Added SDR abstraction layer

impl/CMakeLists.txt

@@ -33,6 +33,8 @@ set(sources
 	src/layer1/modcod.h
 	src/layer2/tundev.c
 	src/layer2/tundev.h
+	src/sdr/sdr.c
+	src/sdr/sdr.h
 )
 
 include_directories(

impl/src/config.h

@@ -3,24 +3,6 @@
 
 #include <liquid/liquid.h>
 
-/*** SDR CONFIG ***/
-
-#define SDR_IS_FULL_DUPLEX       0
-
-#define SDR_RX_SAMPLING_RATE     1e6f
-#define SDR_TX_SAMPLING_RATE     RX_SAMPLING_RATE
-
-// actually transmitted or received signal frequencies, NOT the SDR center frequency.
-#define SDR_TX_FREQ       434.100e6f
-#define SDR_RX_FREQ       434.100e6f
-
-// shift applied in the baseband, to get rid of SDR DC peak. If the value here
-// is not 0, software mixing will be done on the received signal.
-#define SDR_TX_IF_SHIFT     0.000e6f
-#define SDR_RX_IF_SHIFT     0.150e6f
-
-// NOTE: the SDR center frequency will be SDR_RX_FREQ - SDR_RX_IF_SHIFT.
-
 /*** LAYER 1 CONFIG ***/
 
 #define SYMBOL_RATE   100e3f
@@ -44,4 +26,24 @@
 #define TRANSMISSION_RAMP_UP_LEN     64  // symbols
 #define TRANSMISSION_RAMP_DOWN_LEN   32  // symbols
 
+/*** SDR CONFIG ***/
+
+#define SDR_IS_FULL_DUPLEX       0
+
+#define SDR_OVERSAMPLING         3  // integer factor!
+
+#define SDR_RX_SAMPLING_RATE     (SYMBOL_RATE * RRC_SPS * SDR_OVERSAMPLING)
+#define SDR_TX_SAMPLING_RATE     SDR_RX_SAMPLING_RATE
+
+// actually transmitted or received signal frequencies, NOT the SDR center frequency.
+#define SDR_TX_FREQ       434.100e6f
+#define SDR_RX_FREQ       434.100e6f
+
+// shift applied in the baseband, to get rid of SDR DC peak. If the value here
+// is not 0, software mixing will be done on the received signal.
+#define SDR_TX_IF_SHIFT     0.000e6f
+#define SDR_RX_IF_SHIFT     0.150e6f
+
+// NOTE: the SDR center frequency will be SDR_RX_FREQ - SDR_RX_IF_SHIFT.
+
 #endif // CONFIG_H

impl/src/results.h

@@ -6,8 +6,9 @@ typedef enum {
 	ERR_INVALID_STATE,
 	ERR_NO_MEM,
 	ERR_SIZE,
-	ERR_LIQUID,
+	ERR_LIQUID,         // an error occurred in the LiquidDSP library.
-	ERR_SYSCALL         // a syscall failed. Use errno to determine the cause.
+	ERR_SYSCALL,        // a syscall failed. Use errno to determine the cause.
+	ERR_SOAPY,          // an error occurred in the SoapySDR library.
 } result_t;
 
 #ifdef DEBUG_LIQUID

impl/src/sdr/sdr.c

@@ -0,0 +1,249 @@
+#include <SoapySDR/Device.h>
+#include <SoapySDR/Formats.h>
+#include <liquid/liquid.h>
+#include <stdio.h> //printf
+#include <stdlib.h> //free
+#include <complex.h>
+#include <math.h>
+
+#include "config.h"
+
+#include "sdr.h"
+
+static void shutdown_streams(sdr_ctx_t *ctx)
+{
+	if(ctx->rx_stream) {
+		SoapySDRDevice_deactivateStream(ctx->sdr, ctx->rx_stream, 0, 0);
+		SoapySDRDevice_closeStream(ctx->sdr, ctx->rx_stream);
+	}
+
+	if(ctx->tx_stream) {
+		SoapySDRDevice_deactivateStream(ctx->sdr, ctx->tx_stream, 0, 0);
+		SoapySDRDevice_closeStream(ctx->sdr, ctx->tx_stream);
+	}
+}
+
+
+result_t sdr_init(sdr_ctx_t *ctx)
+{
+	size_t length;
+
+	ctx->sdr = NULL;
+	ctx->tx_stream = NULL;
+	ctx->rx_stream = NULL;
+
+	ctx->interp = firinterp_crcf_create_prototype(LIQUID_FIRFILT_PM, SDR_OVERSAMPLING, 10, 0.2, 0);
+	ctx->decim  = firdecim_crcf_create_prototype(LIQUID_FIRFILT_PM, SDR_OVERSAMPLING, 10, 0.2, 0);
+
+	ctx->tx_nco = nco_crcf_create(LIQUID_NCO);
+	ctx->rx_nco = nco_crcf_create(LIQUID_NCO);
+
+	nco_crcf_set_frequency(ctx->tx_nco, -2 * M_PI * SDR_TX_IF_SHIFT / SDR_TX_SAMPLING_RATE);
+	nco_crcf_set_frequency(ctx->rx_nco, -2 * M_PI * SDR_RX_IF_SHIFT / SDR_TX_SAMPLING_RATE);
+
+	//enumerate devices
+	SoapySDRKwargs *results = SoapySDRDevice_enumerate(NULL, &length);
+	for (size_t i = 0; i < length; i++)
+	{
+		fprintf(stderr, "sdr: Found device #%d: ", (int)i);
+		for (size_t j = 0; j < results[i].size; j++)
+		{
+			fprintf(stderr, "sdr: %s=%s, ", results[i].keys[j], results[i].vals[j]);
+		}
+		fprintf(stderr, "sdr: \n");
+	}
+	SoapySDRKwargsList_clear(results, length);
+
+	//create device instance
+	//args can be user defined or from the enumeration result
+	SoapySDRKwargs args;
+	SoapySDRKwargs_set(&args, "driver", "hackrf");
+	ctx->sdr = SoapySDRDevice_make(&args);
+	SoapySDRKwargs_clear(&args);
+
+	if (ctx->sdr == NULL)
+	{
+		fprintf(stderr, "sdr: SoapySDRDevice_make fail: %s\n", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	//query device info
+	char** names = SoapySDRDevice_listAntennas(ctx->sdr, SOAPY_SDR_RX, 0, &length);
+	fprintf(stderr, "sdr: Rx antennas: ");
+	for (size_t i = 0; i < length; i++) fprintf(stderr, "sdr: %s, ", names[i]);
+	fprintf(stderr, "sdr: \n");
+	SoapySDRStrings_clear(&names, length);
+
+	names = SoapySDRDevice_listGains(ctx->sdr, SOAPY_SDR_RX, 0, &length);
+	fprintf(stderr, "sdr: Rx gains: ");
+	for (size_t i = 0; i < length; i++) fprintf(stderr, "sdr: %s, ", names[i]);
+	fprintf(stderr, "sdr: \n");
+	SoapySDRStrings_clear(&names, length);
+
+	SoapySDRRange *ranges = SoapySDRDevice_getFrequencyRange(ctx->sdr, SOAPY_SDR_RX, 0, &length);
+	fprintf(stderr, "sdr: Rx freq ranges: ");
+	for (size_t i = 0; i < length; i++) fprintf(stderr, "sdr: [%g Hz -> %g Hz], ", ranges[i].minimum, ranges[i].maximum);
+	fprintf(stderr, "sdr: \n");
+	free(ranges);
+
+	//apply settings
+	if (SoapySDRDevice_setSampleRate(ctx->sdr, SOAPY_SDR_RX, 0, SDR_RX_SAMPLING_RATE) != 0) {
+		fprintf(stderr, "sdr: setSampleRate fail: %s\n", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+	if (SoapySDRDevice_setFrequency(ctx->sdr, SOAPY_SDR_RX, 0, SDR_RX_FREQ - SDR_RX_IF_SHIFT, NULL) != 0) {
+		fprintf(stderr, "sdr: setFrequency fail: %s\n", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	if (SoapySDRDevice_setSampleRate(ctx->sdr, SOAPY_SDR_TX, 0, SDR_TX_SAMPLING_RATE) != 0) {
+		fprintf(stderr, "sdr: setSampleRate fail: %s\n", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+	if (SoapySDRDevice_setFrequency(ctx->sdr, SOAPY_SDR_TX, 0, SDR_TX_FREQ, NULL) != 0) {
+		fprintf(stderr, "sdr: setFrequency fail: %s\n", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	return OK;
+}
+
+
+result_t sdr_destroy(sdr_ctx_t *ctx)
+{
+	shutdown_streams(ctx);
+
+	nco_crcf_destroy(ctx->rx_nco);
+	nco_crcf_destroy(ctx->tx_nco);
+
+	firdecim_crcf_destroy(ctx->decim);
+	firinterp_crcf_destroy(ctx->interp);
+
+	if(ctx->sdr) {
+		SoapySDRDevice_unmake(ctx->sdr);
+	}
+
+	return OK;
+}
+
+
+result_t sdr_start_rx(sdr_ctx_t *ctx)
+{
+	shutdown_streams(ctx);
+
+	//setup a stream (complex floats)
+	ctx->rx_stream = SoapySDRDevice_setupStream(ctx->sdr, SOAPY_SDR_RX, SOAPY_SDR_CF32, NULL, 0, NULL);
+
+	if(ctx->rx_stream == NULL) {
+		fprintf(stderr, "sdr: setupStream fail: %s\n", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	SoapySDRDevice_activateStream(ctx->sdr, ctx->rx_stream, 0, 0, 0); //start streaming
+
+	return OK;
+}
+
+
+result_t sdr_start_tx(sdr_ctx_t *ctx)
+{
+	shutdown_streams(ctx);
+
+	//setup a stream (complex floats)
+	ctx->tx_stream = SoapySDRDevice_setupStream(ctx->sdr, SOAPY_SDR_RX, SOAPY_SDR_CF32, NULL, 0, NULL);
+
+	if(ctx->tx_stream == NULL) {
+		fprintf(stderr, "sdr: setupStream fail: %s\n", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	SoapySDRDevice_activateStream(ctx->sdr, ctx->tx_stream, 0, 0, 0); //start streaming
+
+	return OK;
+}
+
+
+result_t sdr_transmit(sdr_ctx_t *ctx, const float complex *samples, size_t nsamples, long timeout_us)
+{
+	if(ctx->tx_stream == NULL) {
+		return ERR_INVALID_STATE;
+	}
+
+	void *buffs[] = {(void*)samples};
+
+	int ret = SoapySDRDevice_writeStream(ctx->sdr, ctx->tx_stream, (const void* const*)buffs, nsamples, 0, 0, timeout_us);
+
+	if(ret <= 0) {
+		fprintf(stderr, "sdr: writeStream fail: %s\n", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	return OK;
+}
+
+
+result_t sdr_receive(sdr_ctx_t *ctx, float complex *samples, size_t *nsamples, long timeout_us)
+{
+	if(ctx->rx_stream == NULL) {
+		return ERR_INVALID_STATE;
+	}
+
+	void *buffs[] = {(void*)samples};
+
+	int ret = SoapySDRDevice_readStream(ctx->sdr, ctx->rx_stream, (void* const*)buffs, *nsamples, 0, 0, timeout_us);
+
+	if(ret <= 0) {
+		fprintf(stderr, "sdr: readStream fail: %s\n", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	*nsamples = ret;
+
+	return OK;
+}
+
+
+result_t sdr_rf_to_baseband(sdr_ctx_t *ctx,
+		const float complex *rf_samples, size_t nrf,
+		float complex *bb_samples, size_t nbb)
+{
+	if((nbb * SDR_OVERSAMPLING) > nrf) {
+		return ERR_SIZE;
+	}
+
+	for(size_t i = 0; i < nbb; i++) {
+		float complex tmp[SDR_OVERSAMPLING];
+
+		nco_crcf_mix_block_down(ctx->rx_nco,
+				(complex float*)(rf_samples + i * SDR_OVERSAMPLING),
+				tmp,
+				SDR_OVERSAMPLING);
+
+		firdecim_crcf_execute(ctx->decim, tmp, bb_samples + i);
+	}
+
+	return OK;
+}
+
+
+result_t sdr_baseband_to_rf(sdr_ctx_t *ctx,
+		const float complex *bb_samples, size_t nbb,
+		float complex *rf_samples, size_t nrf)
+{
+	if((nbb * SDR_OVERSAMPLING) > nrf) {
+		return ERR_SIZE;
+	}
+
+	for(size_t i = 0; i < nbb; i++) {
+		float complex tmp[SDR_OVERSAMPLING];
+
+		firinterp_crcf_execute(ctx->interp, bb_samples[i], tmp);
+
+		nco_crcf_mix_block_up(ctx->tx_nco,
+				tmp,
+				rf_samples + i * SDR_OVERSAMPLING,
+				SDR_OVERSAMPLING);
+	}
+
+	return OK;
+}

impl/src/sdr/sdr.h

@@ -0,0 +1,48 @@
+#ifndef SDR_SDR_H
+#define SDR_SDR_H
+
+#include <complex.h>
+
+#include <SoapySDR/Device.h>
+
+#include <liquid/liquid.h>
+
+#include "results.h"
+
+typedef struct {
+	SoapySDRDevice *sdr;
+
+	SoapySDRStream *rx_stream;
+	SoapySDRStream *tx_stream;
+
+	firinterp_crcf interp;
+	nco_crcf       tx_nco;
+
+	firdecim_crcf  decim;
+	nco_crcf       rx_nco;
+} sdr_ctx_t;
+
+result_t sdr_init(sdr_ctx_t *ctx);
+result_t sdr_destroy(sdr_ctx_t *ctx);
+
+result_t sdr_start_rx(sdr_ctx_t *ctx);
+result_t sdr_start_tx(sdr_ctx_t *ctx);
+
+result_t sdr_transmit(sdr_ctx_t *ctx, const float complex *samples, size_t nsamples, long timeout_us);
+result_t sdr_receive(sdr_ctx_t *ctx, float complex *samples, size_t *nsamples, long timeout_us);
+
+/*!
+ * \brief Convert and resample a received signal to baseband.
+ */
+result_t sdr_rf_to_baseband(sdr_ctx_t *ctx,
+		const float complex *rf_samples, size_t nrf,
+		float complex *bb_samples, size_t nbb);
+
+/*!
+ * \brief Convert and resample a baseband signal for transmission.
+ */
+result_t sdr_baseband_to_rf(sdr_ctx_t *ctx,
+		const float complex *bb_samples, size_t nbb,
+		float complex *rf_samples, size_t nrf);
+
+#endif // SDR_SDR_H