hamnet70/impl/src/main.c

#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <math.h>
#include <liquid/liquid.h>

#include "utils.h"
#include "layer1/tx.h"
#include "layer1/rx.h"

#define RESULT_CHECK(stmt) { \
	result_t res = stmt; \
	if(res != OK) { \
		fprintf(stderr, "Error %d in %s:%d!", res, __FILE__, __LINE__); \
		exit(1); \
	} \
}

void print_complex_array(const char *varname, float complex const *array, size_t len)
{
	fprintf(stderr, "%s=np.array([%f%+fj", varname, crealf(array[0]), cimagf(array[0]));
	for(size_t k = 1; k < len; k++) {
		fprintf(stderr, ", %f%+fj", crealf(array[k]), cimagf(array[k]));
	}
	fprintf(stderr, "])\n");
}


void cb_rx(rx_evt_t evt, uint8_t *packet_data, size_t packet_len)
{
	switch(evt)
	{
		case RX_EVT_CHECKSUM_ERROR:
			fprintf(stderr, "Received a message of %zu bytes, but decoding failed.\n", packet_len);
			fprintf(stderr, "=== FAILED PAYLOAD ===\n");
			fprintf(stderr, "%s\n", packet_data);
			fprintf(stderr, "=======================\n");
			break;

		case RX_EVT_PACKET_RECEIVED:
			fprintf(stderr, "=== DECODED PAYLOAD ===\n");
			fprintf(stderr, "%s\n", packet_data);
			fprintf(stderr, "=======================\n");
			break;

		case RX_EVT_PREAMBLE_FOUND:
			fprintf(stderr, "Found preamble!\n");
			break;
	}
}


int main(void)
{
	uint8_t msg_org[] = "Hello Liquid! This is the message to transmit. Hopefully it can be decoded correctly...";

	// ** Modulate packet **

	layer1_tx_t tx;

	RESULT_CHECK(layer1_tx_init(&tx));
	RESULT_CHECK(layer1_tx_add_packet_to_burst(&tx, msg_org, sizeof(msg_org)));
	RESULT_CHECK(layer1_tx_finalize_burst(&tx));

	size_t burst_len = layer1_tx_get_sample_count(&tx);
	const float complex *whole_burst = layer1_tx_get_sample_data(&tx);

	dump_array_cf(whole_burst, burst_len, 1.0f, "/tmp/tx.cpx");

	// ** Apply channel distortions **

	channel_cccf channel = channel_cccf_create();

	float snr = 10.0f;
	channel_cccf_add_awgn(channel, -snr, snr);
	channel_cccf_add_carrier_offset(channel, 0.20f, 1.00f);
	channel_cccf_add_shadowing(channel, 1.00f, 0.1f);

	// channel
	float complex msg_received[burst_len];

	//memcpy(msg_received, whole_burst, sizeof(whole_burst)); // no noise in channel

	channel_cccf_execute_block(channel, whole_burst, burst_len, msg_received);

	// scale the entire signal to give the AGC something to do
	for(size_t i = 0; i < burst_len; i++) {
		msg_received[i] *= 0.02f;
	}

	dump_array_cf(msg_received, burst_len, 1.0f, "/tmp/rx.cpx");

	// ** RX starts here **

	layer1_rx_t rx;

	RESULT_CHECK(layer1_rx_init(&rx, cb_rx));

	RESULT_CHECK(layer1_rx_process(&rx, msg_received, burst_len));

	// cleanup

	channel_cccf_destroy(channel);

	layer1_tx_shutdown(&tx);
	layer1_rx_shutdown(&rx);

	fprintf(stderr, "Done.\n");
}