70 lines
1.9 KiB
C
70 lines
1.9 KiB
C
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/* armando modem - 2014 */
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#ifdef __XC16
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#include <xc.h>
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#include <dsp.h>
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#include <libq.h>
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#elif __unix
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#endif
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#include <stdint.h>
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#include "modem.h"
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#include "modulator.h"
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#include "../peripheral/dac.h"
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#include "../peripheral/gpio.h"
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rotor_symbol rotor_constellation[MAX_MODULATION_ALPHABET_SIZE];
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rotor_symbol silence;
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// buffer dei simboli
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uint8_t tx_symbol_buffer[MAX_SYMBOL_BUFFER_SIZE];
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uint8_t tx_symbol_buffer_index, tx_symbol_buffer_lenght;
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void modulator_setup(void) {
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// TX
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#ifdef USE_GPIO
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set_tx_GPIOs();
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#endif
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modulator_prepare_constellation_symbols(mod.constellation, rotor_constellation);
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}
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// #####################################################
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// genera un buffer di campioni
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void modulator_generate_sample_buffer(fractional *Q_buffer, fractional *I_buffer, uint8_t size, rotor_symbol symbol) {
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uint8_t i;
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static fractional modulator_rotor, modulator_rotor_position;
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i = 0;
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while (i < size) {
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modulator_rotor_position = modulator_rotor + symbol.offset;
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Q_buffer[i] = __builtin_mulss(_Q15sinPI(modulator_rotor_position), // non deve saturare
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symbol.gain) >> 15;
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I_buffer[i] = __builtin_mulss(_Q15cosPI(modulator_rotor_position), // non deve saturare
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symbol.gain) >> 15;
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modulator_rotor += symbol.increment; // la _Q15 satura!
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++i;
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}
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#if ! defined(__DEBUG)
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// viene riasserito dal DMA del dac, dove mettere?
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populate_tx_sample_buffer = 0; // fatto
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#endif
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}
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// traduce da modulazione astratta a parametri per il modulatore
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void modulator_prepare_constellation_symbols(symbol *constellation, rotor_symbol *mod_constellation) {
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uint8_t i;
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for (i = 0; i < mod.alphabet_size; i++) {
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mod_constellation[i].increment = get_angular_frequency(constellation[i].frequency);
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mod_constellation[i].offset = constellation[i].phase;
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mod_constellation[i].gain = constellation[i].amplitude;
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}
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}
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