i915g: Implement srgb textures the easy way.

Since the hw can do it, let's use the hw. It's less accurate
but doesn't have the shader instruction count shortcomings.

src/gallium/drivers/i915/i915_context.h

@@ -155,8 +155,6 @@ struct i915_state
    unsigned sampler[I915_TEX_UNITS][3];
    unsigned sampler_enable_flags;
    unsigned sampler_enable_nr;
-   boolean sampler_srgb[I915_TEX_UNITS];
-   int srgb_const_offset;
 
    /* texture image buffers */
    unsigned texbuffer[I915_TEX_UNITS][2];

src/gallium/drivers/i915/i915_state_emit.c

@@ -314,41 +314,12 @@ emit_sampler(struct i915_context *i915)
    }
 }
 
-static boolean is_tex_instruction(uint32_t* instruction)
-{
-   uint32_t op = instruction[0] &0xFF000000;
-   return ( (op == T0_TEXLD) ||
-            (op == T0_TEXLDP) ||
-            (op == T0_TEXLDB));
-}
-
-static uint32_t tex_sampler(uint32_t* instruction)
-{
-   return ( instruction[0] & T0_SAMPLER_NR_MASK);
-}
-
-static uint additional_constants(struct i915_context *i915)
-{
-   int i;
-
-   for (i = 0 ; i < i915->fs->program_len; i+=3) {
-      if ( is_tex_instruction(i915->fs->program + i)) {
-           int sampler = tex_sampler(i915->fs->program + i);
-           assert(sampler < I915_TEX_UNITS);
-           if ( i915->current.sampler_srgb[sampler] )
-              return 1;
-      }
-   }
-   return 0;
-}
-
 static void
 validate_constants(struct i915_context *i915, unsigned *batch_space)
 {
    int nr = i915->fs->num_constants ?
       2 + 4*i915->fs->num_constants : 0;
 
-   nr += 4*additional_constants(i915);
    *batch_space = nr;
 }
 
@@ -358,11 +329,10 @@ emit_constants(struct i915_context *i915)
    /* Collate the user-defined constants with the fragment shader's
     * immediates according to the constant_flags[] array.
     */
-   const uint nr = i915->fs->num_constants + additional_constants(i915);
+   const uint nr = i915->fs->num_constants;
 
    assert(nr < I915_MAX_CONSTANT);
    if (nr) {
-      const float srgb_constants[4] = {1.0/1.055, 0.055/1.055, 2.4, 0.0822};
       uint i;
 
       OUT_BATCH( _3DSTATE_PIXEL_SHADER_CONSTANTS | (nr * 4) );
@@ -375,16 +345,9 @@ emit_constants(struct i915_context *i915)
             c = (uint *) i915_buffer(i915->constants[PIPE_SHADER_FRAGMENT])->data;
             c += 4 * i;
          }
-         else if (i < i915->fs->num_constants) {
+         else {
             /* emit program constant */
             c = (uint *) i915->fs->constants[i];
-         } else {
-            /* emit constants for sRGB */
-
-            /* save const position in context for use in shader emit */
-            i915->current.srgb_const_offset = i;
-
-            c = (uint *) srgb_constants;
          }
 #if 0 /* debug */
          {
@@ -405,64 +368,14 @@ emit_constants(struct i915_context *i915)
 static void
 validate_program(struct i915_context *i915, unsigned *batch_space)
 {
-   uint additional_size = 0, i;
+   uint additional_size = 0;
 
    additional_size += i915->current.target_fixup_format ? 3 : 0;
 
-   for (i = 0 ; i < i915->fs->program_len; i+=3)
-      if ( is_tex_instruction(i915->fs->program + i) &&
-           i915->current.sampler_srgb[tex_sampler(i915->fs->program+i)] )
-         additional_size += 3 * 8 /* 8 instructions for srgb emulation */;
-
-   /* we need more batch space if we want to emulate rgba framebuffers
-    * or sRGB textures */
+   /* we need more batch space if we want to emulate rgba framebuffers */
    *batch_space = i915->fs->decl_len + i915->fs->program_len + additional_size;
 }
 
-static void emit_instruction(struct i915_context *i915,
-                             int op,
-                             int dst_mask,
-			     int dst_reg,
-                             int src0_reg,
-                             int src1_reg,
-                             int src2_reg)
-{
-   OUT_BATCH(op |
-             dst_mask |
-             0 | /* saturate */
-             A0_DEST(dst_reg) |
-             A0_SRC0(src0_reg)
-             );
-   OUT_BATCH(A1_SRC0(src0_reg) | A1_SRC1(src1_reg));
-   OUT_BATCH(A2_SRC1(src1_reg) | A2_SRC2(src2_reg));
-}
-
-static void
-emit_srgb_fixup(struct i915_context *i915,
-                uint *program)
-{
-   int dst_reg =
-       (program[0] & UREG_TYPE_NR_MASK) >> UREG_A0_DEST_SHIFT_LEFT;
-   int dst_mask = program[0] & A0_DEST_CHANNEL_ALL;
-   int cst_idx = i915->current.srgb_const_offset;
-   int cst0_reg = swizzle(UREG(REG_TYPE_CONST, cst_idx), X, X, X, X);
-   int cst1_reg = swizzle(UREG(REG_TYPE_CONST, cst_idx), Y, Y, Y, Y);
-   int cst2_reg = swizzle(UREG(REG_TYPE_CONST, cst_idx), Z, Z, Z, Z);
-   int t1_reg = UREG(REG_TYPE_R, 1);
-   int t1x_reg = swizzle(UREG(REG_TYPE_R, 1), X, X, X, X);
-   int t1y_reg = swizzle(UREG(REG_TYPE_R, 1), Y, Y, Y, Y);
-   int t1z_reg = swizzle(UREG(REG_TYPE_R, 1), Z, Z, Z, Z);
-   
-   emit_instruction(i915, A0_MAD, A0_DEST_CHANNEL_ALL, t1_reg, dst_reg, cst0_reg, cst1_reg);
-   emit_instruction(i915, A0_LOG, A0_DEST_CHANNEL_X, t1_reg, t1x_reg, 0, 0);
-   emit_instruction(i915, A0_LOG, A0_DEST_CHANNEL_Y, t1_reg, t1y_reg, 0, 0);
-   emit_instruction(i915, A0_LOG, A0_DEST_CHANNEL_Z, t1_reg, t1z_reg, 0, 0);
-   emit_instruction(i915, A0_MUL, A0_DEST_CHANNEL_ALL, t1_reg, t1_reg, cst2_reg, 0);
-   emit_instruction(i915, A0_EXP, dst_mask & A0_DEST_CHANNEL_X, dst_reg, t1x_reg, 0, 0);
-   emit_instruction(i915, A0_EXP, dst_mask & A0_DEST_CHANNEL_Y, dst_reg, t1y_reg, 0, 0);
-   emit_instruction(i915, A0_EXP, dst_mask & A0_DEST_CHANNEL_Z, dst_reg, t1z_reg, 0, 0);
-}
-
 static void
 emit_program(struct i915_context *i915)
 {
@@ -493,12 +406,6 @@ emit_program(struct i915_context *i915)
       OUT_BATCH(i915->fs->program[i]);
       OUT_BATCH(i915->fs->program[i+1]);
       OUT_BATCH(i915->fs->program[i+2]);
-      
-      /* TEX fixup for sRGB */
-      if ( is_tex_instruction(i915->fs->program+i) &&
-           i915->current.sampler_srgb[tex_sampler(i915->fs->program+i)] )
-         emit_srgb_fixup(i915, i915->fs->program);
-
    }
 
    /* we emit an additional mov with swizzle to fake RGBA framebuffers */

src/gallium/drivers/i915/i915_state_sampler.c

@@ -96,7 +96,11 @@ static void update_sampler(struct i915_context *i915,
        pt->format == PIPE_FORMAT_YUYV)
       state[0] |= SS2_COLORSPACE_CONVERSION;
 
-   /* 3D textures don't seem to respect the border color.
+   if (pt->format == PIPE_FORMAT_B8G8R8A8_SRGB ||
+       pt->format == PIPE_FORMAT_L8_SRGB )
+      state[0] |= SS2_REVERSE_GAMMA_ENABLE;
+
+    /* 3D textures don't seem to respect the border color.
     * Fallback if there's ever a danger that they might refer to
     * it.  
     * 
@@ -310,8 +314,6 @@ static void update_map(struct i915_context *i915,
    assert(depth);
 
    format = translate_texture_format(pt->format, view);
-   i915->current.sampler_srgb[unit] = ( pt->format == PIPE_FORMAT_B8G8R8A8_SRGB ||
-                                        pt->format == PIPE_FORMAT_L8_SRGB );
    pitch = tex->stride;
 
    assert(format);