path: root/src/mesa/state_tracker/st_format.c

/**************************************************************************
 * 
 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
 * Copyright (c) 2008 VMware, Inc.
 * 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, 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 TUNGSTEN GRAPHICS AND/OR ITS 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.
 * 
 **************************************************************************/


/**
 * Texture Image-related functions.
 * \author Brian Paul
 */

#include "main/imports.h"
#include "main/context.h"
#include "main/texstore.h"
#include "main/enums.h"
#include "main/macros.h"

#include "pipe/p_context.h"
#include "pipe/p_defines.h"
#include "pipe/p_screen.h"
#include "st_context.h"
#include "st_format.h"

static GLuint
format_bits(
   pipe_format_rgbazs_t  info,
   GLuint comp )
{
   return pf_get_component_bits( (enum pipe_format) info, comp );
}

static GLuint
format_max_bits(
   pipe_format_rgbazs_t  info )
{
   GLuint   size = format_bits( info, PIPE_FORMAT_COMP_R );

   size = MAX2( size, format_bits( info, PIPE_FORMAT_COMP_G ) );
   size = MAX2( size, format_bits( info, PIPE_FORMAT_COMP_B ) );
   size = MAX2( size, format_bits( info, PIPE_FORMAT_COMP_A ) );
   size = MAX2( size, format_bits( info, PIPE_FORMAT_COMP_Z ) );
   size = MAX2( size, format_bits( info, PIPE_FORMAT_COMP_S ) );
   return size;
}

static GLuint
format_size(
   pipe_format_rgbazs_t  info )
{
   return
      format_bits( info, PIPE_FORMAT_COMP_R ) +
      format_bits( info, PIPE_FORMAT_COMP_G ) +
      format_bits( info, PIPE_FORMAT_COMP_B ) +
      format_bits( info, PIPE_FORMAT_COMP_A ) +
      format_bits( info, PIPE_FORMAT_COMP_Z ) +
      format_bits( info, PIPE_FORMAT_COMP_S );
}

/*
 * XXX temporary here
 */
GLboolean
st_get_format_info(enum pipe_format format, struct pipe_format_info *pinfo)
{
   if (pf_layout(format) == PIPE_FORMAT_LAYOUT_RGBAZS) {
      pipe_format_rgbazs_t info;

      info = format;

#if 0
      printf("%s\n", pf_name( format ) );
#endif

      /* Data type */
      if (format == PIPE_FORMAT_A1R5G5B5_UNORM || format == PIPE_FORMAT_R5G6B5_UNORM) {
         pinfo->datatype = GL_UNSIGNED_SHORT;
      }
      else if (format == PIPE_FORMAT_S8Z24_UNORM ||
               format == PIPE_FORMAT_Z24S8_UNORM) {
         pinfo->datatype = GL_UNSIGNED_INT_24_8;
      }
      else {
         const GLuint size = format_max_bits( info );
         if (size == 8) {
            if (pf_type(info) == PIPE_FORMAT_TYPE_UNORM)
               pinfo->datatype = GL_UNSIGNED_BYTE;
            else
               pinfo->datatype = GL_BYTE;
         }
         else if (size == 16) {
            if (pf_type(info) == PIPE_FORMAT_TYPE_UNORM)
               pinfo->datatype = GL_UNSIGNED_SHORT;
            else
               pinfo->datatype = GL_SHORT;
         }
         else {
            assert( size <= 32 );
            if (pf_type(info) == PIPE_FORMAT_TYPE_UNORM)
               pinfo->datatype = GL_UNSIGNED_INT;
            else
               pinfo->datatype = GL_INT;
         }
      }

      /* Component bits */
      pinfo->red_bits = format_bits( info, PIPE_FORMAT_COMP_R );
      pinfo->green_bits = format_bits( info, PIPE_FORMAT_COMP_G );
      pinfo->blue_bits = format_bits( info, PIPE_FORMAT_COMP_B );
      pinfo->alpha_bits = format_bits( info, PIPE_FORMAT_COMP_A );
      pinfo->depth_bits = format_bits( info, PIPE_FORMAT_COMP_Z );
      pinfo->stencil_bits = format_bits( info, PIPE_FORMAT_COMP_S );
      pinfo->luminance_bits = 0;
      pinfo->intensity_bits = 0;

      /* Format size */
      pinfo->size = format_size( info ) / 8;

      /* Luminance & Intensity bits */
      if( pf_swizzle_x(info) == PIPE_FORMAT_COMP_R &&
          pf_swizzle_y(info) == PIPE_FORMAT_COMP_R &&
          pf_swizzle_z(info) == PIPE_FORMAT_COMP_R ) {
         if( pf_swizzle_w(info) == PIPE_FORMAT_COMP_R ) {
            pinfo->intensity_bits = pinfo->red_bits;
         }
         else {
            pinfo->luminance_bits = pinfo->red_bits;
         }
         pinfo->red_bits = 0;
      }

      pinfo->mesa_format = st_pipe_format_to_mesa_format(format);
   }
   else if (pf_layout(format) == PIPE_FORMAT_LAYOUT_YCBCR) {
      pinfo->mesa_format = MESA_FORMAT_YCBCR;
      pinfo->datatype = GL_UNSIGNED_SHORT;
      pinfo->size = 2; /* two bytes per "texel" */
   }
   else {
      /* compressed format? */
      assert(0);
   }

#if 0
   printf(
      "ST_FORMAT: R(%u), G(%u), B(%u), A(%u), Z(%u), S(%u)\n",
      pinfo->red_bits,
      pinfo->green_bits,
      pinfo->blue_bits,
      pinfo->alpha_bits,
      pinfo->depth_bits,
      pinfo->stencil_bits );
#endif

   pinfo->format = format;

   return GL_TRUE;
}


/**
 * Return bytes per pixel for the given format.
 */
GLuint
st_sizeof_format(enum pipe_format format)
{
   struct pipe_format_info info;
   if (!st_get_format_info( format, &info )) {
      assert( 0 );
      return 0;
   }
   return info.size;
}


/**
 * Return bytes per pixel for the given format.
 */
GLenum
st_format_datatype(enum pipe_format format)
{
   struct pipe_format_info info;
   if (!st_get_format_info( format, &info )) {
      assert( 0 );
      return 0;
   }
   return info.datatype;
}


enum pipe_format
st_mesa_format_to_pipe_format(gl_format mesaFormat)
{
   switch (mesaFormat) {
      /* fix this */
   case MESA_FORMAT_ARGB8888_REV:
   case MESA_FORMAT_ARGB8888:
      return PIPE_FORMAT_A8R8G8B8_UNORM;
   case MESA_FORMAT_XRGB8888:
      return PIPE_FORMAT_X8R8G8B8_UNORM;
   case MESA_FORMAT_ARGB1555:
      return PIPE_FORMAT_A1R5G5B5_UNORM;
   case MESA_FORMAT_ARGB4444:
      return PIPE_FORMAT_A4R4G4B4_UNORM;
   case MESA_FORMAT_RGB565:
      return PIPE_FORMAT_R5G6B5_UNORM;
   case MESA_FORMAT_AL88:
      return PIPE_FORMAT_A8L8_UNORM;
   case MESA_FORMAT_A8:
      return PIPE_FORMAT_A8_UNORM;
   case MESA_FORMAT_L8:
      return PIPE_FORMAT_L8_UNORM;
   case MESA_FORMAT_I8:
      return PIPE_FORMAT_I8_UNORM;
   case MESA_FORMAT_Z16:
      return PIPE_FORMAT_Z16_UNORM;
   case MESA_FORMAT_Z32:
      return PIPE_FORMAT_Z32_UNORM;
   case MESA_FORMAT_Z24_S8:
      return PIPE_FORMAT_Z24S8_UNORM;
   case MESA_FORMAT_S8_Z24:
      return PIPE_FORMAT_S8Z24_UNORM;
   case MESA_FORMAT_YCBCR:
      return PIPE_FORMAT_YCBCR;
#if FEATURE_texture_s3tc
   case MESA_FORMAT_RGB_DXT1:
      return PIPE_FORMAT_DXT1_RGB;
   case MESA_FORMAT_RGBA_DXT1:
      return PIPE_FORMAT_DXT1_RGBA;
   case MESA_FORMAT_RGBA_DXT3:
      return PIPE_FORMAT_DXT3_RGBA;
   case MESA_FORMAT_RGBA_DXT5:
      return PIPE_FORMAT_DXT5_RGBA;
#if FEATURE_EXT_texture_sRGB
   case MESA_FORMAT_SRGB_DXT1:
      return PIPE_FORMAT_DXT1_SRGB;
   case MESA_FORMAT_SRGBA_DXT1:
      return PIPE_FORMAT_DXT1_SRGBA;
   case MESA_FORMAT_SRGBA_DXT3:
      return PIPE_FORMAT_DXT3_SRGBA;
   case MESA_FORMAT_SRGBA_DXT5:
      return PIPE_FORMAT_DXT5_SRGBA;
#endif
#endif
#if FEATURE_EXT_texture_sRGB
   case MESA_FORMAT_SLA8:
      return PIPE_FORMAT_A8L8_SRGB;
   case MESA_FORMAT_SL8:
      return PIPE_FORMAT_L8_SRGB;
   case MESA_FORMAT_SRGB8:
      return PIPE_FORMAT_R8G8B8_SRGB;
   case MESA_FORMAT_SRGBA8:
      return PIPE_FORMAT_R8G8B8A8_SRGB;
   case MESA_FORMAT_SARGB8:
      return PIPE_FORMAT_A8R8G8B8_SRGB;
#endif
   default:
      assert(0);
      return 0;
   }
}


gl_format
st_pipe_format_to_mesa_format(enum pipe_format pipeFormat)
{
   switch (pipeFormat) {
   case PIPE_FORMAT_A8R8G8B8_UNORM:
      return MESA_FORMAT_ARGB8888;
   case PIPE_FORMAT_X8R8G8B8_UNORM:
      return MESA_FORMAT_XRGB8888;
   case PIPE_FORMAT_B8G8R8A8_UNORM:
      return MESA_FORMAT_ARGB8888_REV;
   case PIPE_FORMAT_B8G8R8X8_UNORM:
      return MESA_FORMAT_XRGB8888_REV;
   case PIPE_FORMAT_A1R5G5B5_UNORM:
      return MESA_FORMAT_ARGB1555;
   case PIPE_FORMAT_A4R4G4B4_UNORM:
      return MESA_FORMAT_ARGB4444;
   case PIPE_FORMAT_R5G6B5_UNORM:
      return MESA_FORMAT_RGB565;
   case PIPE_FORMAT_A8L8_UNORM:
      return MESA_FORMAT_AL88;
   case PIPE_FORMAT_A8_UNORM:
      return MESA_FORMAT_A8;
   case PIPE_FORMAT_L8_UNORM:
      return MESA_FORMAT_L8;
   case PIPE_FORMAT_I8_UNORM:
      return MESA_FORMAT_I8;
   case PIPE_FORMAT_Z16_UNORM:
      return MESA_FORMAT_Z16;
   case PIPE_FORMAT_Z32_UNORM:
      return MESA_FORMAT_Z32;
   case PIPE_FORMAT_Z24X8_UNORM:
      return MESA_FORMAT_Z24_X8;
   case PIPE_FORMAT_Z24S8_UNORM:
      return MESA_FORMAT_Z24_S8;
   case PIPE_FORMAT_X8Z24_UNORM:
      return MESA_FORMAT_X8_Z24;
   case PIPE_FORMAT_S8Z24_UNORM:
      return MESA_FORMAT_S8_Z24;
   case PIPE_FORMAT_S8_UNORM:
      return MESA_FORMAT_S8;

   case PIPE_FORMAT_YCBCR:
      return MESA_FORMAT_YCBCR;
   case PIPE_FORMAT_R16G16B16A16_SNORM:
      return MESA_FORMAT_SIGNED_RGBA_16;

#if FEATURE_texture_s3tc
   case PIPE_FORMAT_DXT1_RGB:
      return MESA_FORMAT_RGB_DXT1;
   case PIPE_FORMAT_DXT1_RGBA:
      return MESA_FORMAT_RGBA_DXT1;
   case PIPE_FORMAT_DXT3_RGBA:
      return MESA_FORMAT_RGBA_DXT3;
   case PIPE_FORMAT_DXT5_RGBA:
      return MESA_FORMAT_RGBA_DXT5;
#if FEATURE_EXT_texture_sRGB
   case PIPE_FORMAT_DXT1_SRGB:
      return MESA_FORMAT_SRGB_DXT1;
   case PIPE_FORMAT_DXT1_SRGBA:
      return MESA_FORMAT_SRGBA_DXT1;
   case PIPE_FORMAT_DXT3_SRGBA:
      return MESA_FORMAT_SRGBA_DXT3;
   case PIPE_FORMAT_DXT5_SRGBA:
      return MESA_FORMAT_SRGBA_DXT5;
#endif
#endif
#if FEATURE_EXT_texture_sRGB
   case PIPE_FORMAT_A8L8_SRGB:
      return MESA_FORMAT_SLA8;
   case PIPE_FORMAT_L8_SRGB:
      return MESA_FORMAT_SL8;
   case PIPE_FORMAT_R8G8B8_SRGB:
      return MESA_FORMAT_SRGB8;
   case PIPE_FORMAT_R8G8B8A8_SRGB:
      return MESA_FORMAT_SRGBA8;
   case PIPE_FORMAT_A8R8G8B8_SRGB:
      return MESA_FORMAT_SARGB8;
#endif
   default:
      assert(0);
      return 0;
   }
}


/**
 * Find an RGBA format supported by the context/winsys.
 */
static enum pipe_format
default_rgba_format(struct pipe_screen *screen, 
                    enum pipe_texture_target target,
                    unsigned tex_usage, 
                    unsigned geom_flags)
{
   static const enum pipe_format colorFormats[] = {
      PIPE_FORMAT_A8R8G8B8_UNORM,
      PIPE_FORMAT_B8G8R8A8_UNORM,
      PIPE_FORMAT_R8G8B8A8_UNORM,
      PIPE_FORMAT_R5G6B5_UNORM
   };
   uint i;
   for (i = 0; i < Elements(colorFormats); i++) {
      if (screen->is_format_supported( screen, colorFormats[i], target, tex_usage, geom_flags )) {
         return colorFormats[i];
      }
   }
   return PIPE_FORMAT_NONE;
}

/**
 * Find an sRGBA format supported by the context/winsys.
 */
static enum pipe_format
default_srgba_format(struct pipe_screen *screen, 
                    enum pipe_texture_target target,
                    unsigned tex_usage, 
                    unsigned geom_flags)
{
   static const enum pipe_format colorFormats[] = {
      PIPE_FORMAT_A8R8G8B8_SRGB,
      PIPE_FORMAT_B8G8R8A8_SRGB,
      PIPE_FORMAT_R8G8B8A8_SRGB,
   };
   uint i;
   for (i = 0; i < Elements(colorFormats); i++) {
      if (screen->is_format_supported( screen, colorFormats[i], target, tex_usage, geom_flags )) {
         return colorFormats[i];
      }
   }
   return PIPE_FORMAT_NONE;
}

/**
 * Search list of formats for first RGBA format with >8 bits/channel.
 */
static enum pipe_format
default_deep_rgba_format(struct pipe_screen *screen, 
                         enum pipe_texture_target target,
                         unsigned tex_usage, 
                         unsigned geom_flags)
{
   if (screen->is_format_supported(screen, PIPE_FORMAT_R16G16B16A16_SNORM, target, tex_usage, geom_flags)) {
      return PIPE_FORMAT_R16G16B16A16_SNORM;
   }
   if (tex_usage & PIPE_TEXTURE_USAGE_RENDER_TARGET)
      return default_rgba_format(screen, target, tex_usage, geom_flags);
   else
      return PIPE_FORMAT_NONE;
}


/**
 * Find an Z format supported by the context/winsys.
 */
static enum pipe_format
default_depth_format(struct pipe_screen *screen, 
                     enum pipe_texture_target target,
                     unsigned tex_usage, 
                     unsigned geom_flags)
{
   static const enum pipe_format zFormats[] = {
      PIPE_FORMAT_Z16_UNORM,
      PIPE_FORMAT_Z32_UNORM,
      PIPE_FORMAT_S8Z24_UNORM,
      PIPE_FORMAT_Z24S8_UNORM
   };
   uint i;
   for (i = 0; i < Elements(zFormats); i++) {
      if (screen->is_format_supported( screen, zFormats[i], target, tex_usage, geom_flags )) {
         return zFormats[i];
      }
   }
   return PIPE_FORMAT_NONE;
}


/**
 * Given an OpenGL internalFormat value for a texture or surface, return
 * the best matching PIPE_FORMAT_x, or PIPE_FORMAT_NONE if there's no match.
 * \param target  one of PIPE_TEXTURE_x
 * \param tex_usage  either PIPE_TEXTURE_USAGE_RENDER_TARGET
 *                   or PIPE_TEXTURE_USAGE_SAMPLER
 */
enum pipe_format
st_choose_format(struct pipe_screen *screen, GLenum internalFormat,
                 enum pipe_texture_target target, unsigned tex_usage)
{
   unsigned geom_flags = 0;

   switch (internalFormat) {
   case 4:
   case GL_RGBA:
   case GL_COMPRESSED_RGBA:
   case 3:
   case GL_RGB:
   case GL_COMPRESSED_RGB:
   case GL_RGBA8:
   case GL_RGB10_A2:
   case GL_RGBA12:
      return default_rgba_format( screen, target, tex_usage, geom_flags );
   case GL_RGBA16:
      if (tex_usage & PIPE_TEXTURE_USAGE_RENDER_TARGET)
         return default_deep_rgba_format( screen, target, tex_usage, geom_flags );
      else
         return default_rgba_format( screen, target, tex_usage, geom_flags );

   case GL_RGBA4:
   case GL_RGBA2:
      if (screen->is_format_supported( screen, PIPE_FORMAT_A4R4G4B4_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_A4R4G4B4_UNORM;
      return default_rgba_format( screen, target, tex_usage, geom_flags );

   case GL_RGB5_A1:
      if (screen->is_format_supported( screen, PIPE_FORMAT_A1R5G5B5_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_A1R5G5B5_UNORM;
      return default_rgba_format( screen, target, tex_usage, geom_flags );

   case GL_RGB8:
   case GL_RGB10:
   case GL_RGB12:
   case GL_RGB16:
      return default_rgba_format( screen, target, tex_usage, geom_flags );

   case GL_RGB5:
   case GL_RGB4:
   case GL_R3_G3_B2:
      if (screen->is_format_supported( screen, PIPE_FORMAT_R5G6B5_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_R5G6B5_UNORM;
      if (screen->is_format_supported( screen, PIPE_FORMAT_A1R5G5B5_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_A1R5G5B5_UNORM;
      return default_rgba_format( screen, target, tex_usage, geom_flags );

   case GL_ALPHA:
   case GL_ALPHA4:
   case GL_ALPHA8:
   case GL_ALPHA12:
   case GL_ALPHA16:
   case GL_COMPRESSED_ALPHA:
      if (screen->is_format_supported( screen, PIPE_FORMAT_A8_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_A8_UNORM;
      return default_rgba_format( screen, target, tex_usage, geom_flags );

   case 1:
   case GL_LUMINANCE:
   case GL_LUMINANCE4:
   case GL_LUMINANCE8:
   case GL_LUMINANCE12:
   case GL_LUMINANCE16:
   case GL_COMPRESSED_LUMINANCE:
      if (screen->is_format_supported( screen, PIPE_FORMAT_L8_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_L8_UNORM;
      return default_rgba_format( screen, target, tex_usage, geom_flags );

   case 2:
   case GL_LUMINANCE_ALPHA:
   case GL_LUMINANCE4_ALPHA4:
   case GL_LUMINANCE6_ALPHA2:
   case GL_LUMINANCE8_ALPHA8:
   case GL_LUMINANCE12_ALPHA4:
   case GL_LUMINANCE12_ALPHA12:
   case GL_LUMINANCE16_ALPHA16:
   case GL_COMPRESSED_LUMINANCE_ALPHA:
      if (screen->is_format_supported( screen, PIPE_FORMAT_A8L8_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_A8L8_UNORM;
      return default_rgba_format( screen, target, tex_usage, geom_flags );

   case GL_INTENSITY:
   case GL_INTENSITY4:
   case GL_INTENSITY8:
   case GL_INTENSITY12:
   case GL_INTENSITY16:
   case GL_COMPRESSED_INTENSITY:
      if (screen->is_format_supported( screen, PIPE_FORMAT_I8_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_I8_UNORM;
      return default_rgba_format( screen, target, tex_usage, geom_flags );

   case GL_YCBCR_MESA:
      if (screen->is_format_supported(screen, PIPE_FORMAT_YCBCR,
                                      target, tex_usage, geom_flags)) {
         return PIPE_FORMAT_YCBCR;
      }
      if (screen->is_format_supported(screen, PIPE_FORMAT_YCBCR_REV,
                                      target, tex_usage, geom_flags)) {
         return PIPE_FORMAT_YCBCR_REV;
      }
      return PIPE_FORMAT_NONE;

   case GL_RGB_S3TC:
   case GL_RGB4_S3TC:
   case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
      return PIPE_FORMAT_DXT1_RGB;

   case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
      return PIPE_FORMAT_DXT1_RGBA;

   case GL_RGBA_S3TC:
   case GL_RGBA4_S3TC:
   case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
      return PIPE_FORMAT_DXT3_RGBA;

   case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
      return PIPE_FORMAT_DXT5_RGBA;

#if 0
   case GL_COMPRESSED_RGB_FXT1_3DFX:
      return PIPE_FORMAT_RGB_FXT1;
   case GL_COMPRESSED_RGBA_FXT1_3DFX:
      return PIPE_FORMAT_RGB_FXT1;
#endif

   case GL_DEPTH_COMPONENT16:
      if (screen->is_format_supported( screen, PIPE_FORMAT_Z16_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_Z16_UNORM;
      /* fall-through */
   case GL_DEPTH_COMPONENT24:
      if (screen->is_format_supported( screen, PIPE_FORMAT_S8Z24_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_S8Z24_UNORM;
      if (screen->is_format_supported( screen, PIPE_FORMAT_Z24S8_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_Z24S8_UNORM;
      /* fall-through */
   case GL_DEPTH_COMPONENT32:
      if (screen->is_format_supported( screen, PIPE_FORMAT_Z32_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_Z32_UNORM;
      /* fall-through */
   case GL_DEPTH_COMPONENT:
      return default_depth_format( screen, target, tex_usage, geom_flags );

   case GL_STENCIL_INDEX:
   case GL_STENCIL_INDEX1_EXT:
   case GL_STENCIL_INDEX4_EXT:
   case GL_STENCIL_INDEX8_EXT:
   case GL_STENCIL_INDEX16_EXT:
      if (screen->is_format_supported( screen, PIPE_FORMAT_S8_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_S8_UNORM;
      if (screen->is_format_supported( screen, PIPE_FORMAT_S8Z24_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_S8Z24_UNORM;
      if (screen->is_format_supported( screen, PIPE_FORMAT_Z24S8_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_Z24S8_UNORM;
      return PIPE_FORMAT_NONE;

   case GL_DEPTH_STENCIL_EXT:
   case GL_DEPTH24_STENCIL8_EXT:
      if (screen->is_format_supported( screen, PIPE_FORMAT_S8Z24_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_S8Z24_UNORM;
      if (screen->is_format_supported( screen, PIPE_FORMAT_Z24S8_UNORM, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_Z24S8_UNORM;
      return PIPE_FORMAT_NONE;

   case GL_SRGB_EXT:
   case GL_SRGB8_EXT:
   case GL_COMPRESSED_SRGB_EXT:
   case GL_COMPRESSED_SRGB_ALPHA_EXT:
   case GL_SRGB_ALPHA_EXT:
   case GL_SRGB8_ALPHA8_EXT:
      return default_srgba_format( screen, target, tex_usage, geom_flags );
   case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
      return PIPE_FORMAT_DXT1_SRGB;
   case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT:
      return PIPE_FORMAT_DXT1_SRGBA;
   case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT:
      return PIPE_FORMAT_DXT3_SRGBA;
   case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT:
      return PIPE_FORMAT_DXT5_SRGBA;

   case GL_SLUMINANCE_ALPHA_EXT:
   case GL_SLUMINANCE8_ALPHA8_EXT:
   case GL_COMPRESSED_SLUMINANCE_EXT:
   case GL_COMPRESSED_SLUMINANCE_ALPHA_EXT:
      if (screen->is_format_supported( screen, PIPE_FORMAT_A8L8_SRGB, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_A8L8_SRGB;
      return default_srgba_format( screen, target, tex_usage, geom_flags );

   case GL_SLUMINANCE_EXT:
   case GL_SLUMINANCE8_EXT:
      if (screen->is_format_supported( screen, PIPE_FORMAT_L8_SRGB, target, tex_usage, geom_flags ))
         return PIPE_FORMAT_L8_SRGB;
      return default_srgba_format( screen, target, tex_usage, geom_flags );

   default:
      return PIPE_FORMAT_NONE;
   }
}


static GLboolean
is_depth_or_stencil_format(GLenum internalFormat)
{
   switch (internalFormat) {
   case GL_DEPTH_COMPONENT:
   case GL_DEPTH_COMPONENT16:
   case GL_DEPTH_COMPONENT24:
   case GL_DEPTH_COMPONENT32:
   case GL_STENCIL_INDEX:
   case GL_STENCIL_INDEX1_EXT:
   case GL_STENCIL_INDEX4_EXT:
   case GL_STENCIL_INDEX8_EXT:
   case GL_STENCIL_INDEX16_EXT:
   case GL_DEPTH_STENCIL_EXT:
   case GL_DEPTH24_STENCIL8_EXT:
      return GL_TRUE;
   default:
      return GL_FALSE;
   }
}

/**
 * Called by FBO code to choose a PIPE_FORMAT_ for drawing surfaces.
 */
enum pipe_format
st_choose_renderbuffer_format(struct pipe_screen *screen,
                              GLenum internalFormat)
{
   uint usage;
   if (is_depth_or_stencil_format(internalFormat))
      usage = PIPE_TEXTURE_USAGE_DEPTH_STENCIL;
   else
      usage = PIPE_TEXTURE_USAGE_RENDER_TARGET;
   return st_choose_format(screen, internalFormat, PIPE_TEXTURE_2D, usage);
}


static gl_format
translate_gallium_format_to_mesa_format(enum pipe_format format)
{
   switch (format) {
   case PIPE_FORMAT_A8R8G8B8_UNORM:
      return MESA_FORMAT_ARGB8888;
   case PIPE_FORMAT_X8R8G8B8_UNORM:
      return MESA_FORMAT_XRGB8888;
   case PIPE_FORMAT_A1R5G5B5_UNORM:
      return MESA_FORMAT_ARGB1555;
   case PIPE_FORMAT_A4R4G4B4_UNORM:
      return MESA_FORMAT_ARGB4444;
   case PIPE_FORMAT_R5G6B5_UNORM:
      return MESA_FORMAT_RGB565;
   case PIPE_FORMAT_A8L8_UNORM:
      return MESA_FORMAT_AL88;
   case PIPE_FORMAT_A8_UNORM:
      return MESA_FORMAT_A8;
   case PIPE_FORMAT_L8_UNORM:
      return MESA_FORMAT_L8;
   case PIPE_FORMAT_I8_UNORM:
      return MESA_FORMAT_I8;
   case PIPE_FORMAT_Z16_UNORM:
      return MESA_FORMAT_Z16;
   case PIPE_FORMAT_Z32_UNORM:
      return MESA_FORMAT_Z32;
   case PIPE_FORMAT_Z24S8_UNORM:
      return MESA_FORMAT_Z24_S8;
   case PIPE_FORMAT_X8Z24_UNORM:
      return MESA_FORMAT_X8_Z24;
   case PIPE_FORMAT_S8Z24_UNORM:
      return MESA_FORMAT_S8_Z24;
   case PIPE_FORMAT_YCBCR:
      return MESA_FORMAT_YCBCR;
   case PIPE_FORMAT_YCBCR_REV:
      return MESA_FORMAT_YCBCR_REV;
#if FEATURE_texture_s3tc
   case PIPE_FORMAT_DXT1_RGB:
      return MESA_FORMAT_RGB_DXT1;
   case PIPE_FORMAT_DXT1_RGBA:
      return MESA_FORMAT_RGBA_DXT1;
   case PIPE_FORMAT_DXT3_RGBA:
      return MESA_FORMAT_RGBA_DXT3;
   case PIPE_FORMAT_DXT5_RGBA:
      return MESA_FORMAT_RGBA_DXT5;
#if FEATURE_EXT_texture_sRGB
   case PIPE_FORMAT_DXT1_SRGB:
      return MESA_FORMAT_SRGB_DXT1;
   case PIPE_FORMAT_DXT1_SRGBA:
      return MESA_FORMAT_SRGBA_DXT1;
   case PIPE_FORMAT_DXT3_SRGBA:
      return MESA_FORMAT_SRGBA_DXT3;
   case PIPE_FORMAT_DXT5_SRGBA:
      return MESA_FORMAT_SRGBA_DXT5;
#endif
#endif
#if FEATURE_EXT_texture_sRGB
   case PIPE_FORMAT_A8L8_SRGB:
      return MESA_FORMAT_SLA8;
   case PIPE_FORMAT_L8_SRGB:
      return MESA_FORMAT_SL8;
   case PIPE_FORMAT_R8G8B8_SRGB:
      return MESA_FORMAT_SRGB8;
   case PIPE_FORMAT_R8G8B8A8_SRGB:
      return MESA_FORMAT_SRGBA8;
   case PIPE_FORMAT_A8R8G8B8_SRGB:
      return MESA_FORMAT_SARGB8;
#endif
   /* XXX add additional cases */
   default:
      assert(0);
      return MESA_FORMAT_NONE;
   }
}


/**
 * Called via ctx->Driver.chooseTextureFormat().
 */
gl_format
st_ChooseTextureFormat(GLcontext *ctx, GLint internalFormat,
                       GLenum format, GLenum type)
{
   enum pipe_format pFormat;

   (void) format;
   (void) type;

   pFormat = st_choose_format(ctx->st->pipe->screen, internalFormat,
                              PIPE_TEXTURE_2D, PIPE_TEXTURE_USAGE_SAMPLER);
   if (pFormat == PIPE_FORMAT_NONE)
      return MESA_FORMAT_NONE;

   return translate_gallium_format_to_mesa_format(pFormat);
}


/**
 * Test if a gallium format is equivalent to a GL format/type.
 */
GLboolean
st_equal_formats(enum pipe_format pFormat, GLenum format, GLenum type)
{
   switch (pFormat) {
   case PIPE_FORMAT_R8G8B8A8_UNORM:
      return format == GL_RGBA && type == GL_UNSIGNED_BYTE;
   case PIPE_FORMAT_B8G8R8A8_UNORM:
      return format == GL_BGRA && type == GL_UNSIGNED_BYTE;
   case PIPE_FORMAT_R5G6B5_UNORM:
      return format == GL_RGB && type == GL_UNSIGNED_SHORT_5_6_5;
   /* XXX more combos... */
   default:
      return GL_FALSE;
   }
}