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100 lines
3.1 KiB
100 lines
3.1 KiB
7 years ago
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/* Audio Library for Teensy 3.X
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* Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com
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*
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* Development of this audio library was funded by PJRC.COM, LLC by sales of
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* Teensy and Audio Adaptor boards. Please support PJRC's efforts to develop
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* open source software by purchasing Teensy or other PJRC products.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice, development funding notice, and this permission
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* notice shall be included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#ifndef synth_dc_f32_h_
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#define synth_dc_f32_h_
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#include "Arduino.h"
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#include "AudioStream_f32.h"
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#include "utility/dspinst.h"
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#include "arm_math.h"
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// compute (a - b) / c
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// handling 32 bit interger overflow at every step
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// without resorting to slow 64 bit math
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class AudioSynthWaveformDc_F32 : public AudioStream_F32
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{
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public:
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AudioSynthWaveformDc_F32() : AudioStream_F32(0, NULL), state(0), magnitude(0) {}
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// immediately jump to the new DC level
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void amplitude(float n) {
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if (n > 1.0) n = 1.0;
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else if (n < -1.0) n = -1.0;
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// int i;
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// int32_t m = (int32_t)(n * 0x7fff);
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__disable_irq();
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magnitude = n;
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state = 0;
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// incblock = allocate_f32();
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// for(i=0;i<AUDIO_BLOCK_SAMPLES;i++)
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// incblock->data[i]=i+1;
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__enable_irq();
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}
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// slowly transition to the new DC level
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void amplitude(float n, float milliseconds) {
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if (milliseconds <= 0.0) {
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amplitude(n);
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return;
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}
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if (n > 1.0) n = 1.0;
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else if (n < -1.0) n = -1.0;
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float c = (milliseconds*(AUDIO_SAMPLE_RATE_EXACT/1000.0));
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if (c == 0) {
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amplitude(n);
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return;
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}
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// int32_t t = (int32_t)(n * 0x7fff);
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__disable_irq();
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target = n;
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if (target == magnitude) {
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state = 0;
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__enable_irq();
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return;
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}
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increment = (target-magnitude)/ c;
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if (increment == 0) {
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increment = (target > magnitude) ? 1 : -1;
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}
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state = 1;
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__enable_irq();
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}
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float read(void) {
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return magnitude;
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}
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virtual void update(void);
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private:
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uint8_t state; // 0=steady output, 1=transitioning
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float magnitude; // current output
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float target; // designed output (while transitiong)
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float increment; // adjustment per sample (while transitiong)
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// audio_block_f32_t *incblock;
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};
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#endif
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