       /* Do some spot checks to be sure that the dispatch table
        * slots are assigned correctly.
        */
       {
          GLuint BeginOffset = _glapi_get_proc_offset("glBegin");
          char *BeginFunc = (char*) &table->Begin;
          GLuint offset = (BeginFunc - (char *) table) / sizeof(void *);
          assert(BeginOffset == _gloffset_Begin);
          assert(BeginOffset == offset);
       }
       {
          GLuint viewportOffset = _glapi_get_proc_offset("glViewport");
          char *viewportFunc = (char*) &table->Viewport;
          GLuint offset = (viewportFunc - (char *) table) / sizeof(void *);
          assert(viewportOffset == _gloffset_Viewport);
          assert(viewportOffset == offset);
       }
       {
          GLuint VertexPointerOffset = _glapi_get_proc_offset("glVertexPointer");
          char *VertexPointerFunc = (char*) &table->VertexPointer;
          GLuint offset = (VertexPointerFunc - (char *) table) / sizeof(void *);
          assert(VertexPointerOffset == _gloffset_VertexPointer);
          assert(VertexPointerOffset == offset);
       }
       {
          GLuint ResetMinMaxOffset = _glapi_get_proc_offset("glResetMinmax");
          char *ResetMinMaxFunc = (char*) &table->ResetMinmax;
          GLuint offset = (ResetMinMaxFunc - (char *) table) / sizeof(void *);
          assert(ResetMinMaxOffset == _gloffset_ResetMinmax);
          assert(ResetMinMaxOffset == offset);
       }
       {
          GLuint blendColorOffset = _glapi_get_proc_offset("glBlendColor");
          char *blendColorFunc = (char*) &table->BlendColor;
          GLuint offset = (blendColorFunc - (char *) table) / sizeof(void *);
          assert(blendColorOffset == _gloffset_BlendColor);
          assert(blendColorOffset == offset);
       }
       {
          GLuint secondaryColor3fOffset = _glapi_get_proc_offset("glSecondaryColor3fEXT");
          char *secondaryColor3fFunc = (char*) &table->SecondaryColor3fEXT;
          GLuint offset = (secondaryColor3fFunc - (char *) table) / sizeof(void *);
          assert(secondaryColor3fOffset == _gloffset_SecondaryColor3fEXT);
          assert(secondaryColor3fOffset == offset);
       }
       {
          GLuint pointParameterivOffset = _glapi_get_proc_offset("glPointParameterivNV");
          char *pointParameterivFunc = (char*) &table->PointParameterivNV;
          GLuint offset = (pointParameterivFunc - (char *) table) / sizeof(void *);
          assert(pointParameterivOffset == _gloffset_PointParameterivNV);
          assert(pointParameterivOffset == offset);
       }
       {
          GLuint setFenceOffset = _glapi_get_proc_offset("glSetFenceNV");
          char *setFenceFunc = (char*) &table->SetFenceNV;
          GLuint offset = (setFenceFunc - (char *) table) / sizeof(void *);
          assert(setFenceOffset == _gloffset_SetFenceNV);
          assert(setFenceOffset == offset);
       }
    #else
       (void) table;
    #endif
    }
    
    
    #if defined(PTHREADS) || defined(GLX_USE_TLS)
    /**
     * Perform platform-specific GL API entry-point fixups.
     */
    static void
    init_glapi_relocs( void )
    {
    #if defined(USE_X86_ASM) && defined(GLX_USE_TLS) && !defined(GLX_X86_READONLY_TEXT)
        extern unsigned long _x86_get_dispatch(void);
        char run_time_patch[] = {
           0x65, 0xa1, 0, 0, 0, 0 /* movl %gs:0,%eax */
        };
        GLuint *offset = (GLuint *) &run_time_patch[2]; /* 32-bits for x86/32 */
        const GLubyte * const get_disp = (const GLubyte *) run_time_patch;
        GLubyte * curr_func = (GLubyte *) gl_dispatch_functions_start;
    
        *offset = _x86_get_dispatch();
        while ( curr_func != (GLubyte *) gl_dispatch_functions_end ) {
    	(void) memcpy( curr_func, get_disp, sizeof(run_time_patch));
    	curr_func += DISPATCH_FUNCTION_SIZE;
        }
    #endif
    }
    #endif /* defined(PTHREADS) || defined(GLX_USE_TLS) */