Merge remote branch 'origin/gallium-0.2' into gallium-0.2

1 files changed, 498 insertions, 97 deletions

diff --git a/src/gallium/drivers/cell/spu/spu_texture.c b/src/gallium/drivers/cell/spu/spu_texture.c
index 117b8a36f8..42eb06a362 100644
--- a/src/gallium/drivers/cell/spu/spu_texture.c
+++ b/src/gallium/drivers/cell/spu/spu_texture.c
@@ -26,6 +26,8 @@
  **************************************************************************/
 
 
+#include <math.h>
+
 #include "pipe/p_compiler.h"
 #include "spu_main.h"
 #include "spu_texture.h"
@@ -40,37 +42,19 @@
 void
 invalidate_tex_cache(void)
 {
-   uint unit = 0;
-   uint bytes = 4 * spu.texture[unit].width
-      * spu.texture[unit].height;
-
-   spu_dcache_mark_dirty((unsigned) spu.texture[unit].start, bytes);
-}
+   uint lvl;
+   for (lvl = 0; lvl < CELL_MAX_TEXTURE_LEVELS; lvl++) {
+      uint unit = 0;
+      uint bytes = 4 * spu.texture[unit].level[lvl].width
+         * spu.texture[unit].level[lvl].height;
 
+      if (spu.texture[unit].target == PIPE_TEXTURE_CUBE)
+         bytes *= 6;
+      else if (spu.texture[unit].target == PIPE_TEXTURE_3D)
+         bytes *= spu.texture[unit].level[lvl].depth;
 
-/**
- * XXX look into getting texels for all four pixels in a quad at once.
- */
-static uint
-get_texel(uint unit, vec_uint4 coordinate)
-{
-   /*
-    * XXX we could do the "/ TILE_SIZE" and "% TILE_SIZE" operations as
-    * SIMD since X and Y are already in a SIMD register.
-    */
-   const unsigned texture_ea = (uintptr_t) spu.texture[unit].start;
-   ushort x = spu_extract(coordinate, 0);
-   ushort y = spu_extract(coordinate, 1);
-   unsigned tile_offset = sizeof(tile_t)
-      * ((y / TILE_SIZE * spu.texture[unit].tiles_per_row) + (x / TILE_SIZE));
-   ushort texel_offset = (ushort) 4
-      * (ushort) (((ushort) (y % TILE_SIZE) * (ushort) TILE_SIZE) + (x % TILE_SIZE));
-   vec_uint4 tmp;
-
-   spu_dcache_fetch_unaligned((qword *) & tmp,
-                              texture_ea + tile_offset + texel_offset,
-                              4);
-   return spu_extract(tmp, 0);
+      spu_dcache_mark_dirty((unsigned) spu.texture[unit].level[lvl].start, bytes);
+   }
 }
 
 
@@ -88,15 +72,17 @@ get_texel(uint unit, vec_uint4 coordinate)
  * a time.
  */
 static void
-get_four_texels(uint unit, vec_uint4 x, vec_uint4 y, vec_uint4 *texels)
+get_four_texels(uint unit, uint level, uint face, vec_int4 x, vec_int4 y,
+                vec_uint4 *texels)
 {
-   const unsigned texture_ea = (uintptr_t) spu.texture[unit].start;
-   vec_uint4 tile_x = spu_rlmask(x, -5);
-   vec_uint4 tile_y = spu_rlmask(y, -5);
-   const qword offset_x = si_andi((qword) x, 0x1f);
-   const qword offset_y = si_andi((qword) y, 0x1f);
+   const struct spu_texture_level *tlevel = &spu.texture[unit].level[level];
+   unsigned texture_ea = (uintptr_t) tlevel->start;
+   const vec_int4 tile_x = spu_rlmask(x, -5);  /* tile_x = x / 32 */
+   const vec_int4 tile_y = spu_rlmask(y, -5);  /* tile_y = y / 32 */
+   const qword offset_x = si_andi((qword) x, 0x1f); /* offset_x = x & 0x1f */
+   const qword offset_y = si_andi((qword) y, 0x1f); /* offset_y = y & 0x1f */
 
-   const qword tiles_per_row = (qword) spu_splats(spu.texture[unit].tiles_per_row);
+   const qword tiles_per_row = (qword) spu_splats(tlevel->tiles_per_row);
    const qword tile_size = (qword) spu_splats((unsigned) sizeof(tile_t));
 
    qword tile_offset = si_mpya((qword) tile_y, tiles_per_row, (qword) tile_x);
@@ -107,6 +93,8 @@ get_four_texels(uint unit, vec_uint4 x, vec_uint4 y, vec_uint4 *texels)
    
    vec_uint4 offset = (vec_uint4) si_a(tile_offset, texel_offset);
    
+   texture_ea = texture_ea + face * tlevel->bytes_per_image;
+
    spu_dcache_fetch_unaligned((qword *) & texels[0],
                               texture_ea + spu_extract(offset, 0), 4);
    spu_dcache_fetch_unaligned((qword *) & texels[1],
@@ -118,83 +106,496 @@ get_four_texels(uint unit, vec_uint4 x, vec_uint4 y, vec_uint4 *texels)
 }
 
 
+/** clamp vec to [0, max] */
+static INLINE vector signed int
+spu_clamp(vector signed int vec, vector signed int max)
+{
+   static const vector signed int zero = {0,0,0,0};
+   vector unsigned int c;
+   c = spu_cmpgt(vec, zero);    /* c = vec > zero ? ~0 : 0 */
+   vec = spu_sel(zero, vec, c);
+   c = spu_cmpgt(vec, max);    /* c = vec > max ? ~0 : 0 */
+   vec = spu_sel(vec, max, c);
+   return vec;
+}
+
+
+
 /**
- * Get texture sample at texcoord.
+ * Do nearest texture sampling for four pixels.
+ * \param colors  returned colors in SOA format (rrrr, gggg, bbbb, aaaa).
  */
-vector float
-sample_texture_nearest(uint unit, vector float texcoord)
+void
+sample_texture4_nearest(vector float s, vector float t,
+                        vector float r, vector float q,
+                        uint unit, uint level, uint face,
+                        vector float colors[4])
 {
-   vector float tc = spu_mul(texcoord, spu.texture[unit].tex_size);
-   vector unsigned int itc = spu_convtu(tc, 0);  /* convert to int */
-   itc = spu_and(itc, spu.texture[unit].tex_size_mask); /* mask (GL_REPEAT) */
-   uint texel = get_texel(unit, itc);
-   return spu_unpack_A8R8G8B8(texel);
+   const struct spu_texture_level *tlevel = &spu.texture[unit].level[level];
+   vector float ss = spu_mul(s, tlevel->scale_s);
+   vector float tt = spu_mul(t, tlevel->scale_t);
+   vector signed int is = spu_convts(ss, 0);
+   vector signed int it = spu_convts(tt, 0);
+   vec_uint4 texels[4];
+
+   /* PIPE_TEX_WRAP_REPEAT */
+   is = spu_and(is, tlevel->mask_s);
+   it = spu_and(it, tlevel->mask_t);
+
+   /* PIPE_TEX_WRAP_CLAMP */
+   is = spu_clamp(is, tlevel->max_s);
+   it = spu_clamp(it, tlevel->max_t);
+
+   get_four_texels(unit, level, face, is, it, texels);
+
+   /* convert four packed ARGBA pixels to float RRRR,GGGG,BBBB,AAAA */
+   spu_unpack_A8R8G8B8_transpose4(texels, colors);
 }
 
 
-vector float
-sample_texture_bilinear(uint unit, vector float texcoord)
+/**
+ * Do bilinear texture sampling for four pixels.
+ * \param colors  returned colors in SOA format (rrrr, gggg, bbbb, aaaa).
+ */
+void
+sample_texture4_bilinear(vector float s, vector float t,
+                         vector float r, vector float q,
+                         uint unit, uint level, uint face,
+                         vector float colors[4])
 {
-   static const vec_uint4 offset_x = {0, 0, 1, 1};
-   static const vec_uint4 offset_y = {0, 1, 0, 1};
+   const struct spu_texture_level *tlevel = &spu.texture[unit].level[level];
+   static const vector float half = {-0.5f, -0.5f, -0.5f, -0.5f};
 
-   vector float tc = spu_mul(texcoord, spu.texture[unit].tex_size);
-   tc = spu_add(tc, spu_splats(-0.5f));  /* half texel bias */
+   vector float ss = spu_madd(s, tlevel->scale_s, half);
+   vector float tt = spu_madd(t, tlevel->scale_t, half);
 
-   /* integer texcoords S,T: */
-   vec_uint4 itc = spu_convtu(tc, 0);  /* convert to int */
+   vector signed int is0 = spu_convts(ss, 0);
+   vector signed int it0 = spu_convts(tt, 0);
 
-   vec_uint4 texels[4];
-   
-   /* setup texcoords for quad:
-    *  +-----+-----+
-    *  |x0,y0|x1,y1|
-    *  +-----+-----+
-    *  |x2,y2|x3,y3|
-    *  +-----+-----+
-    */
-   vec_uint4 x = spu_splats(spu_extract(itc, 0));
-   vec_uint4 y = spu_splats(spu_extract(itc, 1));
-   x = spu_add(x, offset_x);
-   y = spu_add(y, offset_y);
+   /* is + 1, it + 1 */
+   vector signed int is1 = spu_add(is0, 1);
+   vector signed int it1 = spu_add(it0, 1);
+
+   /* PIPE_TEX_WRAP_REPEAT */
+   is0 = spu_and(is0, tlevel->mask_s);
+   it0 = spu_and(it0, tlevel->mask_t);
+   is1 = spu_and(is1, tlevel->mask_s);
+   it1 = spu_and(it1, tlevel->mask_t);
 
-   /* GL_REPEAT wrap mode: */
-   x = spu_and(x, spu.texture[unit].tex_size_x_mask);
-   y = spu_and(y, spu.texture[unit].tex_size_y_mask);
+   /* PIPE_TEX_WRAP_CLAMP */
+   is0 = spu_clamp(is0, tlevel->max_s);
+   it0 = spu_clamp(it0, tlevel->max_t);
+   is1 = spu_clamp(is1, tlevel->max_s);
+   it1 = spu_clamp(it1, tlevel->max_t);
 
-   get_four_texels(unit, x, y, texels);
+   /* get packed int texels */
+   vector unsigned int texels[16];
+   get_four_texels(unit, level, face, is0, it0, texels + 0);  /* upper-left */
+   get_four_texels(unit, level, face, is1, it0, texels + 4);  /* upper-right */
+   get_four_texels(unit, level, face, is0, it1, texels + 8);  /* lower-left */
+   get_four_texels(unit, level, face, is1, it1, texels + 12); /* lower-right */
 
-   /* integer A8R8G8B8 to float texel conversion */
-   vector float texel00 = spu_unpack_A8R8G8B8(spu_extract(texels[0], 0));
-   vector float texel01 = spu_unpack_A8R8G8B8(spu_extract(texels[1], 0));
-   vector float texel10 = spu_unpack_A8R8G8B8(spu_extract(texels[2], 0));
-   vector float texel11 = spu_unpack_A8R8G8B8(spu_extract(texels[3], 0));
+   /* XXX possibly rework following code to compute the weighted sample
+    * colors with integer arithmetic for fewer int->float conversions.
+    */
 
+   /* convert packed int texels to float colors */
+   vector float ftexels[16];
+   spu_unpack_A8R8G8B8_transpose4(texels + 0, ftexels + 0);
+   spu_unpack_A8R8G8B8_transpose4(texels + 4, ftexels + 4);
+   spu_unpack_A8R8G8B8_transpose4(texels + 8, ftexels + 8);
+   spu_unpack_A8R8G8B8_transpose4(texels + 12, ftexels + 12);
 
    /* Compute weighting factors in [0,1]
     * Multiply texcoord by 1024, AND with 1023, convert back to float.
     */
-   vector float tc1024 = spu_mul(tc, spu_splats(1024.0f));
-   vector signed int itc1024 = spu_convts(tc1024, 0);
-   itc1024 = spu_and(itc1024, spu_splats((1 << 10) - 1));
-   vector float weight = spu_convtf(itc1024, 10);
-
-   /* smeared frac and 1-frac */
-   vector float sfrac = spu_splats(spu_extract(weight, 0));
-   vector float tfrac = spu_splats(spu_extract(weight, 1));
-   vector float sfrac1 = spu_sub(spu_splats(1.0f), sfrac);
-   vector float tfrac1 = spu_sub(spu_splats(1.0f), tfrac);
-
-   /* multiply the samples (colors) by the S/T weights */
-   texel00 = spu_mul(spu_mul(texel00, sfrac1), tfrac1);
-   texel10 = spu_mul(spu_mul(texel10, sfrac ), tfrac1);
-   texel01 = spu_mul(spu_mul(texel01, sfrac1), tfrac );
-   texel11 = spu_mul(spu_mul(texel11, sfrac ), tfrac );
-
-   /* compute sum of weighted samples */
-   vector float texel_sum = spu_add(texel00, texel01);
-   texel_sum = spu_add(texel_sum, texel10);
-   texel_sum = spu_add(texel_sum, texel11);
-
-   return texel_sum;
+   vector float ss1024 = spu_mul(ss, spu_splats(1024.0f));
+   vector signed int iss1024 = spu_convts(ss1024, 0);
+   iss1024 = spu_and(iss1024, 1023);
+   vector float sWeights0 = spu_convtf(iss1024, 10);
+
+   vector float tt1024 = spu_mul(tt, spu_splats(1024.0f));
+   vector signed int itt1024 = spu_convts(tt1024, 0);
+   itt1024 = spu_and(itt1024, 1023);
+   vector float tWeights0 = spu_convtf(itt1024, 10);
+
+   /* 1 - sWeight and 1 - tWeight */
+   vector float sWeights1 = spu_sub(spu_splats(1.0f), sWeights0);
+   vector float tWeights1 = spu_sub(spu_splats(1.0f), tWeights0);
+
+   /* reds, for four pixels */
+   ftexels[ 0] = spu_mul(ftexels[ 0], spu_mul(sWeights1, tWeights1)); /*ul*/
+   ftexels[ 4] = spu_mul(ftexels[ 4], spu_mul(sWeights0, tWeights1)); /*ur*/
+   ftexels[ 8] = spu_mul(ftexels[ 8], spu_mul(sWeights1, tWeights0)); /*ll*/
+   ftexels[12] = spu_mul(ftexels[12], spu_mul(sWeights0, tWeights0)); /*lr*/
+   colors[0] = spu_add(spu_add(ftexels[0], ftexels[4]),
+                       spu_add(ftexels[8], ftexels[12]));
+
+   /* greens, for four pixels */
+   ftexels[ 1] = spu_mul(ftexels[ 1], spu_mul(sWeights1, tWeights1)); /*ul*/
+   ftexels[ 5] = spu_mul(ftexels[ 5], spu_mul(sWeights0, tWeights1)); /*ur*/
+   ftexels[ 9] = spu_mul(ftexels[ 9], spu_mul(sWeights1, tWeights0)); /*ll*/
+   ftexels[13] = spu_mul(ftexels[13], spu_mul(sWeights0, tWeights0)); /*lr*/
+   colors[1] = spu_add(spu_add(ftexels[1], ftexels[5]),
+                       spu_add(ftexels[9], ftexels[13]));
+
+   /* blues, for four pixels */
+   ftexels[ 2] = spu_mul(ftexels[ 2], spu_mul(sWeights1, tWeights1)); /*ul*/
+   ftexels[ 6] = spu_mul(ftexels[ 6], spu_mul(sWeights0, tWeights1)); /*ur*/
+   ftexels[10] = spu_mul(ftexels[10], spu_mul(sWeights1, tWeights0)); /*ll*/
+   ftexels[14] = spu_mul(ftexels[14], spu_mul(sWeights0, tWeights0)); /*lr*/
+   colors[2] = spu_add(spu_add(ftexels[2], ftexels[6]),
+                       spu_add(ftexels[10], ftexels[14]));
+
+   /* alphas, for four pixels */
+   ftexels[ 3] = spu_mul(ftexels[ 3], spu_mul(sWeights1, tWeights1)); /*ul*/
+   ftexels[ 7] = spu_mul(ftexels[ 7], spu_mul(sWeights0, tWeights1)); /*ur*/
+   ftexels[11] = spu_mul(ftexels[11], spu_mul(sWeights1, tWeights0)); /*ll*/
+   ftexels[15] = spu_mul(ftexels[15], spu_mul(sWeights0, tWeights0)); /*lr*/
+   colors[3] = spu_add(spu_add(ftexels[3], ftexels[7]),
+                       spu_add(ftexels[11], ftexels[15]));
+}
+
+
+
+/**
+ * Adapted from /opt/cell/sdk/usr/spu/include/transpose_matrix4x4.h
+ */
+static INLINE void
+transpose(vector unsigned int *mOut0,
+          vector unsigned int *mOut1,
+          vector unsigned int *mOut2,
+          vector unsigned int *mOut3,
+          vector unsigned int *mIn)
+{
+  vector unsigned int abcd, efgh, ijkl, mnop;	/* input vectors */
+  vector unsigned int aeim, bfjn, cgko, dhlp;	/* output vectors */
+  vector unsigned int aibj, ckdl, emfn, gohp;	/* intermediate vectors */
+
+  vector unsigned char shufflehi = ((vector unsigned char) {
+					       0x00, 0x01, 0x02, 0x03,
+					       0x10, 0x11, 0x12, 0x13,
+					       0x04, 0x05, 0x06, 0x07,
+					       0x14, 0x15, 0x16, 0x17});
+  vector unsigned char shufflelo = ((vector unsigned char) {
+					       0x08, 0x09, 0x0A, 0x0B,
+					       0x18, 0x19, 0x1A, 0x1B,
+					       0x0C, 0x0D, 0x0E, 0x0F,
+					       0x1C, 0x1D, 0x1E, 0x1F});
+  abcd = *(mIn+0);
+  efgh = *(mIn+1);
+  ijkl = *(mIn+2);
+  mnop = *(mIn+3);
+
+  aibj = spu_shuffle(abcd, ijkl, shufflehi);
+  ckdl = spu_shuffle(abcd, ijkl, shufflelo);
+  emfn = spu_shuffle(efgh, mnop, shufflehi);
+  gohp = spu_shuffle(efgh, mnop, shufflelo);
+
+  aeim = spu_shuffle(aibj, emfn, shufflehi);
+  bfjn = spu_shuffle(aibj, emfn, shufflelo);
+  cgko = spu_shuffle(ckdl, gohp, shufflehi);
+  dhlp = spu_shuffle(ckdl, gohp, shufflelo);
+
+  *mOut0 = aeim;
+  *mOut1 = bfjn;
+  *mOut2 = cgko;
+  *mOut3 = dhlp;
+}
+
+
+/**
+ * Bilinear filtering, using int intead of float arithmetic
+ */
+void
+sample_texture4_bilinear_2(vector float s, vector float t,
+                           vector float r, vector float q,
+                           uint unit, uint level, uint face,
+                           vector float colors[4])
+{
+   const struct spu_texture_level *tlevel = &spu.texture[unit].level[level];
+   static const vector float half = {-0.5f, -0.5f, -0.5f, -0.5f};
+
+   /* Scale texcoords by size of texture, and add half pixel bias */
+   vector float ss = spu_madd(s, tlevel->scale_s, half);
+   vector float tt = spu_madd(t, tlevel->scale_t, half);
+
+   /* convert float coords to fixed-pt coords with 8 fraction bits */
+   vector signed int is = spu_convts(ss, 8);
+   vector signed int it = spu_convts(tt, 8);
+
+   /* compute integer texel weights in [0, 255] */
+   vector signed int sWeights0 = spu_and(is, 255);
+   vector signed int tWeights0 = spu_and(it, 255);
+   vector signed int sWeights1 = spu_sub(255, sWeights0);
+   vector signed int tWeights1 = spu_sub(255, tWeights0);
+
+   /* texel coords: is0 = is / 256, it0 = is / 256 */
+   vector signed int is0 = spu_rlmask(is, -8);
+   vector signed int it0 = spu_rlmask(it, -8);
+
+   /* texel coords: i1 = is0 + 1, it1 = it0 + 1 */
+   vector signed int is1 = spu_add(is0, 1);
+   vector signed int it1 = spu_add(it0, 1);
+
+   /* PIPE_TEX_WRAP_REPEAT */
+   is0 = spu_and(is0, tlevel->mask_s);
+   it0 = spu_and(it0, tlevel->mask_t);
+   is1 = spu_and(is1, tlevel->mask_s);
+   it1 = spu_and(it1, tlevel->mask_t);
+
+   /* PIPE_TEX_WRAP_CLAMP */
+   is0 = spu_clamp(is0, tlevel->max_s);
+   it0 = spu_clamp(it0, tlevel->max_t);
+   is1 = spu_clamp(is1, tlevel->max_s);
+   it1 = spu_clamp(it1, tlevel->max_t);
+
+   /* get packed int texels */
+   vector unsigned int texels[16];
+   get_four_texels(unit, level, face, is0, it0, texels + 0);  /* upper-left */
+   get_four_texels(unit, level, face, is1, it0, texels + 4);  /* upper-right */
+   get_four_texels(unit, level, face, is0, it1, texels + 8);  /* lower-left */
+   get_four_texels(unit, level, face, is1, it1, texels + 12); /* lower-right */
+
+   /* twiddle packed 32-bit BGRA pixels into RGBA as four unsigned ints */
+   {
+      static const unsigned char ZERO = 0x80;
+      int i;
+      for (i = 0; i < 16; i++) {
+         texels[i] = spu_shuffle(texels[i], texels[i],
+                                 ((vector unsigned char) {
+                                    ZERO, ZERO, ZERO, 1,
+                                    ZERO, ZERO, ZERO, 2,
+                                    ZERO, ZERO, ZERO, 3,
+                                    ZERO, ZERO, ZERO, 0}));
+      }
+   }
+
+   /* convert RGBA,RGBA,RGBA,RGBA to RRRR,GGGG,BBBB,AAAA */
+   vector unsigned int texel0, texel1, texel2, texel3, texel4, texel5, texel6, texel7,
+      texel8, texel9, texel10, texel11, texel12, texel13, texel14, texel15;
+   transpose(&texel0, &texel1, &texel2, &texel3, texels + 0);
+   transpose(&texel4, &texel5, &texel6, &texel7, texels + 4);
+   transpose(&texel8, &texel9, &texel10, &texel11, texels + 8);
+   transpose(&texel12, &texel13, &texel14, &texel15, texels + 12);
+
+   /* computed weighted colors */
+   vector unsigned int c0, c1, c2, c3, cSum;
+
+   /* red */
+   c0 = (vector unsigned int) si_mpyu((qword) texel0, si_mpyu((qword) sWeights1, (qword) tWeights1)); /*ul*/
+   c1 = (vector unsigned int) si_mpyu((qword) texel4, si_mpyu((qword) sWeights0, (qword) tWeights1)); /*ur*/
+   c2 = (vector unsigned int) si_mpyu((qword) texel8, si_mpyu((qword) sWeights1, (qword) tWeights0)); /*ll*/
+   c3 = (vector unsigned int) si_mpyu((qword) texel12, si_mpyu((qword) sWeights0, (qword) tWeights0)); /*lr*/
+   cSum = spu_add(spu_add(c0, c1), spu_add(c2, c3));
+   colors[0] = spu_convtf(cSum, 24);
+
+   /* green */
+   c0 = (vector unsigned int) si_mpyu((qword) texel1, si_mpyu((qword) sWeights1, (qword) tWeights1)); /*ul*/
+   c1 = (vector unsigned int) si_mpyu((qword) texel5, si_mpyu((qword) sWeights0, (qword) tWeights1)); /*ur*/
+   c2 = (vector unsigned int) si_mpyu((qword) texel9, si_mpyu((qword) sWeights1, (qword) tWeights0)); /*ll*/
+   c3 = (vector unsigned int) si_mpyu((qword) texel13, si_mpyu((qword) sWeights0, (qword) tWeights0)); /*lr*/
+   cSum = spu_add(spu_add(c0, c1), spu_add(c2, c3));
+   colors[1] = spu_convtf(cSum, 24);
+
+   /* blue */
+   c0 = (vector unsigned int) si_mpyu((qword) texel2, si_mpyu((qword) sWeights1, (qword) tWeights1)); /*ul*/
+   c1 = (vector unsigned int) si_mpyu((qword) texel6, si_mpyu((qword) sWeights0, (qword) tWeights1)); /*ur*/
+   c2 = (vector unsigned int) si_mpyu((qword) texel10, si_mpyu((qword) sWeights1, (qword) tWeights0)); /*ll*/
+   c3 = (vector unsigned int) si_mpyu((qword) texel14, si_mpyu((qword) sWeights0, (qword) tWeights0)); /*lr*/
+   cSum = spu_add(spu_add(c0, c1), spu_add(c2, c3));
+   colors[2] = spu_convtf(cSum, 24);
+
+   /* alpha */
+   c0 = (vector unsigned int) si_mpyu((qword) texel3, si_mpyu((qword) sWeights1, (qword) tWeights1)); /*ul*/
+   c1 = (vector unsigned int) si_mpyu((qword) texel7, si_mpyu((qword) sWeights0, (qword) tWeights1)); /*ur*/
+   c2 = (vector unsigned int) si_mpyu((qword) texel11, si_mpyu((qword) sWeights1, (qword) tWeights0)); /*ll*/
+   c3 = (vector unsigned int) si_mpyu((qword) texel15, si_mpyu((qword) sWeights0, (qword) tWeights0)); /*lr*/
+   cSum = spu_add(spu_add(c0, c1), spu_add(c2, c3));
+   colors[3] = spu_convtf(cSum, 24);
+}
+
+
+
+/**
+ * Compute level of detail factor from texcoords.
+ */
+static float
+compute_lambda(uint unit, vector float s, vector float t)
+{
+   uint baseLevel = 0;
+   float width = spu.texture[unit].level[baseLevel].width;
+   float height = spu.texture[unit].level[baseLevel].width;
+   float dsdx = width * (spu_extract(s, 1) - spu_extract(s, 0));
+   float dsdy = width * (spu_extract(s, 2) - spu_extract(s, 0));
+   float dtdx = height * (spu_extract(t, 1) - spu_extract(t, 0));
+   float dtdy = height * (spu_extract(t, 2) - spu_extract(t, 0));
+   float x = dsdx * dsdx + dtdx * dtdx;
+   float y = dsdy * dsdy + dtdy * dtdy;
+   float rho = x > y ? x : y;
+   rho = sqrtf(rho);
+   float lambda = logf(rho) * 1.442695f;
+   return lambda;
+}
+
+
+
+/**
+ * Texture sampling with level of detail selection.
+ */
+void
+sample_texture4_lod(vector float s, vector float t,
+                    vector float r, vector float q,
+                    uint unit, uint level_ignored, uint face,
+                    vector float colors[4])
+{
+   /*
+    * Note that we're computing a lambda/lod here that's used for all
+    * four pixels in the quad.
+    */
+   float lambda = compute_lambda(unit, s, t);
+
+   /* apply lod bias */
+   lambda += spu.sampler[unit].lod_bias;
+
+   /* clamp */
+   if (lambda < spu.sampler[unit].min_lod)
+      lambda = spu.sampler[unit].min_lod;
+   else if (lambda > spu.sampler[unit].max_lod)
+      lambda = spu.sampler[unit].max_lod;
+
+   if (lambda <= 0.0f) {
+      /* magnify */
+      spu.mag_sample_texture4[unit](s, t, r, q, unit, 0, 0, colors);
+   }
+   else {
+      /* minify */
+      int level = (int) (lambda + 0.5f);
+      if (level > (int) spu.texture[unit].max_level)
+         level = spu.texture[unit].max_level;
+      spu.min_sample_texture4[unit](s, t, r, q, unit, level, 0, colors);
+      /* XXX to do: mipmap level interpolation */
+   }
+}
+
+
+/** XXX need a SIMD version of this */
+static unsigned
+choose_cube_face(float rx, float ry, float rz, float *newS, float *newT)
+{
+   /*
+      major axis
+      direction     target                             sc     tc    ma
+      ----------    -------------------------------    ---    ---   ---
+       +rx          TEXTURE_CUBE_MAP_POSITIVE_X_EXT    -rz    -ry   rx
+       -rx          TEXTURE_CUBE_MAP_NEGATIVE_X_EXT    +rz    -ry   rx
+       +ry          TEXTURE_CUBE_MAP_POSITIVE_Y_EXT    +rx    +rz   ry
+       -ry          TEXTURE_CUBE_MAP_NEGATIVE_Y_EXT    +rx    -rz   ry
+       +rz          TEXTURE_CUBE_MAP_POSITIVE_Z_EXT    +rx    -ry   rz
+       -rz          TEXTURE_CUBE_MAP_NEGATIVE_Z_EXT    -rx    -ry   rz
+   */
+   const float arx = fabsf(rx);
+   const float ary = fabsf(ry);
+   const float arz = fabsf(rz);
+   unsigned face;
+   float sc, tc, ma;
+
+   if (arx > ary && arx > arz) {
+      if (rx >= 0.0F) {
+         face = PIPE_TEX_FACE_POS_X;
+         sc = -rz;
+         tc = -ry;
+         ma = arx;
+      }
+      else {
+         face = PIPE_TEX_FACE_NEG_X;
+         sc = rz;
+         tc = -ry;
+         ma = arx;
+      }
+   }
+   else if (ary > arx && ary > arz) {
+      if (ry >= 0.0F) {
+         face = PIPE_TEX_FACE_POS_Y;
+         sc = rx;
+         tc = rz;
+         ma = ary;
+      }
+      else {
+         face = PIPE_TEX_FACE_NEG_Y;
+         sc = rx;
+         tc = -rz;
+         ma = ary;
+      }
+   }
+   else {
+      if (rz > 0.0F) {
+         face = PIPE_TEX_FACE_POS_Z;
+         sc = rx;
+         tc = -ry;
+         ma = arz;
+      }
+      else {
+         face = PIPE_TEX_FACE_NEG_Z;
+         sc = -rx;
+         tc = -ry;
+         ma = arz;
+      }
+   }
+
+   *newS = (sc / ma + 1.0F) * 0.5F;
+   *newT = (tc / ma + 1.0F) * 0.5F;
+
+   return face;
+}
+
+
+
+void
+sample_texture4_cube(vector float s, vector float t,
+                     vector float r, vector float q,
+                     uint unit, uint level, uint face_ignored,
+                     vector float colors[4])
+{
+   static const vector float zero = {0.0f, 0.0f, 0.0f, 0.0f};
+   uint p, faces[4];
+   float newS[4], newT[4];
+
+   /* Compute cube face referenced by the four sets of texcoords.
+    * XXX we should SIMD-ize this.
+    */
+   for (p = 0; p < 4; p++) {      
+      float rx = spu_extract(s, p);
+      float ry = spu_extract(t, p);
+      float rz = spu_extract(r, p);
+      faces[p] = choose_cube_face(rx, ry, rz, &newS[p], &newT[p]);
+   }
+
+   if (faces[0] == faces[1] &&
+       faces[0] == faces[2] &&
+       faces[0] == faces[3]) {
+      /* GOOD!  All four texcoords refer to the same cube face */
+      s = (vector float) {newS[0], newS[1], newS[2], newS[3]};
+      t = (vector float) {newT[0], newT[1], newT[2], newT[3]};
+      sample_texture4_nearest(s, t, zero, zero, unit, level, faces[0], colors);
+   }
+   else {
+      /* BAD!  The four texcoords refer to different faces */
+      for (p = 0; p < 4; p++) {      
+         vector float c[4];
+
+         sample_texture4_nearest(spu_splats(newS[p]), spu_splats(newT[p]),
+                                 zero, zero, unit, level, faces[p], c);
+
+         float red = spu_extract(c[0], p);
+         float green = spu_extract(c[1], p);
+         float blue = spu_extract(c[2], p);
+         float alpha = spu_extract(c[3], p);
+
+         colors[0] = spu_insert(red,   colors[0], p);
+         colors[1] = spu_insert(green, colors[1], p);
+         colors[2] = spu_insert(blue,  colors[2], p);
+         colors[3] = spu_insert(alpha, colors[3], p);
+      }
+   }
 }