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sse_functions_xmm.cc

/*
    Copyright (C) 2007 Paul sDavis
      Written by Sampo Savolainen

    This program 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; either version 2 of the License, or
    (at your option) any later version.

    This program 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.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#include <xmmintrin.h>
#include <ardour/types.h>

void
x86_sse_find_peaks(float *buf, nframes_t nframes, float *min, float *max)
{
      __m128 current_max, current_min, work;

      // Load max and min values into all four slots of the XMM registers
      current_min = _mm_set1_ps(*min);
      current_max = _mm_set1_ps(*max);

      // Work input until "buf" reaches 16 byte alignment
      while ( ((unsigned long)buf) % 16 != 0 && nframes > 0) {

            // Load the next float into the work buffer
            work = _mm_set1_ps(*buf);

            current_min = _mm_min_ps(current_min, work);
            current_max = _mm_max_ps(current_max, work);
            
            buf++;
            nframes--;
      }

        // use 64 byte prefetch for quadruple quads
        while (nframes >= 16) {
                __builtin_prefetch(buf+64,0,0);

                work = _mm_load_ps(buf);
                current_min = _mm_min_ps(current_min, work);
                current_max = _mm_max_ps(current_max, work);
                buf+=4;
                work = _mm_load_ps(buf);
                current_min = _mm_min_ps(current_min, work);
                current_max = _mm_max_ps(current_max, work);
                buf+=4;
                work = _mm_load_ps(buf);
                current_min = _mm_min_ps(current_min, work);
                current_max = _mm_max_ps(current_max, work);
                buf+=4;
                work = _mm_load_ps(buf);
                current_min = _mm_min_ps(current_min, work);
                current_max = _mm_max_ps(current_max, work);
                buf+=4;
                nframes-=16;
        }

      // work through aligned buffers
      while (nframes >= 4) {

            work = _mm_load_ps(buf);

            current_min = _mm_min_ps(current_min, work);
            current_max = _mm_max_ps(current_max, work);

            buf+=4;
            nframes-=4;
      }
      
      // work through the rest < 4 samples
      while ( nframes > 0) {

            // Load the next float into the work buffer
            work = _mm_set1_ps(*buf);

            current_min = _mm_min_ps(current_min, work);
            current_max = _mm_max_ps(current_max, work);
            
            buf++;
            nframes--;
      }

      // Find min & max value in current_max through shuffle tricks

      work = current_min;
      work = _mm_shuffle_ps(work, work, _MM_SHUFFLE(2, 3, 0, 1));
      work = _mm_min_ps (work, current_min);
      current_min = work;
      work = _mm_shuffle_ps(work, work, _MM_SHUFFLE(1, 0, 3, 2));
      work = _mm_min_ps (work, current_min);

      _mm_store_ss(min, work);

      work = current_max;
      work = _mm_shuffle_ps(work, work, _MM_SHUFFLE(2, 3, 0, 1));
      work = _mm_max_ps (work, current_max);
      current_max = work;
      work = _mm_shuffle_ps(work, work, _MM_SHUFFLE(1, 0, 3, 2));
      work = _mm_max_ps (work, current_max);

      _mm_store_ss(max, work);
}




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