Re: [Mesa3d-dev] Texutil optimizations - an interesting story

[Gareth H. <ga...@va...>]

I guess the C code might help, although not much...


Original:

GLboolean
_mesa_convert_teximage(MesaIntTexFormat dstFormat,
                       GLint dstWidth, GLint dstHeight, GLvoid
*dstImage,
                       GLint dstRowStride,
                       GLint srcWidth, GLint srcHeight,
                       GLenum srcFormat, GLenum srcType,
                       const GLvoid *srcImage,
                       const struct gl_pixelstore_attrib *packing)
{
   const GLint wScale = dstWidth / srcWidth;   /* must be power of two
*/
   const GLint hScale = dstHeight / srcHeight; /* must be power of two
*/
   ASSERT(dstWidth >= srcWidth);
   ASSERT(dstHeight >= srcHeight);
   ASSERT(dstImage);
   ASSERT(srcImage);
   ASSERT(packing);

   switch (dstFormat) {
      ...
      case MESA_A4_R4_G4_B4:
         /* store as 16-bit texels (GR_TEXFMT_ARGB_4444) */
         if (srcFormat == GL_BGRA && srcType ==
GL_UNSIGNED_SHORT_4_4_4_4_REV){
            ...
         }
         else if (srcFormat == GL_RGBA && srcType == GL_UNSIGNED_BYTE) {
            /* general case */
            if (wScale == 1 && hScale == 1) {
               const GLubyte *src = _mesa_image_address(packing,
srcImage,
                             srcWidth, srcHeight, srcFormat, srcType, 0,
0, 0);
               const GLint srcStride = _mesa_image_row_stride(packing,
                                                 srcWidth, srcFormat,
srcType);
               GLushort *dst = (GLushort *) dstImage;
               GLint row;
               for (row = 0; row < dstHeight; row++) {
                  GLint col, col4;
                  for (col = col4 = 0; col < dstWidth; col++, col4 += 4)
{
                     GLubyte r = src[col4 + 0];
                     GLubyte g = src[col4 + 1];
                     GLubyte b = src[col4 + 2];
                     GLubyte a = src[col4 + 3];
                     dst[col] = ((a & 0xf0) << 8)
                              | ((r & 0xf0) << 4)
                              | ((g & 0xf0)     )
                              | ((b & 0xf0) >> 4);
                  }
                  src += srcStride;
                  dst = (GLushort *) ((GLubyte *) dst + dstRowStride);
               }
            }
            else {
               ...
            }
         }
         else {
            ...
         }
         break;
      ...
   }
   return GL_TRUE;
}


Special case:

GLboolean
_mesa_convert_teximage_argb_4444(MesaIntTexFormat dstFormat,
				 GLint dstWidth, GLint dstHeight,
				 GLvoid *dstImage, GLint dstRowStride,
				 GLint srcWidth, GLint srcHeight,
				 GLenum srcFormat, GLenum srcType,
				 const GLvoid *srcImage,
				 const struct gl_pixelstore_attrib *packing)
{
   const GLubyte *src = srcImage;
   const GLint srcStride = srcWidth * 2;
   GLushort *dst = (GLushort *) dstImage;
   GLint row;
   for (row = 0; row < dstHeight; row++) {
      GLint col, col4;
      for (col = col4 = 0; col < dstWidth; col++, col4 += 4) {
	 GLubyte r = src[col4 + 0];
	 GLubyte g = src[col4 + 1];
	 GLubyte b = src[col4 + 2];
	 GLubyte a = src[col4 + 3];
	 dst[col] = ((a & 0xf0) << 8)
	          | ((r & 0xf0) << 4)
	          | ((g & 0xf0)     )
	          | ((b & 0xf0) >> 4);
      }
      src += srcStride;
      dst = (GLushort *) ((GLubyte *) dst + dstRowStride);
   }

   return GL_TRUE;
}

Figure that one out...