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effect_fade.cpp
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effect_fade.cpp
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/* Audio Library for Teensy 3.X
* Copyright (c) 2014, Paul Stoffregen, [email protected]
*
* Development of this audio library was funded by PJRC.COM, LLC by sales of
* Teensy and Audio Adaptor boards. Please support PJRC's efforts to develop
* open source software by purchasing Teensy or other PJRC products.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice, development funding notice, and this permission
* notice shall be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <Arduino.h>
#include "effect_fade.h"
#include "utility/dspinst.h"
extern "C" {
extern const int16_t fader_table[257];
};
void AudioEffectFade::update(void)
{
audio_block_t *block;
uint32_t i, pos, inc, index, scale;
int32_t val1, val2, val, sample;
uint8_t dir;
pos = position;
if (pos == 0) {
// output is silent
block = receiveReadOnly();
if (block) release(block);
return;
} else if (pos == 0xFFFFFFFF) {
// output is 100%
block = receiveReadOnly();
if (!block) return;
transmit(block);
release(block);
return;
}
block = receiveWritable();
if (!block) return;
inc = rate;
dir = direction;
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
index = pos >> 24;
val1 = fader_table[index];
val2 = fader_table[index+1];
scale = (pos >> 8) & 0xFFFF;
val2 *= scale;
val1 *= 0x10000 - scale;
val = (val1 + val2) >> 16;
sample = block->data[i];
sample = (sample * val) >> 15;
block->data[i] = sample;
if (dir > 0) {
// output is increasing
if (inc < 0xFFFFFFFF - pos) pos += inc;
else pos = 0xFFFFFFFF;
} else {
// output is decreasing
if (inc < pos) pos -= inc;
else pos = 0;
}
}
position = pos;
transmit(block);
release(block);
}
void AudioEffectFade::fadeBegin(uint32_t newrate, uint8_t dir)
{
__disable_irq();
uint32_t pos = position;
if (pos == 0) position = 1;
else if (pos == 0xFFFFFFFF) position = 0xFFFFFFFE;
rate = newrate;
direction = dir;
__enable_irq();
}