kopia lustrzana https://github.com/eleccoder/raspi-pico-aprs-tnc
271 wiersze
10 KiB
C
271 wiersze
10 KiB
C
/*
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* Project 'raspi-pico-aprs-tnc'
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* Copyright (C) 2021-2023 Thomas Glau, DL3TG
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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 3 of the License, or
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* (at your option) any later version.
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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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* 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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#include "aprs_pico.h"
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#include "ax25beacon.h"
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#include "pico/stdlib.h"
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#include <math.h>
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// NOTE: ATTOW, the pico-extra audio PWM lib worked only at a fixed 22050 Hz sampling frequency, while the
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// system clock runs at 48 MHz. This is documented here: https://github.com/raspberrypi/pico-extras
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#define APRS_PICO__PICO_EXTRA_AUDIO_PWM_LIB__FIXED_SAMPLE_FREQ_IN_HZ (22050)
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#define APRS_PICO__PICO_EXTRA_AUDIO_PWM_LIB__SYS_CLOCK_FREQ_OF_IN_MHZ (48)
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typedef struct AudioCallBackUserData
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{
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audio_buffer_pool_t* audio_buffer_pool; // The pool of audio buffers to be used for rendering an audio signal
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uint16_t volume; // Valid range: 0 ... 256
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} AudioCallBackUserData_t;
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/** \brief Init function for the Pico audio PWM library
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*
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* \param[in] sample_freq_in_hz The sampling frequency to be used for audio signals
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* \param[in] audio_buffer_format The format of the audio buffers to be created, representing
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* the data format of the audio samples
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*
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* \return A pool of audio buffers to be used for rendering any audio signal
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*/
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static audio_buffer_pool_t* aprs_pico_initAudio(unsigned int sample_freq_in_hz, uint16_t audio_buffer_format)
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{
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const int NUM_AUDIO_BUFFERS = 3;
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const int SAMPLES_PER_BUFFER = 256;
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const audio_format_t audio_format = {.format = audio_buffer_format,
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.sample_freq = sample_freq_in_hz,
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.channel_count = 1};
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audio_buffer_format_t producer_format = {.format = &audio_format,
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.sample_stride = 2};
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audio_buffer_pool_t* producer_pool = audio_new_producer_pool(&producer_format, NUM_AUDIO_BUFFERS, SAMPLES_PER_BUFFER);
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if (!audio_pwm_setup(&audio_format, -1, &default_mono_channel_config))
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{
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panic("PicoAudio: Unable to open audio device.\n");
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}
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bool __unused is_ok = audio_pwm_default_connect(producer_pool, false);
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assert(is_ok);
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audio_pwm_set_enabled(true);
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return producer_pool;
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}
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/** \brief Init function for the Pico's clock system
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*
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* \param[in] sample_freq_in_hz The sampling frequency to be used for rendering audio signals
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*/
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static void aprs_pico_initClock(unsigned int sample_freq_in_hz)
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{
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// NOTE: ATTOW, the pico-extra audio PWM lib worked only at a fixed 22050 Hz sampling frequency, while the
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// system clock runs at 48 MHz. This is documented here: https://github.com/raspberrypi/pico-extras
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// Compensate a non-'APRS_PICO__PICO_EXTRA_AUDIO_PWM_LIB__FIXED_SAMPLE_FREQ_IN_HZ' sampling frequency
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// by adapting the system clock frequency accordingly.
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float sys_clock_in_mhz = (float)APRS_PICO__PICO_EXTRA_AUDIO_PWM_LIB__SYS_CLOCK_FREQ_OF_IN_MHZ *
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((float)sample_freq_in_hz / (float)APRS_PICO__PICO_EXTRA_AUDIO_PWM_LIB__FIXED_SAMPLE_FREQ_IN_HZ);
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if (!set_sys_clock_khz((uint32_t)(1000.0f * sys_clock_in_mhz), false))
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{
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// Round to full MHz to increase the chance that 'set_sys_clock_khz()' can exactly attain this frequency
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sys_clock_in_mhz = round(sys_clock_in_mhz);
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// With the second parameter set 'true', the function will assert if the frequency is not attainable
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set_sys_clock_khz(1000u * (uint32_t)sys_clock_in_mhz, true);
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}
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}
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/** \brief Renders given PCM audio samples
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*
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* \param[in, out] audio_buffer_pool The pool of audio buffers to be used for rendering any audio signal
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* \param[in] pcm_data The PCM audio samples to be rendered
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* \param[in] num_samples The number of PCM audio samples to be rendered
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* \param[in] volume The volume level of the generated AFSK signal (0 ... 256)
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* \param[in] num_loops For 'num_loops' >= 0 rendering of the audio samples will be repeated 'num_loops' times
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* For 'num_loops' < 0, rendering of the audio samples will be endlessly repeated
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*/
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static void aprs_pico_renderAudioSamples(audio_buffer_pool_t* audio_buffer_pool, const int16_t* pcm_data,
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unsigned int num_samples, uint16_t volume, int num_loops)
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{
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assert(audio_buffer_pool != NULL);
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assert(pcm_data != NULL);
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bool do_loop_forever = num_loops < 0;
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bool is_all_samples_processed = (num_samples == 0u) || (num_loops == 0);
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unsigned int idx_src = 0u;
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// Write the PCM sample data into the next audio buffer while applying the 'volume' value
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// Loop over audio buffers
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while (!is_all_samples_processed)
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{
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audio_buffer_t* audio_buffer = take_audio_buffer(audio_buffer_pool, true);
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int16_t* audio_buffer_pcm_data = (int16_t*)audio_buffer->buffer->bytes;
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unsigned int idx_dst = 0u;
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// Fill the current audio buffer
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while (!is_all_samples_processed && (idx_dst < audio_buffer->max_sample_count))
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{
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audio_buffer_pcm_data[idx_dst] = ((int32_t)volume * (int32_t)pcm_data[idx_src]) >> 8u;
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idx_src++;
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idx_dst++;
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if (idx_src == num_samples)
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{
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if (!do_loop_forever)
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{
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num_loops--;
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}
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if (num_loops == 0)
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{
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is_all_samples_processed = true;
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}
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else
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{
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idx_src = 0u;
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}
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}
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}
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assert(idx_src <= num_samples);
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assert(idx_dst <= audio_buffer->max_sample_count);
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audio_buffer->sample_count = idx_dst;
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give_audio_buffer(audio_buffer_pool, audio_buffer);
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}
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}
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/** \brief The callback function to render the generated PCM audio samples of an APRS message
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*
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* \param[in] callback_user_data User data provided by the caller function of this callback
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* \param[in] pcm_data The PCM audio samples to be rendered
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* \param[in] num_samples The number of samples the PCM data consist of
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* \param[in] sample_freq_in_hz The sample frequency of the PCM data (in Hz)
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*/
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static void aprs_pico_sendAPRSAudioCallback(const void* callback_user_data, const int16_t* pcm_data, size_t num_samples, uint16_t sample_freq_in_hz)
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{
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assert(callback_user_data != NULL);
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assert(pcm_data != NULL);
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const AudioCallBackUserData_t user_data = *((AudioCallBackUserData_t*)callback_user_data);
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aprs_pico_initClock(sample_freq_in_hz);
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aprs_pico_renderAudioSamples(user_data.audio_buffer_pool, pcm_data, num_samples, user_data.volume, 1);
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}
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// See the header file for documentation
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audio_buffer_pool_t* aprs_pico_init()
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{
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audio_buffer_pool_t* audio_buffer_pool = aprs_pico_initAudio(APRS_PICO__PICO_EXTRA_AUDIO_PWM_LIB__FIXED_SAMPLE_FREQ_IN_HZ,
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AUDIO_BUFFER_FORMAT_PCM_S16);
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return audio_buffer_pool;
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}
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// See the header file for documentation
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void aprs_pico_play_sine_wave(audio_buffer_pool_t* audio_buffer_pool, unsigned int freq_in_hz,
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unsigned int sample_freq_in_hz, uint16_t volume, int duration_in_ms)
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{
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assert(audio_buffer_pool != NULL);
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typedef int16_t wave_table_value_t;
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const wave_table_value_t WAVE_TABLE_VALUE_MAX = INT16_MAX;
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aprs_pico_initClock(sample_freq_in_hz);
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const unsigned int num_samples_per_period = sample_freq_in_hz / freq_in_hz;
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wave_table_value_t* sine_period_wave_table = malloc(num_samples_per_period * sizeof(wave_table_value_t));
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if (sine_period_wave_table == NULL)
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{
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panic("Out of memory: malloc() failed.\n");
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}
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for (unsigned int i = 0u; i < num_samples_per_period; i++)
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{
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sine_period_wave_table[i] = (wave_table_value_t)((float)WAVE_TABLE_VALUE_MAX * sinf(2.0f * (float)M_PI * (float)i / (float)num_samples_per_period));
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}
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const int num_loops = duration_in_ms < 0 ? -1 : (duration_in_ms * (int)freq_in_hz / 1000);
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aprs_pico_renderAudioSamples(audio_buffer_pool, sine_period_wave_table, num_samples_per_period, volume, num_loops);
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free(sine_period_wave_table);
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}
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// See the header file for documentation
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bool aprs_pico_sendAPRS(audio_buffer_pool_t* audio_buffer_pool,
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const char* call_sign_src,
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const char* call_sign_dst,
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const char* aprs_path_1,
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const char* aprs_path_2,
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const char* aprs_message,
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double latitude_in_deg,
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double longitude_in_deg,
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double altitude_in_m,
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char sym_table,
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char sym_code,
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uint16_t volume)
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{
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// NOTE: 'aprs_message' is allowed to be 'NULL'
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assert(audio_buffer_pool != NULL);
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assert(call_sign_src != NULL);
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assert(call_sign_dst != NULL);
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assert(aprs_path_1 != NULL);
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assert(aprs_path_2 != NULL);
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static AudioCallBackUserData_t callback_user_data;
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callback_user_data.audio_buffer_pool = audio_buffer_pool;
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callback_user_data.volume = volume;
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int ret_val = ax25_beacon((void*)&callback_user_data,
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aprs_pico_sendAPRSAudioCallback,
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call_sign_src,
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call_sign_dst,
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aprs_path_1,
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aprs_path_2,
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latitude_in_deg,
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longitude_in_deg,
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altitude_in_m,
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aprs_message,
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sym_table,
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sym_code);
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return ret_val == AX25_OK;
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}
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