test tty writer

main.cpp

@@ -381,7 +381,7 @@ void print_help(const char* exe_name) {
         << "                [internal_ref_hz:2000000]\n"
         << "                [di1:zero|trace|ignore]\n"
         << "                [duration_ms:100] [packet_limit:0] [csv:capture.csv] [svg:capture.svg]\n"
-        << "                [live_html:live_plot.html] [live_json:live_plot.json] [tty:/dev/ttyADC_data]\n"
+        << "                [live_html:live_plot.html] [live_json:live_plot.json] [tty:/tmp/ttyADC_data]\n"
         << "                [recv_block:32768] [stats_period_ms:1000] [live_update_period_ms:1000] [svg_history_packets:50] [start_wait_ms:10000]\n"
         << "                [buffer_words:8388608] [step_words:32768]\n"
         << "                [pullup_syn1] [pullup_syn2] [pulldown_conv_in] [pulldown_start_in]\n"
@@ -412,7 +412,7 @@ void print_help(const char* exe_name) {
         << "  buffer_words:8388608 -> input stream buffer size in 32-bit words\n"
         << "  step_words:32768 -> input stream transfer step in 32-bit words\n"
         << "  live_html/live_json -> live graph files updated as packets arrive\n"
-        << "  tty:/dev/ttyADC_data -> write binary step frames to a Linux/POSIX tty path\n"
+        << "  tty:/tmp/ttyADC_data -> write binary step frames to a Linux/POSIX tty or PTY link path\n"
         << "  If sample_clock_hz is omitted together with clock:internal, the maximum ADC speed is used\n"
         << "\n"
         << "Differential physical channel mapping:\n"
@@ -747,6 +747,19 @@ Fn load_symbol(ModuleHandle module, const char* name) {
 #endif
 }
 
+template <typename Fn>
+Fn try_load_symbol(ModuleHandle module, const char* name) {
+#ifdef _WIN32
+    const auto addr = GetProcAddress(module, name);
+    return reinterpret_cast<Fn>(addr);
+#else
+    dlerror();
+    void* addr = dlsym(module, name);
+    (void) dlerror();
+    return reinterpret_cast<Fn>(addr);
+#endif
+}
+
 struct Api {
     ModuleHandle x502_module = nullptr;
     ModuleHandle e502_module = nullptr;
@@ -755,6 +768,7 @@ struct Api {
     decltype(&X502_Free) Free = nullptr;
     decltype(&X502_Close) Close = nullptr;
     decltype(&X502_GetErrorString) GetErrorString = nullptr;
+    decltype(&X502_GetDevInfo) GetDevInfo = nullptr;
     decltype(&X502_GetDevInfo2) GetDevInfo2 = nullptr;
     decltype(&X502_SetMode) SetMode = nullptr;
     decltype(&X502_StreamsStop) StreamsStop = nullptr;
@@ -804,7 +818,11 @@ struct Api {
         Free = load_symbol<decltype(Free)>(x502_module, "X502_Free");
         Close = load_symbol<decltype(Close)>(x502_module, "X502_Close");
         GetErrorString = load_symbol<decltype(GetErrorString)>(x502_module, "X502_GetErrorString");
-        GetDevInfo2 = load_symbol<decltype(GetDevInfo2)>(x502_module, "X502_GetDevInfo2");
+        GetDevInfo = try_load_symbol<decltype(GetDevInfo)>(x502_module, "X502_GetDevInfo");
+        GetDevInfo2 = try_load_symbol<decltype(GetDevInfo2)>(x502_module, "X502_GetDevInfo2");
+        if ((GetDevInfo == nullptr) && (GetDevInfo2 == nullptr)) {
+            fail("Neither X502_GetDevInfo nor X502_GetDevInfo2 is available in x502 API library");
+        }
         SetMode = load_symbol<decltype(SetMode)>(x502_module, "X502_SetMode");
         StreamsStop = load_symbol<decltype(StreamsStop)>(x502_module, "X502_StreamsStop");
         StreamsDisable = load_symbol<decltype(StreamsDisable)>(x502_module, "X502_StreamsDisable");
@@ -859,6 +877,8 @@ void expect_ok(const Api& api, int32_t err, const std::string& what) {
 constexpr uint32_t kE502DiSyn2Mask =
     (static_cast<uint32_t>(1U) << 13U) | (static_cast<uint32_t>(1U) << 17U);
 constexpr uint32_t kE502Digital1Mask = (static_cast<uint32_t>(1U) << 0U);
+constexpr uint32_t kStreamInputAdcFlag = 0x80000000U;
+constexpr uint32_t kStreamInputCalibratedAdcFlag = 0x40000000U;
 
 using TickMs = uint64_t;
 
@@ -1012,6 +1032,30 @@ int16_t pack_raw_code_to_int16(double avg_raw_code) {
     return static_cast<int16_t>(clamped);
 }
 
+bool try_extract_raw_adc_code(uint32_t word, double& raw_code) {
+    if ((word & kStreamInputAdcFlag) == 0U) {
+        return false;
+    }
+
+    int32_t value = 0;
+    if ((word & kStreamInputCalibratedAdcFlag) != 0U) {
+        const uint32_t payload = word & 0x00FFFFFFU;
+        value = static_cast<int32_t>(payload);
+        if ((payload & 0x00800000U) != 0U) {
+            value |= static_cast<int32_t>(0xFF000000U);
+        }
+    } else {
+        const uint32_t payload = word & 0x0000FFFFU;
+        value = static_cast<int32_t>(payload);
+        if ((payload & 0x00008000U) != 0U) {
+            value |= static_cast<int32_t>(0xFFFF0000U);
+        }
+    }
+
+    raw_code = static_cast<double>(value);
+    return true;
+}
+
 struct ConsoleCtrlGuard {
     bool installed = false;
 
@@ -1113,7 +1157,11 @@ int run(const Config& cfg) {
     device.opened = true;
 
     t_x502_info info{};
-    err = api.GetDevInfo2(device.hnd, &info, sizeof(info));
+    if (api.GetDevInfo2 != nullptr) {
+        err = api.GetDevInfo2(device.hnd, &info, sizeof(info));
+    } else {
+        err = api.GetDevInfo(device.hnd, &info);
+    }
     expect_ok(api, err, "Get device info");
     print_device_info(info);
 
@@ -1356,7 +1404,9 @@ int run(const Config& cfg) {
             return;
         }
         if (tty_step.next_step_index >= 0xFFFFU) {
-            fail("TTY protocol step index overflow within packet");
+            std::cerr << "Warning: TTY protocol step index overflow, forcing tty packet restart\n";
+            tty_step.reset_packet();
+            tty_writer->emit_packet_start();
         }
 
         const double ch1_avg = tty_step.sum_ch1 / static_cast<double>(tty_step.count_ch1);
@@ -1531,18 +1581,18 @@ int run(const Config& cfg) {
 
         uint32_t raw_adc_count = 0;
         if (tty_writer) {
-            raw_adc_count = static_cast<uint32_t>(adc_raw_buffer.size());
-            const int32_t raw_process_err = api.ProcessData(device.hnd,
-                                                            raw.data(),
-                                                            static_cast<uint32_t>(recvd),
-                                                            0,
-                                                            adc_raw_buffer.data(),
-                                                            &raw_adc_count,
-                                                            nullptr,
-                                                            nullptr);
-            expect_ok(api, raw_process_err, "Process raw ADC data");
+            for (std::size_t i = 0; i < recvd; ++i) {
+                double raw_code = 0.0;
+                if (!try_extract_raw_adc_code(raw[i], raw_code)) {
+                    continue;
+                }
+                if (raw_adc_count >= adc_raw_buffer.size()) {
+                    fail("Raw ADC parsing overflowed the temporary buffer");
+                }
+                adc_raw_buffer[raw_adc_count++] = raw_code;
+            }
             if (raw_adc_count != adc_count) {
-                fail("Raw ADC processing returned a different sample count than voltage processing");
+                fail("Raw ADC parsing returned a different sample count than voltage processing");
             }
         }
 
@@ -1624,7 +1674,14 @@ int run(const Config& cfg) {
                 start_packet();
             }
 
-            if (!packet_active && start_edge) {
+            if (packet_active && start_edge) {
+                finish_packet(PacketCloseReason::ExternalStopEdge);
+                if ((cfg.packet_limit != 0U) && (total_completed_packets >= cfg.packet_limit)) {
+                    stop_loop_requested = true;
+                    continue;
+                }
+                start_packet();
+            } else if (!packet_active && start_edge) {
                 start_packet();
             }
 

tty_protocol_writer.cpp

@@ -38,11 +38,17 @@ void TtyProtocolWriter::close_fd() noexcept {}
 
 #else
 
+#include <array>
 #include <cerrno>
 #include <cstring>
 #include <fcntl.h>
+#include <limits.h>
+#include <optional>
+#include <pty.h>
 #include <sstream>
+#include <sys/stat.h>
 #include <sys/types.h>
+#include <termios.h>
 #include <unistd.h>
 
 namespace {
@@ -53,31 +59,113 @@ std::string io_error(const std::string& action, const std::string& path) {
     return out.str();
 }
 
-} // namespace
-
-TtyProtocolWriter::TtyProtocolWriter(std::string path) : path_(std::move(path)) {
-    fd_ = ::open(path_.c_str(), O_WRONLY | O_NOCTTY);
-    if (fd_ < 0) {
-        throw std::runtime_error(io_error("Cannot open tty output", path_));
+void set_fd_raw(int fd) {
+    struct termios tio {};
+    if (::tcgetattr(fd, &tio) != 0) {
+        throw std::runtime_error(io_error("Cannot read tty attributes for", std::to_string(fd)));
+    }
+    ::cfmakeraw(&tio);
+    if (::tcsetattr(fd, TCSANOW, &tio) != 0) {
+        throw std::runtime_error(io_error("Cannot apply raw tty attributes to", std::to_string(fd)));
     }
 }
 
+bool is_character_device_path(const std::string& path) {
+    struct stat st {};
+    if (::stat(path.c_str(), &st) != 0) {
+        if (errno == ENOENT) {
+            return false;
+        }
+        throw std::runtime_error(io_error("Cannot stat tty output", path));
+    }
+    return S_ISCHR(st.st_mode);
+}
+
+std::optional<std::string> read_link_target(const std::string& path) {
+    std::array<char, PATH_MAX> buf {};
+    const ssize_t len = ::readlink(path.c_str(), buf.data(), buf.size() - 1U);
+    if (len < 0) {
+        if (errno == EINVAL || errno == ENOENT) {
+            return std::nullopt;
+        }
+        throw std::runtime_error(io_error("Cannot read symlink", path));
+    }
+    buf[static_cast<std::size_t>(len)] = '\0';
+    return std::string(buf.data());
+}
+
+} // namespace
+
+TtyProtocolWriter::TtyProtocolWriter(std::string path) : path_(std::move(path)) {
+    if (is_character_device_path(path_)) {
+        fd_ = ::open(path_.c_str(), O_WRONLY | O_NOCTTY);
+        if (fd_ < 0) {
+            throw std::runtime_error(io_error("Cannot open tty output", path_));
+        }
+        return;
+    }
+
+    std::array<char, PATH_MAX> slave_name {};
+    if (::openpty(&fd_, &slave_fd_, slave_name.data(), nullptr, nullptr) != 0) {
+        throw std::runtime_error(io_error("Cannot create PTY bridge for", path_));
+    }
+    try {
+        slave_path_ = slave_name.data();
+        set_fd_raw(slave_fd_);
+
+        struct stat st {};
+        if (::lstat(path_.c_str(), &st) == 0) {
+            if (!S_ISLNK(st.st_mode) && !S_ISREG(st.st_mode)) {
+                throw std::runtime_error("Refusing to replace non-link path '" + path_ + "'");
+            }
+            if (::unlink(path_.c_str()) != 0) {
+                throw std::runtime_error(io_error("Cannot remove existing tty link", path_));
+            }
+        } else if (errno != ENOENT) {
+            throw std::runtime_error(io_error("Cannot inspect tty link path", path_));
+        }
+
+        if (::symlink(slave_path_.c_str(), path_.c_str()) != 0) {
+            throw std::runtime_error(io_error("Cannot create tty symlink", path_));
+        }
+    } catch (...) {
+        close_slave_fd();
+        close_fd();
+        throw;
+    }
+    owns_link_ = true;
+}
+
 TtyProtocolWriter::~TtyProtocolWriter() {
+    remove_owned_link();
+    close_slave_fd();
     close_fd();
 }
 
 TtyProtocolWriter::TtyProtocolWriter(TtyProtocolWriter&& other) noexcept
     : path_(std::move(other.path_)),
-      fd_(other.fd_) {
+      fd_(other.fd_),
+      slave_fd_(other.slave_fd_),
+      slave_path_(std::move(other.slave_path_)),
+      owns_link_(other.owns_link_) {
     other.fd_ = -1;
+    other.slave_fd_ = -1;
+    other.owns_link_ = false;
 }
 
 TtyProtocolWriter& TtyProtocolWriter::operator=(TtyProtocolWriter&& other) noexcept {
     if (this != &other) {
+        remove_owned_link();
+        close_slave_fd();
         close_fd();
         path_ = std::move(other.path_);
         fd_ = other.fd_;
+        slave_fd_ = other.slave_fd_;
+        slave_path_ = std::move(other.slave_path_);
+        owns_link_ = other.owns_link_;
         other.fd_ = -1;
+        other.slave_fd_ = -1;
+        other.owns_link_ = false;
     }
     return *this;
 }
@@ -125,4 +213,27 @@ void TtyProtocolWriter::close_fd() noexcept {
     }
 }
 
+void TtyProtocolWriter::close_slave_fd() noexcept {
+    if (slave_fd_ >= 0) {
+        ::close(slave_fd_);
+        slave_fd_ = -1;
+    }
+}
+
+void TtyProtocolWriter::remove_owned_link() noexcept {
+    if (!owns_link_ || path_.empty()) {
+        return;
+    }
+
+    try {
+        const auto target = read_link_target(path_);
+        if (target && (*target == slave_path_)) {
+            ::unlink(path_.c_str());
+        }
+    } catch (...) {
+    }
+
+    owns_link_ = false;
+}
+
 #endif

tty_protocol_writer.h

@@ -21,9 +21,14 @@ public:
 private:
     void write_frame(uint16_t word0, uint16_t word1, uint16_t word2, uint16_t word3) const;
     void close_fd() noexcept;
+    void close_slave_fd() noexcept;
+    void remove_owned_link() noexcept;
 
     std::string path_;
 #ifndef _WIN32
     int fd_ = -1;
+    int slave_fd_ = -1;
+    std::string slave_path_;
+    bool owns_link_ = false;
 #endif
 };