drivers/softpipe/sp_quad_blend.c

/**************************************************************************
 *
 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
 * 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.
 *
 **************************************************************************/

/**
 * quad blending
 * \author Brian Paul
 */

#include "pipe/p_defines.h"
#include "pipe/p_util.h"
#include "sp_context.h"
#include "sp_headers.h"
#include "sp_surface.h"
#include "sp_tile_cache.h"
#include "sp_quad.h"


#define VEC4_COPY(DST, SRC) \
do { \
    DST[0] = SRC[0]; \
    DST[1] = SRC[1]; \
    DST[2] = SRC[2]; \
    DST[3] = SRC[3]; \
} while(0)

#define VEC4_SCALAR(DST, SRC) \
do { \
    DST[0] = SRC; \
    DST[1] = SRC; \
    DST[2] = SRC; \
    DST[3] = SRC; \
} while(0)

#define VEC4_ADD(R, A, B) \
do { \
   R[0] = A[0] + B[0]; \
   R[1] = A[1] + B[1]; \
   R[2] = A[2] + B[2]; \
   R[3] = A[3] + B[3]; \
} while (0)

#define VEC4_SUB(R, A, B) \
do { \
   R[0] = A[0] - B[0]; \
   R[1] = A[1] - B[1]; \
   R[2] = A[2] - B[2]; \
   R[3] = A[3] - B[3]; \
} while (0)

#define VEC4_MUL(R, A, B) \
do { \
   R[0] = A[0] * B[0]; \
   R[1] = A[1] * B[1]; \
   R[2] = A[2] * B[2]; \
   R[3] = A[3] * B[3]; \
} while (0)

#define VEC4_MIN(R, A, B) \
do { \
   R[0] = (A[0] < B[0]) ? A[0] : B[0]; \
   R[1] = (A[1] < B[1]) ? A[1] : B[1]; \
   R[2] = (A[2] < B[2]) ? A[2] : B[2]; \
   R[3] = (A[3] < B[3]) ? A[3] : B[3]; \
} while (0)

#define VEC4_MAX(R, A, B) \
do { \
   R[0] = (A[0] > B[0]) ? A[0] : B[0]; \
   R[1] = (A[1] > B[1]) ? A[1] : B[1]; \
   R[2] = (A[2] > B[2]) ? A[2] : B[2]; \
   R[3] = (A[3] > B[3]) ? A[3] : B[3]; \
} while (0)


static void
logicop_quad(struct quad_stage *qs, struct quad_header *quad)
{
   struct softpipe_context *softpipe = qs->softpipe;
   float dest[4][QUAD_SIZE];
   ubyte src[4][4], dst[4][4], res[4][4];
   uint *src4 = (uint *) src;
   uint *dst4 = (uint *) dst;
   uint *res4 = (uint *) res;
   struct softpipe_cached_tile *
      tile = sp_get_cached_tile(softpipe,
                                softpipe->cbuf_cache[softpipe->current_cbuf],
                                quad->x0, quad->y0);
   float (*quadColor)[4] = quad->outputs.color;
   uint i, j;

   /* get/swizzle dest colors */
   for (j = 0; j < QUAD_SIZE; j++) {
      int x = (quad->x0 & (TILE_SIZE-1)) + (j & 1);
      int y = (quad->y0 & (TILE_SIZE-1)) + (j >> 1);
      for (i = 0; i < 4; i++) {
         dest[i][j] = tile->data.color[y][x][i];
      }
   }

   /* convert to ubyte */
   for (j = 0; j < 4; j++) { /* loop over R,G,B,A channels */
      UNCLAMPED_FLOAT_TO_UBYTE(dst[j][0], dest[j][0]); /* P0 */
      UNCLAMPED_FLOAT_TO_UBYTE(dst[j][1], dest[j][1]); /* P1 */
      UNCLAMPED_FLOAT_TO_UBYTE(dst[j][2], dest[j][2]); /* P2 */
      UNCLAMPED_FLOAT_TO_UBYTE(dst[j][3], dest[j][3]); /* P3 */

      UNCLAMPED_FLOAT_TO_UBYTE(src[j][0], quadColor[j][0]); /* P0 */
      UNCLAMPED_FLOAT_TO_UBYTE(src[j][1], quadColor[j][1]); /* P1 */
      UNCLAMPED_FLOAT_TO_UBYTE(src[j][2], quadColor[j][2]); /* P2 */
      UNCLAMPED_FLOAT_TO_UBYTE(src[j][3], quadColor[j][3]); /* P3 */
   }

   switch (softpipe->blend->logicop_func) {
   case PIPE_LOGICOP_CLEAR:
      for (j = 0; j < 4; j++)
         res4[j] = 0;
      break;
   case PIPE_LOGICOP_NOR:
      for (j = 0; j < 4; j++)
         res4[j] = ~(src4[j] | dst4[j]);
      break;
   case PIPE_LOGICOP_AND_INVERTED:
      for (j = 0; j < 4; j++)
         res4[j] = ~src4[j] & dst4[j];
      break;
   case PIPE_LOGICOP_COPY_INVERTED:
      for (j = 0; j < 4; j++)
         res4[j] = ~src4[j];
      break;
   case PIPE_LOGICOP_AND_REVERSE:
      for (j = 0; j < 4; j++)
         res4[j] = src4[j] & ~dst4[j];
      break;
   case PIPE_LOGICOP_INVERT:
      for (j = 0; j < 4; j++)
         res4[j] = ~dst4[j];
      break;
   case PIPE_LOGICOP_XOR:
      for (j = 0; j < 4; j++)
         res4[j] = dst4[j] ^ src4[j];
      break;
   case PIPE_LOGICOP_NAND:
      for (j = 0; j < 4; j++)
         res4[j] = ~(src4[j] & dst4[j]);
      break;
   case PIPE_LOGICOP_AND:
      for (j = 0; j < 4; j++)
         res4[j] = src4[j] & dst4[j];
      break;
   case PIPE_LOGICOP_EQUIV:
      for (j = 0; j < 4; j++)
         res4[j] = ~(src4[j] ^ dst4[j]);
      break;
   case PIPE_LOGICOP_NOOP:
      for (j = 0; j < 4; j++)
         res4[j] = dst4[j];
      break;
   case PIPE_LOGICOP_OR_INVERTED:
      for (j = 0; j < 4; j++)
         res4[j] = ~src4[j] | dst4[j];
      break;
   case PIPE_LOGICOP_COPY:
      for (j = 0; j < 4; j++)
         res4[j] = src4[j];
      break;
   case PIPE_LOGICOP_OR_REVERSE:
      for (j = 0; j < 4; j++)
         res4[j] = src4[j] | ~dst4[j];
      break;
   case PIPE_LOGICOP_OR:
      for (j = 0; j < 4; j++)
         res4[j] = src4[j] | dst4[j];
      break;
   case PIPE_LOGICOP_SET:
      for (j = 0; j < 4; j++)
         res4[j] = ~0;
      break;
   default:
      assert(0);
   }

   for (j = 0; j < 4; j++) {
      quadColor[j][0] = UBYTE_TO_FLOAT(res[j][0]);
      quadColor[j][1] = UBYTE_TO_FLOAT(res[j][1]);
      quadColor[j][2] = UBYTE_TO_FLOAT(res[j][2]);
      quadColor[j][3] = UBYTE_TO_FLOAT(res[j][3]);
   }

   /* pass quad to next stage */
   qs->next->run(qs->next, quad);
}


static void
blend_quad(struct quad_stage *qs, struct quad_header *quad)
{
   struct softpipe_context *softpipe = qs->softpipe;
   static const float zero[4] = { 0, 0, 0, 0 };
   static const float one[4] = { 1, 1, 1, 1 };
   float source[4][QUAD_SIZE], dest[4][QUAD_SIZE];
   struct softpipe_cached_tile *tile
      = sp_get_cached_tile(softpipe,
                           softpipe->cbuf_cache[softpipe->current_cbuf],
                           quad->x0, quad->y0);
   float (*quadColor)[4] = quad->outputs.color;
   uint i, j;

   if (softpipe->blend->logicop_enable) {
      logicop_quad(qs, quad);
      return;
   }

   /* get/swizzle dest colors */
   for (j = 0; j < QUAD_SIZE; j++) {
      int x = (quad->x0 & (TILE_SIZE-1)) + (j & 1);
      int y = (quad->y0 & (TILE_SIZE-1)) + (j >> 1);
      for (i = 0; i < 4; i++) {
         dest[i][j] = tile->data.color[y][x][i];
      }
   }

   /*
    * Compute src/first term RGB
    */
   switch (softpipe->blend->rgb_src_factor) {
   case PIPE_BLENDFACTOR_ONE:
      VEC4_COPY(source[0], quadColor[0]); /* R */
      VEC4_COPY(source[1], quadColor[1]); /* G */
      VEC4_COPY(source[2], quadColor[2]); /* B */
      break;
   case PIPE_BLENDFACTOR_SRC_COLOR:
      VEC4_MUL(source[0], quadColor[0], quadColor[0]); /* R */
      VEC4_MUL(source[1], quadColor[1], quadColor[1]); /* G */
      VEC4_MUL(source[2], quadColor[2], quadColor[2]); /* B */
      break;
   case PIPE_BLENDFACTOR_SRC_ALPHA:
      {
         const float *alpha = quadColor[3];
         VEC4_MUL(source[0], quadColor[0], alpha); /* R */
         VEC4_MUL(source[1], quadColor[1], alpha); /* G */
         VEC4_MUL(source[2], quadColor[2], alpha); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_DST_COLOR:
      VEC4_MUL(source[0], quadColor[0], dest[0]); /* R */
      VEC4_MUL(source[1], quadColor[1], dest[1]); /* G */
      VEC4_MUL(source[2], quadColor[2], dest[2]); /* B */
      break;
   case PIPE_BLENDFACTOR_DST_ALPHA:
      {
         const float *alpha = dest[3];
         VEC4_MUL(source[0], quadColor[0], alpha); /* R */
         VEC4_MUL(source[1], quadColor[1], alpha); /* G */
         VEC4_MUL(source[2], quadColor[2], alpha); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
      {
         const float *alpha = quadColor[3];
         float diff[4];
         VEC4_SUB(diff, one, dest[3]);
         VEC4_MIN(source[0], alpha, diff); /* R */
         VEC4_MIN(source[1], alpha, diff); /* G */
         VEC4_MIN(source[2], alpha, diff); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_CONST_COLOR:
      {
         float comp[4];
         VEC4_SCALAR(comp, softpipe->blend_color.color[0]); /* R */
         VEC4_MUL(source[0], quadColor[0], comp); /* R */
         VEC4_SCALAR(comp, softpipe->blend_color.color[1]); /* G */
         VEC4_MUL(source[1], quadColor[1], comp); /* G */
         VEC4_SCALAR(comp, softpipe->blend_color.color[2]); /* B */
         VEC4_MUL(source[2], quadColor[2], comp); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_CONST_ALPHA:
      {
         float alpha[4];
         VEC4_SCALAR(alpha, softpipe->blend_color.color[3]);
         VEC4_MUL(source[0], quadColor[0], alpha); /* R */
         VEC4_MUL(source[1], quadColor[1], alpha); /* G */
         VEC4_MUL(source[2], quadColor[2], alpha); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_SRC1_COLOR:
      assert(0); /* to do */
      break;
   case PIPE_BLENDFACTOR_SRC1_ALPHA:
      assert(0); /* to do */
      break;
   case PIPE_BLENDFACTOR_ZERO:
      VEC4_COPY(source[0], zero); /* R */
      VEC4_COPY(source[1], zero); /* G */
      VEC4_COPY(source[2], zero); /* B */
      break;
   case PIPE_BLENDFACTOR_INV_SRC_COLOR:
      {
         float inv_comp[4];
         VEC4_SUB(inv_comp, one, quadColor[0]); /* R */
         VEC4_MUL(source[0], quadColor[0], inv_comp); /* R */
         VEC4_SUB(inv_comp, one, quadColor[1]); /* G */
         VEC4_MUL(source[1], quadColor[1], inv_comp); /* G */
         VEC4_SUB(inv_comp, one, quadColor[2]); /* B */
         VEC4_MUL(source[2], quadColor[2], inv_comp); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
      {
         float inv_alpha[4];
         VEC4_SUB(inv_alpha, one, quadColor[3]);
         VEC4_MUL(source[0], quadColor[0], inv_alpha); /* R */
         VEC4_MUL(source[1], quadColor[1], inv_alpha); /* G */
         VEC4_MUL(source[2], quadColor[2], inv_alpha); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_INV_DST_ALPHA:
      {
         float inv_alpha[4];
         VEC4_SUB(inv_alpha, one, dest[3]);
         VEC4_MUL(source[0], quadColor[0], inv_alpha); /* R */
         VEC4_MUL(source[1], quadColor[1], inv_alpha); /* G */
         VEC4_MUL(source[2], quadColor[2], inv_alpha); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_INV_DST_COLOR:
      {
         float inv_comp[4];
         VEC4_SUB(inv_comp, one, dest[0]); /* R */
         VEC4_MUL(source[0], quadColor[0], inv_comp); /* R */
         VEC4_SUB(inv_comp, one, dest[1]); /* G */
         VEC4_MUL(source[1], quadColor[1], inv_comp); /* G */
         VEC4_SUB(inv_comp, one, dest[2]); /* B */
         VEC4_MUL(source[2], quadColor[2], inv_comp); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_INV_CONST_COLOR:
      {
         float inv_comp[4];
         /* R */
         VEC4_SCALAR(inv_comp, 1.0f - softpipe->blend_color.color[0]);
         VEC4_MUL(source[0], quadColor[0], inv_comp);
         /* G */
         VEC4_SCALAR(inv_comp, 1.0f - softpipe->blend_color.color[1]);
         VEC4_MUL(source[1], quadColor[1], inv_comp);
         /* B */
         VEC4_SCALAR(inv_comp, 1.0f - softpipe->blend_color.color[2]);
         VEC4_MUL(source[2], quadColor[2], inv_comp);
      }
      break;
   case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
      {
         float inv_alpha[4];
         VEC4_SCALAR(inv_alpha, 1.0f - softpipe->blend_color.color[3]);
         VEC4_MUL(source[0], quadColor[0], inv_alpha); /* R */
         VEC4_MUL(source[1], quadColor[1], inv_alpha); /* G */
         VEC4_MUL(source[2], quadColor[2], inv_alpha); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_INV_SRC1_COLOR:
      assert(0); /* to do */
      break;
   case PIPE_BLENDFACTOR_INV_SRC1_ALPHA:
      assert(0); /* to do */
      break;
   default:
      abort();
   }

   /*
    * Compute src/first term A
    */
   switch (softpipe->blend->alpha_src_factor) {
   case PIPE_BLENDFACTOR_ONE:
      VEC4_COPY(source[3], quadColor[3]); /* A */
      break;
   case PIPE_BLENDFACTOR_SRC_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_SRC_ALPHA:
      {
         const float *alpha = quadColor[3];
         VEC4_MUL(source[3], quadColor[3], alpha); /* A */
      }
      break;
   case PIPE_BLENDFACTOR_DST_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_DST_ALPHA:
      VEC4_MUL(source[3], quadColor[3], dest[3]); /* A */
      break;
   case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
      {
         const float *alpha = quadColor[3];
         float diff[4];
         VEC4_SUB(diff, one, dest[3]);
         VEC4_MIN(source[3], alpha, diff); /* A */
      }
      break;
   case PIPE_BLENDFACTOR_CONST_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_CONST_ALPHA:
      {
         float comp[4];
         VEC4_SCALAR(comp, softpipe->blend_color.color[3]); /* A */
         VEC4_MUL(source[3], quadColor[3], comp); /* A */
      }
      break;
   case PIPE_BLENDFACTOR_ZERO:
      VEC4_COPY(source[3], zero); /* A */
      break;
   case PIPE_BLENDFACTOR_INV_SRC_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
      {
         float inv_alpha[4];
         VEC4_SUB(inv_alpha, one, quadColor[3]);
         VEC4_MUL(source[3], quadColor[3], inv_alpha); /* A */
      }
      break;
   case PIPE_BLENDFACTOR_INV_DST_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_INV_DST_ALPHA:
      {
         float inv_alpha[4];
         VEC4_SUB(inv_alpha, one, dest[3]);
         VEC4_MUL(source[3], quadColor[3], inv_alpha); /* A */
      }
      break;
   case PIPE_BLENDFACTOR_INV_CONST_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
      {
         float inv_comp[4];
         /* A */
         VEC4_SCALAR(inv_comp, 1.0f - softpipe->blend_color.color[3]);
         VEC4_MUL(source[3], quadColor[3], inv_comp);
      }
      break;
   default:
      abort();
   }


   /*
    * Compute dest/second term RGB
    */
   switch (softpipe->blend->rgb_dst_factor) {
   case PIPE_BLENDFACTOR_ONE:
      /* dest = dest * 1   NO-OP, leave dest as-is */
      break;
   case PIPE_BLENDFACTOR_SRC_COLOR:
      VEC4_MUL(dest[0], dest[0], quadColor[0]); /* R */
      VEC4_MUL(dest[1], dest[1], quadColor[1]); /* G */
      VEC4_MUL(dest[2], dest[2], quadColor[2]); /* B */
      break;
   case PIPE_BLENDFACTOR_SRC_ALPHA:
      VEC4_MUL(dest[0], dest[0], quadColor[3]); /* R * A */
      VEC4_MUL(dest[1], dest[1], quadColor[3]); /* G * A */
      VEC4_MUL(dest[2], dest[2], quadColor[3]); /* B * A */
      break;
   case PIPE_BLENDFACTOR_DST_ALPHA:
      VEC4_MUL(dest[0], dest[0], dest[3]); /* R * A */
      VEC4_MUL(dest[1], dest[1], dest[3]); /* G * A */
      VEC4_MUL(dest[2], dest[2], dest[3]); /* B * A */
      break;
   case PIPE_BLENDFACTOR_DST_COLOR:
      VEC4_MUL(dest[0], dest[0], dest[0]); /* R */
      VEC4_MUL(dest[1], dest[1], dest[1]); /* G */
      VEC4_MUL(dest[2], dest[2], dest[2]); /* B */
      break;
   case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
      assert(0); /* illegal */
      break;
   case PIPE_BLENDFACTOR_CONST_COLOR:
      {
         float comp[4];
         VEC4_SCALAR(comp, softpipe->blend_color.color[0]); /* R */
         VEC4_MUL(dest[0], dest[0], comp); /* R */
         VEC4_SCALAR(comp, softpipe->blend_color.color[1]); /* G */
         VEC4_MUL(dest[1], dest[1], comp); /* G */
         VEC4_SCALAR(comp, softpipe->blend_color.color[2]); /* B */
         VEC4_MUL(dest[2], dest[2], comp); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_CONST_ALPHA:
      {
         float comp[4];
         VEC4_SCALAR(comp, softpipe->blend_color.color[3]); /* A */
         VEC4_MUL(dest[0], dest[0], comp); /* R */
         VEC4_MUL(dest[1], dest[1], comp); /* G */
         VEC4_MUL(dest[2], dest[2], comp); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_ZERO:
      VEC4_COPY(dest[0], zero); /* R */
      VEC4_COPY(dest[1], zero); /* G */
      VEC4_COPY(dest[2], zero); /* B */
      break;
   case PIPE_BLENDFACTOR_SRC1_COLOR:
   case PIPE_BLENDFACTOR_SRC1_ALPHA:
      /* XXX what are these? */
      assert(0);
      break;
   case PIPE_BLENDFACTOR_INV_SRC_COLOR:
      {
         float inv_comp[4];
         VEC4_SUB(inv_comp, one, quadColor[0]); /* R */
         VEC4_MUL(dest[0], inv_comp, dest[0]); /* R */
         VEC4_SUB(inv_comp, one, quadColor[1]); /* G */
         VEC4_MUL(dest[1], inv_comp, dest[1]); /* G */
         VEC4_SUB(inv_comp, one, quadColor[2]); /* B */
         VEC4_MUL(dest[2], inv_comp, dest[2]); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
      {
         float one_minus_alpha[QUAD_SIZE];
         VEC4_SUB(one_minus_alpha, one, quadColor[3]);
         VEC4_MUL(dest[0], dest[0], one_minus_alpha); /* R */
         VEC4_MUL(dest[1], dest[1], one_minus_alpha); /* G */
         VEC4_MUL(dest[2], dest[2], one_minus_alpha); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_INV_DST_ALPHA:
      {
         float inv_comp[4];
         VEC4_SUB(inv_comp, one, quadColor[3]); /* A */
         VEC4_MUL(dest[0], inv_comp, dest[0]); /* R */
         VEC4_MUL(dest[1], inv_comp, dest[1]); /* G */
         VEC4_MUL(dest[2], inv_comp, dest[2]); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_INV_DST_COLOR:
      {
         float inv_comp[4];
         VEC4_SUB(inv_comp, one, dest[0]); /* R */
         VEC4_MUL(dest[0], dest[0], inv_comp); /* R */
         VEC4_SUB(inv_comp, one, dest[1]); /* G */
         VEC4_MUL(dest[1], dest[1], inv_comp); /* G */
         VEC4_SUB(inv_comp, one, dest[2]); /* B */
         VEC4_MUL(dest[2], dest[2], inv_comp); /* B */
      }
      break;
   case PIPE_BLENDFACTOR_INV_CONST_COLOR:
      {
         float inv_comp[4];
         /* R */
         VEC4_SCALAR(inv_comp, 1.0f - softpipe->blend_color.color[0]);
         VEC4_MUL(dest[0], dest[0], inv_comp);
         /* G */
         VEC4_SCALAR(inv_comp, 1.0f - softpipe->blend_color.color[1]);
         VEC4_MUL(dest[1], dest[1], inv_comp);
         /* B */
         VEC4_SCALAR(inv_comp, 1.0f - softpipe->blend_color.color[2]);
         VEC4_MUL(dest[2], dest[2], inv_comp);
      }
      break;
   case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
      {
         float inv_comp[4];
         VEC4_SCALAR(inv_comp, 1.0f - softpipe->blend_color.color[3]);
         VEC4_MUL(dest[0], dest[0], inv_comp);
         VEC4_MUL(dest[1], dest[1], inv_comp);
         VEC4_MUL(dest[2], dest[2], inv_comp);
      }
      break;
   case PIPE_BLENDFACTOR_INV_SRC1_COLOR:
   case PIPE_BLENDFACTOR_INV_SRC1_ALPHA:
      /* XXX what are these? */
      assert(0);
      break;
   default:
      assert(0);
   }

   /*
    * Compute dest/second term A
    */
   switch (softpipe->blend->alpha_dst_factor) {
   case PIPE_BLENDFACTOR_ONE:
      /* dest = dest * 1   NO-OP, leave dest as-is */
      break;
   case PIPE_BLENDFACTOR_SRC_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_SRC_ALPHA:
      VEC4_MUL(dest[3], dest[3], quadColor[3]); /* A * A */
      break;
   case PIPE_BLENDFACTOR_DST_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_DST_ALPHA:
      VEC4_MUL(dest[3], dest[3], dest[3]); /* A */
      break;
   case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
      assert(0); /* illegal */
      break;
   case PIPE_BLENDFACTOR_CONST_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_CONST_ALPHA:
      {
         float comp[4];
         VEC4_SCALAR(comp, softpipe->blend_color.color[3]); /* A */
         VEC4_MUL(dest[3], dest[3], comp); /* A */
      }
      break;
   case PIPE_BLENDFACTOR_ZERO:
      VEC4_COPY(dest[3], zero); /* A */
      break;
   case PIPE_BLENDFACTOR_INV_SRC_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
      {
         float one_minus_alpha[QUAD_SIZE];
         VEC4_SUB(one_minus_alpha, one, quadColor[3]);
         VEC4_MUL(dest[3], dest[3], one_minus_alpha); /* A */
      }
      break;
   case PIPE_BLENDFACTOR_INV_DST_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_INV_DST_ALPHA:
      {
         float inv_comp[4];
         VEC4_SUB(inv_comp, one, dest[3]); /* A */
         VEC4_MUL(dest[3], inv_comp, dest[3]); /* A */
      }
      break;
   case PIPE_BLENDFACTOR_INV_CONST_COLOR:
      /* fall-through */
   case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
      {
         float inv_comp[4];
         VEC4_SCALAR(inv_comp, 1.0f - softpipe->blend_color.color[3]);
         VEC4_MUL(dest[3], dest[3], inv_comp);
      }
      break;
   default:
      assert(0);
   }

   /*
    * Combine RGB terms
    */
   switch (softpipe->blend->rgb_func) {
   case PIPE_BLEND_ADD:
      VEC4_ADD(quadColor[0], source[0], dest[0]); /* R */
      VEC4_ADD(quadColor[1], source[1], dest[1]); /* G */
      VEC4_ADD(quadColor[2], source[2], dest[2]); /* B */
      break;
   case PIPE_BLEND_SUBTRACT:
      VEC4_SUB(quadColor[0], source[0], dest[0]); /* R */
      VEC4_SUB(quadColor[1], source[1], dest[1]); /* G */
      VEC4_SUB(quadColor[2], source[2], dest[2]); /* B */
      break;
   case PIPE_BLEND_REVERSE_SUBTRACT:
      VEC4_SUB(quadColor[0], dest[0], source[0]); /* R */
      VEC4_SUB(quadColor[1], dest[1], source[1]); /* G */
      VEC4_SUB(quadColor[2], dest[2], source[2]); /* B */
      break;
   case PIPE_BLEND_MIN:
      VEC4_MIN(quadColor[0], source[0], dest[0]); /* R */
      VEC4_MIN(quadColor[1], source[1], dest[1]); /* G */
      VEC4_MIN(quadColor[2], source[2], dest[2]); /* B */
      break;
   case PIPE_BLEND_MAX:
      VEC4_MAX(quadColor[0], source[0], dest[0]); /* R */
      VEC4_MAX(quadColor[1], source[1], dest[1]); /* G */
      VEC4_MAX(quadColor[2], source[2], dest[2]); /* B */
      break;
   default:
      assert(0);
   }

   /*
    * Combine A terms
    */
   switch (softpipe->blend->alpha_func) {
   case PIPE_BLEND_ADD:
      VEC4_ADD(quadColor[3], source[3], dest[3]); /* A */
      break;
   case PIPE_BLEND_SUBTRACT:
      VEC4_SUB(quadColor[3], source[3], dest[3]); /* A */
      break;
   case PIPE_BLEND_REVERSE_SUBTRACT:
      VEC4_SUB(quadColor[3], dest[3], source[3]); /* A */
      break;
   case PIPE_BLEND_MIN:
      VEC4_MIN(quadColor[3], source[3], dest[3]); /* A */
      break;
   case PIPE_BLEND_MAX:
      VEC4_MAX(quadColor[3], source[3], dest[3]); /* A */
      break;
   default:
      abort();
   }

   /* pass blended quad to next stage */
   qs->next->run(qs->next, quad);
}


static void blend_begin(struct quad_stage *qs)
{
   qs->next->begin(qs->next);
}


static void blend_destroy(struct quad_stage *qs)
{
   FREE( qs );
}


struct quad_stage *sp_quad_blend_stage( struct softpipe_context *softpipe )
{
   struct quad_stage *stage = CALLOC_STRUCT(quad_stage);

   stage->softpipe = softpipe;
   stage->begin = blend_begin;
   stage->run = blend_quad;
   stage->destroy = blend_destroy;

   return stage;
}