src/viewport_sprite_sorter_sse4.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file viewport_sprite_sorter_sse4.cpp Sprite sorter that uses SSE4.1. */
   9
  10 #ifdef WITH_SSE
  11
  12 #include "stdafx.h"
  13 #include "cpu.h"
  14 #include "smmintrin.h"
  15 #include "viewport_sprite_sorter.h"
  16
  17 #include "safeguards.h"
  18
  19 #ifdef _SQ64
  20         assert_compile((sizeof(ParentSpriteToDraw) % 16) == 0);
  21         #define LOAD_128 _mm_load_si128
  22 #else
  23         #define LOAD_128 _mm_loadu_si128
  24 #endif
  25
  26 /** Sort parent sprites pointer array using SSE4.1 optimizations. */
  27 void ViewportSortParentSpritesSSE41(ParentSpriteToSortVector *psdv)
  28 {
  29         const __m128i mask_ptest = _mm_setr_epi8(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  0,  0,  0,  0);
  30         auto const psdvend = psdv->end();
  31         auto psd = psdv->begin();
  32         while (psd != psdvend) {
  33                 ParentSpriteToDraw * const ps = *psd;
  34
  35                 if (ps->comparison_done) {
  36                         psd++;
  37                         continue;
  38                 }
  39
  40                 ps->comparison_done = true;
  41
  42                 for (auto psd2 = psd + 1; psd2 != psdvend; psd2++) {
  43                         ParentSpriteToDraw * const ps2 = *psd2;
  44
  45                         if (ps2->comparison_done) continue;
  46
  47                         /*
  48                          * Decide which comparator to use, based on whether the bounding boxes overlap
  49                          *
  50                          * Original code:
  51                          * if (ps->xmax >= ps2->xmin && ps->xmin <= ps2->xmax && // overlap in X?
  52                          *     ps->ymax >= ps2->ymin && ps->ymin <= ps2->ymax && // overlap in Y?
  53                          *     ps->zmax >= ps2->zmin && ps->zmin <= ps2->zmax) { // overlap in Z?
  54                          *
  55                          * Above conditions are equivalent to:
  56                          * 1/    !( (ps->xmax >= ps2->xmin) && (ps->ymax >= ps2->ymin) && (ps->zmax >= ps2->zmin)   &&    (ps->xmin <= ps2->xmax) && (ps->ymin <= ps2->ymax) && (ps->zmin <= ps2->zmax) )
  57                          * 2/    !( (ps->xmax >= ps2->xmin) && (ps->ymax >= ps2->ymin) && (ps->zmax >= ps2->zmin)   &&    (ps2->xmax >= ps->xmin) && (ps2->ymax >= ps->ymin) && (ps2->zmax >= ps->zmin) )
  58                          * 3/  !( ( (ps->xmax >= ps2->xmin) && (ps->ymax >= ps2->ymin) && (ps->zmax >= ps2->zmin) ) &&  ( (ps2->xmax >= ps->xmin) && (ps2->ymax >= ps->ymin) && (ps2->zmax >= ps->zmin) ) )
  59                          * 4/ !( !( (ps->xmax <  ps2->xmin) || (ps->ymax <  ps2->ymin) || (ps->zmax <  ps2->zmin) ) && !( (ps2->xmax <  ps->xmin) || (ps2->ymax <  ps->ymin) || (ps2->zmax <  ps->zmin) ) )
  60                          * 5/ PTEST <---------------------------------- rslt1 ---------------------------------->         <------------------------------ rslt2 -------------------------------------->
  61                          */
  62                         __m128i ps1_max = LOAD_128((__m128i*) &ps->xmax);
  63                         __m128i ps2_min = LOAD_128((__m128i*) &ps2->xmin);
  64                         __m128i rslt1 = _mm_cmplt_epi32(ps1_max, ps2_min);
  65                         if (!_mm_testz_si128(mask_ptest, rslt1))
  66                                 continue;
  67
  68                         __m128i ps1_min = LOAD_128((__m128i*) &ps->xmin);
  69                         __m128i ps2_max = LOAD_128((__m128i*) &ps2->xmax);
  70                         __m128i rslt2 = _mm_cmplt_epi32(ps2_max, ps1_min);
  71                         if (_mm_testz_si128(mask_ptest, rslt2)) {
  72                                 /* Use X+Y+Z as the sorting order, so sprites closer to the bottom of
  73                                  * the screen and with higher Z elevation, are drawn in front.
  74                                  * Here X,Y,Z are the coordinates of the "center of mass" of the sprite,
  75                                  * i.e. X=(left+right)/2, etc.
  76                                  * However, since we only care about order, don't actually divide / 2
  77                                  */
  78                                 if (ps->xmin + ps->xmax + ps->ymin + ps->ymax + ps->zmin + ps->zmax <=
  79                                                 ps2->xmin + ps2->xmax + ps2->ymin + ps2->ymax + ps2->zmin + ps2->zmax) {
  80                                         continue;
  81                                 }
  82                         }
  83
  84                         /* Move ps2 in front of ps */
  85                         ParentSpriteToDraw * const temp = ps2;
  86                         for (auto psd3 = psd2; psd3 > psd; psd3--) {
  87                                 *psd3 = *(psd3 - 1);
  88                         }
  89                         *psd = temp;
  90                 }
  91         }
  92 }
  93
  94 /**
  95  * Check whether the current CPU supports SSE 4.1.
  96  * @return True iff the CPU supports SSE 4.1.
  97  */
  98 bool ViewportSortParentSpritesSSE41Checker()
  99 {
 100         return HasCPUIDFlag(1, 2, 19);
 101 }
 102
 103 #endif /* WITH_SSE */