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62 lines
1.5 KiB
C
62 lines
1.5 KiB
C
/*!
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* Polyphonic synthesizer for microcontrollers. Voice generation.
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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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#include "waveform.h"
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#include "adsr.h"
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/*!
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* Voice channel state. 30 bytes.
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*/
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struct voice_ch_t {
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/*!
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* ADSR Envelope generator state.
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*/
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struct adsr_env_gen_t adsr;
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/*!
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* Waveform generator state.
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*/
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struct voice_wf_gen_t wf;
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};
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/*!
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* Compute the next voice channel sample.
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*/
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inline static int8_t voice_ch_next(struct voice_ch_t* const voice) {
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uint8_t amplitude = adsr_next(&(voice->adsr));
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if (!amplitude)
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return 0;
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int16_t value = voice_wf_next(&(voice->wf));
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value *= amplitude;
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/* Saturation handling */
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if (value < INT8_MIN)
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return INT8_MIN;
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else if (value > INT8_MAX)
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return INT8_MAX;
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else
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return value;
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}
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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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