95 lines
3.1 KiB
C++
95 lines
3.1 KiB
C++
/***************************************************************************
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* Copyright (C) 2008 by Sindre Aamås *
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* sinamas@users.sourceforge.net *
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License version 2 as *
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* published by the Free Software Foundation. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License version 2 for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* version 2 along with this program; if not, write to the *
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* Free Software Foundation, Inc., *
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* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
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***************************************************************************/
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#include "rateest.h"
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#include <cstdlib>
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void RateEst::SumQueue::reset() {
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q.clear();
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samples_ = usecs_ = 0;
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}
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void RateEst::SumQueue::push(const long samples, const usec_t usecs) {
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q.push_back(pair_t(samples, usecs));
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samples_ += samples;
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usecs_ += usecs;
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}
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void RateEst::SumQueue::pop() {
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const pair_t &f = q.front();
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samples_ -= f.first;
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usecs_ -= f.second;
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q.pop_front();
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}
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static usec_t sampleUsecs(long samples, long rate) {
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return usec_t((samples * 1000000.0f) / (rate ? rate : 1) + 0.5f);
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}
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static long limit(long est, const long reference) {
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if (est > reference + (reference >> 6))
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est = reference + (reference >> 6);
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else if (est < reference - (reference >> 6))
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est = reference - (reference >> 6);
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return est;
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}
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void RateEst::init(long srate, long reference, const long maxSamplePeriod) {
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maxPeriod = sampleUsecs(maxSamplePeriod, reference);
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srate <<= UPSHIFT;
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reference <<= UPSHIFT;
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this->srate = limit(srate, reference);
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last = 0;
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this->reference = reference;
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samples = (this->srate >> UPSHIFT) * 12 << 5;
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usecs = 12000000 << 5;
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sumq.reset();
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}
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void RateEst::feed(long samplesIn, const usec_t now) {
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usec_t usecsIn = now - last;
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if (last && usecsIn < maxPeriod) {
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sumq.push(samplesIn, usecsIn);
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while ((usecsIn = sumq.usecs()) > 100000) {
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samplesIn = sumq.samples();
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sumq.pop();
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if (std::abs(long(samplesIn * (1000000.0f * UP) / usecsIn) - reference) < reference >> 1) {
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samples += (samplesIn - sumq.samples()) << 5;
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usecs += ( usecsIn - sumq.usecs() ) << 5;
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long est = long(samples * (1000000.0f * UP) / usecs + 0.5f);
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est = limit((srate * 31 + est + 16) >> 5, reference);
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srate = est;
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if (usecs > 16000000 << 5) {
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samples = (samples * 3 + 2) >> 2;
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usecs = (usecs * 3 + 2) >> 2;
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}
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}
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}
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}
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last = now;
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}
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