Mesa (master): gallivm: fix repeat() function for NPOT textures

[Brian Paul]

Module: Mesa
Branch: master
Commit: 4e2f53bacb670b824593dce70668a8f92796ed93
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=4e2f53bacb670b824593dce70668a8f92796ed93

Author: Brian Paul <brianp at vmware.com>
Date:   Sat Sep 25 13:09:25 2010 -0600

gallivm: fix repeat() function for NPOT textures

The trick of casting the coord to an unsigned value only works for POT
textures.  Add a bias instead.  This fixes a few piglit texwrap failures.

---

 src/gallium/auxiliary/gallivm/lp_bld_sample_aos.c |   13 ++++++++-----
 src/gallium/auxiliary/gallivm/lp_bld_sample_soa.c |   14 +++++++++-----
 2 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_sample_aos.c b/src/gallium/auxiliary/gallivm/lp_bld_sample_aos.c
index 9a1c693..49a6eed 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_sample_aos.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_sample_aos.c
@@ -90,10 +90,12 @@ lp_build_sample_wrap_nearest_int(struct lp_build_sample_context *bld,
    case PIPE_TEX_WRAP_REPEAT:
       if(is_pot)
          coord = LLVMBuildAnd(bld->builder, coord, length_minus_one, "");
-      else
-         /* Signed remainder won't give the right results for negative
-          * dividends but unsigned remainder does.*/
+      else {
+         /* Add a bias to the texcoord to handle negative coords */
+         LLVMValueRef bias = lp_build_mul_imm(uint_coord_bld, length, 1024);
+         coord = LLVMBuildAdd(bld->builder, coord, bias, "");
          coord = LLVMBuildURem(bld->builder, coord, length, "");
+      }
       break;
 
    case PIPE_TEX_WRAP_CLAMP_TO_EDGE:
@@ -197,8 +199,9 @@ lp_build_sample_wrap_linear_int(struct lp_build_sample_context *bld,
          coord0 = LLVMBuildAnd(bld->builder, coord0, length_minus_one, "");
       }
       else {
-         /* Signed remainder won't give the right results for negative
-          * dividends but unsigned remainder does.*/
+         /* Add a bias to the texcoord to handle negative coords */
+         LLVMValueRef bias = lp_build_mul_imm(uint_coord_bld, length, 1024);
+         coord0 = LLVMBuildAdd(bld->builder, coord0, bias, "");
          coord0 = LLVMBuildURem(bld->builder, coord0, length, "");
       }
 
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_sample_soa.c b/src/gallium/auxiliary/gallivm/lp_bld_sample_soa.c
index e3e8548..f53ad91 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_sample_soa.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_sample_soa.c
@@ -280,8 +280,10 @@ lp_build_sample_wrap_linear(struct lp_build_sample_context *bld,
          coord1 = LLVMBuildAnd(bld->builder, coord1, length_minus_one, "");
       }
       else {
-         /* Signed remainder won't give the right results for negative
-          * dividends but unsigned remainder does.*/
+         /* Add a bias to the texcoord to handle negative coords */
+         LLVMValueRef bias = lp_build_mul_imm(uint_coord_bld, length, 1024);
+         coord0 = LLVMBuildAdd(bld->builder, coord0, bias, "");
+         coord1 = LLVMBuildAdd(bld->builder, coord1, bias, "");
          coord0 = LLVMBuildURem(bld->builder, coord0, length, "");
          coord1 = LLVMBuildURem(bld->builder, coord1, length, "");
       }
@@ -476,10 +478,12 @@ lp_build_sample_wrap_nearest(struct lp_build_sample_context *bld,
       icoord = lp_build_ifloor(coord_bld, coord);
       if (is_pot)
          icoord = LLVMBuildAnd(bld->builder, icoord, length_minus_one, "");
-      else
-         /* Signed remainder won't give the right results for negative
-          * dividends but unsigned remainder does.*/
+      else {
+         /* Add a bias to the texcoord to handle negative coords */
+         LLVMValueRef bias = lp_build_mul_imm(uint_coord_bld, length, 1024);
+         icoord = LLVMBuildAdd(bld->builder, icoord, bias, "");
          icoord = LLVMBuildURem(bld->builder, icoord, length, "");
+      }
       break;
 
    case PIPE_TEX_WRAP_CLAMP: