/**************************************************************************
 *
 * Copyright 2009 VMware, Inc.
 * All Rights Reserved.
 *
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 * copy of this software and associated documentation files (the
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 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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/**
 * @file
 * Blend LLVM IR generation -- AoS layout.
 *
 * AoS blending is in general much slower than SoA, but there are some cases
 * where it might be faster. In particular, if a pixel is rendered only once
 * then the overhead of tiling and untiling will dominate over the speedup that
 * SoA gives. So we might want to detect such cases and fallback to AoS in the
 * future, but for now this function is here for historical/benchmarking
 * purposes.
 *
 * Run lp_blend_test after any change to this file.
 *
 * @author Jose Fonseca <jfonseca@vmware.com>
 */


#include "pipe/p_state.h"
#include "util/u_debug.h"
#include "util/u_format.h"

#include "gallivm/lp_bld_type.h"
#include "gallivm/lp_bld_const.h"
#include "gallivm/lp_bld_arit.h"
#include "gallivm/lp_bld_logic.h"
#include "gallivm/lp_bld_swizzle.h"
#include "gallivm/lp_bld_bitarit.h"
#include "gallivm/lp_bld_debug.h"

#include "lp_bld_blend.h"


/**
 * We may the same values several times, so we keep them here to avoid
 * recomputing them. Also reusing the values allows us to do simplifications
 * that LLVM optimization passes wouldn't normally be able to do.
 */
struct lp_build_blend_aos_context
{
   struct lp_build_context base;
   
   LLVMValueRef src;
   LLVMValueRef dst;
   LLVMValueRef const_;

   LLVMValueRef inv_src;
   LLVMValueRef inv_dst;
   LLVMValueRef inv_const;
   LLVMValueRef saturate;

   LLVMValueRef rgb_src_factor;
   LLVMValueRef alpha_src_factor;
   LLVMValueRef rgb_dst_factor;
   LLVMValueRef alpha_dst_factor;
};


static LLVMValueRef
lp_build_blend_factor_unswizzled(struct lp_build_blend_aos_context *bld,
                                 unsigned factor,
                                 boolean alpha)
{
   switch (factor) {
   case PIPE_BLENDFACTOR_ZERO:
      return bld->base.zero;
   case PIPE_BLENDFACTOR_ONE:
      return bld->base.one;
   case PIPE_BLENDFACTOR_SRC_COLOR:
   case PIPE_BLENDFACTOR_SRC_ALPHA:
      return bld->src;
   case PIPE_BLENDFACTOR_DST_COLOR:
   case PIPE_BLENDFACTOR_DST_ALPHA:
      return bld->dst;
   case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
      if(alpha)
         return bld->base.one;
      else {
         if(!bld->inv_dst)
            bld->inv_dst = lp_build_comp(&bld->base, bld->dst);
         if(!bld->saturate)
            bld->saturate = lp_build_min(&bld->base, bld->src, bld->inv_dst);
         return bld->saturate;
      }
   case PIPE_BLENDFACTOR_CONST_COLOR:
   case PIPE_BLENDFACTOR_CONST_ALPHA:
      return bld->const_;
   case PIPE_BLENDFACTOR_SRC1_COLOR:
   case PIPE_BLENDFACTOR_SRC1_ALPHA:
      /* TODO */
      assert(0);
      return bld->base.zero;
   case PIPE_BLENDFACTOR_INV_SRC_COLOR:
   case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
      if(!bld->inv_src)
         bld->inv_src = lp_build_comp(&bld->base, bld->src);
      return bld->inv_src;
   case PIPE_BLENDFACTOR_INV_DST_COLOR:
   case PIPE_BLENDFACTOR_INV_DST_ALPHA:
      if(!bld->inv_dst)
         bld->inv_dst = lp_build_comp(&bld->base, bld->dst);
      return bld->inv_dst;
   case PIPE_BLENDFACTOR_INV_CONST_COLOR:
   case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
      if(!bld->inv_const)
         bld->inv_const = lp_build_comp(&bld->base, bld->const_);
      return bld->inv_const;
   case PIPE_BLENDFACTOR_INV_SRC1_COLOR:
   case PIPE_BLENDFACTOR_INV_SRC1_ALPHA:
      /* TODO */
      assert(0);
      return bld->base.zero;
   default:
      assert(0);
      return bld->base.zero;
   }
}


enum lp_build_blend_swizzle {
   LP_BUILD_BLEND_SWIZZLE_RGBA = 0,
   LP_BUILD_BLEND_SWIZZLE_AAAA = 1
};


/**
 * How should we shuffle the base factor.
 */
static enum lp_build_blend_swizzle
lp_build_blend_factor_swizzle(unsigned factor)
{
   switch (factor) {
   case PIPE_BLENDFACTOR_ONE:
   case PIPE_BLENDFACTOR_ZERO:
   case PIPE_BLENDFACTOR_SRC_COLOR:
   case PIPE_BLENDFACTOR_DST_COLOR:
   case PIPE_BLENDFACTOR_CONST_COLOR:
   case PIPE_BLENDFACTOR_SRC1_COLOR:
   case PIPE_BLENDFACTOR_INV_SRC_COLOR:
   case PIPE_BLENDFACTOR_INV_DST_COLOR:
   case PIPE_BLENDFACTOR_INV_CONST_COLOR:
   case PIPE_BLENDFACTOR_INV_SRC1_COLOR:
      return LP_BUILD_BLEND_SWIZZLE_RGBA;
   case PIPE_BLENDFACTOR_SRC_ALPHA:
   case PIPE_BLENDFACTOR_DST_ALPHA:
   case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
   case PIPE_BLENDFACTOR_SRC1_ALPHA:
   case PIPE_BLENDFACTOR_CONST_ALPHA:
   case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
   case PIPE_BLENDFACTOR_INV_DST_ALPHA:
   case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
   case PIPE_BLENDFACTOR_INV_SRC1_ALPHA:
      return LP_BUILD_BLEND_SWIZZLE_AAAA;
   default:
      assert(0);
      return LP_BUILD_BLEND_SWIZZLE_RGBA;
   }
}


static LLVMValueRef
lp_build_blend_swizzle(struct lp_build_blend_aos_context *bld,
                       LLVMValueRef rgb, 
                       LLVMValueRef alpha, 
                       enum lp_build_blend_swizzle rgb_swizzle,
                       unsigned alpha_swizzle)
{
   LLVMValueRef swizzled_rgb;

   switch (rgb_swizzle) {
   case LP_BUILD_BLEND_SWIZZLE_RGBA:
      swizzled_rgb = rgb;
      break;
   case LP_BUILD_BLEND_SWIZZLE_AAAA:
      swizzled_rgb = lp_build_swizzle_scalar_aos(&bld->base, rgb, alpha_swizzle);
      break;
   default:
      assert(0);
      swizzled_rgb = bld->base.undef;
   }

   if (rgb != alpha) {
      swizzled_rgb = lp_build_select_aos(&bld->base, 1 << alpha_swizzle,
                                         alpha, swizzled_rgb);
   }

   return swizzled_rgb;
}


/**
 * @sa http://www.opengl.org/sdk/docs/man/xhtml/glBlendFuncSeparate.xml
 */
static LLVMValueRef
lp_build_blend_factor(struct lp_build_blend_aos_context *bld,
                      unsigned rgb_factor,
                      unsigned alpha_factor,
                      unsigned alpha_swizzle)
{
   LLVMValueRef rgb_factor_, alpha_factor_;
   enum lp_build_blend_swizzle rgb_swizzle;

   rgb_factor_ = lp_build_blend_factor_unswizzled(bld, rgb_factor, FALSE);

   if (alpha_swizzle != UTIL_FORMAT_SWIZZLE_NONE) {
      rgb_swizzle   = lp_build_blend_factor_swizzle(rgb_factor);
      alpha_factor_ = lp_build_blend_factor_unswizzled(bld, alpha_factor, TRUE);
      return lp_build_blend_swizzle(bld, rgb_factor_, alpha_factor_, rgb_swizzle, alpha_swizzle);
   } else {
      return rgb_factor_;
   }
}


/**
 * Performs blending of src and dst pixels
 *
 * @param blend         the blend state of the shader variant
 * @param cbuf_format   format of the colour buffer
 * @param type          data type of the pixel vector
 * @param rt            rt number
 * @param src           blend src
 * @param dst           blend dst
 * @param mask          optional mask to apply to the blending result
 * @param const_        const blend color
 * @param swizzle       swizzle values for RGBA
 *
 * @return the result of blending src and dst
 */
LLVMValueRef
lp_build_blend_aos(struct gallivm_state *gallivm,
                   const struct pipe_blend_state *blend,
                   const enum pipe_format *cbuf_format,
                   struct lp_type type,
                   unsigned rt,
                   LLVMValueRef src,
                   LLVMValueRef dst,
                   LLVMValueRef mask,
                   LLVMValueRef const_,
                   const unsigned char swizzle[4])
{
   const struct pipe_rt_blend_state * state = &blend->rt[rt];
   struct lp_build_blend_aos_context bld;
   LLVMValueRef src_factor, dst_factor;
   LLVMValueRef result;
   unsigned alpha_swizzle = swizzle[3];
   boolean fullcolormask;

   /* Setup build context */
   memset(&bld, 0, sizeof bld);
   lp_build_context_init(&bld.base, gallivm, type);
   bld.src = src;
   bld.dst = dst;
   bld.const_ = const_;

   if (swizzle[3] > UTIL_FORMAT_SWIZZLE_W || swizzle[3] == swizzle[0])
      alpha_swizzle = UTIL_FORMAT_SWIZZLE_NONE;

   if (!state->blend_enable) {
      result = src;
   } else {
      boolean rgb_alpha_same = state->rgb_src_factor == state->rgb_dst_factor && state->alpha_src_factor == state->alpha_dst_factor;
      assert(rgb_alpha_same || alpha_swizzle != UTIL_FORMAT_SWIZZLE_NONE);

      src_factor = lp_build_blend_factor(&bld, state->rgb_src_factor,
                                         state->alpha_src_factor, alpha_swizzle);
      dst_factor = lp_build_blend_factor(&bld, state->rgb_dst_factor,
                                         state->alpha_dst_factor, alpha_swizzle);

      result = lp_build_blend(&bld.base,
                              state->rgb_func,
                              state->rgb_src_factor,
                              state->rgb_dst_factor,
                              src,
                              dst,
                              src_factor,
                              dst_factor,
                              rgb_alpha_same,
                              false);

      if(state->rgb_func != state->alpha_func && alpha_swizzle != UTIL_FORMAT_SWIZZLE_NONE) {
         LLVMValueRef alpha;

         alpha = lp_build_blend(&bld.base,
                                state->alpha_func,
                                state->alpha_src_factor,
                                state->alpha_dst_factor,
                                src,
                                dst,
                                src_factor,
                                dst_factor,
                                rgb_alpha_same,
                                false);

         result = lp_build_blend_swizzle(&bld,
                                         result,
                                         alpha,
                                         LP_BUILD_BLEND_SWIZZLE_RGBA,
                                         alpha_swizzle);
      }
   }

   /* Check if color mask is necessary */
   fullcolormask = util_format_colormask_full(util_format_description(cbuf_format[rt]), state->colormask);

   if (!fullcolormask) {
      LLVMValueRef color_mask;

      color_mask = lp_build_const_mask_aos_swizzled(gallivm, bld.base.type, state->colormask, swizzle);
      lp_build_name(color_mask, "color_mask");

      /* Combine with input mask if necessary */
      if (mask) {
         mask = lp_build_and(&bld.base, color_mask, mask);
      } else {
         mask = color_mask;
      }
   }

   /* Apply mask, if one exists */
   if (mask) {
      result = lp_build_select(&bld.base, mask, result, dst);
   }

   return result;
}