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85 lines
2.3 KiB
C
85 lines
2.3 KiB
C
/*!
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* Polyphonic synthesizer for microcontrollers. Voice waveform generator.
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* (C) 2017 Stuart Longland
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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 as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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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 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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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
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* MA 02110-1301 USA
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*/
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#ifndef _WAVEFORM_H
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#define _WAVEFORM_H
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#include <stdint.h>
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/*!
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* Waveform generator state. 12 bytes.
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*/
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struct voice_wf_gen_t {
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/*! Waveform output sample in fixed-point */
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int16_t sample;
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/*! Amplitude sample in fixed point */
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int16_t amplitude;
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/*! Samples to next waveform period (12.4 fixed point) */
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uint16_t period_remain;
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/*!
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* Period duration in samples (12.4 fixed point).
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* (Half period for SQUARE and TRIANGLE)
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*/
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uint16_t period;
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/*! Amplitude step for TRIANGLE and SAWTOOTH */
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int16_t step;
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uint8_t reserved;
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/*! Waveform generation mode */
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uint8_t mode;
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};
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/*!
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* Configure the generator for a DC offset synthesis.
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*/
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void voice_wf_set_dc(struct voice_wf_gen_t* const wf_gen,
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int8_t amplitude);
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/*!
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* Configure the generator for square wave synthesis.
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*/
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void voice_wf_set_square(struct voice_wf_gen_t* const wf_gen,
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uint16_t freq, int8_t amplitude);
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/*!
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* Configure the generator for sawtooth wave synthesis.
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*/
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void voice_wf_set_sawtooth(struct voice_wf_gen_t* const wf_gen,
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uint16_t freq, int8_t amplitude);
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/*!
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* Configure the generator for sawtooth wave synthesis.
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*/
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void voice_wf_set_triangle(struct voice_wf_gen_t* const wf_gen,
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uint16_t freq, int8_t amplitude);
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/*!
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* Configure the generator for pseudorandom noise synthesis.
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*/
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void voice_wf_set_noise(struct voice_wf_gen_t* const wf_gen,
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int8_t amplitude);
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/*!
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* Retrieve the next sample from the generator.
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*/
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int8_t voice_wf_next(struct voice_wf_gen_t* const wf_gen);
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#endif
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/*
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* vim: set sw=8 ts=8 noet si tw=72
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*/
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