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/**
* OpenAL cross platform audio library
* Copyright (C) 2009 by Chris Robinson.
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
* Or go to http://www.gnu.org/copyleft/lgpl.html
*/
#include "config.h"
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include "al/auxeffectslot.h"
#include "al/filter.h"
#include "alcmain.h"
#include "alcontext.h"
#include "alu.h"
#include "filters/biquad.h"
#include "vector.h"
namespace {
struct EchoState final : public EffectState {
al::vector<float,16> mSampleBuffer;
// The echo is two tap. The delay is the number of samples from before the
// current offset
struct {
size_t delay{0u};
} mTap[2];
size_t mOffset{0u};
/* The panning gains for the two taps */
struct {
float Current[MAX_OUTPUT_CHANNELS]{};
float Target[MAX_OUTPUT_CHANNELS]{};
} mGains[2];
BiquadFilter mFilter;
float mFeedGain{0.0f};
alignas(16) float mTempBuffer[2][BUFFERSIZE];
void deviceUpdate(const ALCdevice *device) override;
void update(const ALCcontext *context, const EffectSlot *slot, const EffectProps *props,
const EffectTarget target) override;
void process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn,
const al::span<FloatBufferLine> samplesOut) override;
DEF_NEWDEL(EchoState)
};
void EchoState::deviceUpdate(const ALCdevice *Device)
{
const auto frequency = static_cast<float>(Device->Frequency);
// Use the next power of 2 for the buffer length, so the tap offsets can be
// wrapped using a mask instead of a modulo
const ALuint maxlen{NextPowerOf2(float2uint(AL_ECHO_MAX_DELAY*frequency + 0.5f) +
float2uint(AL_ECHO_MAX_LRDELAY*frequency + 0.5f))};
if(maxlen != mSampleBuffer.size())
al::vector<float,16>(maxlen).swap(mSampleBuffer);
std::fill(mSampleBuffer.begin(), mSampleBuffer.end(), 0.0f);
for(auto &e : mGains)
{
std::fill(std::begin(e.Current), std::end(e.Current), 0.0f);
std::fill(std::begin(e.Target), std::end(e.Target), 0.0f);
}
}
void EchoState::update(const ALCcontext *context, const EffectSlot *slot,
const EffectProps *props, const EffectTarget target)
{
const ALCdevice *device{context->mDevice.get()};
const auto frequency = static_cast<float>(device->Frequency);
mTap[0].delay = maxu(float2uint(props->Echo.Delay*frequency + 0.5f), 1);
mTap[1].delay = float2uint(props->Echo.LRDelay*frequency + 0.5f) + mTap[0].delay;
const float gainhf{maxf(1.0f - props->Echo.Damping, 0.0625f)}; /* Limit -24dB */
mFilter.setParamsFromSlope(BiquadType::HighShelf, LOWPASSFREQREF/frequency, gainhf, 1.0f);
mFeedGain = props->Echo.Feedback;
/* Convert echo spread (where 0 = center, +/-1 = sides) to angle. */
const float angle{std::asin(props->Echo.Spread)};
const auto coeffs0 = CalcAngleCoeffs(-angle, 0.0f, 0.0f);
const auto coeffs1 = CalcAngleCoeffs( angle, 0.0f, 0.0f);
mOutTarget = target.Main->Buffer;
ComputePanGains(target.Main, coeffs0.data(), slot->Gain, mGains[0].Target);
ComputePanGains(target.Main, coeffs1.data(), slot->Gain, mGains[1].Target);
}
void EchoState::process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn, const al::span<FloatBufferLine> samplesOut)
{
const size_t mask{mSampleBuffer.size()-1};
float *RESTRICT delaybuf{mSampleBuffer.data()};
size_t offset{mOffset};
size_t tap1{offset - mTap[0].delay};
size_t tap2{offset - mTap[1].delay};
float z1, z2;
ASSUME(samplesToDo > 0);
const BiquadFilter filter{mFilter};
std::tie(z1, z2) = mFilter.getComponents();
for(size_t i{0u};i < samplesToDo;)
{
offset &= mask;
tap1 &= mask;
tap2 &= mask;
size_t td{minz(mask+1 - maxz(offset, maxz(tap1, tap2)), samplesToDo-i)};
do {
/* Feed the delay buffer's input first. */
delaybuf[offset] = samplesIn[0][i];
/* Get delayed output from the first and second taps. Use the
* second tap for feedback.
*/
mTempBuffer[0][i] = delaybuf[tap1++];
mTempBuffer[1][i] = delaybuf[tap2++];
const float feedb{mTempBuffer[1][i++]};
/* Add feedback to the delay buffer with damping and attenuation. */
delaybuf[offset++] += filter.processOne(feedb, z1, z2) * mFeedGain;
} while(--td);
}
mFilter.setComponents(z1, z2);
mOffset = offset;
for(ALsizei c{0};c < 2;c++)
MixSamples({mTempBuffer[c], samplesToDo}, samplesOut, mGains[c].Current, mGains[c].Target,
samplesToDo, 0);
}
struct EchoStateFactory final : public EffectStateFactory {
EffectState *create() override { return new EchoState{}; }
};
} // namespace
EffectStateFactory *EchoStateFactory_getFactory()
{
static EchoStateFactory EchoFactory{};
return &EchoFactory;
}
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