xref: /external/chromium_org/third_party/mesa/src/src/mesa/drivers/dri/common/utils.c

/*
 * (C) Copyright IBM Corporation 2002, 2004
 * 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
 * on the rights to use, copy, modify, merge, publish, distribute, sub
 * license, 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 (including the next
 * paragraph) 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 NON-INFRINGEMENT.  IN NO EVENT SHALL
 * VA LINUX SYSTEM, IBM AND/OR THEIR SUPPLIERS 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 utils.c
 * Utility functions for DRI drivers.
 *
 * \author Ian Romanick <idr@us.ibm.com>
 */

#include <string.h>
#include <stdlib.h>
#include "main/mtypes.h"
#include "main/cpuinfo.h"
#include "main/extensions.h"
#include "utils.h"


unsigned
driParseDebugString( const char * debug,
		     const struct dri_debug_control * control  )
{
   unsigned   flag;


   flag = 0;
   if ( debug != NULL ) {
      while( control->string != NULL ) {
	 if ( !strcmp( debug, "all" ) ||
	      strstr( debug, control->string ) != NULL ) {
	    flag |= control->flag;
	 }

	 control++;
      }
   }

   return flag;
}



/**
 * Create the \c GL_RENDERER string for DRI drivers.
 *
 * Almost all DRI drivers use a \c GL_RENDERER string of the form:
 *
 *    "Mesa DRI <chip> <driver date> <AGP speed) <CPU information>"
 *
 * Using the supplied chip name, driver data, and AGP speed, this function
 * creates the string.
 *
 * \param buffer         Buffer to hold the \c GL_RENDERER string.
 * \param hardware_name  Name of the hardware.
 * \param agp_mode       AGP mode (speed).
 *
 * \returns
 * The length of the string stored in \c buffer.  This does \b not include
 * the terminating \c NUL character.
 */
unsigned
driGetRendererString( char * buffer, const char * hardware_name,
		      GLuint agp_mode )
{
   unsigned offset;
   char *cpu;

   offset = sprintf( buffer, "Mesa DRI %s", hardware_name );

   /* Append any AGP-specific information.
    */
   switch ( agp_mode ) {
   case 1:
   case 2:
   case 4:
   case 8:
      offset += sprintf( & buffer[ offset ], " AGP %ux", agp_mode );
      break;

   default:
      break;
   }

   /* Append any CPU-specific information.
    */
   cpu = _mesa_get_cpu_string();
   if (cpu) {
      offset += sprintf(buffer + offset, " %s", cpu);
      free(cpu);
   }

   return offset;
}


/**
 * Creates a set of \c struct gl_config that a driver will expose.
 *
 * A set of \c struct gl_config will be created based on the supplied
 * parameters.  The number of modes processed will be 2 *
 * \c num_depth_stencil_bits * \c num_db_modes.
 *
 * For the most part, data is just copied from \c depth_bits, \c stencil_bits,
 * \c db_modes, and \c visType into each \c struct gl_config element.
 * However, the meanings of \c fb_format and \c fb_type require further
 * explanation.  The \c fb_format specifies which color components are in
 * each pixel and what the default order is.  For example, \c GL_RGB specifies
 * that red, green, blue are available and red is in the "most significant"
 * position and blue is in the "least significant".  The \c fb_type specifies
 * the bit sizes of each component and the actual ordering.  For example, if
 * \c GL_UNSIGNED_SHORT_5_6_5_REV is specified with \c GL_RGB, bits [15:11]
 * are the blue value, bits [10:5] are the green value, and bits [4:0] are
 * the red value.
 *
 * One sublte issue is the combination of \c GL_RGB  or \c GL_BGR and either
 * of the \c GL_UNSIGNED_INT_8_8_8_8 modes.  The resulting mask values in the
 * \c struct gl_config structure is \b identical to the \c GL_RGBA or
 * \c GL_BGRA case, except the \c alphaMask is zero.  This means that, as
 * far as this routine is concerned, \c GL_RGB with \c GL_UNSIGNED_INT_8_8_8_8
 * still uses 32-bits.
 *
 * If in doubt, look at the tables used in the function.
 *
 * \param ptr_to_modes  Pointer to a pointer to a linked list of
 *                      \c struct gl_config.  Upon completion, a pointer to
 *                      the next element to be process will be stored here.
 *                      If the function fails and returns \c GL_FALSE, this
 *                      value will be unmodified, but some elements in the
 *                      linked list may be modified.
 * \param fb_format     Format of the framebuffer.  Currently only \c GL_RGB,
 *                      \c GL_RGBA, \c GL_BGR, and \c GL_BGRA are supported.
 * \param fb_type       Type of the pixels in the framebuffer.  Currently only
 *                      \c GL_UNSIGNED_SHORT_5_6_5,
 *                      \c GL_UNSIGNED_SHORT_5_6_5_REV,
 *                      \c GL_UNSIGNED_INT_8_8_8_8, and
 *                      \c GL_UNSIGNED_INT_8_8_8_8_REV are supported.
 * \param depth_bits    Array of depth buffer sizes to be exposed.
 * \param stencil_bits  Array of stencil buffer sizes to be exposed.
 * \param num_depth_stencil_bits  Number of entries in both \c depth_bits and
 *                      \c stencil_bits.
 * \param db_modes      Array of buffer swap modes.  If an element has a
 *                      value of \c GLX_NONE, then it represents a
 *                      single-buffered mode.  Other valid values are
 *                      \c GLX_SWAP_EXCHANGE_OML, \c GLX_SWAP_COPY_OML, and
 *                      \c GLX_SWAP_UNDEFINED_OML.  See the
 *                      GLX_OML_swap_method extension spec for more details.
 * \param num_db_modes  Number of entries in \c db_modes.
 * \param msaa_samples  Array of msaa sample count. 0 represents a visual
 *                      without a multisample buffer.
 * \param num_msaa_modes Number of entries in \c msaa_samples.
 * \param visType       GLX visual type.  Usually either \c GLX_TRUE_COLOR or
 *                      \c GLX_DIRECT_COLOR.
 *
 * \returns
 * \c GL_TRUE on success or \c GL_FALSE on failure.  Currently the only
 * cause of failure is a bad parameter (i.e., unsupported \c fb_format or
 * \c fb_type).
 *
 * \todo
 * There is currently no way to support packed RGB modes (i.e., modes with
 * exactly 3 bytes per pixel) or floating-point modes.  This could probably
 * be done by creating some new, private enums with clever names likes
 * \c GL_UNSIGNED_3BYTE_8_8_8, \c GL_4FLOAT_32_32_32_32,
 * \c GL_4HALF_16_16_16_16, etc.  We can cross that bridge when we come to it.
 */
__DRIconfig **
driCreateConfigs(GLenum fb_format, GLenum fb_type,
		 const uint8_t * depth_bits, const uint8_t * stencil_bits,
		 unsigned num_depth_stencil_bits,
		 const GLenum * db_modes, unsigned num_db_modes,
		 const uint8_t * msaa_samples, unsigned num_msaa_modes,
		 GLboolean enable_accum)
{
   static const uint8_t bits_table[4][4] = {
     /* R  G  B  A */
      { 3, 3, 2, 0 }, /* Any GL_UNSIGNED_BYTE_3_3_2 */
      { 5, 6, 5, 0 }, /* Any GL_UNSIGNED_SHORT_5_6_5 */
      { 8, 8, 8, 0 }, /* Any RGB with any GL_UNSIGNED_INT_8_8_8_8 */
      { 8, 8, 8, 8 }  /* Any RGBA with any GL_UNSIGNED_INT_8_8_8_8 */
   };

   static const uint32_t masks_table_rgb[6][4] = {
      { 0x000000E0, 0x0000001C, 0x00000003, 0x00000000 }, /* 3_3_2       */
      { 0x00000007, 0x00000038, 0x000000C0, 0x00000000 }, /* 2_3_3_REV   */
      { 0x0000F800, 0x000007E0, 0x0000001F, 0x00000000 }, /* 5_6_5       */
      { 0x0000001F, 0x000007E0, 0x0000F800, 0x00000000 }, /* 5_6_5_REV   */
      { 0xFF000000, 0x00FF0000, 0x0000FF00, 0x00000000 }, /* 8_8_8_8     */
      { 0x000000FF, 0x0000FF00, 0x00FF0000, 0x00000000 }  /* 8_8_8_8_REV */
   };

   static const uint32_t masks_table_rgba[6][4] = {
      { 0x000000E0, 0x0000001C, 0x00000003, 0x00000000 }, /* 3_3_2       */
      { 0x00000007, 0x00000038, 0x000000C0, 0x00000000 }, /* 2_3_3_REV   */
      { 0x0000F800, 0x000007E0, 0x0000001F, 0x00000000 }, /* 5_6_5       */
      { 0x0000001F, 0x000007E0, 0x0000F800, 0x00000000 }, /* 5_6_5_REV   */
      { 0xFF000000, 0x00FF0000, 0x0000FF00, 0x000000FF }, /* 8_8_8_8     */
      { 0x000000FF, 0x0000FF00, 0x00FF0000, 0xFF000000 }, /* 8_8_8_8_REV */
   };

   static const uint32_t masks_table_bgr[6][4] = {
      { 0x00000007, 0x00000038, 0x000000C0, 0x00000000 }, /* 3_3_2       */
      { 0x000000E0, 0x0000001C, 0x00000003, 0x00000000 }, /* 2_3_3_REV   */
      { 0x0000001F, 0x000007E0, 0x0000F800, 0x00000000 }, /* 5_6_5       */
      { 0x0000F800, 0x000007E0, 0x0000001F, 0x00000000 }, /* 5_6_5_REV   */
      { 0x0000FF00, 0x00FF0000, 0xFF000000, 0x00000000 }, /* 8_8_8_8     */
      { 0x00FF0000, 0x0000FF00, 0x000000FF, 0x00000000 }, /* 8_8_8_8_REV */
   };

   static const uint32_t masks_table_bgra[6][4] = {
      { 0x00000007, 0x00000038, 0x000000C0, 0x00000000 }, /* 3_3_2       */
      { 0x000000E0, 0x0000001C, 0x00000003, 0x00000000 }, /* 2_3_3_REV   */
      { 0x0000001F, 0x000007E0, 0x0000F800, 0x00000000 }, /* 5_6_5       */
      { 0x0000F800, 0x000007E0, 0x0000001F, 0x00000000 }, /* 5_6_5_REV   */
      { 0x0000FF00, 0x00FF0000, 0xFF000000, 0x000000FF }, /* 8_8_8_8     */
      { 0x00FF0000, 0x0000FF00, 0x000000FF, 0xFF000000 }, /* 8_8_8_8_REV */
   };

   static const uint8_t bytes_per_pixel[6] = {
      1, /* 3_3_2       */
      1, /* 2_3_3_REV   */
      2, /* 5_6_5       */
      2, /* 5_6_5_REV   */
      4, /* 8_8_8_8     */
      4  /* 8_8_8_8_REV */
   };

   const uint8_t  * bits;
   const uint32_t * masks;
   int index;
   __DRIconfig **configs, **c;
   struct gl_config *modes;
   unsigned i, j, k, h;
   unsigned num_modes;
   unsigned num_accum_bits = (enable_accum) ? 2 : 1;

   switch ( fb_type ) {
      case GL_UNSIGNED_BYTE_3_3_2:
	 index = 0;
	 break;
      case GL_UNSIGNED_BYTE_2_3_3_REV:
	 index = 1;
	 break;
      case GL_UNSIGNED_SHORT_5_6_5:
	 index = 2;
	 break;
      case GL_UNSIGNED_SHORT_5_6_5_REV:
	 index = 3;
	 break;
      case GL_UNSIGNED_INT_8_8_8_8:
	 index = 4;
	 break;
      case GL_UNSIGNED_INT_8_8_8_8_REV:
	 index = 5;
	 break;
      default:
	 fprintf( stderr, "[%s:%u] Unknown framebuffer type 0x%04x.\n",
               __FUNCTION__, __LINE__, fb_type );
	 return NULL;
   }


   /* Valid types are GL_UNSIGNED_SHORT_5_6_5 and GL_UNSIGNED_INT_8_8_8_8 and
    * the _REV versions.
    *
    * Valid formats are GL_RGBA, GL_RGB, and GL_BGRA.
    */

   switch ( fb_format ) {
      case GL_RGB:
         masks = masks_table_rgb[ index ];
         break;

      case GL_RGBA:
         masks = masks_table_rgba[ index ];
         break;

      case GL_BGR:
         masks = masks_table_bgr[ index ];
         break;

      case GL_BGRA:
         masks = masks_table_bgra[ index ];
         break;

      default:
         fprintf( stderr, "[%s:%u] Unknown framebuffer format 0x%04x.\n",
               __FUNCTION__, __LINE__, fb_format );
         return NULL;
   }

   switch ( bytes_per_pixel[ index ] ) {
      case 1:
	 bits = bits_table[0];
	 break;
      case 2:
	 bits = bits_table[1];
	 break;
      default:
	 bits = ((fb_format == GL_RGB) || (fb_format == GL_BGR))
	    ? bits_table[2]
	    : bits_table[3];
	 break;
   }

   num_modes = num_depth_stencil_bits * num_db_modes * num_accum_bits * num_msaa_modes;
   configs = calloc(1, (num_modes + 1) * sizeof *configs);
   if (configs == NULL)
       return NULL;

    c = configs;
    for ( k = 0 ; k < num_depth_stencil_bits ; k++ ) {
	for ( i = 0 ; i < num_db_modes ; i++ ) {
	    for ( h = 0 ; h < num_msaa_modes; h++ ) {
	    	for ( j = 0 ; j < num_accum_bits ; j++ ) {
		    *c = malloc (sizeof **c);
		    modes = &(*c)->modes;
		    c++;

		    memset(modes, 0, sizeof *modes);
		    modes->redBits   = bits[0];
		    modes->greenBits = bits[1];
		    modes->blueBits  = bits[2];
		    modes->alphaBits = bits[3];
		    modes->redMask   = masks[0];
		    modes->greenMask = masks[1];
		    modes->blueMask  = masks[2];
		    modes->alphaMask = masks[3];
		    modes->rgbBits   = modes->redBits + modes->greenBits
		    	+ modes->blueBits + modes->alphaBits;

		    modes->accumRedBits   = 16 * j;
		    modes->accumGreenBits = 16 * j;
		    modes->accumBlueBits  = 16 * j;
		    modes->accumAlphaBits = (masks[3] != 0) ? 16 * j : 0;
		    modes->visualRating = (j == 0) ? GLX_NONE : GLX_SLOW_CONFIG;

		    modes->stencilBits = stencil_bits[k];
		    modes->depthBits = depth_bits[k];

		    modes->transparentPixel = GLX_NONE;
		    modes->transparentRed = GLX_DONT_CARE;
		    modes->transparentGreen = GLX_DONT_CARE;
		    modes->transparentBlue = GLX_DONT_CARE;
		    modes->transparentAlpha = GLX_DONT_CARE;
		    modes->transparentIndex = GLX_DONT_CARE;
		    modes->rgbMode = GL_TRUE;

		    if ( db_modes[i] == GLX_NONE ) {
		    	modes->doubleBufferMode = GL_FALSE;
		    }
		    else {
		    	modes->doubleBufferMode = GL_TRUE;
		    	modes->swapMethod = db_modes[i];
		    }

		    modes->samples = msaa_samples[h];
		    modes->sampleBuffers = modes->samples ? 1 : 0;


		    modes->haveAccumBuffer = ((modes->accumRedBits +
					   modes->accumGreenBits +
					   modes->accumBlueBits +
					   modes->accumAlphaBits) > 0);
		    modes->haveDepthBuffer = (modes->depthBits > 0);
		    modes->haveStencilBuffer = (modes->stencilBits > 0);

		    modes->bindToTextureRgb = GL_TRUE;
		    modes->bindToTextureRgba = GL_TRUE;
		    modes->bindToMipmapTexture = GL_FALSE;
		    modes->bindToTextureTargets =
			__DRI_ATTRIB_TEXTURE_1D_BIT |
			__DRI_ATTRIB_TEXTURE_2D_BIT |
			__DRI_ATTRIB_TEXTURE_RECTANGLE_BIT;

		    modes->sRGBCapable = GL_FALSE;
		}
	    }
	}
    }
    *c = NULL;

    return configs;
}

__DRIconfig **driConcatConfigs(__DRIconfig **a,
			       __DRIconfig **b)
{
    __DRIconfig **all;
    int i, j, index;

    if (a == NULL || a[0] == NULL)
       return b;
    else if (b == NULL || b[0] == NULL)
       return a;

    i = 0;
    while (a[i] != NULL)
	i++;
    j = 0;
    while (b[j] != NULL)
	j++;

    all = malloc((i + j + 1) * sizeof *all);
    index = 0;
    for (i = 0; a[i] != NULL; i++)
	all[index++] = a[i];
    for (j = 0; b[j] != NULL; j++)
	all[index++] = b[j];
    all[index++] = NULL;

    free(a);
    free(b);

    return all;
}

#define __ATTRIB(attrib, field) \
    { attrib, offsetof(struct gl_config, field) }

static const struct { unsigned int attrib, offset; } attribMap[] = {
    __ATTRIB(__DRI_ATTRIB_BUFFER_SIZE,			rgbBits),
    __ATTRIB(__DRI_ATTRIB_LEVEL,			level),
    __ATTRIB(__DRI_ATTRIB_RED_SIZE,			redBits),
    __ATTRIB(__DRI_ATTRIB_GREEN_SIZE,			greenBits),
    __ATTRIB(__DRI_ATTRIB_BLUE_SIZE,			blueBits),
    __ATTRIB(__DRI_ATTRIB_ALPHA_SIZE,			alphaBits),
    __ATTRIB(__DRI_ATTRIB_DEPTH_SIZE,			depthBits),
    __ATTRIB(__DRI_ATTRIB_STENCIL_SIZE,			stencilBits),
    __ATTRIB(__DRI_ATTRIB_ACCUM_RED_SIZE,		accumRedBits),
    __ATTRIB(__DRI_ATTRIB_ACCUM_GREEN_SIZE,		accumGreenBits),
    __ATTRIB(__DRI_ATTRIB_ACCUM_BLUE_SIZE,		accumBlueBits),
    __ATTRIB(__DRI_ATTRIB_ACCUM_ALPHA_SIZE,		accumAlphaBits),
    __ATTRIB(__DRI_ATTRIB_SAMPLE_BUFFERS,		sampleBuffers),
    __ATTRIB(__DRI_ATTRIB_SAMPLES,			samples),
    __ATTRIB(__DRI_ATTRIB_DOUBLE_BUFFER,		doubleBufferMode),
    __ATTRIB(__DRI_ATTRIB_STEREO,			stereoMode),
    __ATTRIB(__DRI_ATTRIB_AUX_BUFFERS,			numAuxBuffers),
    __ATTRIB(__DRI_ATTRIB_TRANSPARENT_TYPE,		transparentPixel),
    __ATTRIB(__DRI_ATTRIB_TRANSPARENT_INDEX_VALUE,	transparentPixel),
    __ATTRIB(__DRI_ATTRIB_TRANSPARENT_RED_VALUE,	transparentRed),
    __ATTRIB(__DRI_ATTRIB_TRANSPARENT_GREEN_VALUE,	transparentGreen),
    __ATTRIB(__DRI_ATTRIB_TRANSPARENT_BLUE_VALUE,	transparentBlue),
    __ATTRIB(__DRI_ATTRIB_TRANSPARENT_ALPHA_VALUE,	transparentAlpha),
    __ATTRIB(__DRI_ATTRIB_FLOAT_MODE,			floatMode),
    __ATTRIB(__DRI_ATTRIB_RED_MASK,			redMask),
    __ATTRIB(__DRI_ATTRIB_GREEN_MASK,			greenMask),
    __ATTRIB(__DRI_ATTRIB_BLUE_MASK,			blueMask),
    __ATTRIB(__DRI_ATTRIB_ALPHA_MASK,			alphaMask),
    __ATTRIB(__DRI_ATTRIB_MAX_PBUFFER_WIDTH,		maxPbufferWidth),
    __ATTRIB(__DRI_ATTRIB_MAX_PBUFFER_HEIGHT,		maxPbufferHeight),
    __ATTRIB(__DRI_ATTRIB_MAX_PBUFFER_PIXELS,		maxPbufferPixels),
    __ATTRIB(__DRI_ATTRIB_OPTIMAL_PBUFFER_WIDTH,	optimalPbufferWidth),
    __ATTRIB(__DRI_ATTRIB_OPTIMAL_PBUFFER_HEIGHT,	optimalPbufferHeight),
    __ATTRIB(__DRI_ATTRIB_SWAP_METHOD,			swapMethod),
    __ATTRIB(__DRI_ATTRIB_BIND_TO_TEXTURE_RGB,		bindToTextureRgb),
    __ATTRIB(__DRI_ATTRIB_BIND_TO_TEXTURE_RGBA,		bindToTextureRgba),
    __ATTRIB(__DRI_ATTRIB_BIND_TO_MIPMAP_TEXTURE,	bindToMipmapTexture),
    __ATTRIB(__DRI_ATTRIB_BIND_TO_TEXTURE_TARGETS,	bindToTextureTargets),
    __ATTRIB(__DRI_ATTRIB_YINVERTED,			yInverted),
    __ATTRIB(__DRI_ATTRIB_FRAMEBUFFER_SRGB_CAPABLE,	sRGBCapable),

    /* The struct field doesn't matter here, these are handled by the
     * switch in driGetConfigAttribIndex.  We need them in the array
     * so the iterator includes them though.*/
    __ATTRIB(__DRI_ATTRIB_RENDER_TYPE,			level),
    __ATTRIB(__DRI_ATTRIB_CONFIG_CAVEAT,		level),
    __ATTRIB(__DRI_ATTRIB_SWAP_METHOD,			level)
};

#define ARRAY_SIZE(a) (sizeof (a) / sizeof ((a)[0]))


/**
 * Return the value of a configuration attribute.  The attribute is
 * indicated by the index.
 */
static int
driGetConfigAttribIndex(const __DRIconfig *config,
			unsigned int index, unsigned int *value)
{
    switch (attribMap[index].attrib) {
    case __DRI_ATTRIB_RENDER_TYPE:
        /* no support for color index mode */
	*value = __DRI_ATTRIB_RGBA_BIT;
	break;
    case __DRI_ATTRIB_CONFIG_CAVEAT:
	if (config->modes.visualRating == GLX_NON_CONFORMANT_CONFIG)
	    *value = __DRI_ATTRIB_NON_CONFORMANT_CONFIG;
	else if (config->modes.visualRating == GLX_SLOW_CONFIG)
	    *value = __DRI_ATTRIB_SLOW_BIT;
	else
	    *value = 0;
	break;
    case __DRI_ATTRIB_SWAP_METHOD:
        /* XXX no return value??? */
	break;

    case __DRI_ATTRIB_FLOAT_MODE:
        /* this field is not int-sized */
        *value = config->modes.floatMode;
        break;

    default:
        /* any other int-sized field */
	*value = *(unsigned int *)
	    ((char *) &config->modes + attribMap[index].offset);

	break;
    }

    return GL_TRUE;
}


/**
 * Get the value of a configuration attribute.
 * \param attrib  the attribute (one of the _DRI_ATTRIB_x tokens)
 * \param value  returns the attribute's value
 * \return 1 for success, 0 for failure
 */
int
driGetConfigAttrib(const __DRIconfig *config,
		   unsigned int attrib, unsigned int *value)
{
    int i;

    for (i = 0; i < ARRAY_SIZE(attribMap); i++)
	if (attribMap[i].attrib == attrib)
	    return driGetConfigAttribIndex(config, i, value);

    return GL_FALSE;
}


/**
 * Get a configuration attribute name and value, given an index.
 * \param index  which field of the __DRIconfig to query
 * \param attrib  returns the attribute name (one of the _DRI_ATTRIB_x tokens)
 * \param value  returns the attribute's value
 * \return 1 for success, 0 for failure
 */
int
driIndexConfigAttrib(const __DRIconfig *config, int index,
		     unsigned int *attrib, unsigned int *value)
{
    if (index >= 0 && index < ARRAY_SIZE(attribMap)) {
	*attrib = attribMap[index].attrib;
	return driGetConfigAttribIndex(config, index, value);
    }

    return GL_FALSE;
}