fix(modem): Added support for inflatable buffer

As a configurable option, if disabled we report an error.

Closes espressif#272

components/esp_modem/Kconfig

@@ -16,6 +16,17 @@ menu "esp-modem"
             in command mode might come fragmented in rare cases so might need to retry
             AT commands.
 
+    config ESP_MODEM_USE_INFLATABLE_BUFFER_IF_NEEDED
+        bool "Use inflatable buffer in DCE"
+        default n
+        help
+            If enabled we will process the ongoing AT command by growing the current
+            buffer (if we've run out the preconfigured buffer).
+            If disabled, we simply report a failure.
+            Use this if additional allocation is not a problem and you need to reliably process
+            all commands, usually with sporadically longer responses than the configured buffer.
+            Could be also used to defragment AT replies in CMUX mode if CMUX_DEFRAGMENT_PAYLOAD=n
+
     config ESP_MODEM_CMUX_DELAY_AFTER_DLCI_SETUP
         int "Delay in ms to wait before creating another virtual terminal"
         default 0

components/esp_modem/include/cxx_include/esp_modem_dte.hpp

@@ -79,6 +79,13 @@ class DTE : public CommandableIf {
      */
     void set_read_cb(std::function<bool(uint8_t *data, size_t len)> f);
 
+    /**
+     * @brief Sets read callback for manual command processing
+     * Note that this API also locks the command API, which can only be used
+     * after you remove the callback by dte->on_read(nullptr)
+     *
+     * @param on_data Function to be called when a command response is available
+     */
     void on_read(got_line_cb on_data) override;
 
     /**
@@ -122,7 +129,6 @@ class DTE : public CommandableIf {
     }
     friend class Scoped<DTE>;                               /*!< Declaring "Scoped<DTE> lock(dte)" locks this instance */
 private:
-    static const size_t GOT_LINE = SignalGroup::bit0;       /*!< Bit indicating response available */
 
     [[nodiscard]] bool setup_cmux();                        /*!< Internal setup of CMUX mode */
     [[nodiscard]] bool exit_cmux();                         /*!< Exit of CMUX mode */
@@ -133,9 +139,68 @@ class DTE : public CommandableIf {
     std::shared_ptr<Terminal> primary_term;                 /*!< Reference to the primary terminal (mostly for sending commands) */
     std::shared_ptr<Terminal> secondary_term;               /*!< Secondary terminal for this DTE */
     modem_mode mode;                                        /*!< DTE operation mode */
-    SignalGroup signal;                                     /*!< Event group used to signal request-response operations */
-    command_result result;                                  /*!< Command result of the currently exectuted command */
     std::function<bool(uint8_t *data, size_t len)> on_data; /*!< on data callback for current terminal */
+
+#ifdef CONFIG_ESP_MODEM_USE_INFLATABLE_BUFFER_IF_NEEDED
+    /**
+     * @brief Implements an extra buffer that is used to capture partial reads from underlying terminals
+     * when we run out of the standard buffer
+     */
+    struct extra_buffer {
+        extra_buffer(): buffer(nullptr) {}
+        ~extra_buffer()
+        {
+            delete buffer;
+        }
+        std::vector<uint8_t> *buffer;
+        size_t consumed{0};
+        void grow(size_t need_size);
+        void deflate()
+        {
+            grow(0);
+            consumed = 0;
+        }
+        [[nodiscard]] uint8_t *begin() const
+        {
+            return &buffer->at(0);
+        }
+        [[nodiscard]] uint8_t *current() const
+        {
+            return &buffer->at(0) + consumed;
+        }
+    } inflatable;
+#endif // CONFIG_ESP_MODEM_USE_INFLATABLE_BUFFER_IF_NEEDED
+
+    /**
+     * @brief Set internal command callbacks to the underlying terminal.
+     * Here we capture command replies to be processed by supplied command callbacks in  struct command_cb.
+     */
+    void set_command_callbacks();
+
+    /**
+     * @brief This abstracts command callback processing and implements its locking, signaling of completion and timeouts.
+     */
+    struct command_cb {
+        static const size_t GOT_LINE = SignalGroup::bit0;       /*!< Bit indicating response available */
+        got_line_cb got_line;                                   /*!< Supplied command callback */
+        Lock line_lock{};                                       /*!< Command callback locking mechanism */
+        char separator{};                                       /*!< Command reply separator (end of line/processing unit) */
+        command_result result{};                                /*!< Command return code */
+        SignalGroup signal;                                     /*!< Event group used to signal request-response operations */
+        bool process_line(uint8_t *data, size_t consumed, size_t len);  /*!< Lets the processing callback handle one line (processing unit) */
+        bool wait_for_line(uint32_t time_ms);                   /*!< Waiting for command processing */
+        void set(got_line_cb l, char s = '\n')                  /*!< Sets the command callback atomically */
+        {
+            Scoped<Lock> lock(line_lock);
+            got_line = std::move(l);
+            separator = s;
+        }
+        void give_up()                                          /*!< Reports other than timeout error when processing replies (out of buffer) */
+        {
+            result = command_result::FAIL;
+            signal.set(GOT_LINE);
+        }
+    } command_cb;                                               /*!< Command callback utility class */
 };
 
 /**

components/esp_modem/src/esp_modem_dte.cpp

@@ -17,53 +17,118 @@ static const size_t dte_default_buffer_size = 1000;
 DTE::DTE(const esp_modem_dte_config *config, std::unique_ptr<Terminal> terminal):
     buffer(config->dte_buffer_size),
     cmux_term(nullptr), primary_term(std::move(terminal)), secondary_term(primary_term),
-    mode(modem_mode::UNDEF) {}
+    mode(modem_mode::UNDEF)
+{
+    set_command_callbacks();
+}
 
 DTE::DTE(std::unique_ptr<Terminal> terminal):
     buffer(dte_default_buffer_size),
     cmux_term(nullptr), primary_term(std::move(terminal)), secondary_term(primary_term),
-    mode(modem_mode::UNDEF) {}
+    mode(modem_mode::UNDEF)
+{
+    set_command_callbacks();
+}
 
 DTE::DTE(const esp_modem_dte_config *config, std::unique_ptr<Terminal> t, std::unique_ptr<Terminal> s):
     buffer(config->dte_buffer_size),
     cmux_term(nullptr), primary_term(std::move(t)), secondary_term(std::move(s)),
-    mode(modem_mode::DUAL_MODE) {}
+    mode(modem_mode::UNDEF)
+{
+    set_command_callbacks();
+}
 
 DTE::DTE(std::unique_ptr<Terminal> t, std::unique_ptr<Terminal> s):
     buffer(dte_default_buffer_size),
     cmux_term(nullptr), primary_term(std::move(t)), secondary_term(std::move(s)),
-    mode(modem_mode::DUAL_MODE) {}
+    mode(modem_mode::UNDEF)
+{
+    set_command_callbacks();
+}
 
-command_result DTE::command(const std::string &command, got_line_cb got_line, uint32_t time_ms, const char separator)
+void DTE::set_command_callbacks()
 {
-    Scoped<Lock> l(internal_lock);
-    result = command_result::TIMEOUT;
-    signal.clear(GOT_LINE);
-    primary_term->set_read_cb([this, got_line, separator](uint8_t *data, size_t len) {
-        if (!data) {
+    primary_term->set_read_cb([this](uint8_t *data, size_t len) {
+        Scoped<Lock> l(command_cb.line_lock);
+        if (command_cb.got_line == nullptr) {
+            return false;
+        }
+        if (data) {
+            // For terminals which post data directly with the callback (CMUX)
+            // we cannot defragment unless we allocate, but
+            // we'll try to process the data on the actual buffer
+#ifdef CONFIG_ESP_MODEM_USE_INFLATABLE_BUFFER_IF_NEEDED
+            if (inflatable.consumed != 0) {
+                inflatable.grow(inflatable.consumed + len);
+                std::memcpy(inflatable.current(), data, len);
+                data = inflatable.begin();
+            }
+            if (command_cb.process_line(data, inflatable.consumed, len)) {
+                return true;
+            }
+            // at this point we're sure that the data processing hasn't finished,
+            // and we have to grow the inflatable buffer (if enabled) or give up
+            if (inflatable.consumed == 0) {
+                inflatable.grow(len);
+                std::memcpy(inflatable.begin(), data, len);
+            }
+            inflatable.consumed += len;
+            return false;
+#else
+            if (command_cb.process_line(data, 0, len)) {
+                return true;
+            }
+            // cannot inflate and the processing hasn't finishes in the first iteration -> report a failure
+            command_cb.give_up();
+            return true;
+#endif
+        }
+        // data == nullptr: Terminals which request users to read current data
+        // we're able to use DTE's buffer to defragment it; as long as we consume less that the buffer size
+        if (buffer.size > buffer.consumed) {
             data = buffer.get();
             len = primary_term->read(data + buffer.consumed, buffer.size - buffer.consumed);
-        } else {
-            buffer.consumed = 0; // if the underlying terminal contains data, we cannot fragment
-        }
-        if (memchr(data + buffer.consumed, separator, len)) {
-            result = got_line(data, buffer.consumed + len);
-            if (result == command_result::OK || result == command_result::FAIL) {
-                signal.set(GOT_LINE);
+            if (command_cb.process_line(data, buffer.consumed, len)) {
                 return true;
             }
+            buffer.consumed += len;
+            return false;
+        }
+        // we have used the entire DTE's buffer, need to use the inflatable buffer to continue
+#ifdef CONFIG_ESP_MODEM_USE_INFLATABLE_BUFFER_IF_NEEDED
+        if (inflatable.consumed == 0) {
+            inflatable.grow(buffer.size + len);
+            std::memcpy(inflatable.begin(), buffer.get(), buffer.size);
+            inflatable.consumed = buffer.size;
+        } else {
+            inflatable.grow(inflatable.consumed + len);
+        }
+        len = primary_term->read(inflatable.current(), len);
+        if (command_cb.process_line(inflatable.begin(), inflatable.consumed, len)) {
+            return true;
         }
-        buffer.consumed += len;
+        inflatable.consumed += len;
         return false;
+#else
+        // cannot inflate -> report a failure
+        command_cb.give_up();
+        return true;
+#endif
     });
+}
+
+command_result DTE::command(const std::string &command, got_line_cb got_line, uint32_t time_ms, const char separator)
+{
+    Scoped<Lock> l1(internal_lock);
+    command_cb.set(got_line, separator);
     primary_term->write((uint8_t *)command.c_str(), command.length());
-    auto got_lf = signal.wait(GOT_LINE, time_ms);
-    if (got_lf && result == command_result::TIMEOUT) {
-        ESP_MODEM_THROW_IF_ERROR(ESP_ERR_INVALID_STATE);
-    }
+    command_cb.wait_for_line(time_ms);
+    command_cb.set(nullptr);
     buffer.consumed = 0;
-    primary_term->set_read_cb(nullptr);
-    return result;
+#ifdef CONFIG_ESP_MODEM_USE_INFLATABLE_BUFFER_IF_NEEDED
+    inflatable.deflate();
+#endif
+    return command_cb.result;
 }
 
 command_result DTE::command(const std::string &cmd, got_line_cb got_line, uint32_t time_ms)
@@ -81,6 +146,7 @@ bool DTE::exit_cmux()
     primary_term = std::move(ejected.first);
     buffer = std::move(ejected.second);
     secondary_term = primary_term;
+    set_command_callbacks();
     return true;
 }
 
@@ -98,6 +164,7 @@ bool DTE::setup_cmux()
         return false;
     }
     secondary_term = std::make_unique<CMuxInstance>(cmux_term, 1);
+    set_command_callbacks();
     return true;
 }
 
@@ -169,6 +236,10 @@ bool DTE::set_mode(modem_mode m)
 
 void DTE::set_read_cb(std::function<bool(uint8_t *, size_t)> f)
 {
+    if (f == nullptr) {
+        set_command_callbacks();
+        return;
+    }
     on_data = std::move(f);
     secondary_term->set_read_cb([this](uint8_t *data, size_t len) {
         if (!data) { // if no data available from terminal callback -> need to explicitly read some
@@ -230,6 +301,41 @@ void DTE::on_read(got_line_cb on_read_cb)
     });
 }
 
+bool DTE::command_cb::process_line(uint8_t *data, size_t consumed, size_t len)
+{
+    if (memchr(data + consumed, separator, len)) {
+        result = got_line(data, consumed + len);
+        if (result == command_result::OK || result == command_result::FAIL) {
+            signal.set(GOT_LINE);
+            return true;
+        }
+    }
+    return false;
+}
+
+bool DTE::command_cb::wait_for_line(uint32_t time_ms)
+{
+    auto got_lf = signal.wait(command_cb::GOT_LINE, time_ms);
+    if (got_lf && result == command_result::TIMEOUT) {
+        ESP_MODEM_THROW_IF_ERROR(ESP_ERR_INVALID_STATE);
+    }
+    return got_lf;
+}
+
+#ifdef CONFIG_ESP_MODEM_USE_INFLATABLE_BUFFER_IF_NEEDED
+void DTE::extra_buffer::grow(size_t need_size)
+{
+    if (need_size == 0) {
+        delete buffer;
+        buffer = nullptr;
+    } else if (buffer == nullptr) {
+        buffer = new std::vector<uint8_t>(need_size);
+    } else {
+        buffer->resize(need_size);
+    }
+}
+#endif
+
 /**
  * Implemented here to keep all headers C++11 compliant
  */

components/esp_modem/src/esp_modem_uart.cpp

@@ -64,7 +64,6 @@ class UartTerminal : public Terminal {
 
     void set_read_cb(std::function<bool(uint8_t *data, size_t len)> f) override
     {
-        ESP_MODEM_THROW_IF_FALSE(signal.wait(TASK_PARAMS, 1000), "Failed to set UART task params");
         on_read = std::move(f);
     }
 
@@ -91,7 +90,6 @@ class UartTerminal : public Terminal {
     static const size_t TASK_INIT = BIT0;
     static const size_t TASK_START = BIT1;
     static const size_t TASK_STOP = BIT2;
-    static const size_t TASK_PARAMS = BIT3;
 
     QueueHandle_t event_queue;
     uart_resource uart;
@@ -118,9 +116,7 @@ void UartTerminal::task()
         return; // exits to the static method where the task gets deleted
     }
     while (signal.is_any(TASK_START)) {
-        signal.set(TASK_PARAMS);
         if (get_event(event, 100)) {
-            signal.clear(TASK_PARAMS);
             switch (event.type) {
             case UART_DATA:
                 uart_get_buffered_data_len(uart.port, &len);