path: root/xc/extras/Mesa/src/texstore.c

/*
 * Mesa 3-D graphics library
 * Version:  5.0.1
 *
 * Copyright (C) 1999-2003  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.
 */

/*
 * Authors:
 *   Brian Paul
 */

/*
 * The GL texture image functions in teximage.c basically just do
 * error checking and data structure allocation.  They in turn call
 * device driver functions which actually copy/convert/store the user's
 * texture image data.
 *
 * However, most device drivers will be able to use the fallback functions
 * in this file.  That is, most drivers will have the following bit of
 * code:
 *   ctx->Driver.TexImage1D = _mesa_store_teximage1d;
 *   ctx->Driver.TexImage2D = _mesa_store_teximage2d;
 *   ctx->Driver.TexImage3D = _mesa_store_teximage3d;
 *   etc...
 *
 * Texture image processing is actually kind of complicated.  We have to do:
 *    Format/type conversions
 *    pixel unpacking
 *    pixel transfer (scale, bais, lookup, convolution!, etc)
 *
 * These functions can handle most everything, including processing full
 * images and sub-images.
 */


#include "glheader.h"
#include "colormac.h"
#include "context.h"
#include "convolve.h"
#include "image.h"
#include "macros.h"
#include "imports.h"
#include "texcompress.h"
#include "texformat.h"
#include "teximage.h"
#include "texstore.h"
#include "texutil.h"


/*
 * Given an internal texture format enum or 1, 2, 3, 4 return the
 * corresponding _base_ internal format:  GL_ALPHA, GL_LUMINANCE,
 * GL_LUMANCE_ALPHA, GL_INTENSITY, GL_RGB, or GL_RGBA.  Return the
 * number of components for the format.  Return -1 if invalid enum.
 */
static GLint
components_in_intformat( GLint format )
{
   switch (format) {
      case GL_ALPHA:
      case GL_ALPHA4:
      case GL_ALPHA8:
      case GL_ALPHA12:
      case GL_ALPHA16:
         return 1;
      case 1:
      case GL_LUMINANCE:
      case GL_LUMINANCE4:
      case GL_LUMINANCE8:
      case GL_LUMINANCE12:
      case GL_LUMINANCE16:
         return 1;
      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:
         return 2;
      case GL_INTENSITY:
      case GL_INTENSITY4:
      case GL_INTENSITY8:
      case GL_INTENSITY12:
      case GL_INTENSITY16:
         return 1;
      case 3:
      case GL_RGB:
      case GL_R3_G3_B2:
      case GL_RGB4:
      case GL_RGB5:
      case GL_RGB8:
      case GL_RGB10:
      case GL_RGB12:
      case GL_RGB16:
         return 3;
      case 4:
      case GL_RGBA:
      case GL_RGBA2:
      case GL_RGBA4:
      case GL_RGB5_A1:
      case GL_RGBA8:
      case GL_RGB10_A2:
      case GL_RGBA12:
      case GL_RGBA16:
         return 4;
      case GL_COLOR_INDEX:
      case GL_COLOR_INDEX1_EXT:
      case GL_COLOR_INDEX2_EXT:
      case GL_COLOR_INDEX4_EXT:
      case GL_COLOR_INDEX8_EXT:
      case GL_COLOR_INDEX12_EXT:
      case GL_COLOR_INDEX16_EXT:
         return 1;
      case GL_DEPTH_COMPONENT:
      case GL_DEPTH_COMPONENT16_SGIX:
      case GL_DEPTH_COMPONENT24_SGIX:
      case GL_DEPTH_COMPONENT32_SGIX:
         return 1;
      case GL_YCBCR_MESA:
         return 2; /* Y + (Cb or Cr) */
      default:
         return -1;  /* error */
   }
}


/*
 * This function is used to transfer the user's image data into a texture
 * image buffer.  We handle both full texture images and subtexture images.
 * We also take care of all image transfer operations here, including
 * convolution, scale/bias, colortables, etc.
 *
 * The destination texel type is always GLchan.
 * The destination texel format is one of the 6 basic types.
 *
 * A hardware driver may use this as a helper routine to unpack and
 * apply pixel transfer ops into a temporary image buffer.  Then,
 * convert the temporary image into the special hardware format.
 *
 * Input:
 *   dimensions - 1, 2, or 3
 *   texDestFormat - GL_LUMINANCE, GL_INTENSITY, GL_LUMINANCE_ALPHA, GL_ALPHA,
 *                   GL_RGB or GL_RGBA (the destination format)
 *   texDestAddr - destination image address
 *   srcWidth, srcHeight, srcDepth - size (in pixels) of src and dest images
 *   dstXoffset, dstYoffset, dstZoffset - position to store the image within
 *      the destination 3D texture
 *   dstRowStride, dstImageStride - dest image strides in bytes
 *   srcFormat - source image format (GL_ALPHA, GL_RED, GL_RGB, etc)
 *   srcType - GL_UNSIGNED_BYTE, GL_UNSIGNED_SHORT_5_6_5, GL_FLOAT, etc
 *   srcPacking - describes packing of incoming image.
 *   transferOps - mask of pixel transfer operations
 */
static void
transfer_teximage(GLcontext *ctx, GLuint dimensions,
                  GLenum texDestFormat, GLvoid *texDestAddr,
                  GLint srcWidth, GLint srcHeight, GLint srcDepth,
                  GLint dstXoffset, GLint dstYoffset, GLint dstZoffset,
                  GLint dstRowStride, GLint dstImageStride,
                  GLenum srcFormat, GLenum srcType,
                  const GLvoid *srcAddr,
                  const struct gl_pixelstore_attrib *srcPacking,
                  GLuint transferOps)
{
   GLint texComponents;

   ASSERT(ctx);
   ASSERT(dimensions >= 1 && dimensions <= 3);
   ASSERT(texDestFormat == GL_LUMINANCE ||
          texDestFormat == GL_INTENSITY ||
          texDestFormat == GL_LUMINANCE_ALPHA ||
          texDestFormat == GL_ALPHA ||
          texDestFormat == GL_RGB ||
          texDestFormat == GL_RGBA ||
          texDestFormat == GL_COLOR_INDEX ||
          texDestFormat == GL_DEPTH_COMPONENT);
   ASSERT(texDestAddr);
   ASSERT(srcWidth >= 1);
   ASSERT(srcHeight >= 1);
   ASSERT(srcDepth >= 1);
   ASSERT(dstXoffset >= 0);
   ASSERT(dstYoffset >= 0);
   ASSERT(dstZoffset >= 0);
   ASSERT(dstRowStride >= 0);
   ASSERT(dstImageStride >= 0);
   ASSERT(srcAddr);
   ASSERT(srcPacking);

   texComponents = components_in_intformat(texDestFormat);

   /* try common 2D texture cases first */
   if (!transferOps && dimensions == 2 && srcType == CHAN_TYPE) {

      if (srcFormat == texDestFormat) {
         /* This will cover the common GL_RGB, GL_RGBA, GL_ALPHA,
          * GL_LUMINANCE_ALPHA, etc. texture formats.  Use memcpy().
          */
         const GLchan *src = (const GLchan *) _mesa_image_address(
                                   srcPacking, srcAddr, srcWidth, srcHeight,
                                   srcFormat, srcType, 0, 0, 0);
         const GLint srcRowStride = _mesa_image_row_stride(srcPacking,
                                               srcWidth, srcFormat, srcType);
         const GLint widthInBytes = srcWidth * texComponents * sizeof(GLchan);
         GLchan *dst = (GLchan *) texDestAddr
                     + dstYoffset * (dstRowStride / sizeof(GLchan))
                     + dstXoffset * texComponents;
         if (srcRowStride == widthInBytes && dstRowStride == widthInBytes) {
            MEMCPY(dst, src, srcHeight * widthInBytes);
         }
         else {
            GLint i;
            for (i = 0; i < srcHeight; i++) {
               MEMCPY(dst, src, widthInBytes);
               src += (srcRowStride / sizeof(GLchan));
               dst += (dstRowStride / sizeof(GLchan));
            }
         }
         return;  /* all done */
      }
      else if (srcFormat == GL_RGBA && texDestFormat == GL_RGB) {
         /* commonly used by Quake */
         const GLchan *src = (const GLchan *) _mesa_image_address(
                                   srcPacking, srcAddr, srcWidth, srcHeight,
                                   srcFormat, srcType, 0, 0, 0);
         const GLint srcRowStride = _mesa_image_row_stride(srcPacking,
                                               srcWidth, srcFormat, srcType);
         GLchan *dst = (GLchan *) texDestAddr
                     + dstYoffset * (dstRowStride / sizeof(GLchan))
                     + dstXoffset * texComponents;
         GLint i, j;
         for (i = 0; i < srcHeight; i++) {
            const GLchan *s = src;
            GLchan *d = dst;
            for (j = 0; j < srcWidth; j++) {
               *d++ = *s++;  /*red*/
               *d++ = *s++;  /*green*/
               *d++ = *s++;  /*blue*/
               s++;          /*alpha*/
            }
            src += (srcRowStride / sizeof(GLchan));
            dst += (dstRowStride / sizeof(GLchan));
         }
         return;  /* all done */
      }
   }

   /*
    * General case solutions
    */
   if (texDestFormat == GL_COLOR_INDEX) {
      /* color index texture */
      const GLenum texType = CHAN_TYPE;
      GLint img, row;
      GLchan *dest = (GLchan *) texDestAddr
                   + dstZoffset * (dstImageStride / sizeof(GLchan))
                   + dstYoffset * (dstRowStride / sizeof(GLchan))
                   + dstXoffset * texComponents;
      for (img = 0; img < srcDepth; img++) {
         GLchan *destRow = dest;
         for (row = 0; row < srcHeight; row++) {
            const GLvoid *src = _mesa_image_address(srcPacking,
                srcAddr, srcWidth, srcHeight, srcFormat, srcType, img, row, 0);
            _mesa_unpack_index_span(ctx, srcWidth, texType, destRow,
                                    srcType, src, srcPacking, transferOps);
            destRow += (dstRowStride / sizeof(GLchan));
         }
         dest += dstImageStride;
      }
   }
   else if (texDestFormat == GL_YCBCR_MESA) {
      /* YCbCr texture */
      GLint img, row;
      GLushort *dest = (GLushort *) texDestAddr
                     + dstZoffset * (dstImageStride / sizeof(GLushort))
                     + dstYoffset * (dstRowStride / sizeof(GLushort))
                     + dstXoffset * texComponents;
      ASSERT(ctx->Extensions.MESA_ycbcr_texture);
      for (img = 0; img < srcDepth; img++) {
         GLushort *destRow = dest;
         for (row = 0; row < srcHeight; row++) {
            const GLvoid *srcRow = _mesa_image_address(srcPacking,
                                          srcAddr, srcWidth, srcHeight,
                                          srcFormat, srcType, img, row, 0);
            MEMCPY(destRow, srcRow, srcWidth * sizeof(GLushort));
            destRow += (dstRowStride / sizeof(GLushort));
         }
         dest += dstImageStride / sizeof(GLushort);
      }
   }
   else if (texDestFormat == GL_DEPTH_COMPONENT) {
      /* Depth texture (shadow maps) */
      GLint img, row;
      GLubyte *dest = (GLubyte *) texDestAddr
                    + dstZoffset * dstImageStride
                    + dstYoffset * (dstRowStride / sizeof(GLchan))
                    + dstXoffset * texComponents;
      for (img = 0; img < srcDepth; img++) {
         GLubyte *destRow = dest;
         for (row = 0; row < srcHeight; row++) {
            const GLvoid *src = _mesa_image_address(srcPacking,
                srcAddr, srcWidth, srcHeight, srcFormat, srcType, img, row, 0);
            _mesa_unpack_depth_span(ctx, srcWidth, (GLfloat *) destRow,
                                    srcType, src, srcPacking);
            destRow += (dstRowStride / sizeof(GLchan));
         }
         dest += dstImageStride;
      }
   }
   else {
      /* regular, color texture */
      if ((dimensions == 1 && ctx->Pixel.Convolution1DEnabled) ||
          (dimensions >= 2 && ctx->Pixel.Convolution2DEnabled) ||
          (dimensions >= 2 && ctx->Pixel.Separable2DEnabled)) {
         /*
          * Fill texture image with convolution
          */
         GLint img, row;
         GLint convWidth = srcWidth, convHeight = srcHeight;
         GLfloat *tmpImage, *convImage;
         tmpImage = (GLfloat *) MALLOC(srcWidth * srcHeight * 4 * sizeof(GLfloat));
         if (!tmpImage) {
            _mesa_error(ctx, GL_OUT_OF_MEMORY, "glTexImage");
            return;
         }
         convImage = (GLfloat *) MALLOC(srcWidth * srcHeight * 4 * sizeof(GLfloat));
         if (!convImage) {
            _mesa_error(ctx, GL_OUT_OF_MEMORY, "glTexImage");
            FREE(tmpImage);
            return;
         }

         for (img = 0; img < srcDepth; img++) {
            const GLfloat *srcf;
            GLfloat *dstf = tmpImage;
            GLchan *dest;

            /* unpack and do transfer ops up to convolution */
            for (row = 0; row < srcHeight; row++) {
               const GLvoid *src = _mesa_image_address(srcPacking,
                                              srcAddr, srcWidth, srcHeight,
                                              srcFormat, srcType, img, row, 0);
               _mesa_unpack_float_color_span(ctx, srcWidth, GL_RGBA, dstf,
                         srcFormat, srcType, src, srcPacking,
                         transferOps & IMAGE_PRE_CONVOLUTION_BITS,
                         GL_TRUE);
               dstf += srcWidth * 4;
            }

            /* convolve */
            if (dimensions == 1) {
               ASSERT(ctx->Pixel.Convolution1DEnabled);
               _mesa_convolve_1d_image(ctx, &convWidth, tmpImage, convImage);
            }
            else {
               if (ctx->Pixel.Convolution2DEnabled) {
                  _mesa_convolve_2d_image(ctx, &convWidth, &convHeight,
                                          tmpImage, convImage);
               }
               else {
                  ASSERT(ctx->Pixel.Separable2DEnabled);
                  _mesa_convolve_sep_image(ctx, &convWidth, &convHeight,
                                           tmpImage, convImage);
               }
            }

            /* packing and transfer ops after convolution */
            srcf = convImage;
            dest = (GLchan *) texDestAddr
                 + (dstZoffset + img) * (dstImageStride / sizeof(GLchan))
                 + dstYoffset * (dstRowStride / sizeof(GLchan));
            for (row = 0; row < convHeight; row++) {
               _mesa_pack_float_rgba_span(ctx, convWidth,
                                          (const GLfloat (*)[4]) srcf,
                                          texDestFormat, CHAN_TYPE,
                                          dest, &_mesa_native_packing,
                                          transferOps
                                          & IMAGE_POST_CONVOLUTION_BITS);
               srcf += convWidth * 4;
               dest += (dstRowStride / sizeof(GLchan));
            }
         }

         FREE(convImage);
         FREE(tmpImage);
      }
      else {
         /*
          * no convolution
          */
         GLint img, row;
         GLchan *dest = (GLchan *) texDestAddr
                      + dstZoffset * (dstImageStride / sizeof(GLchan))
                      + dstYoffset * (dstRowStride / sizeof(GLchan))
                      + dstXoffset * texComponents;
         for (img = 0; img < srcDepth; img++) {
            GLchan *destRow = dest;
            for (row = 0; row < srcHeight; row++) {
               const GLvoid *srcRow = _mesa_image_address(srcPacking,
                                              srcAddr, srcWidth, srcHeight,
                                              srcFormat, srcType, img, row, 0);
               _mesa_unpack_chan_color_span(ctx, srcWidth, texDestFormat,
                                       destRow, srcFormat, srcType, srcRow,
                                       srcPacking, transferOps);
               destRow += (dstRowStride / sizeof(GLchan));
            }
            dest += dstImageStride / sizeof(GLchan);
         }
      }
   }
}



/*
 * Transfer a texture image from user space to <destAddr> applying all
 * needed image transfer operations and storing the result in the format
 * specified by <dstFormat>.  <dstFormat> may be any format from texformat.h.
 * Input:
 *   dimensions - 1, 2 or 3
 *   baseInternalFormat - base format of the internal texture format
 *       specified by the user.  This is very important, see below.
 *   dstFormat - destination image format
 *   dstAddr - destination address
 *   srcWidth, srcHeight, srcDepth - size of source iamge
 *   dstX/Y/Zoffset - as specified by glTexSubImage
 *   dstRowStride - stride between dest rows in bytes
 *   dstImageStride - stride between dest images in bytes
 *   srcFormat, srcType - incoming image format and datatype
 *   srcAddr - source image address
 *   srcPacking - packing params of source image
 *
 * XXX this function is a bit more complicated than it should be.  If
 * _mesa_convert_texsubimage[123]d could handle any dest/source formats
 * or if transfer_teximage() could store in any MESA_FORMAT_* format, we
 * could simplify things here.
 */
void
_mesa_transfer_teximage(GLcontext *ctx, GLuint dimensions,
                        GLenum baseInternalFormat,
                        const struct gl_texture_format *dstFormat,
                        GLvoid *dstAddr,
                        GLint srcWidth, GLint srcHeight, GLint srcDepth,
                        GLint dstXoffset, GLint dstYoffset, GLint dstZoffset,
                        GLint dstRowStride, GLint dstImageStride,
                        GLenum srcFormat, GLenum srcType,
                        const GLvoid *srcAddr,
                        const struct gl_pixelstore_attrib *srcPacking)
{
   const GLint dstRowStridePixels = dstRowStride / dstFormat->TexelBytes;
   const GLint dstImageStridePixels = dstImageStride / dstFormat->TexelBytes;
   GLboolean makeTemp;
   GLuint transferOps = ctx->_ImageTransferState;
   GLboolean freeSourceData = GL_FALSE;
   GLint postConvWidth = srcWidth, postConvHeight = srcHeight;

   assert(baseInternalFormat > 0);
   ASSERT(baseInternalFormat == GL_LUMINANCE ||
          baseInternalFormat == GL_INTENSITY ||
          baseInternalFormat == GL_LUMINANCE_ALPHA ||
          baseInternalFormat == GL_ALPHA ||
          baseInternalFormat == GL_RGB ||
          baseInternalFormat == GL_RGBA ||
          baseInternalFormat == GL_COLOR_INDEX ||
          baseInternalFormat == GL_DEPTH_COMPONENT);

   if (transferOps & IMAGE_CONVOLUTION_BIT) {
      _mesa_adjust_image_for_convolution(ctx, dimensions, &postConvWidth,
                                         &postConvHeight);
   }

   /*
    * Consider this scenario:  The user's source image is GL_RGB and the
    * requested internal format is GL_LUMINANCE.  Now suppose the device
    * driver doesn't support GL_LUMINANCE and instead uses RGB16 as the
    * texture format.  In that case we still need to do an intermediate
    * conversion to luminance format so that the incoming red channel gets
    * replicated into the dest red, green and blue channels.  The following
    * code takes care of that.
    */
   if (dstFormat->BaseFormat != baseInternalFormat) {
      /* Allocate storage for temporary image in the baseInternalFormat */
      const GLint texelSize = _mesa_components_in_format(baseInternalFormat)
         * sizeof(GLchan);
      const GLint bytes = texelSize * postConvWidth * postConvHeight *srcDepth;
      const GLint tmpRowStride = texelSize * postConvWidth;
      const GLint tmpImgStride = texelSize * postConvWidth * postConvHeight;
      GLvoid *tmpImage = MALLOC(bytes);
      if (!tmpImage)
         return;
      transfer_teximage(ctx, dimensions, baseInternalFormat, tmpImage,
                        srcWidth, srcHeight, srcDepth,
                        0, 0, 0, /* x/y/zoffset */
                        tmpRowStride, tmpImgStride,
                        srcFormat, srcType, srcAddr, srcPacking, transferOps);

      /* this is our new source image */
      srcWidth = postConvWidth;
      srcHeight = postConvHeight;
      srcFormat = baseInternalFormat;
      srcType = CHAN_TYPE;
      srcAddr = tmpImage;
      srcPacking = &_mesa_native_packing;
      freeSourceData = GL_TRUE;
      transferOps = 0;  /* image transfer ops were completed */
   }

   /* Let the optimized tex conversion functions take a crack at the
    * image conversion if the dest format is a h/w format.
    */
   if (_mesa_is_hardware_tex_format(dstFormat)) {
      if (transferOps) {
         makeTemp = GL_TRUE;
      }
      else {
         if (dimensions == 1) {
            makeTemp = !_mesa_convert_texsubimage1d(dstFormat->MesaFormat,
                                                    dstXoffset,
                                                    srcWidth,
                                                    srcFormat, srcType,
                                                    srcPacking, srcAddr,
                                                    dstAddr);
         }
         else if (dimensions == 2) {
            makeTemp = !_mesa_convert_texsubimage2d(dstFormat->MesaFormat,
                                                    dstXoffset, dstYoffset,
                                                    srcWidth, srcHeight,
                                                    dstRowStridePixels,
                                                    srcFormat, srcType,
                                                    srcPacking, srcAddr,
                                                    dstAddr);
         }
         else {
            assert(dimensions == 3);
            makeTemp = !_mesa_convert_texsubimage3d(dstFormat->MesaFormat,
                                      dstXoffset, dstYoffset, dstZoffset,
                                      srcWidth, srcHeight, srcDepth,
                                      dstRowStridePixels, dstImageStridePixels,
                                      srcFormat, srcType,
                                      srcPacking, srcAddr, dstAddr);
         }
         if (!makeTemp) {
            /* all done! */
            if (freeSourceData)
               FREE((void *) srcAddr);
            return;
         }
      }
   }
   else {
      /* software texture format */
      makeTemp = GL_FALSE;
   }

   if (makeTemp) {
      GLint postConvWidth = srcWidth, postConvHeight = srcHeight;
      GLenum tmpFormat;
      GLuint tmpComps, tmpTexelSize;
      GLint tmpRowStride, tmpImageStride;
      GLubyte *tmpImage;

      if (transferOps & IMAGE_CONVOLUTION_BIT) {
         _mesa_adjust_image_for_convolution(ctx, dimensions, &postConvWidth,
                                            &postConvHeight);
      }

      tmpFormat = dstFormat->BaseFormat;
      tmpComps = _mesa_components_in_format(tmpFormat);
      tmpTexelSize = tmpComps * sizeof(GLchan);
      tmpRowStride = postConvWidth * tmpTexelSize;
      tmpImageStride = postConvWidth * postConvHeight * tmpTexelSize;
      tmpImage = (GLubyte *) MALLOC(postConvWidth * postConvHeight *
                                    srcDepth * tmpTexelSize);
      if (!tmpImage) {
         if (freeSourceData)
            FREE((void *) srcAddr);
         return;
      }

      transfer_teximage(ctx, dimensions, tmpFormat, tmpImage,
                        srcWidth, srcHeight, srcDepth,
                        0, 0, 0, /* x/y/zoffset */
                        tmpRowStride, tmpImageStride,
                        srcFormat, srcType, srcAddr, srcPacking, transferOps);

      if (freeSourceData)
         FREE((void *) srcAddr);

      /* the temp image is our new source image */
      srcWidth = postConvWidth;
      srcHeight = postConvHeight;
      srcFormat = tmpFormat;
      srcType = CHAN_TYPE;
      srcAddr = tmpImage;
      srcPacking = &_mesa_native_packing;
      freeSourceData = GL_TRUE;
   }

   if (_mesa_is_hardware_tex_format(dstFormat)) {
      assert(makeTemp);
      if (dimensions == 1) {
         GLboolean b;
         b = _mesa_convert_texsubimage1d(dstFormat->MesaFormat,
                                         dstXoffset,
                                         srcWidth,
                                         srcFormat, srcType,
                                         srcPacking, srcAddr,
                                         dstAddr);
         assert(b);
      }
      else if (dimensions == 2) {
         GLboolean b;
         b = _mesa_convert_texsubimage2d(dstFormat->MesaFormat,
                                         dstXoffset, dstYoffset,
                                         srcWidth, srcHeight,
                                         dstRowStridePixels,
                                         srcFormat, srcType,
                                         srcPacking, srcAddr,
                                         dstAddr);
         assert(b);
      }
      else {
         GLboolean b;
         b = _mesa_convert_texsubimage3d(dstFormat->MesaFormat,
                                      dstXoffset, dstYoffset, dstZoffset,
                                      srcWidth, srcHeight, srcDepth,
                                      dstRowStridePixels, dstImageStridePixels,
                                      srcFormat, srcType,
                                      srcPacking, srcAddr, dstAddr);
         assert(b);
      }
   }
   else {
      /* software format */
      assert(!makeTemp);
      transfer_teximage(ctx, dimensions, dstFormat->BaseFormat, dstAddr,
                        srcWidth, srcHeight, srcDepth,
                        dstXoffset, dstYoffset, dstZoffset,
                        dstRowStride, dstImageStride,
                        srcFormat, srcType, srcAddr, srcPacking, transferOps);
   }

   if (freeSourceData)
      FREE((void *) srcAddr);  /* the temp image */
}



/**
 * Given a user's uncompressed texture image, this function takes care of
 * pixel unpacking, pixel transfer, format conversion and compression.
 */
static void
transfer_compressed_teximage(GLcontext *ctx, GLuint dimensions,
                             GLsizei width, GLsizei height, GLsizei depth,
                             GLenum srcFormat, GLenum srcType,
                             const struct gl_pixelstore_attrib *unpacking,
                             const GLvoid *source,
                             const struct gl_texture_format *dstFormat,
                             GLubyte *dest,
                             GLint dstRowStride)
{
   GLchan *tempImage = NULL;
   GLint srcRowStride;
   GLenum baseFormat;

   ASSERT(dimensions == 2);
   /* TexelBytes is zero if and only if it's a compressed format */
   ASSERT(dstFormat->TexelBytes == 0);

   baseFormat = dstFormat->BaseFormat;

   if (srcFormat != baseFormat || srcType != CHAN_TYPE ||
       ctx->_ImageTransferState != 0 || unpacking->SwapBytes) {
      /* need to convert user's image to texImage->Format, GLchan */
      GLint comps = components_in_intformat(baseFormat);
      GLint postConvWidth = width, postConvHeight = height;

      /* XXX convolution untested */
      if (ctx->_ImageTransferState & IMAGE_CONVOLUTION_BIT) {
         _mesa_adjust_image_for_convolution(ctx, dimensions, &postConvWidth,
                                            &postConvHeight);
      }

      tempImage = (GLchan*) MALLOC(width * height * comps * sizeof(GLchan));
      if (!tempImage) {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glTexImage2D");
         return;
      }
      transfer_teximage(ctx, dimensions,
                        baseFormat,             /* dest format */
                        tempImage,              /* dst address */
                        width, height, depth,   /* src size */
                        0, 0, 0,                /* x/y/zoffset */
                        comps * width,          /* dst row stride */
                        comps * width * height, /* dst image stride */
                        srcFormat, srcType,     /* src format, type */
                        source, unpacking,      /* src and src packing */
                        ctx->_ImageTransferState);
      source = tempImage;
      width = postConvWidth;
      height = postConvHeight;
      srcRowStride = width;
   }
   else {
      if (unpacking->RowLength)
         srcRowStride = unpacking->RowLength;
      else
         srcRowStride = width;
   }

   _mesa_compress_teximage(ctx, width, height, baseFormat,
                           (const GLchan *) source, srcRowStride,
                           dstFormat, dest, dstRowStride);
   if (tempImage) {
      FREE(tempImage);
   }
}



/*
 * This is the software fallback for Driver.TexImage1D()
 * and Driver.CopyTexImage2D().
 * The texture image type will be GLchan.
 * The texture image format will be GL_COLOR_INDEX, GL_INTENSITY,
 * GL_LUMINANCE, GL_LUMINANCE_ALPHA, GL_ALPHA, GL_RGB or GL_RGBA.
 */
void
_mesa_store_teximage1d(GLcontext *ctx, GLenum target, GLint level,
                       GLint internalFormat,
                       GLint width, GLint border,
                       GLenum format, GLenum type, const GLvoid *pixels,
                       const struct gl_pixelstore_attrib *packing,
                       struct gl_texture_object *texObj,
                       struct gl_texture_image *texImage)
{
   GLint postConvWidth = width;
   GLint texelBytes, sizeInBytes;

   if (ctx->_ImageTransferState & IMAGE_CONVOLUTION_BIT) {
      _mesa_adjust_image_for_convolution(ctx, 1, &postConvWidth, NULL);
   }

   /* choose the texture format */
   assert(ctx->Driver.ChooseTextureFormat);
   texImage->TexFormat = (*ctx->Driver.ChooseTextureFormat)(ctx,
                                          internalFormat, format, type);
   assert(texImage->TexFormat);
   texImage->FetchTexel = texImage->TexFormat->FetchTexel1D;

   texelBytes = texImage->TexFormat->TexelBytes;

   /* allocate memory */
   if (texImage->IsCompressed)
      sizeInBytes = texImage->CompressedSize;
   else
      sizeInBytes = postConvWidth * texelBytes;
   texImage->Data = MESA_PBUFFER_ALLOC(sizeInBytes);
   if (!texImage->Data) {
      _mesa_error(ctx, GL_OUT_OF_MEMORY, "glTexImage1D");
      return;
   }

   if (!pixels)
      return;

   /* unpack image, apply transfer ops and store in texImage->Data */
   if (texImage->IsCompressed) {
      GLint dstRowStride = _mesa_compressed_row_stride(texImage->IntFormat,
                                                       width);
      transfer_compressed_teximage(ctx, 1, width, 1, 1,
                                   format, type, packing,
                                   pixels, texImage->TexFormat,
                                   (GLubyte *) texImage->Data, dstRowStride);
   }
   else {
      _mesa_transfer_teximage(ctx, 1,
                              texImage->Format, /* base format */
                              texImage->TexFormat, texImage->Data,
                              width, 1, 1,  /* src size */
                              0, 0, 0,      /* dstX/Y/Zoffset */
                              0, /* dstRowStride */
                              0, /* dstImageStride */
                              format, type, pixels, packing);
   }

   /* GL_SGIS_generate_mipmap */
   if (level == texObj->BaseLevel && texObj->GenerateMipmap) {
      _mesa_generate_mipmap(ctx, target,
                            &ctx->Texture.Unit[ctx->Texture.CurrentUnit],
                            texObj);
   }
}


/*
 * This is the software fallback for Driver.TexImage2D()
 * and Driver.CopyTexImage2D().
 * The texture image type will be GLchan.
 * The texture image format will be GL_COLOR_INDEX, GL_INTENSITY,
 * GL_LUMINANCE, GL_LUMINANCE_ALPHA, GL_ALPHA, GL_RGB or GL_RGBA.
 */
void
_mesa_store_teximage2d(GLcontext *ctx, GLenum target, GLint level,
                       GLint internalFormat,
                       GLint width, GLint height, GLint border,
                       GLenum format, GLenum type, const void *pixels,
                       const struct gl_pixelstore_attrib *packing,
                       struct gl_texture_object *texObj,
                       struct gl_texture_image *texImage)
{
   GLint postConvWidth = width, postConvHeight = height;
   GLint texelBytes, sizeInBytes;

   if (ctx->_ImageTransferState & IMAGE_CONVOLUTION_BIT) {
      _mesa_adjust_image_for_convolution(ctx, 2, &postConvWidth,
                                         &postConvHeight);
   }

   /* choose the texture format */
   assert(ctx->Driver.ChooseTextureFormat);
   texImage->TexFormat = (*ctx->Driver.ChooseTextureFormat)(ctx,
                                          internalFormat, format, type);
   assert(texImage->TexFormat);
   texImage->FetchTexel = texImage->TexFormat->FetchTexel2D;

   texelBytes = texImage->TexFormat->TexelBytes;

   /* allocate memory */
   if (texImage->IsCompressed)
      sizeInBytes = texImage->CompressedSize;
   else
      sizeInBytes = postConvWidth * postConvHeight * texelBytes;
   texImage->Data = MESA_PBUFFER_ALLOC(sizeInBytes);
   if (!texImage->Data) {
      _mesa_error(ctx, GL_OUT_OF_MEMORY, "glTexImage2D");
      return;
   }

   if (!pixels)
      return;

   /* unpack image, apply transfer ops and store in texImage->Data */
   if (texImage->IsCompressed) {
      GLint dstRowStride = _mesa_compressed_row_stride(texImage->IntFormat,
                                                       width);
      transfer_compressed_teximage(ctx, 2, width, height, 1,
                                   format, type, packing,
                                   pixels, texImage->TexFormat,
                                   (GLubyte *) texImage->Data, dstRowStride);
   }
   else {
      _mesa_transfer_teximage(ctx, 2,
                              texImage->Format,
                              texImage->TexFormat, texImage->Data,
                              width, height, 1,  /* src size */
                              0, 0, 0,           /* dstX/Y/Zoffset */
                              texImage->Width * texelBytes, /* dstRowStride */
                              0, /* dstImageStride */
                              format, type, pixels, packing);
   }

   /* GL_SGIS_generate_mipmap */
   if (level == texObj->BaseLevel && texObj->GenerateMipmap) {
      _mesa_generate_mipmap(ctx, target,
                            &ctx->Texture.Unit[ctx->Texture.CurrentUnit],
                            texObj);
   }
}



/*
 * This is the software fallback for Driver.TexImage3D()
 * and Driver.CopyTexImage3D().
 * The texture image type will be GLchan.
 * The texture image format will be GL_COLOR_INDEX, GL_INTENSITY,
 * GL_LUMINANCE, GL_LUMINANCE_ALPHA, GL_ALPHA, GL_RGB or GL_RGBA.
 */
void
_mesa_store_teximage3d(GLcontext *ctx, GLenum target, GLint level,
                       GLint internalFormat,
                       GLint width, GLint height, GLint depth, GLint border,
                       GLenum format, GLenum type, const void *pixels,
                       const struct gl_pixelstore_attrib *packing,
                       struct gl_texture_object *texObj,
                       struct gl_texture_image *texImage)
{
   GLint texelBytes, sizeInBytes;

   /* choose the texture format */
   assert(ctx->Driver.ChooseTextureFormat);
   texImage->TexFormat = (*ctx->Driver.ChooseTextureFormat)(ctx,
                                          internalFormat, format, type);
   assert(texImage->TexFormat);
   texImage->FetchTexel = texImage->TexFormat->FetchTexel3D;

   texelBytes = texImage->TexFormat->TexelBytes;

   /* allocate memory */
   if (texImage->IsCompressed)
      sizeInBytes = texImage->CompressedSize;
   else
      sizeInBytes = width * height * depth * texelBytes;
   texImage->Data = MESA_PBUFFER_ALLOC(sizeInBytes);
   if (!texImage->Data) {
      _mesa_error(ctx, GL_OUT_OF_MEMORY, "glTexImage3D");
      return;
   }

   if (!pixels)
      return;

   /* unpack image, apply transfer ops and store in texImage->Data */
   if (texImage->IsCompressed) {
      GLint dstRowStride = _mesa_compressed_row_stride(texImage->IntFormat,
                                                       width);
      transfer_compressed_teximage(ctx, 3, width, height, depth,
                                   format, type, packing,
                                   pixels, texImage->TexFormat,
                                   (GLubyte *) texImage->Data, dstRowStride);
   }
   else {
      _mesa_transfer_teximage(ctx, 3,
                              texImage->Format,
                              texImage->TexFormat, texImage->Data,
                              width, height, depth, /* src size */
                              0, 0, 0,  /* dstX/Y/Zoffset */
                              texImage->Width * texelBytes, /* dstRowStride */
                              texImage->Width * texImage->Height * texelBytes,
                              format, type, pixels, packing);
   }

   /* GL_SGIS_generate_mipmap */
   if (level == texObj->BaseLevel && texObj->GenerateMipmap) {
      _mesa_generate_mipmap(ctx, target,
                            &ctx->Texture.Unit[ctx->Texture.CurrentUnit],
                            texObj);
   }
}




/*
 * This is the software fallback for Driver.TexSubImage1D()
 * and Driver.CopyTexSubImage1D().
 */
void
_mesa_store_texsubimage1d(GLcontext *ctx, GLenum target, GLint level,
                          GLint xoffset, GLint width,
                          GLenum format, GLenum type, const void *pixels,
                          const struct gl_pixelstore_attrib *packing,
                          struct gl_texture_object *texObj,
                          struct gl_texture_image *texImage)
{
   if (texImage->IsCompressed) {
      GLint dstRowStride = _mesa_compressed_row_stride(texImage->IntFormat,
                                                       texImage->Width);
      GLubyte *dest = _mesa_compressed_image_address(xoffset, 0, 0,
                                                     texImage->IntFormat,
                                                     texImage->Width,
                                          (GLubyte*) texImage->Data);
      transfer_compressed_teximage(ctx, 1,             /* dimensions */
                                   width, 1, 1,        /* size to replace */
                                   format, type,       /* source format/type */
                                   packing,            /* source packing */
                                   pixels,             /* source data */
                                   texImage->TexFormat,/* dest format */
                                   dest, dstRowStride);
   }
   else {
      _mesa_transfer_teximage(ctx, 1,
                              texImage->Format,
                              texImage->TexFormat, texImage->Data,
                              width, 1, 1, /* src size */
                              xoffset, 0, 0, /* dest offsets */
                              0, /* dstRowStride */
                              0, /* dstImageStride */
                              format, type, pixels, packing);
   }

   /* GL_SGIS_generate_mipmap */
   if (level == texObj->BaseLevel && texObj->GenerateMipmap) {
      _mesa_generate_mipmap(ctx, target,
                            &ctx->Texture.Unit[ctx->Texture.CurrentUnit],
                            texObj);
   }
}



/*
 * This is the software fallback for Driver.TexSubImage2D()
 * and Driver.CopyTexSubImage2D().
 */
void
_mesa_store_texsubimage2d(GLcontext *ctx, GLenum target, GLint level,
                          GLint xoffset, GLint yoffset,
                          GLint width, GLint height,
                          GLenum format, GLenum type, const void *pixels,
                          const struct gl_pixelstore_attrib *packing,
                          struct gl_texture_object *texObj,
                          struct gl_texture_image *texImage)
{
   if (texImage->IsCompressed) {
      GLint dstRowStride = _mesa_compressed_row_stride(texImage->IntFormat,
                                                       texImage->Width);
      GLubyte *dest = _mesa_compressed_image_address(xoffset, yoffset, 0,
                                                     texImage->IntFormat,
                                                     texImage->Width,
                                          (GLubyte*) texImage->Data);
      transfer_compressed_teximage(ctx, 2,             /* dimensions */
                                   width, height, 1,   /* size to replace */
                                   format, type,       /* source format/type */
                                   packing,            /* source packing */
                                   pixels,             /* source data */
                                   texImage->TexFormat,/* dest format */
                                   dest, dstRowStride);
   }
   else {
      _mesa_transfer_teximage(ctx, 2,
                              texImage->Format,
                              texImage->TexFormat, texImage->Data,
                              width, height, 1, /* src size */
                              xoffset, yoffset, 0, /* dest offsets */
                              texImage->Width *texImage->TexFormat->TexelBytes,
                              0, /* dstImageStride */
                              format, type, pixels, packing);
   }

   /* GL_SGIS_generate_mipmap */
   if (level == texObj->BaseLevel && texObj->GenerateMipmap) {
      _mesa_generate_mipmap(ctx, target,
                            &ctx->Texture.Unit[ctx->Texture.CurrentUnit],
                            texObj);
   }
}


/*
 * This is the software fallback for Driver.TexSubImage3D().
 * and Driver.CopyTexSubImage3D().
 */
void
_mesa_store_texsubimage3d(GLcontext *ctx, GLenum target, GLint level,
                          GLint xoffset, GLint yoffset, GLint zoffset,
                          GLint width, GLint height, GLint depth,
                          GLenum format, GLenum type, const void *pixels,
                          const struct gl_pixelstore_attrib *packing,
                          struct gl_texture_object *texObj,
                          struct gl_texture_image *texImage)
{
   if (texImage->IsCompressed) {
      GLint dstRowStride = _mesa_compressed_row_stride(texImage->IntFormat,
                                                       texImage->Width);
      GLubyte *dest = _mesa_compressed_image_address(xoffset, yoffset, zoffset,
                                                     texImage->IntFormat,
                                                     texImage->Width,
                                          (GLubyte*) texImage->Data);
      transfer_compressed_teximage(ctx, 3,              /* dimensions */
                                   width, height, depth,/* size to replace */
                                   format, type,       /* source format/type */
                                   packing,            /* source packing */
                                   pixels,             /* source data */
                                   texImage->TexFormat,/* dest format */
                                   dest, dstRowStride);
   }
   else {
      const GLint texelBytes = texImage->TexFormat->TexelBytes;
      _mesa_transfer_teximage(ctx, 3,
                           texImage->Format,
                           texImage->TexFormat, texImage->Data,
                           width, height, depth, /* src size */
                           xoffset, yoffset, xoffset, /* dest offsets */
                           texImage->Width * texelBytes,  /* dst row stride */
                           texImage->Width * texImage->Height * texelBytes,
                           format, type, pixels, packing);
   }

   /* GL_SGIS_generate_mipmap */
   if (level == texObj->BaseLevel && texObj->GenerateMipmap) {
      _mesa_generate_mipmap(ctx, target,
                            &ctx->Texture.Unit[ctx->Texture.CurrentUnit],
                            texObj);
   }
}




/*
 * Fallback for Driver.CompressedTexImage1D()
 */
void
_mesa_store_compressed_teximage1d(GLcontext *ctx, GLenum target, GLint level,
                                  GLint internalFormat,
                                  GLint width, GLint border,
                                  GLsizei imageSize, const GLvoid *data,
                                  struct gl_texture_object *texObj,
                                  struct gl_texture_image *texImage)
{
   /* this space intentionally left blank */
}



/*
 * Fallback for Driver.CompressedTexImage2D()
 */
void
_mesa_store_compressed_teximage2d(GLcontext *ctx, GLenum target, GLint level,
                                  GLint internalFormat,
                                  GLint width, GLint height, GLint border,
                                  GLsizei imageSize, const GLvoid *data,
                                  struct gl_texture_object *texObj,
                                  struct gl_texture_image *texImage)
{
   /* This is pretty simple, basically just do a memcpy without worrying
    * about the usual image unpacking or image transfer operations.
    */
   ASSERT(texObj);
   ASSERT(texImage);
   ASSERT(texImage->Width > 0);
   ASSERT(texImage->Height > 0);
   ASSERT(texImage->Depth == 1);
   ASSERT(texImage->Data == NULL); /* was freed in glCompressedTexImage2DARB */

   /* choose the texture format */
   assert(ctx->Driver.ChooseTextureFormat);
   texImage->TexFormat = (*ctx->Driver.ChooseTextureFormat)(ctx,
                                          internalFormat, 0, 0);
   assert(texImage->TexFormat);
   texImage->FetchTexel = texImage->TexFormat->FetchTexel2D;

   /* allocate storage */
   texImage->Data = MESA_PBUFFER_ALLOC(imageSize);
   if (!texImage->Data) {
      _mesa_error(ctx, GL_OUT_OF_MEMORY, "glCompressedTexImage2DARB");
      return;
   }

   /* copy the data */
   ASSERT(texImage->CompressedSize == imageSize);
   MEMCPY(texImage->Data, data, imageSize);
}



/*
 * Fallback for Driver.CompressedTexImage3D()
 */
void
_mesa_store_compressed_teximage3d(GLcontext *ctx, GLenum target, GLint level,
                                  GLint internalFormat,
                                  GLint width, GLint height, GLint depth,
                                  GLint border,
                                  GLsizei imageSize, const GLvoid *data,
                                  struct gl_texture_object *texObj,
                                  struct gl_texture_image *texImage)
{
   /* this space intentionally left blank */
}



/**
 * Fallback for Driver.CompressedTexSubImage1D()
 */
void
_mesa_store_compressed_texsubimage1d(GLcontext *ctx, GLenum target,
                                     GLint level,
                                     GLint xoffset, GLsizei width,
                                     GLenum format,
                                     GLsizei imageSize, const GLvoid *data,
                                     struct gl_texture_object *texObj,
                                     struct gl_texture_image *texImage)
{
   /* this space intentionally left blank */
}


/**
 * Fallback for Driver.CompressedTexSubImage2D()
 */
void
_mesa_store_compressed_texsubimage2d(GLcontext *ctx, GLenum target,
                                     GLint level,
                                     GLint xoffset, GLint yoffset,
                                     GLsizei width, GLsizei height,
                                     GLenum format,
                                     GLsizei imageSize, const GLvoid *data,
                                     struct gl_texture_object *texObj,
                                     struct gl_texture_image *texImage)
{
   GLint bytesPerRow, destRowStride, srcRowStride;
   GLint i, rows;
   GLubyte *dest;
   const GLubyte *src;

   /* these should have been caught sooner */
   ASSERT((width & 3) == 0 || width == 2 || width == 1);
   ASSERT((height & 3) == 0 || height == 2 || height == 1);
   ASSERT((xoffset & 3) == 0);
   ASSERT((yoffset & 3) == 0);

   srcRowStride = _mesa_compressed_row_stride(texImage->IntFormat, width);
   src = (const GLubyte *) data;

   destRowStride = _mesa_compressed_row_stride(texImage->IntFormat,
                                               texImage->Width);
   dest = _mesa_compressed_image_address(xoffset, yoffset, 0,
                                         texImage->IntFormat,
                                         texImage->Width,
                              (GLubyte*) texImage->Data);

   bytesPerRow = srcRowStride;
   rows = height / 4;

   for (i = 0; i < rows; i++) {
      MEMCPY(dest, src, bytesPerRow);
      dest += destRowStride;
      src += srcRowStride;
   }
}


/**
 * Fallback for Driver.CompressedTexSubImage3D()
 */
void
_mesa_store_compressed_texsubimage3d(GLcontext *ctx, GLenum target,
                                GLint level,
                                GLint xoffset, GLint yoffset, GLint zoffset,
                                GLsizei width, GLsizei height, GLsizei depth,
                                GLenum format,
                                GLsizei imageSize, const GLvoid *data,
                                struct gl_texture_object *texObj,
                                struct gl_texture_image *texImage)
{
   /* this space intentionally left blank */
}





/*
 * This is the fallback for Driver.TestProxyTexImage().
 */
GLboolean
_mesa_test_proxy_teximage(GLcontext *ctx, GLenum target, GLint level,
                          GLint internalFormat, GLenum format, GLenum type,
                          GLint width, GLint height, GLint depth, GLint border)
{
   struct gl_texture_unit *texUnit;
   struct gl_texture_object *texObj;
   struct gl_texture_image *texImage;

   (void) format;
   (void) type;

   texUnit = &ctx->Texture.Unit[ctx->Texture.CurrentUnit];
   texObj = _mesa_select_tex_object(ctx, texUnit, target);
   texImage = _mesa_select_tex_image(ctx, texUnit, target, level);

   /* We always pass.
    * The core Mesa code will have already tested the image size, etc.
    * If a driver has more stringent texture limits to enforce it will
    * have to override this function.
    */
   /* choose the texture format */
   assert(ctx->Driver.ChooseTextureFormat);
   texImage->TexFormat = (*ctx->Driver.ChooseTextureFormat)(ctx,
                                          internalFormat, format, type);
   assert(texImage->TexFormat);

   return GL_TRUE;
}



/*
 * Average together two rows of a source image to produce a single new
 * row in the dest image.  It's legal for the two source rows to point
 * to the same data.  The source width must be equal to either the
 * dest width or two times the dest width.
 */
static void
do_row(const struct gl_texture_format *format, GLint srcWidth,
       const GLvoid *srcRowA, const GLvoid *srcRowB,
       GLint dstWidth, GLvoid *dstRow)
{
   const GLuint k0 = (srcWidth == dstWidth) ? 0 : 1;
   const GLuint colStride = (srcWidth == dstWidth) ? 1 : 2;

   assert(srcWidth == dstWidth || srcWidth == 2 * dstWidth);

   switch (format->MesaFormat) {
   case MESA_FORMAT_RGBA:
      {
         GLuint i, j, k;
         const GLchan (*rowA)[4] = (const GLchan (*)[4]) srcRowA;
         const GLchan (*rowB)[4] = (const GLchan (*)[4]) srcRowB;
         GLchan (*dst)[4] = (GLchan (*)[4]) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            dst[i][0] = (rowA[j][0] + rowA[k][0] +
                         rowB[j][0] + rowB[k][0]) / 4;
            dst[i][1] = (rowA[j][1] + rowA[k][1] +
                         rowB[j][1] + rowB[k][1]) / 4;
            dst[i][2] = (rowA[j][2] + rowA[k][2] +
                         rowB[j][2] + rowB[k][2]) / 4;
            dst[i][3] = (rowA[j][3] + rowA[k][3] +
                         rowB[j][3] + rowB[k][3]) / 4;
         }
      }
      return;
   case MESA_FORMAT_RGB:
      {
         GLuint i, j, k;
         const GLchan (*rowA)[3] = (const GLchan (*)[3]) srcRowA;
         const GLchan (*rowB)[3] = (const GLchan (*)[3]) srcRowB;
         GLchan (*dst)[3] = (GLchan (*)[3]) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            dst[i][0] = (rowA[j][0] + rowA[k][0] +
                         rowB[j][0] + rowB[k][0]) / 4;
            dst[i][1] = (rowA[j][1] + rowA[k][1] +
                         rowB[j][1] + rowB[k][1]) / 4;
            dst[i][2] = (rowA[j][2] + rowA[k][2] +
                         rowB[j][2] + rowB[k][2]) / 4;
         }
      }
      return;
   case MESA_FORMAT_ALPHA:
   case MESA_FORMAT_LUMINANCE:
   case MESA_FORMAT_INTENSITY:
   case MESA_FORMAT_COLOR_INDEX:
      {
         GLuint i, j, k;
         const GLchan *rowA = (const GLchan *) srcRowA;
         const GLchan *rowB = (const GLchan *) srcRowB;
         GLchan *dst = (GLchan *) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            dst[i] = (rowA[j] + rowA[k] + rowB[j] + rowB[k]) / 4;
         }
      }
      return;
   case MESA_FORMAT_LUMINANCE_ALPHA:
      {
         GLuint i, j, k;
         const GLchan (*rowA)[2] = (const GLchan (*)[2]) srcRowA;
         const GLchan (*rowB)[2] = (const GLchan (*)[2]) srcRowB;
         GLchan (*dst)[2] = (GLchan (*)[2]) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            dst[i][0] = (rowA[j][0] + rowA[k][0] +
                         rowB[j][0] + rowB[k][0]) / 4;
            dst[i][1] = (rowA[j][1] + rowA[k][1] +
                         rowB[j][1] + rowB[k][1]) / 4;
         }
      }
      return;
   case MESA_FORMAT_DEPTH_COMPONENT:
      {
         GLuint i, j, k;
         const GLfloat *rowA = (const GLfloat *) srcRowA;
         const GLfloat *rowB = (const GLfloat *) srcRowB;
         GLfloat *dst = (GLfloat *) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            dst[i] = (rowA[j] + rowA[k] + rowB[j] + rowB[k]) * 0.25F;
         }
      }
      return;
   /* Begin hardware formats */
   case MESA_FORMAT_RGBA8888:
   case MESA_FORMAT_ARGB8888:
      {
         GLuint i, j, k;
         const GLubyte (*rowA)[4] = (const GLubyte (*)[4]) srcRowA;
         const GLubyte (*rowB)[4] = (const GLubyte (*)[4]) srcRowB;
         GLubyte (*dst)[4] = (GLubyte (*)[4]) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            dst[i][0] = (rowA[j][0] + rowA[k][0] +
                         rowB[j][0] + rowB[k][0]) / 4;
            dst[i][1] = (rowA[j][1] + rowA[k][1] +
                         rowB[j][1] + rowB[k][1]) / 4;
            dst[i][2] = (rowA[j][2] + rowA[k][2] +
                         rowB[j][2] + rowB[k][2]) / 4;
            dst[i][3] = (rowA[j][3] + rowA[k][3] +
                         rowB[j][3] + rowB[k][3]) / 4;
         }
      }
      return;
   case MESA_FORMAT_RGB888:
      {
         GLuint i, j, k;
         const GLubyte (*rowA)[3] = (const GLubyte (*)[3]) srcRowA;
         const GLubyte (*rowB)[3] = (const GLubyte (*)[3]) srcRowB;
         GLubyte (*dst)[3] = (GLubyte (*)[3]) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            dst[i][0] = (rowA[j][0] + rowA[k][0] +
                         rowB[j][0] + rowB[k][0]) / 4;
            dst[i][1] = (rowA[j][1] + rowA[k][1] +
                         rowB[j][1] + rowB[k][1]) / 4;
            dst[i][2] = (rowA[j][2] + rowA[k][2] +
                         rowB[j][2] + rowB[k][2]) / 4;
         }
      }
      return;
   case MESA_FORMAT_RGB565:
      {
         GLuint i, j, k;
         const GLushort *rowA = (const GLushort *) srcRowA;
         const GLushort *rowB = (const GLushort *) srcRowB;
         GLushort *dst = (GLushort *) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            const GLint rowAr0 = rowA[j] & 0x1f;
            const GLint rowAr1 = rowA[k] & 0x1f;
            const GLint rowBr0 = rowB[j] & 0x1f;
            const GLint rowBr1 = rowB[k] & 0x1f;
            const GLint rowAg0 = (rowA[j] >> 5) & 0x3f;
            const GLint rowAg1 = (rowA[k] >> 5) & 0x3f;
            const GLint rowBg0 = (rowB[j] >> 5) & 0x3f;
            const GLint rowBg1 = (rowB[k] >> 5) & 0x3f;
            const GLint rowAb0 = (rowA[j] >> 11) & 0x1f;
            const GLint rowAb1 = (rowA[k] >> 11) & 0x1f;
            const GLint rowBb0 = (rowB[j] >> 11) & 0x1f;
            const GLint rowBb1 = (rowB[k] >> 11) & 0x1f;
            const GLint red   = (rowAr0 + rowAr1 + rowBr0 + rowBr1) >> 4;
            const GLint green = (rowAg0 + rowAg1 + rowBg0 + rowBg1) >> 4;
            const GLint blue  = (rowAb0 + rowAb1 + rowBb0 + rowBb1) >> 4;
            dst[i] = (blue << 11) | (green << 5) | red;
         }
      }
      return;
   case MESA_FORMAT_ARGB4444:
      {
         GLuint i, j, k;
         const GLushort *rowA = (const GLushort *) srcRowA;
         const GLushort *rowB = (const GLushort *) srcRowB;
         GLushort *dst = (GLushort *) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            const GLint rowAr0 = rowA[j] & 0xf;
            const GLint rowAr1 = rowA[k] & 0xf;
            const GLint rowBr0 = rowB[j] & 0xf;
            const GLint rowBr1 = rowB[k] & 0xf;
            const GLint rowAg0 = (rowA[j] >> 4) & 0xf;
            const GLint rowAg1 = (rowA[k] >> 4) & 0xf;
            const GLint rowBg0 = (rowB[j] >> 4) & 0xf;
            const GLint rowBg1 = (rowB[k] >> 4) & 0xf;
            const GLint rowAb0 = (rowA[j] >> 8) & 0xf;
            const GLint rowAb1 = (rowA[k] >> 8) & 0xf;
            const GLint rowBb0 = (rowB[j] >> 8) & 0xf;
            const GLint rowBb1 = (rowB[k] >> 8) & 0xf;
            const GLint rowAa0 = (rowA[j] >> 12) & 0xf;
            const GLint rowAa1 = (rowA[k] >> 12) & 0xf;
            const GLint rowBa0 = (rowB[j] >> 12) & 0xf;
            const GLint rowBa1 = (rowB[k] >> 12) & 0xf;
            const GLint red   = (rowAr0 + rowAr1 + rowBr0 + rowBr1) >> 4;
            const GLint green = (rowAg0 + rowAg1 + rowBg0 + rowBg1) >> 4;
            const GLint blue  = (rowAb0 + rowAb1 + rowBb0 + rowBb1) >> 4;
            const GLint alpha = (rowAa0 + rowAa1 + rowBa0 + rowBa1) >> 4;
            dst[i] = (alpha << 12) | (blue << 8) | (green << 4) | red;
         }
      }
      return;
   case MESA_FORMAT_ARGB1555:
      {
         GLuint i, j, k;
         const GLushort *rowA = (const GLushort *) srcRowA;
         const GLushort *rowB = (const GLushort *) srcRowB;
         GLushort *dst = (GLushort *) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            const GLint rowAr0 = rowA[j] & 0x1f;
            const GLint rowAr1 = rowA[k] & 0x1f;
            const GLint rowBr0 = rowB[j] & 0x1f;
            const GLint rowBr1 = rowB[k] & 0xf;
            const GLint rowAg0 = (rowA[j] >> 5) & 0x1f;
            const GLint rowAg1 = (rowA[k] >> 5) & 0x1f;
            const GLint rowBg0 = (rowB[j] >> 5) & 0x1f;
            const GLint rowBg1 = (rowB[k] >> 5) & 0x1f;
            const GLint rowAb0 = (rowA[j] >> 10) & 0x1f;
            const GLint rowAb1 = (rowA[k] >> 10) & 0x1f;
            const GLint rowBb0 = (rowB[j] >> 10) & 0x1f;
            const GLint rowBb1 = (rowB[k] >> 10) & 0x1f;
            const GLint rowAa0 = (rowA[j] >> 15) & 0x1;
            const GLint rowAa1 = (rowA[k] >> 15) & 0x1;
            const GLint rowBa0 = (rowB[j] >> 15) & 0x1;
            const GLint rowBa1 = (rowB[k] >> 15) & 0x1;
            const GLint red   = (rowAr0 + rowAr1 + rowBr0 + rowBr1) >> 4;
            const GLint green = (rowAg0 + rowAg1 + rowBg0 + rowBg1) >> 4;
            const GLint blue  = (rowAb0 + rowAb1 + rowBb0 + rowBb1) >> 4;
            const GLint alpha = (rowAa0 + rowAa1 + rowBa0 + rowBa1) >> 4;
            dst[i] = (alpha << 15) | (blue << 10) | (green << 5) | red;
         }
      }
      return;
   case MESA_FORMAT_AL88:
      {
         GLuint i, j, k;
         const GLubyte (*rowA)[2] = (const GLubyte (*)[2]) srcRowA;
         const GLubyte (*rowB)[2] = (const GLubyte (*)[2]) srcRowB;
         GLubyte (*dst)[2] = (GLubyte (*)[2]) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            dst[i][0] = (rowA[j][0] + rowA[k][0] +
                         rowB[j][0] + rowB[k][0]) >> 2;
            dst[i][1] = (rowA[j][1] + rowA[k][1] +
                         rowB[j][1] + rowB[k][1]) >> 2;
         }
      }
      return;
   case MESA_FORMAT_RGB332:
      {
         GLuint i, j, k;
         const GLubyte *rowA = (const GLubyte *) srcRowA;
         const GLubyte *rowB = (const GLubyte *) srcRowB;
         GLubyte *dst = (GLubyte *) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            const GLint rowAr0 = rowA[j] & 0x3;
            const GLint rowAr1 = rowA[k] & 0x3;
            const GLint rowBr0 = rowB[j] & 0x3;
            const GLint rowBr1 = rowB[k] & 0x3;
            const GLint rowAg0 = (rowA[j] >> 2) & 0x7;
            const GLint rowAg1 = (rowA[k] >> 2) & 0x7;
            const GLint rowBg0 = (rowB[j] >> 2) & 0x7;
            const GLint rowBg1 = (rowB[k] >> 2) & 0x7;
            const GLint rowAb0 = (rowA[j] >> 5) & 0x7;
            const GLint rowAb1 = (rowA[k] >> 5) & 0x7;
            const GLint rowBb0 = (rowB[j] >> 5) & 0x7;
            const GLint rowBb1 = (rowB[k] >> 5) & 0x7;
            const GLint red   = (rowAr0 + rowAr1 + rowBr0 + rowBr1) >> 4;
            const GLint green = (rowAg0 + rowAg1 + rowBg0 + rowBg1) >> 4;
            const GLint blue  = (rowAb0 + rowAb1 + rowBb0 + rowBb1) >> 4;
            dst[i] = (blue << 5) | (green << 2) | red;
         }
      }
      return;
   case MESA_FORMAT_A8:
   case MESA_FORMAT_L8:
   case MESA_FORMAT_I8:
   case MESA_FORMAT_CI8:
      {
         GLuint i, j, k;
         const GLubyte *rowA = (const GLubyte *) srcRowA;
         const GLubyte *rowB = (const GLubyte *) srcRowB;
         GLubyte *dst = (GLubyte *) dstRow;
         for (i = j = 0, k = k0; i < (GLuint) dstWidth;
              i++, j += colStride, k += colStride) {
            dst[i] = (rowA[j] + rowA[k] + rowB[j] + rowB[k]) >> 2;
         }
      }
      return;
   default:
      _mesa_problem(NULL, "bad format in do_row()");
   }
}


/*
 * These functions generate a 1/2-size mipmap image from a source image.
 * Texture borders are handled by copying or averaging the source image's
 * border texels, depending on the scale-down factor.
 */

static void
make_1d_mipmap(const struct gl_texture_format *format, GLint border,
               GLint srcWidth, const GLubyte *srcPtr,
               GLint dstWidth, GLubyte *dstPtr)
{
   const GLint bpt = format->TexelBytes;
   const GLubyte *src;
   GLubyte *dst;

   /* skip the border pixel, if any */
   src = srcPtr + border * bpt;
   dst = dstPtr + border * bpt;

   /* we just duplicate the input row, kind of hack, saves code */
   do_row(format, srcWidth - 2 * border, src, src,
          dstWidth - 2 * border, dst);

   if (border) {
      /* copy left-most pixel from source */
      MEMCPY(dstPtr, srcPtr, bpt);
      /* copy right-most pixel from source */
      MEMCPY(dstPtr + (dstWidth - 1) * bpt,
             srcPtr + (srcWidth - 1) * bpt,
             bpt);
   }
}


static void
make_2d_mipmap(const struct gl_texture_format *format, GLint border,
               GLint srcWidth, GLint srcHeight, const GLubyte *srcPtr,
               GLint dstWidth, GLint dstHeight, GLubyte *dstPtr)
{
   const GLint bpt = format->TexelBytes;
   const GLint srcWidthNB = srcWidth - 2 * border;  /* sizes w/out border */
   const GLint dstWidthNB = dstWidth - 2 * border;
   const GLint dstHeightNB = dstHeight - 2 * border;
   const GLint srcRowStride = bpt * srcWidth;
   const GLint dstRowStride = bpt * dstWidth;
   const GLubyte *srcA, *srcB;
   GLubyte *dst;
   GLint row, colStride;

   colStride = (srcWidth == dstWidth) ? 1 : 2;

   /* Compute src and dst pointers, skipping any border */
   srcA = srcPtr + border * ((srcWidth + 1) * bpt);
   if (srcHeight > 1)
      srcB = srcA + srcRowStride;
   else
      srcB = srcA;
   dst = dstPtr + border * ((dstWidth + 1) * bpt);

   for (row = 0; row < dstHeightNB; row++) {
      do_row(format, srcWidthNB, srcA, srcB,
             dstWidthNB, dst);
      srcA += 2 * srcRowStride;
      srcB += 2 * srcRowStride;
      dst += dstRowStride;
   }

   /* This is ugly but probably won't be used much */
   if (border > 0) {
      /* fill in dest border */
      /* lower-left border pixel */
      MEMCPY(dstPtr, srcPtr, bpt);
      /* lower-right border pixel */
      MEMCPY(dstPtr + (dstWidth - 1) * bpt,
             srcPtr + (srcWidth - 1) * bpt, bpt);
      /* upper-left border pixel */
      MEMCPY(dstPtr + dstWidth * (dstHeight - 1) * bpt,
             srcPtr + srcWidth * (srcHeight - 1) * bpt, bpt);
      /* upper-right border pixel */
      MEMCPY(dstPtr + (dstWidth * dstHeight - 1) * bpt,
             srcPtr + (srcWidth * srcHeight - 1) * bpt, bpt);
      /* lower border */
      do_row(format, srcWidthNB,
             srcPtr + bpt,
             srcPtr + bpt,
             dstWidthNB, dstPtr + bpt);
      /* upper border */
      do_row(format, srcWidthNB,
             srcPtr + (srcWidth * (srcHeight - 1) + 1) * bpt,
             srcPtr + (srcWidth * (srcHeight - 1) + 1) * bpt,
             dstWidthNB,
             dstPtr + (dstWidth * (dstHeight - 1) + 1) * bpt);
      /* left and right borders */
      if (srcHeight == dstHeight) {
         /* copy border pixel from src to dst */
         for (row = 1; row < srcHeight; row++) {
            MEMCPY(dstPtr + dstWidth * row * bpt,
                   srcPtr + srcWidth * row * bpt, bpt);
            MEMCPY(dstPtr + (dstWidth * row + dstWidth - 1) * bpt,
                   srcPtr + (srcWidth * row + srcWidth - 1) * bpt, bpt);
         }
      }
      else {
         /* average two src pixels each dest pixel */
         for (row = 0; row < dstHeightNB; row += 2) {
            do_row(format, 1,
                   srcPtr + (srcWidth * (row * 2 + 1)) * bpt,
                   srcPtr + (srcWidth * (row * 2 + 2)) * bpt,
                   1, dstPtr + (dstWidth * row + 1) * bpt);
            do_row(format, 1,
                   srcPtr + (srcWidth * (row * 2 + 1) + srcWidth - 1) * bpt,
                   srcPtr + (srcWidth * (row * 2 + 2) + srcWidth - 1) * bpt,
                   1, dstPtr + (dstWidth * row + 1 + dstWidth - 1) * bpt);
         }
      }
   }
}


static void
make_3d_mipmap(const struct gl_texture_format *format, GLint border,
               GLint srcWidth, GLint srcHeight, GLint srcDepth,
               const GLubyte *srcPtr,
               GLint dstWidth, GLint dstHeight, GLint dstDepth,
               GLubyte *dstPtr)
{
   const GLint bpt = format->TexelBytes;
   const GLint srcWidthNB = srcWidth - 2 * border;  /* sizes w/out border */
   const GLint srcDepthNB = srcDepth - 2 * border;
   const GLint dstWidthNB = dstWidth - 2 * border;
   const GLint dstHeightNB = dstHeight - 2 * border;
   const GLint dstDepthNB = dstDepth - 2 * border;
   GLvoid *tmpRowA, *tmpRowB;
   GLint img, row;
   GLint bytesPerSrcImage, bytesPerDstImage;
   GLint bytesPerSrcRow, bytesPerDstRow;
   GLint srcImageOffset, srcRowOffset;

   (void) srcDepthNB; /* silence warnings */

   /* Need two temporary row buffers */
   tmpRowA = MALLOC(srcWidth * bpt);
   if (!tmpRowA)
      return;
   tmpRowB = MALLOC(srcWidth * bpt);
   if (!tmpRowB) {
      FREE(tmpRowA);
      return;
   }

   bytesPerSrcImage = srcWidth * srcHeight * bpt;
   bytesPerDstImage = dstWidth * dstHeight * bpt;

   bytesPerSrcRow = srcWidth * bpt;
   bytesPerDstRow = dstWidth * bpt;

   /* Offset between adjacent src images to be averaged together */
   srcImageOffset = (srcDepth == dstDepth) ? 0 : bytesPerSrcImage;

   /* Offset between adjacent src rows to be averaged together */
   srcRowOffset = (srcHeight == dstHeight) ? 0 : srcWidth * bpt;

   /*
    * Need to average together up to 8 src pixels for each dest pixel.
    * Break that down into 3 operations:
    *   1. take two rows from source image and average them together.
    *   2. take two rows from next source image and average them together.
    *   3. take the two averaged rows and average them for the final dst row.
    */

   /*
   _mesa_printf("mip3d %d x %d x %d  ->  %d x %d x %d\n",
          srcWidth, srcHeight, srcDepth, dstWidth, dstHeight, dstDepth);
   */

   for (img = 0; img < dstDepthNB; img++) {
      /* first source image pointer, skipping border */
      const GLubyte *imgSrcA = srcPtr
         + (bytesPerSrcImage + bytesPerSrcRow + border) * bpt * border
         + img * (bytesPerSrcImage + srcImageOffset);
      /* second source image pointer, skipping border */
      const GLubyte *imgSrcB = imgSrcA + srcImageOffset;
      /* address of the dest image, skipping border */
      GLubyte *imgDst = dstPtr
         + (bytesPerDstImage + bytesPerDstRow + border) * bpt * border
         + img * bytesPerDstImage;

      /* setup the four source row pointers and the dest row pointer */
      const GLubyte *srcImgARowA = imgSrcA;
      const GLubyte *srcImgARowB = imgSrcA + srcRowOffset;
      const GLubyte *srcImgBRowA = imgSrcB;
      const GLubyte *srcImgBRowB = imgSrcB + srcRowOffset;
      GLubyte *dstImgRow = imgDst;

      for (row = 0; row < dstHeightNB; row++) {
         /* Average together two rows from first src image */
         do_row(format, srcWidthNB, srcImgARowA, srcImgARowB,
                srcWidthNB, tmpRowA);
         /* Average together two rows from second src image */
         do_row(format, srcWidthNB, srcImgBRowA, srcImgBRowB,
                srcWidthNB, tmpRowB);
         /* Average together the temp rows to make the final row */
         do_row(format, srcWidthNB, tmpRowA, tmpRowB,
                dstWidthNB, dstImgRow);
         /* advance to next rows */
         srcImgARowA += bytesPerSrcRow + srcRowOffset;
         srcImgARowB += bytesPerSrcRow + srcRowOffset;
         srcImgBRowA += bytesPerSrcRow + srcRowOffset;
         srcImgBRowB += bytesPerSrcRow + srcRowOffset;
         dstImgRow += bytesPerDstRow;
      }
   }

   FREE(tmpRowA);
   FREE(tmpRowB);

   /* Luckily we can leverage the make_2d_mipmap() function here! */
   if (border > 0) {
      /* do front border image */
      make_2d_mipmap(format, 1, srcWidth, srcHeight, srcPtr,
                     dstWidth, dstHeight, dstPtr);
      /* do back border image */
      make_2d_mipmap(format, 1, srcWidth, srcHeight,
                     srcPtr + bytesPerSrcImage * (srcDepth - 1),
                     dstWidth, dstHeight,
                     dstPtr + bytesPerDstImage * (dstDepth - 1));
      /* do four remaining border edges that span the image slices */
      if (srcDepth == dstDepth) {
         /* just copy border pixels from src to dst */
         for (img = 0; img < dstDepthNB; img++) {
            const GLubyte *src;
            GLubyte *dst;

            /* do border along [img][row=0][col=0] */
            src = srcPtr + (img + 1) * bytesPerSrcImage;
            dst = dstPtr + (img + 1) * bytesPerDstImage;
            MEMCPY(dst, src, bpt);

            /* do border along [img][row=dstHeight-1][col=0] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (srcHeight - 1) * bytesPerSrcRow;
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (dstHeight - 1) * bytesPerDstRow;
            MEMCPY(dst, src, bpt);

            /* do border along [img][row=0][col=dstWidth-1] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (srcWidth - 1) * bpt;
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (dstWidth - 1) * bpt;
            MEMCPY(dst, src, bpt);

            /* do border along [img][row=dstHeight-1][col=dstWidth-1] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (bytesPerSrcImage - bpt);
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (bytesPerDstImage - bpt);
            MEMCPY(dst, src, bpt);
         }
      }
      else {
         /* average border pixels from adjacent src image pairs */
         ASSERT(srcDepthNB == 2 * dstDepthNB);
         for (img = 0; img < dstDepthNB; img++) {
            const GLubyte *src;
            GLubyte *dst;

            /* do border along [img][row=0][col=0] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage;
            dst = dstPtr + (img + 1) * bytesPerDstImage;
            do_row(format, 1, src, src + srcImageOffset, 1, dst);

            /* do border along [img][row=dstHeight-1][col=0] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (srcHeight - 1) * bytesPerSrcRow;
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (dstHeight - 1) * bytesPerDstRow;
            do_row(format, 1, src, src + srcImageOffset, 1, dst);

            /* do border along [img][row=0][col=dstWidth-1] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (srcWidth - 1) * bpt;
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (dstWidth - 1) * bpt;
            do_row(format, 1, src, src + srcImageOffset, 1, dst);

            /* do border along [img][row=dstHeight-1][col=dstWidth-1] */
            src = srcPtr + (img * 2 + 1) * bytesPerSrcImage
                         + (bytesPerSrcImage - bpt);
            dst = dstPtr + (img + 1) * bytesPerDstImage
                         + (bytesPerDstImage - bpt);
            do_row(format, 1, src, src + srcImageOffset, 1, dst);
         }
      }
   }
}


/*
 * For GL_SGIX_generate_mipmap:
 * Generate a complete set of mipmaps from texObj's base-level image.
 * Stop at texObj's MaxLevel or when we get to the 1x1 texture.
 */
void
_mesa_generate_mipmap(GLcontext *ctx, GLenum target,
                      const struct gl_texture_unit *texUnit,
                      struct gl_texture_object *texObj)
{
   const struct gl_texture_image *srcImage;
   const struct gl_texture_format *convertFormat;
   const GLubyte *srcData = NULL;
   GLubyte *dstData = NULL;
   GLint level, maxLevels;

   ASSERT(texObj);
   srcImage = texObj->Image[texObj->BaseLevel];
   ASSERT(srcImage);

   maxLevels = _mesa_max_texture_levels(ctx, texObj->Target);
   ASSERT(maxLevels > 0);  /* bad target */

   /* Find convertFormat - the format that do_row() will process */
   if (srcImage->IsCompressed) {
      /* setup for compressed textures */
      GLuint row;
      GLint  components, size;
      GLchan *dst;

      assert(texObj->Target == GL_TEXTURE_2D);

      if (srcImage->Format == GL_RGB) {
         convertFormat = &_mesa_texformat_rgb;
         components = 3;
      }
      else if (srcImage->Format == GL_RGBA) {
         convertFormat = &_mesa_texformat_rgba;
         components = 4;
      }
      else {
         _mesa_problem(ctx, "bad srcImage->Format in _mesa_generate_mipmaps");
         return;
      }

      /* allocate storage for uncompressed GL_RGB or GL_RGBA images */
      size = _mesa_bytes_per_pixel(srcImage->Format, CHAN_TYPE)
         * srcImage->Width * srcImage->Height * srcImage->Depth + 20;
      /* 20 extra bytes, just be safe when calling last FetchTexel */
      srcData = (GLubyte *) MALLOC(size);
      if (!srcData) {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "generate mipmaps");
         return;
      }
      dstData = (GLubyte *) MALLOC(size / 2);  /* 1/4 would probably be OK */
      if (!dstData) {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "generate mipmaps");
         FREE((void *) srcData);
         return;
      }

      /* decompress base image here */
      dst = (GLchan *) srcData;
      for (row = 0; row < srcImage->Height; row++) {
         GLuint col;
         for (col = 0; col < srcImage->Width; col++) {
            (*srcImage->FetchTexel)(srcImage, col, row, 0, (GLvoid *) dst);
            dst += components;
         }
      }
   }
   else {
      /* uncompressed */
      convertFormat = srcImage->TexFormat;
   }

   for (level = texObj->BaseLevel; level < texObj->MaxLevel
           && level < maxLevels - 1; level++) {
      /* generate image[level+1] from image[level] */
      const struct gl_texture_image *srcImage;
      struct gl_texture_image *dstImage;
      GLint srcWidth, srcHeight, srcDepth;
      GLint dstWidth, dstHeight, dstDepth;
      GLint border, bytesPerTexel;

      /* get src image parameters */
      srcImage = _mesa_select_tex_image(ctx, texUnit, target, level);
      ASSERT(srcImage);
      srcWidth = srcImage->Width;
      srcHeight = srcImage->Height;
      srcDepth = srcImage->Depth;
      border = srcImage->Border;

      /* compute next (level+1) image size */
      if (srcWidth - 2 * border > 1) {
         dstWidth = (srcWidth - 2 * border) / 2 + 2 * border;
      }
      else {
         dstWidth = srcWidth; /* can't go smaller */
      }
      if (srcHeight - 2 * border > 1) {
         dstHeight = (srcHeight - 2 * border) / 2 + 2 * border;
      }
      else {
         dstHeight = srcHeight; /* can't go smaller */
      }
      if (srcDepth - 2 * border > 1) {
         dstDepth = (srcDepth - 2 * border) / 2 + 2 * border;
      }
      else {
         dstDepth = srcDepth; /* can't go smaller */
      }

      if (dstWidth == srcWidth &&
          dstHeight == srcHeight &&
          dstDepth == srcDepth) {
         /* all done */
         if (srcImage->IsCompressed) {
            FREE((void *) srcData);
            FREE(dstData);
         }
         return;
      }

      /* get dest gl_texture_image */
      dstImage = _mesa_select_tex_image(ctx, texUnit, target, level+1);
      if (!dstImage) {
         dstImage = _mesa_alloc_texture_image();
         if (!dstImage) {
            _mesa_error(ctx, GL_OUT_OF_MEMORY, "generating mipmaps");
            return;
         }
         _mesa_set_tex_image(texObj, target, level + 1, dstImage);
      }

      /* Free old image data */
      if (dstImage->Data)
         MESA_PBUFFER_FREE(dstImage->Data);

      /* initialize new image */
      _mesa_init_teximage_fields(ctx, target, dstImage, dstWidth, dstHeight,
                                 dstDepth, border, srcImage->IntFormat);
      dstImage->DriverData = NULL;
      dstImage->TexFormat = srcImage->TexFormat;
      dstImage->FetchTexel = srcImage->FetchTexel;
      ASSERT(dstImage->TexFormat);
      ASSERT(dstImage->FetchTexel);

      /* Alloc new teximage data buffer.
       * Setup src and dest data pointers.
       */
      if (dstImage->IsCompressed) {
         ASSERT(dstImage->CompressedSize > 0); /* set by init_teximage_fields*/
         dstImage->Data = MESA_PBUFFER_ALLOC(dstImage->CompressedSize);
         if (!dstImage->Data) {
            _mesa_error(ctx, GL_OUT_OF_MEMORY, "generating mipmaps");
            return;
         }
         /* srcData and dstData are already set */
         ASSERT(srcData);
         ASSERT(dstData);
      }
      else {
         bytesPerTexel = srcImage->TexFormat->TexelBytes;
         ASSERT(dstWidth * dstHeight * dstDepth * bytesPerTexel > 0);
         dstImage->Data = MESA_PBUFFER_ALLOC(dstWidth * dstHeight * dstDepth
                                             * bytesPerTexel);
         if (!dstImage->Data) {
            _mesa_error(ctx, GL_OUT_OF_MEMORY, "generating mipmaps");
            return;
         }
         srcData = (const GLubyte *) srcImage->Data;
         dstData = (GLubyte *) dstImage->Data;
      }

      /*
       * We use simple 2x2 averaging to compute the next mipmap level.
       */
      switch (target) {
         case GL_TEXTURE_1D:
            make_1d_mipmap(convertFormat, border,
                           srcWidth, srcData,
                           dstWidth, dstData);
            break;
         case GL_TEXTURE_2D:
         case GL_TEXTURE_CUBE_MAP_POSITIVE_X_ARB:
         case GL_TEXTURE_CUBE_MAP_NEGATIVE_X_ARB:
         case GL_TEXTURE_CUBE_MAP_POSITIVE_Y_ARB:
         case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y_ARB:
         case GL_TEXTURE_CUBE_MAP_POSITIVE_Z_ARB:
         case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z_ARB:
            make_2d_mipmap(convertFormat, border,
                           srcWidth, srcHeight, srcData,
                           dstWidth, dstHeight, dstData);
            break;
         case GL_TEXTURE_3D:
            make_3d_mipmap(convertFormat, border,
                           srcWidth, srcHeight, srcDepth, srcData,
                           dstWidth, dstHeight, dstDepth, dstData);
            break;
         case GL_TEXTURE_RECTANGLE_NV:
            /* no mipmaps, do nothing */
            break;
         default:
            _mesa_problem(ctx, "bad dimensions in _mesa_generate_mipmaps");
            return;
      }

      if (dstImage->IsCompressed) {
         GLubyte *temp;
         /* compress image from dstData into dstImage->Data */
         const GLenum srcFormat = convertFormat->BaseFormat;
         GLint dstRowStride = _mesa_compressed_row_stride(srcImage->IntFormat,
                                                          dstWidth);
         ASSERT(srcFormat == GL_RGB || srcFormat == GL_RGBA);
         _mesa_compress_teximage(ctx,
                                 dstWidth, dstHeight, /* size */
                                 srcFormat,           /* source format */
                (const GLchan *) dstData,             /* source buffer */
                                 dstWidth,            /* source row stride */
                                 dstImage->TexFormat, /* dest format */
                      (GLubyte*) dstImage->Data,      /* dest buffer */
                                 dstRowStride );      /* dest row stride */

         /* swap src and dest pointers */
         temp = (GLubyte *) srcData;
         srcData = dstData;
         dstData = temp;
      }

   } /* loop over mipmap levels */
}