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/*
* Copyright (C) 2008-2011 Fons Adriaensen <fons@linuxaudio.org>
* Copyright (C) 2013-2019 Robin Gareus <robin@gareus.org>
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <math.h>
#include "ardour/kmeterdsp.h"
float Kmeterdsp::_omega;
Kmeterdsp::Kmeterdsp (void)
: _z1 (0)
, _z2 (0)
, _rms (0)
, _flag (false)
{}
Kmeterdsp::~Kmeterdsp (void) {}
void
Kmeterdsp::init (int fsamp)
{
_omega = 9.72f / fsamp; // ballistic filter coefficient
}
void
Kmeterdsp::process (float const* p, int n)
{
float s, z1, z2;
// Get filter state.
z1 = _z1 > 50 ? 50 : (_z1 < 0 ? 0 : _z1);
z2 = _z2 > 50 ? 50 : (_z2 < 0 ? 0 : _z2);
// Perform filtering. The second filter is evaluated
// only every 4th sample - this is just an optimisation.
n /= 4; // Loop is unrolled by 4.
while (n--) {
s = *p++;
s *= s;
z1 += _omega * (s - z1); // Update first filter.
s = *p++;
s *= s;
z1 += _omega * (s - z1); // Update first filter.
s = *p++;
s *= s;
z1 += _omega * (s - z1); // Update first filter.
s = *p++;
s *= s;
z1 += _omega * (s - z1); // Update first filter.
z2 += 4 * _omega * (z1 - z2); // Update second filter.
}
if (isnan(z1)) z1 = 0;
if (isnan(z2)) z2 = 0;
// Save filter state. The added constants avoid denormals.
_z1 = z1 + 1e-20f;
_z2 = z2 + 1e-20f;
s = sqrtf (2.0f * z2);
if (_flag) {
// Display thread has read the rms value.
_rms = s;
_flag = false;
} else {
// Adjust RMS value and update maximum since last read().
if (s > _rms) _rms = s;
}
}
/* Returns highest _rms value since last call */
float
Kmeterdsp::read ()
{
float rv= _rms;
_flag = true; // Resets _rms in next process().
return rv;
}
void
Kmeterdsp::reset ()
{
_z1 = _z2 = _rms = .0f;
_flag = false;
}
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