fix: move RTL-SDR to userspace

tests/Makefile

@@ -3,10 +3,11 @@ CXXFLAGS ?= -std=c++20 -O2 -Wall -Wextra
 
 HTTP_TEST := http_test
 SVG_TEST := svg_renderer_test
+RTLSDR_TEST := rtlsdr_r820t_test
 
 .PHONY: all check clean
 
-all: $(HTTP_TEST) $(SVG_TEST)
+all: $(HTTP_TEST) $(SVG_TEST) $(RTLSDR_TEST)
 
 $(HTTP_TEST): http_test.cpp
 	$(CXX) $(CXXFLAGS) -I../programs/include \
@@ -15,9 +16,13 @@ $(HTTP_TEST): http_test.cpp
 $(SVG_TEST): svg_renderer_test.cpp ../programs/include/gui/svg.hpp
 	$(CXX) $(CXXFLAGS) -I../programs/include $< -o $@
 
-check: $(HTTP_TEST) $(SVG_TEST)
+$(RTLSDR_TEST): rtlsdr_r820t_test.cpp ../programs/src/rtlsdr/r820t.cpp
+	$(CXX) $(CXXFLAGS) -I../programs/src/rtlsdr $^ -o $@
+
+check: $(HTTP_TEST) $(SVG_TEST) $(RTLSDR_TEST)
 	./$(HTTP_TEST)
 	./$(SVG_TEST)
+	./$(RTLSDR_TEST)
 
 clean:
-	rm -f $(HTTP_TEST) $(SVG_TEST)
+	rm -f $(HTTP_TEST) $(SVG_TEST) $(RTLSDR_TEST)

tests/rtlsdr_r820t_test.cpp

@@ -0,0 +1,54 @@
+#include "../programs/src/rtlsdr/r820t.hpp"
+#include <cassert>
+#include <cstdio>
+#include <cstring>
+#include <vector>
+
+struct rtlsdr_device {};
+
+struct I2cMessage {
+    uint8_t address;
+    std::vector<uint8_t> data;
+};
+static std::vector<I2cMessage> g_writes;
+
+namespace rtlsdr_internal {
+bool RtlI2cWrite(rtlsdr_device*, uint8_t address, const uint8_t* data, uint8_t len) {
+    g_writes.push_back({address, std::vector<uint8_t>(data, data + len)});
+    return true;
+}
+
+bool RtlI2cRead(rtlsdr_device*, uint8_t, uint8_t* data, uint8_t len) {
+    std::memset(data, 0, len);
+    if (len == 1) data[0] = R820T_CHECK_VAL;
+    if (len == 5) data[4] = 0x80; // bit-reversed logical value 0x01
+    if (len == 3) data[2] = 0x02; // bit-reversed PLL lock bit 0x40
+    return true;
+}
+}
+
+int main() {
+    using namespace rtlsdr_internal;
+    rtlsdr_device owner;
+    assert(R820tDetect(&owner));
+
+    R820tDev tuner{};
+    assert(R820tInit(tuner, &owner, 28800000, 3570000));
+    assert(tuner.inited);
+    assert(R820tSetFreq(tuner, 100100000));
+    assert(tuner.hasLock);
+    assert(R820tSetGain(tuner, 0, 0));
+    assert(R820tSetGain(tuner, 1, 297));
+    R820tStandby(tuner);
+
+    int gainCount = 0;
+    const int* gains = R820tGainTable(&gainCount);
+    assert(gainCount == 29);
+    assert(gains[0] == 0 && gains[gainCount - 1] == 496);
+    assert(!g_writes.empty());
+    for (const auto& message : g_writes) {
+        assert(message.address == R820T_I2C_ADDR);
+        assert(!message.data.empty() && message.data.size() <= 8);
+    }
+    std::puts("rtlsdr R820T transport test passed");
+}