Initial import

modulator.c

@@ -0,0 +1,70 @@
+/* armando modem - 2014 */
+
+#ifdef __XC16
+#include <xc.h>
+#include <dsp.h>
+#include <libq.h>
+#elif __unix
+
+#endif 
+
+#include <stdint.h>
+
+#include "modem.h"
+#include "modulator.h"
+
+#include "../peripheral/dac.h"
+#include "../peripheral/gpio.h"
+
+rotor_symbol rotor_constellation[MAX_MODULATION_ALPHABET_SIZE];
+rotor_symbol silence;
+
+// buffer dei simboli
+uint8_t tx_symbol_buffer[MAX_SYMBOL_BUFFER_SIZE];
+uint8_t tx_symbol_buffer_index, tx_symbol_buffer_lenght;
+
+void modulator_setup(void) {
+    // TX
+#ifdef USE_GPIO
+    set_tx_GPIOs();
+#endif
+    modulator_prepare_constellation_symbols(mod.constellation, rotor_constellation);
+}
+
+// #####################################################
+
+// genera un buffer di campioni
+
+void modulator_generate_sample_buffer(fractional *Q_buffer, fractional *I_buffer, uint8_t size, rotor_symbol symbol) {
+    uint8_t i;
+
+    static fractional modulator_rotor, modulator_rotor_position;
+    i = 0;
+    while (i < size) {
+        modulator_rotor_position = modulator_rotor + symbol.offset;
+        Q_buffer[i] = __builtin_mulss(_Q15sinPI(modulator_rotor_position), // non deve saturare
+                symbol.gain) >> 15;
+
+        I_buffer[i] = __builtin_mulss(_Q15cosPI(modulator_rotor_position), // non deve saturare
+                symbol.gain) >> 15;
+
+        modulator_rotor += symbol.increment; // la _Q15 satura!
+        ++i;
+    }
+
+#if ! defined(__DEBUG)
+    // viene riasserito dal DMA del dac, dove mettere?
+    populate_tx_sample_buffer = 0; // fatto
+#endif        
+}
+
+// traduce da modulazione astratta a parametri per il modulatore
+
+void modulator_prepare_constellation_symbols(symbol *constellation, rotor_symbol *mod_constellation) {
+    uint8_t i;
+    for (i = 0; i < mod.alphabet_size; i++) {
+        mod_constellation[i].increment = get_angular_frequency(constellation[i].frequency);
+        mod_constellation[i].offset = constellation[i].phase;
+        mod_constellation[i].gain = constellation[i].amplitude;
+    }
+}