dspXMM.cpp

//=========================================================
//  OOMidi
//  OpenOctave Midi and Audio Editor
//  $Id: dspXMM.cpp,v 1.1.2.2 2009/12/20 00:04:25 spamatica Exp $
//
//  (C) Copyright 2007-2009 Werner Schweer (ws@seh.de)
//      file originally from Ardour DAW project by Paul Davis (c) 2007
//      licensed through GPL
//    	Original author Sampo Savolainen
//
//  This program is free software; you can redistribute it and/or modify
//  it under the terms of the GNU General Public License version 2.
//
//  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>

void
x86_sse_find_peaks(float *buf, unsigned 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);
}