Add direct test for sxceiver TX operation

The test generates a continuous carrier signal, offset by 20 kHz from
the center frequency. The generated carrier must be clean when
received by another device.

impl/test/CMakeLists.txt

@@ -222,3 +222,24 @@ target_link_libraries(
 	test_interleaver
 	m
 )
+
+#------------------------------------
+
+add_executable(
+	test_sx
+	../src/utils.c
+	../src/utils.h
+	../src/logger.c
+	../src/logger.h
+	test_sx.c
+)
+
+target_link_libraries(
+	test_sx
+	liquid
+	m
+	rt
+	fftw3f
+	fec
+	SoapySDR
+)

impl/test/test_sx.c

@@ -0,0 +1,110 @@
+#include <SoapySDR/Device.h>
+#include <SoapySDR/Formats.h>
+#include <SoapySDR/Logger.h>
+
+#include <string.h>
+
+#include "logger.h"
+#include "config.h"
+#include "results.h"
+#include "utils.h"
+
+
+typedef struct {
+	SoapySDRDevice *sdr;
+
+	SoapySDRStream *rx_stream;
+	SoapySDRStream *tx_stream;
+} sdr_ctx_t;
+
+
+int main(void)
+{
+	sdr_ctx_t ctx;
+
+	SoapySDRKwargs args;
+	memset(&args, 0, sizeof(args));
+	SoapySDRKwargs_set(&args, "driver", "sx");
+	ctx.sdr = SoapySDRDevice_make(&args);
+	SoapySDRKwargs_clear(&args);
+
+	if (ctx.sdr == NULL)
+	{
+		LOG(LVL_ERR, "SoapySDRDevice_make fail: %s", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	//setup streams
+	ctx.rx_stream = SoapySDRDevice_setupStream(ctx.sdr, SOAPY_SDR_RX, SOAPY_SDR_CF32, NULL, 0, NULL);
+
+	if(ctx.rx_stream == NULL) {
+		LOG(LVL_ERR, "setupStream fail: %s", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	ctx.tx_stream = SoapySDRDevice_setupStream(ctx.sdr, SOAPY_SDR_TX, SOAPY_SDR_CF32, NULL, 0, NULL);
+
+	if(ctx.tx_stream == NULL) {
+		LOG(LVL_ERR, "setupStream fail: %s", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	//apply settings
+	if (SoapySDRDevice_setSampleRate(ctx.sdr, SOAPY_SDR_RX, 0, SDR_RX_SAMPLING_RATE) != 0) {
+		LOG(LVL_ERR, "setSampleRate fail: %s", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+	if (SoapySDRDevice_setFrequency(ctx.sdr, SOAPY_SDR_RX, 0, SDR_RX_FREQ - SDR_RX_IF_SHIFT, NULL) != 0) {
+		LOG(LVL_ERR, "setFrequency fail: %s", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	if (SoapySDRDevice_setSampleRate(ctx.sdr, SOAPY_SDR_TX, 0, SDR_TX_SAMPLING_RATE) != 0) {
+		LOG(LVL_ERR, "setSampleRate fail: %s", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+	if (SoapySDRDevice_setFrequency(ctx.sdr, SOAPY_SDR_TX, 0, SDR_TX_FREQ, NULL) != 0) {
+		LOG(LVL_ERR, "setFrequency fail: %s", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	if(SoapySDRDevice_setGain(ctx.sdr, SOAPY_SDR_TX, 0, SDR_GAIN_TX) != 0) {
+		LOG(LVL_ERR, "setGain fail: %s", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+#define BUFSIZE 300000
+
+	if(SoapySDRDevice_activateStream(ctx.sdr, ctx.tx_stream, 0, 0, 0) != 0) {
+		LOG(LVL_ERR, "activateStream fail: %s", SoapySDRDevice_lastError());
+		return ERR_SOAPY;
+	}
+
+	float complex samples[BUFSIZE];
+
+	float dphi = 6.28 * 20e3 / SDR_TX_SAMPLING_RATE;
+	float phi = 0.0f;
+	float twopi = 6.283185307;
+
+	while(true) {
+		for(size_t i = 0; i < BUFSIZE; i++) {
+			phi += dphi;
+			if(phi > twopi) {
+				phi -= twopi;
+			}
+			samples[i] = cexpf(I * phi);
+		}
+
+		int flags = 0;
+		void *buffs[] = {(void*)samples};
+		size_t timeout_us = 100000;
+		int ret = SoapySDRDevice_writeStream(ctx.sdr, ctx.tx_stream, (const void* const*)buffs, BUFSIZE, &flags, 0, timeout_us);
+
+		if(ret <= 0) {
+			LOG(LVL_ERR, "writeStream fail: %s", SoapySDRDevice_lastError());
+			return ERR_SOAPY;
+		}
+	}
+
+	return OK;
+}