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90 lines
2.5 KiB
90 lines
2.5 KiB
6 years ago
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/* Copyright 2019 Jack Humbert
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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, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "ch.h"
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/**
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* Size of the dac_buffer arrays. All must be the same size.
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*/
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#define DAC_BUFFER_SIZE 256U
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/**
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* Highest value allowed by our 12bit DAC.
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*/
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#ifndef DAC_SAMPLE_MAX
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#define DAC_SAMPLE_MAX 4095U
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#endif
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// #define DAC_LOW_QUALITY
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/**
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* These presets allow you to quickly switch between quality/voice settings for
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* the DAC. The sample rate and number of voices roughly has an inverse
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* relationship - slightly higher sample rates may be possible.
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*/
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#ifdef DAC_VERY_LOW_QUALITY
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#define DAC_SAMPLE_RATE 11025U
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#define DAC_VOICES_MAX 8
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#endif
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#ifdef DAC_LOW_QUALITY
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#define DAC_SAMPLE_RATE 22050U
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#define DAC_VOICES_MAX 4
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#endif
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#ifdef DAC_HIGH_QUALITY
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#define DAC_SAMPLE_RATE 44100U
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#define DAC_VOICES_MAX 2
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#endif
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#ifdef DAC_VERY_HIGH_QUALITY
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#define DAC_SAMPLE_RATE 88200U
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#define DAC_VOICES_MAX 1
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#endif
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/**
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* Effective bitrate of the DAC. 44.1khz is the standard for most audio - any
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* lower will sacrifice perceptible audio quality. Any higher will limit the
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* number of simultaneous voices. In most situations, a tenth (1/10) of the
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* sample rate is where notes become unbearable.
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*/
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#ifndef DAC_SAMPLE_RATE
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#define DAC_SAMPLE_RATE 44100U
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#endif
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/**
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* The number of voices (in polyphony) that are supported. If too high a value
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* is used here, the keyboard will freeze and glitch-out when that many voices
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* are being played.
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*/
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#ifndef DAC_VOICES_MAX
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#define DAC_VOICES_MAX 2
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#endif
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/**
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* The default value of the DAC when not playing anything. Certain hardware
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* setups may require a high (DAC_SAMPLE_MAX) or low (0) value here.
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*/
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#ifndef DAC_OFF_VALUE
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#define DAC_OFF_VALUE DAC_SAMPLE_MAX / 2
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#endif
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uint8_t dac_number_of_voices(void);
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float dac_get_frequency(uint8_t index);
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uint16_t dac_value_generate(void);
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void dac_setup_note(void);
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