softpipe: optimized path for simple mipmap sampling

linear-mip-linear-repeat-POT sampling faspath, provides a very nice
speedup to apps that do this common type of texturing.

Test case: demos/terrain, turn fog off, turn texturing on.
Without patch: 12 fps
With patch: 20 fps.

1 files changed, 71 insertions, 24 deletions

diff --git a/src/gallium/drivers/softpipe/sp_tex_sample.c b/src/gallium/drivers/softpipe/sp_tex_sample.c
index 4651d781a9..b32ac9dabb 100644
--- a/src/gallium/drivers/softpipe/sp_tex_sample.c
+++ b/src/gallium/drivers/softpipe/sp_tex_sample.c
@@ -921,8 +921,8 @@ sp_get_samples_2d_linear_repeat_POT(struct tgsi_sampler *tgsi_sampler,
       }
       else 
       {
-         unsigned x1 = (uflr + 1) & (xpot - 1);
-         unsigned y1 = (vflr + 1) & (ypot - 1);
+         unsigned x1 = (x0 + 1) & (xpot - 1);
+         unsigned y1 = (y0 + 1) & (ypot - 1);
          get_texel_quad_2d_mt(tgsi_sampler, 0, level, 
                               x0, y0, x1, y1, tx);
       }
@@ -1028,42 +1028,92 @@ sp_get_samples_2d_linear_mip_linear_repeat_POT(struct tgsi_sampler *tgsi_sampler
    struct sp_shader_sampler *samp = sp_shader_sampler(tgsi_sampler);
    const struct pipe_texture *texture = samp->texture;
    const struct pipe_sampler_state *sampler = samp->sampler;
-   int level0, level1;
+   int level0;
    float lambda;
 
    lambda = compute_lambda(texture, sampler, s, t, p, lodbias);
    level0 = (int)lambda;
-   level1 = level0 + 1;
 
    if (lambda < 0.0) { 
       samp->level = 0;
       sp_get_samples_2d_linear_repeat_POT( tgsi_sampler,
-                                           s, t, p, lodbias, rgba );
+                                           s, t, p, 0, rgba );
    }
    else if (level0 >= texture->last_level) {
       samp->level = texture->last_level;
       sp_get_samples_2d_linear_repeat_POT( tgsi_sampler,
-                                           s, t, p, lodbias, rgba );
+                                           s, t, p, 0, rgba );
    }
    else {
-      float rgba0[4][4];
-      float rgba1[4][4];
-      int c,j;
-
       float levelBlend = lambda - level0;  /* blending weight between levels */
+      unsigned xpot = 1 << (samp->xpot - level0);
+      unsigned ypot = 1 << (samp->ypot - level0);
+      unsigned xpot1 = 1 << (samp->xpot - (level0+1));
+      unsigned ypot1 = 1 << (samp->ypot - (level0+1));
+      unsigned j;
 
-      samp->level = level0;
-      sp_get_samples_2d_linear_repeat_POT( tgsi_sampler,
-                                           s, t, p, lodbias, rgba0 );
+      for (j = 0; j < QUAD_SIZE; j++) {
+         int c;
+         
+         float u = s[j] * xpot - 0.5F;
+         float v = t[j] * ypot - 0.5F;
 
-      samp->level++;
-      sp_get_samples_2d_linear_repeat_POT( tgsi_sampler,
-                                           s, t, p, lodbias, rgba1 );
+         int uflr = util_ifloor(u);
+         int vflr = util_ifloor(v);
+
+         float xw = u - (float)uflr;
+         float yw = v - (float)vflr;
+
+         int x0 = uflr & (xpot - 1);
+         int y0 = vflr & (ypot - 1);
+
+         const float *tx0[4];
+         const float *tx1[4];
+      
+         if (x0 % TILE_SIZE != TILE_SIZE-1 &&
+             y0 % TILE_SIZE != TILE_SIZE-1)
+         {
+            get_texel_quad_2d(tgsi_sampler, 0, level0, x0, y0, tx0);
+         }
+         else 
+         {
+            unsigned x1 = (x0 + 1) & (xpot - 1);
+            unsigned y1 = (y0 + 1) & (ypot - 1);
+            get_texel_quad_2d_mt(tgsi_sampler, 0, level0, 
+                                 x0, y0, x1, y1, tx0);
+         }
 
-      for (c = 0; c < 4; c++) 
-         for (j = 0; j < 4; j++)
-            rgba[c][j] = lerp(levelBlend, rgba0[c][j], rgba1[c][j]);
-  }
+         x0 /= 2;
+         y0 /= 2;
+         /* also need to adjust xw, yw?? */
+
+         if (x0 % TILE_SIZE != TILE_SIZE-1 &&
+             y0 % TILE_SIZE != TILE_SIZE-1)
+         {
+            get_texel_quad_2d(tgsi_sampler, 0, level0+1, x0, y0, tx1);
+         }
+         else 
+         {
+            unsigned x1 = (x0 + 1) & (xpot1 - 1);
+            unsigned y1 = (y0 + 1) & (ypot1 - 1);
+            get_texel_quad_2d_mt(tgsi_sampler, 0, level0+1, 
+                                 x0, y0, x1, y1, tx1);
+         }
+
+         /* interpolate R, G, B, A */
+         for (c = 0; c < 4; c++) {
+            float rgba0 = lerp_2d(xw, yw, 
+                                  tx0[0][c], tx0[1][c], 
+                                  tx0[2][c], tx0[3][c]);
+
+            float rgba1 = lerp_2d(xw, yw, 
+                                  tx1[0][c], tx1[1][c], 
+                                  tx1[2][c], tx1[3][c]);
+
+            rgba[c][j] = lerp(levelBlend, rgba0, rgba1);
+         }
+      }
+   }
 }
 
 /**
@@ -1567,10 +1617,7 @@ sp_get_samples_fragment(struct tgsi_sampler *tgsi_sampler,
          if (sampler->wrap_s == PIPE_TEX_WRAP_REPEAT) {
             switch (sampler->min_img_filter) {
             case PIPE_TEX_FILTER_LINEAR:
-               /* This one not working yet:
-                */
-               if (0)
-                  tgsi_sampler->get_samples = sp_get_samples_2d_linear_mip_linear_repeat_POT;
+               tgsi_sampler->get_samples = sp_get_samples_2d_linear_mip_linear_repeat_POT;
                break;
             default:
                break;