98 lines
2.8 KiB
C++
98 lines
2.8 KiB
C++
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/**
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* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <stdio.h>
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#include <math.h>
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#if PICO_ON_DEVICE
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#include "hardware/clocks.h"
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#include "hardware/structs/clocks.h"
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#endif
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#include "pico/stdlib.h"
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#include "pico/audio_i2s.h"
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#define PICO_AUDIO_PAC_I2S_DATA 9
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#define PICO_AUDIO_PAC_I2S_BITCLOCK 10
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#define SINE_WAVE_TABLE_LEN 2048
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#define SAMPLES_PER_BUFFER 256
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static int16_t sine_wave_table[SINE_WAVE_TABLE_LEN];
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struct audio_buffer_pool *init_audio() {
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static audio_format_t audio_format = {
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.sample_freq = 24000,
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.format = AUDIO_BUFFER_FORMAT_PCM_S16,
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.channel_count = 1,
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};
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static struct audio_buffer_format producer_format = {
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.format = &audio_format,
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.sample_stride = 2
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};
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struct audio_buffer_pool *producer_pool = audio_new_producer_pool(&producer_format, 3,
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SAMPLES_PER_BUFFER); // todo correct size
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bool __unused ok;
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const struct audio_format *output_format;
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struct audio_i2s_config config = {
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.data_pin = PICO_AUDIO_PAC_I2S_DATA,
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.clock_pin_base = PICO_AUDIO_PAC_I2S_BITCLOCK,
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.dma_channel = 0,
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.pio_sm = 0,
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};
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output_format = audio_i2s_setup(&audio_format, &config);
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if (!output_format) {
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panic("PicoAudio: Unable to open audio device.\n");
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}
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ok = audio_i2s_connect(producer_pool);
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assert(ok);
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audio_i2s_set_enabled(true);
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return producer_pool;
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}
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int main() {
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stdio_init_all();
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for (int i = 0; i < SINE_WAVE_TABLE_LEN; i++) {
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sine_wave_table[i] = 32767 * cosf(i * 2 * (float) (M_PI / SINE_WAVE_TABLE_LEN));
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}
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struct audio_buffer_pool *ap = init_audio();
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uint32_t step = 0x200000;
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uint32_t pos = 0;
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uint32_t pos_max = 0x10000 * SINE_WAVE_TABLE_LEN;
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uint vol = 128;
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while (true) {
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int c = getchar_timeout_us(0);
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if (c >= 0) {
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if (c == '-' && vol) vol -= 4;
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if ((c == '=' || c == '+') && vol < 255) vol += 4;
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if (c == '[' && step > 0x10000) step -= 0x10000;
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if (c == ']' && step < (SINE_WAVE_TABLE_LEN / 16) * 0x20000) step += 0x10000;
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if (c == 'q') break;
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printf("vol = %d, step = %d \r", vol, step >> 16);
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}
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struct audio_buffer *buffer = take_audio_buffer(ap, true);
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int16_t *samples = (int16_t *) buffer->buffer->bytes;
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for (uint i = 0; i < buffer->max_sample_count; i++) {
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samples[i] = (vol * sine_wave_table[pos >> 16u]) >> 8u;
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pos += step;
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if (pos >= pos_max) pos -= pos_max;
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}
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buffer->sample_count = buffer->max_sample_count;
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give_audio_buffer(ap, buffer);
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}
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puts("\n");
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return 0;
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}
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