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  1. /*
  2.  * Copyright © 2014 Timothy Arceri
  3.  *
  4.  * Permission is hereby granted, free of charge, to any person obtaining a
  5.  * copy of this software and associated documentation files (the "Software"),
  6.  * to deal in the Software without restriction, including without limitation
  7.  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  8.  * and/or sell copies of the Software, and to permit persons to whom the
  9.  * Software is furnished to do so, subject to the following conditions:
  10.  *
  11.  * The above copyright notice and this permission notice (including the next
  12.  * paragraph) shall be included in all copies or substantial portions of the
  13.  * Software.
  14.  *
  15.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16.  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17.  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18.  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19.  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20.  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21.  * IN THE SOFTWARE.
  22.  *
  23.  * Author:
  24.  *    Timothy Arceri <t_arceri@yahoo.com.au>
  25.  *
  26.  */
  27.  
  28. #include "main/sse_minmax.h"
  29. #include <smmintrin.h>
  30. #include <stdint.h>
  31.  
  32. void
  33. _mesa_uint_array_min_max(const unsigned *ui_indices, unsigned *min_index,
  34.                          unsigned *max_index, const unsigned count)
  35. {
  36.    unsigned max_ui = 0;
  37.    unsigned min_ui = ~0U;
  38.    unsigned i = 0;
  39.    unsigned aligned_count = count;
  40.  
  41.    /* handle the first few values without SSE until the pointer is aligned */
  42.    while (((uintptr_t)ui_indices & 15) && aligned_count) {
  43.       if (*ui_indices > max_ui)
  44.          max_ui = *ui_indices;
  45.       if (*ui_indices < min_ui)
  46.          min_ui = *ui_indices;
  47.  
  48.       aligned_count--;
  49.       ui_indices++;
  50.    }
  51.  
  52.    /* TODO: The actual threshold for SSE begin useful may be higher than 8.
  53.     * Some careful microbenchmarks and measurement are required to
  54.     * find the actual tipping point.
  55.     */
  56.    if (aligned_count >= 8) {
  57.       unsigned max_arr[4] __attribute__ ((aligned (16)));
  58.       unsigned min_arr[4] __attribute__ ((aligned (16)));
  59.       unsigned vec_count;
  60.       __m128i max_ui4 = _mm_setzero_si128();
  61.       __m128i min_ui4 = _mm_set1_epi32(~0U);
  62.       __m128i ui_indices4;
  63.       __m128i *ui_indices_ptr;
  64.  
  65.       vec_count = aligned_count & ~0x3;
  66.       ui_indices_ptr = (__m128i *)ui_indices;
  67.       for (i = 0; i < vec_count / 4; i++) {
  68.          ui_indices4 = _mm_load_si128(&ui_indices_ptr[i]);
  69.          max_ui4 = _mm_max_epu32(ui_indices4, max_ui4);
  70.          min_ui4 = _mm_min_epu32(ui_indices4, min_ui4);
  71.       }
  72.  
  73.       _mm_store_si128((__m128i *)max_arr, max_ui4);
  74.       _mm_store_si128((__m128i *)min_arr, min_ui4);
  75.  
  76.       for (i = 0; i < 4; i++) {
  77.          if (max_arr[i] > max_ui)
  78.             max_ui = max_arr[i];
  79.          if (min_arr[i] < min_ui)
  80.             min_ui = min_arr[i];
  81.       }
  82.       i = vec_count;
  83.    }
  84.  
  85.    for (; i < aligned_count; i++) {
  86.       if (ui_indices[i] > max_ui)
  87.          max_ui = ui_indices[i];
  88.       if (ui_indices[i] < min_ui)
  89.          min_ui = ui_indices[i];
  90.    }
  91.  
  92.    *min_index = min_ui;
  93.    *max_index = max_ui;
  94. }
  95.