i965: Extract helper function for surface state pointer adjustment

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/mesa/drivers/dri/i965/brw_eu.h

@@ -281,6 +281,11 @@ void brw_SAMPLE(struct brw_compile *p,
 		unsigned simd_mode,
 		unsigned return_format);
 
+void brw_adjust_sampler_state_pointer(struct brw_compile *p,
+                                      struct brw_reg header,
+                                      struct brw_reg sampler_index,
+                                      struct brw_reg scratch);
+
 void gen4_math(struct brw_compile *p,
 	       struct brw_reg dest,
 	       unsigned function,

src/mesa/drivers/dri/i965/brw_eu_emit.c

@@ -2355,6 +2355,41 @@ void brw_SAMPLE(struct brw_compile *p,
                            return_format);
 }
 
+/* Adjust the message header's sampler state pointer to
+ * select the correct group of 16 samplers.
+ */
+void brw_adjust_sampler_state_pointer(struct brw_compile *p,
+                                      struct brw_reg header,
+                                      struct brw_reg sampler_index,
+                                      struct brw_reg scratch)
+{
+   /* The "Sampler Index" field can only store values between 0 and 15.
+    * However, we can add an offset to the "Sampler State Pointer"
+    * field, effectively selecting a different set of 16 samplers.
+    *
+    * The "Sampler State Pointer" needs to be aligned to a 32-byte
+    * offset, and each sampler state is only 16-bytes, so we can't
+    * exclusively use the offset - we have to use both.
+    */
+
+   struct brw_context *brw = p->brw;
+
+   if (sampler_index.file == BRW_IMMEDIATE_VALUE) {
+      const int sampler_state_size = 16; /* 16 bytes */
+      uint32_t sampler = sampler_index.dw1.ud;
+
+      if (sampler >= 16) {
+         assert(brw->is_haswell || brw->gen >= 8);
+         brw_ADD(p,
+                 get_element_ud(header, 3),
+                 get_element_ud(brw_vec8_grf(0, 0), 3),
+                 brw_imm_ud(16 * (sampler / 16) * sampler_state_size));
+      }
+   } else {
+      /* XXX: Non-const sampler array indexing case */
+   }
+}
+
 /* All these variables are pretty confusing - we might be better off
  * using bitmasks and macros for this, in the old style.  Or perhaps
  * just having the caller instantiate the fields in dword3 itself.

src/mesa/drivers/dri/i965/brw_vec4_generator.cpp

@@ -344,22 +344,7 @@ vec4_generator::generate_tex(vec4_instruction *inst,
                     brw_imm_ud(inst->texture_offset));
          }
 
-         if (sampler >= 16) {
-            /* The "Sampler Index" field can only store values between 0 and 15.
-             * However, we can add an offset to the "Sampler State Pointer"
-             * field, effectively selecting a different set of 16 samplers.
-             *
-             * The "Sampler State Pointer" needs to be aligned to a 32-byte
-             * offset, and each sampler state is only 16-bytes, so we can't
-             * exclusively use the offset - we have to use both.
-             */
-            const int sampler_state_size = 16; /* 16 bytes */
-            assert(brw->gen >= 8 || brw->is_haswell);
-            brw_ADD(p,
-                    get_element_ud(header, 3),
-                    get_element_ud(brw_vec8_grf(0, 0), 3),
-                    brw_imm_ud(16 * (sampler / 16) * sampler_state_size));
-         }
+         brw_adjust_sampler_state_pointer(p, header, sampler_index, dst);
          brw_pop_insn_state(p);
       }
    }