Merge pull request 'hotfix-v0.1.0' (#8) from hotfix-v0.1.0 into v0.1

Reviewed-on: https://kozmotronik.nohost.me/gitea/KozmotronikTech/relay_chn/pulls/8

.gitignore

@@ -100,3 +100,8 @@ CTestTestfile.cmake
 _deps
 CMakeUserPresets.json
 
+# Build directory
+build
+
+# unity-app directory
+unity-app

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "files.associations": {
+        "relay_chn.h": "c"
+    }
+}

include/relay_chn.h

@@ -23,11 +23,14 @@
 
 #include "esp_err.h"
 #include "driver/gpio.h"
+#include <stdint.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+#define RELAY_CHN_ID_ALL   CONFIG_RELAY_CHN_COUNT ///< Special ID to address all channels
+
 /**
  * @brief Enumeration for relay channel direction.
  */
@@ -58,6 +61,20 @@ enum relay_chn_state_enum {
  */
 typedef enum relay_chn_state_enum relay_chn_state_t;
 
+/**
+ * @brief Relay channel state change listener.
+ *
+ * An optional interface to listen to the channel state change events.
+ * The listeners SHOULD be implemented as light functions and SHOULD NOT contain
+ * any blocking calls. Otherwise the relay_chn module would not function properly
+ * since it is designed as event driven.
+ *
+ * @param chn_id The ID of the channel whose state has changed.
+ * @param old_state The old state of the channel.
+ * @param new_state The new state of the channel.
+ */
+typedef void (*relay_chn_state_listener_t)(uint8_t chn_id, relay_chn_state_t old_state, relay_chn_state_t new_state);
+
 
 /**
  * @brief Create and initialize relay channels.
@@ -74,6 +91,26 @@ typedef enum relay_chn_state_enum relay_chn_state_t;
  */
 esp_err_t relay_chn_create(const gpio_num_t* gpio_map, uint8_t gpio_count);
 
+/**
+ * @brief Register a channel state change listener.
+ * 
+ * @param listener A function that implements relay_chn_state_listener_t interface.
+ *
+ * @return
+ *     - ESP_OK: Success
+ *     - ESP_ERR_INVALID_ARG: Invalid argument
+ *     - ESP_ERR_NO_MEM: No enough memory
+ *     - ESP_FAIL: General failure
+ */
+esp_err_t relay_chn_register_listener(relay_chn_state_listener_t listener);
+
+/**
+ * @brief Unregister a channel state change listener.
+ * 
+ * @param listener A function that implements relay_chn_state_listener_t interface.
+ */
+void relay_chn_unregister_listener(relay_chn_state_listener_t listener);
+
 /**
  * @brief Get the state of the specified relay channel.
  *
@@ -100,6 +137,14 @@ relay_chn_state_t relay_chn_get_state(uint8_t chn_id);
  */
 char *relay_chn_get_state_str(uint8_t chn_id);
 
+/**
+ * @brief Return the text presentation of an state.
+ * 
+ * @param state A state with type of relay_chn_state_t.
+ * @return char* The text presentation of the state. "UNKNOWN" if the state is not known.
+ */
+char *relay_chn_state_str(relay_chn_state_t state);
+
 /**
  * @brief Runs the relay channel in the forward direction.
  *

src/relay_chn.c

@@ -13,6 +13,7 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include "esp_err.h"
 #include "esp_log.h"
 #include "esp_task.h"
@@ -23,12 +24,11 @@
 #include "relay_chn.h"
 #include "sdkconfig.h"
 
-// TODO: on_state change API si ekle
 
 #define RELAY_CHN_OPPOSITE_INERTIA_MS CONFIG_RELAY_CHN_OPPOSITE_INERTIA_MS
 #define RELAY_CHN_COUNT CONFIG_RELAY_CHN_COUNT
 
-const char* TAG = "relay_chn";
+static const char *TAG = "relay_chn";
 
 ESP_EVENT_DEFINE_BASE(RELAY_CHN_CMD_EVENT);
 
@@ -82,9 +82,17 @@ typedef struct relay_chn_type {
     relay_chn_run_info_t run_info;  ///< Runtime information of the relay channel.
     relay_chn_output_t output;      ///< Output configuration of the relay channel.
     relay_chn_cmd_t pending_cmd;    ///< The command that is pending to be issued
-    esp_timer_handle_t timer;       ///< Timer to handle the opposite direction inertia time.
+    esp_timer_handle_t inertia_timer;       ///< Timer to handle the opposite direction inertia time.
 } relay_chn_t;
 
+/**
+ * @brief Structure to manage the state change listeners. 
+ */
+struct relay_chn_state_listener_manager_type {
+    uint8_t listener_count;                 ///< The number of registered listeners.
+    relay_chn_state_listener_t *listeners;  ///< The list that holds references to the registered listeners.
+} relay_chn_state_listener_manager;
+
 
 static relay_chn_t relay_channels[RELAY_CHN_COUNT];
 static esp_event_loop_handle_t relay_chn_event_loop;
@@ -154,7 +162,7 @@ static esp_err_t relay_chn_init_timer(relay_chn_t *relay_chn)
         .arg = &relay_chn->id,
         .name = timer_name
     };
-    return esp_timer_create(&timer_args, &relay_chn->timer);
+    return esp_timer_create(&timer_args, &relay_chn->inertia_timer);
 }
 
 /**
@@ -172,7 +180,7 @@ static bool relay_chn_is_gpio_valid(gpio_num_t gpio)
 static esp_err_t relay_chn_create_event_loop()
 {
     esp_event_loop_args_t loop_args = {
-        .queue_size = 10,
+        .queue_size = RELAY_CHN_COUNT * 8,
         .task_name = "relay_chn_event_loop",
         .task_priority = ESP_TASKD_EVENT_PRIO - 1,
         .task_stack_size = 2048,
@@ -204,8 +212,9 @@ esp_err_t relay_chn_create(const gpio_num_t* gpio_map, uint8_t gpio_count)
 
     esp_err_t ret;
     for (int i = 0; i < RELAY_CHN_COUNT; i++) {
-        gpio_num_t forward_pin = gpio_map[i];
+        int gpio_index = i << 1; // gpio_index = i * 2
-        gpio_num_t reverse_pin = gpio_map[i+1];
+        gpio_num_t forward_pin = gpio_map[gpio_index];
+        gpio_num_t reverse_pin = gpio_map[gpio_index + 1];
         // Check if the GPIOs are valid
         if (!relay_chn_is_gpio_valid(forward_pin)) {
             ESP_LOGE(TAG, "Invalid GPIO pin number: %d", forward_pin);
@@ -235,7 +244,7 @@ esp_err_t relay_chn_create(const gpio_num_t* gpio_map, uint8_t gpio_count)
         relay_chn->output.forward_pin = forward_pin;
         relay_chn->output.reverse_pin = reverse_pin;
         relay_chn->output.direction = RELAY_CHN_DIRECTION_DEFAULT;
-        relay_chn->state = RELAY_CHN_STATE_STOPPED;
+        relay_chn->state = RELAY_CHN_STATE_FREE;
         relay_chn->pending_cmd = RELAY_CHN_CMD_NONE;
         relay_chn->run_info.last_run_cmd = RELAY_CHN_CMD_NONE;
         ret |= relay_chn_init_timer(relay_chn);// Create direction change inertia timer
@@ -248,9 +257,86 @@ esp_err_t relay_chn_create(const gpio_num_t* gpio_map, uint8_t gpio_count)
     // Create relay channel command event loop
     ret |= relay_chn_create_event_loop();
 
+    // Init the state listener manager
+    relay_chn_state_listener_manager.listeners = malloc(sizeof(relay_chn_state_listener_t*));
+    if (relay_chn_state_listener_manager.listeners == NULL) {
+        ESP_LOGE(TAG, "Failed to initialize memory for the listeners!");
+        ret = ESP_ERR_NO_MEM;
+    }
+
     return ret;
 }
 
+static int relay_chn_listener_index(relay_chn_state_listener_t listener)
+{
+    for (int i = 0; i < relay_chn_state_listener_manager.listener_count; i++) {
+        if (relay_chn_state_listener_manager.listeners[i] == listener) {
+            // This is the listener to unregister. Check if it is in the middle
+            ESP_LOGD(TAG, "relay_chn_listener_index: Listener %p; found at index %d.", listener, i);
+            return i;
+        }
+    }
+    return -1;
+}
+
+esp_err_t relay_chn_register_listener(relay_chn_state_listener_t listener)
+{
+    if (listener == NULL) {
+        ESP_LOGE(TAG, "relay_chn_register_listener: A NULL listener given.");
+        return ESP_ERR_INVALID_ARG;
+    }
+
+    if (relay_chn_listener_index(listener) > -1) {
+        ESP_LOGD(TAG, "relay_chn_register_listener: The listener %p is already registered.", listener);
+        return ESP_OK;
+    }
+
+    ESP_LOGD(TAG, "relay_chn_register_listener: Register listener: %p", listener);
+    relay_chn_state_listener_manager.listeners[relay_chn_state_listener_manager.listener_count] = listener;
+    // Update listener count
+    relay_chn_state_listener_manager.listener_count++;
+
+    return ESP_OK;
+}
+
+void relay_chn_unregister_listener(relay_chn_state_listener_t listener)
+{
+    if (listener == NULL) {
+        ESP_LOGD(TAG, "relay_chn_unregister_listener: A NULL listener given, nothing to do.");
+        return;
+    }
+    // Search the listener in the listeners list and get its index if exists
+    int i = relay_chn_listener_index(listener);
+    if (i == -1) {
+        ESP_LOGD(TAG, "relay_chn_unregister_listener: %p is not registered already.", listener);
+        return;
+    }
+
+    uint8_t max_index = relay_chn_state_listener_manager.listener_count - 1;
+    // Check whether the listener's index is in the middle
+    if (i == max_index) {
+        // free(&relay_chn_state_listener_manager.listeners[i]);
+        relay_chn_state_listener_manager.listeners[i] = NULL;
+    }
+    else {
+        // It is in the middle, so align the next elements in the list and then free the last empty pointer
+        // Align the next elements
+        uint8_t num_of_elements = max_index - i;
+        relay_chn_state_listener_t *pnext = NULL;
+        // (i + j): current index; (i + j + 1): next index
+        for (uint8_t j = 0; j < num_of_elements; j++) {
+            uint8_t current_index = i + j;
+            uint8_t next_index = current_index + 1;
+            pnext = &relay_chn_state_listener_manager.listeners[next_index];
+            relay_chn_state_listener_manager.listeners[current_index] = *pnext;
+        }
+        // free(&relay_chn_state_listener_manager.listeners[max_index]); // Free the last element
+        relay_chn_state_listener_manager.listeners[max_index] = NULL; // Free the last element
+    }
+    // Decrease listener count
+    relay_chn_state_listener_manager.listener_count--;
+}
+
 /**
  * @brief Check channel ID validity
  * 
@@ -260,7 +346,7 @@ esp_err_t relay_chn_create(const gpio_num_t* gpio_map, uint8_t gpio_count)
  */
 static bool relay_chn_is_channel_id_valid(uint8_t chn_id)
 {
-    bool valid = chn_id >= 0 && chn_id < RELAY_CHN_COUNT;
+    bool valid = (chn_id < RELAY_CHN_COUNT) || chn_id == RELAY_CHN_ID_ALL;
     if (!valid) {
         ESP_LOGE(TAG, "Invalid channel ID: %d", chn_id);
     }
@@ -280,19 +366,35 @@ static void relay_chn_dispatch_cmd(relay_chn_t *relay_chn, relay_chn_cmd_t cmd)
                         sizeof(relay_chn->id), portMAX_DELAY);
 }
 
-static esp_err_t relay_chn_invalidate_timer(relay_chn_t *relay_chn)
+
+static esp_err_t relay_chn_start_esp_timer_once(esp_timer_handle_t esp_timer, uint32_t time_ms)
 {
-    if (esp_timer_is_active(relay_chn->timer)) {
+    // Invalidate the channel's timer if it is active
-        return esp_timer_stop(relay_chn->timer);
+    esp_err_t ret = esp_timer_start_once(esp_timer, time_ms * 1000);
+    if (ret == ESP_ERR_INVALID_STATE) {
+        // This timer is already running, stop the timer first
+        ret = esp_timer_stop(esp_timer);
+        if (ret != ESP_OK && ret != ESP_ERR_INVALID_STATE) {
+            return ret;
+        }
+        ret = esp_timer_start_once(esp_timer, time_ms * 1000);
     }
     return ESP_OK;
 }
 
-static esp_err_t relay_chn_start_timer(relay_chn_t *relay_chn, uint32_t time_ms)
+static void relay_chn_update_state(relay_chn_t *relay_chn, relay_chn_state_t new_state)
 {
-    // Invalidate the channel's timer if it is active
+    relay_chn_state_t old = relay_chn->state;
-    relay_chn_invalidate_timer(relay_chn);
+    relay_chn->state = new_state;
-    return esp_timer_start_once(relay_chn->timer, time_ms * 1000);
+    for (uint8_t i = 0; i < relay_chn_state_listener_manager.listener_count; i++) {
+        relay_chn_state_listener_t listener = relay_chn_state_listener_manager.listeners[i];
+        if (listener == NULL) {
+            relay_chn_state_listener_manager.listener_count -= 1;
+            ESP_LOGD(TAG, "relay_chn_update_state: A listener is NULL at index: %u", i);
+        }
+        // Emit the state change to the listeners
+        listener(relay_chn->id, old, new_state);
+    }
 }
 
 /**
@@ -344,8 +446,14 @@ static void relay_chn_issue_cmd(relay_chn_t* relay_chn, relay_chn_cmd_t cmd)
             break;
         
         case RELAY_CHN_STATE_STOPPED:
-            if (relay_chn->run_info.last_run_cmd == cmd) {
+            if (relay_chn->run_info.last_run_cmd == cmd || relay_chn->run_info.last_run_cmd == RELAY_CHN_CMD_NONE) {
-                // If the last run command is the same as the current command, run the command immediately
+                // Since the state is STOPPED, the inertia timer should be running and must be invalidated
+                // with the pending FREE command
+                esp_timer_stop(relay_chn->inertia_timer);
+                relay_chn->pending_cmd = RELAY_CHN_CMD_NONE;
+                                
+                // If this is the first run or the last run command is the same as the current command,
+                // run the command immediately
                 relay_chn_dispatch_cmd(relay_chn, cmd);
             }
             else {
@@ -355,11 +463,11 @@ static void relay_chn_issue_cmd(relay_chn_t* relay_chn, relay_chn_cmd_t cmd)
                 uint32_t inertia_time_ms = RELAY_CHN_OPPOSITE_INERTIA_MS - inertia_time_passed_ms;
                 if (inertia_time_ms > 0) {
                     relay_chn->pending_cmd = cmd;
-                    relay_chn->state = cmd == RELAY_CHN_CMD_FORWARD 
+                    relay_chn_state_t new_state = cmd == RELAY_CHN_CMD_FORWARD 
-                                                ? RELAY_CHN_STATE_FORWARD_PENDING
+                            ? RELAY_CHN_STATE_FORWARD_PENDING : RELAY_CHN_STATE_REVERSE_PENDING;
-                                                : RELAY_CHN_STATE_REVERSE_PENDING;
+                    relay_chn_update_state(relay_chn, new_state);
                     // If the time passed is less than the opposite inertia time, wait for the remaining time
-                    relay_chn_start_timer(relay_chn, inertia_time_ms);
+                    relay_chn_start_esp_timer_once(relay_chn->inertia_timer, inertia_time_ms);
                 }
                 else {
                     // If the time passed is more than the opposite inertia time, run the command immediately
@@ -376,16 +484,21 @@ static void relay_chn_issue_cmd(relay_chn_t* relay_chn, relay_chn_cmd_t cmd)
                 relay_chn_dispatch_cmd(relay_chn, cmd);
                 return;
             }
-
+            
             if (relay_chn->run_info.last_run_cmd == cmd) {
                 // If the last run command is the same as the current command, do nothing
                 return;
             }
+            
+            // Stop the channel first before the schedule
+            relay_chn_dispatch_cmd(relay_chn, RELAY_CHN_CMD_STOP);
 
             // If the last run command is different from the current command, wait for the opposite inertia time
             relay_chn->pending_cmd = cmd;
-            relay_chn->state = cmd == RELAY_CHN_CMD_FORWARD ? RELAY_CHN_STATE_FORWARD_PENDING : RELAY_CHN_STATE_REVERSE_PENDING;
+            relay_chn_state_t new_state = cmd == RELAY_CHN_CMD_FORWARD 
-            relay_chn_start_timer(relay_chn, RELAY_CHN_OPPOSITE_INERTIA_MS);
+                    ? RELAY_CHN_STATE_FORWARD_PENDING : RELAY_CHN_STATE_REVERSE_PENDING;
+            relay_chn_update_state(relay_chn, new_state);
+            relay_chn_start_esp_timer_once(relay_chn->inertia_timer, RELAY_CHN_OPPOSITE_INERTIA_MS);
             break;
 
         default: ESP_LOGD(TAG, "relay_chn_evaluate: Unknown relay channel state!");
@@ -406,21 +519,13 @@ char *relay_chn_get_state_str(uint8_t chn_id)
     if (!relay_chn_is_channel_id_valid(chn_id)) {
         return "INVALID";
     }
-    switch (relay_channels[chn_id].state) {
+    return relay_chn_state_str(relay_channels[chn_id].state);
-        case RELAY_CHN_STATE_FREE:
+}
-            return "FREE";
+
-        case RELAY_CHN_STATE_STOPPED:
+static void relay_chn_issue_cmd_on_all_channels(relay_chn_cmd_t cmd)
-            return "STOPPED";
+{
-        case RELAY_CHN_STATE_FORWARD:
+    for (int i = 0; i < RELAY_CHN_COUNT; i++) {
-            return "FORWARD";
+        relay_chn_issue_cmd(&relay_channels[i], cmd);
-        case RELAY_CHN_STATE_REVERSE:
-            return "REVERSE";
-        case RELAY_CHN_STATE_FORWARD_PENDING:
-            return "FORWARD_PENDING";
-        case RELAY_CHN_STATE_REVERSE_PENDING:
-            return "REVERSE_PENDING";
-        default:
-            return "UNKNOWN";
     }
 }
 
@@ -428,6 +533,11 @@ void relay_chn_run_forward(uint8_t chn_id)
 {
     if (!relay_chn_is_channel_id_valid(chn_id)) return;
 
+    if (chn_id == RELAY_CHN_ID_ALL) {
+        relay_chn_issue_cmd_on_all_channels(RELAY_CHN_CMD_FORWARD);
+        return;
+    }
+
     relay_chn_t* relay_chn = &relay_channels[chn_id];
     relay_chn_issue_cmd(relay_chn, RELAY_CHN_CMD_FORWARD);
 }
@@ -436,6 +546,11 @@ void relay_chn_run_reverse(uint8_t chn_id)
 {
     if (!relay_chn_is_channel_id_valid(chn_id)) return;
 
+    if (chn_id == RELAY_CHN_ID_ALL) {
+        relay_chn_issue_cmd_on_all_channels(RELAY_CHN_CMD_REVERSE);
+        return;
+    }
+
     relay_chn_t* relay_chn = &relay_channels[chn_id];
     relay_chn_issue_cmd(relay_chn, RELAY_CHN_CMD_REVERSE);
 }
@@ -444,6 +559,11 @@ void relay_chn_stop(uint8_t chn_id)
 {
     if (!relay_chn_is_channel_id_valid(chn_id)) return;
 
+    if (chn_id == RELAY_CHN_ID_ALL) {
+        relay_chn_issue_cmd_on_all_channels(RELAY_CHN_CMD_STOP);
+        return;
+    }
+
     relay_chn_t* relay_chn = &relay_channels[chn_id];
     relay_chn_issue_cmd(relay_chn, RELAY_CHN_CMD_STOP);
 }
@@ -452,6 +572,11 @@ void relay_chn_flip_direction(uint8_t chn_id)
 {
     if (!relay_chn_is_channel_id_valid(chn_id)) return;
 
+    if (chn_id == RELAY_CHN_ID_ALL) {
+        relay_chn_issue_cmd_on_all_channels(RELAY_CHN_CMD_FLIP);
+        return;
+    }
+
     relay_chn_t* relay_chn = &relay_channels[chn_id];
     relay_chn_issue_cmd(relay_chn, RELAY_CHN_CMD_FLIP);    
 }
@@ -470,12 +595,12 @@ static void relay_chn_execute_stop(relay_chn_t *relay_chn)
 {
     gpio_set_level(relay_chn->output.forward_pin, 0);
     gpio_set_level(relay_chn->output.reverse_pin, 0);
-    relay_chn->state = RELAY_CHN_STATE_STOPPED;
+    relay_chn_update_state(relay_chn, RELAY_CHN_STATE_STOPPED);
     
     // If there is any pending command, cancel it since the STOP command is issued right after it
     relay_chn->pending_cmd = RELAY_CHN_CMD_NONE;
     // Invalidate the channel's timer if it is active
-    relay_chn_invalidate_timer(relay_chn);
+    esp_timer_stop(relay_chn->inertia_timer);
 
     // If the channel was running, schedule a free command for the channel
     relay_chn_cmd_t last_run_cmd = relay_chn->run_info.last_run_cmd;
@@ -484,7 +609,7 @@ static void relay_chn_execute_stop(relay_chn_t *relay_chn)
         relay_chn->run_info.last_run_cmd_time_ms = esp_timer_get_time() / 1000;
         // Schedule a free command for the channel
         relay_chn->pending_cmd = RELAY_CHN_CMD_FREE;
-        relay_chn_start_timer(relay_chn, RELAY_CHN_OPPOSITE_INERTIA_MS);
+        relay_chn_start_esp_timer_once(relay_chn->inertia_timer, RELAY_CHN_OPPOSITE_INERTIA_MS);
     } else {
         // If the channel was not running, issue a free command immediately
         relay_chn_dispatch_cmd(relay_chn, RELAY_CHN_CMD_FREE);
@@ -495,16 +620,16 @@ static void relay_chn_execute_forward(relay_chn_t *relay_chn)
 {
     gpio_set_level(relay_chn->output.reverse_pin, 0);
     gpio_set_level(relay_chn->output.forward_pin, 1);
-    relay_chn->state = RELAY_CHN_STATE_FORWARD;
     relay_chn->run_info.last_run_cmd = RELAY_CHN_CMD_FORWARD;
+    relay_chn_update_state(relay_chn, RELAY_CHN_STATE_FORWARD);
 }
 
 static void relay_chn_execute_reverse(relay_chn_t *relay_chn)
 {
     gpio_set_level(relay_chn->output.forward_pin, 0);
     gpio_set_level(relay_chn->output.reverse_pin, 1);
-    relay_chn->state = RELAY_CHN_STATE_REVERSE;
     relay_chn->run_info.last_run_cmd = RELAY_CHN_CMD_REVERSE;
+    relay_chn_update_state(relay_chn, RELAY_CHN_STATE_REVERSE);
 }
 
 static void relay_chn_execute_flip(relay_chn_t *relay_chn)
@@ -519,15 +644,15 @@ static void relay_chn_execute_flip(relay_chn_t *relay_chn)
                                     : RELAY_CHN_DIRECTION_DEFAULT;
     // Set an inertia on the channel to prevent any immediate movement
     relay_chn->pending_cmd = RELAY_CHN_CMD_FREE;
-    relay_chn_start_timer(relay_chn, RELAY_CHN_OPPOSITE_INERTIA_MS);
+    relay_chn_start_esp_timer_once(relay_chn->inertia_timer, RELAY_CHN_OPPOSITE_INERTIA_MS);
 }
 
 void relay_chn_execute_free(relay_chn_t *relay_chn)
 {
-    relay_chn->state = RELAY_CHN_STATE_FREE;
     relay_chn->pending_cmd = RELAY_CHN_CMD_NONE;
     // Invalidate the channel's timer if it is active
-    relay_chn_invalidate_timer(relay_chn);
+    esp_timer_stop(relay_chn->inertia_timer);
+    relay_chn_update_state(relay_chn, RELAY_CHN_STATE_FREE);
 }
 
 static void relay_chn_event_handler(void* handler_arg, esp_event_base_t event_base, int32_t event_id, void* event_data)
@@ -577,4 +702,24 @@ static char *relay_chn_cmd_str(relay_chn_cmd_t cmd)
     }
 }
 
+char *relay_chn_state_str(relay_chn_state_t state)
+{
+    switch (state) {
+        case RELAY_CHN_STATE_FREE:
+            return "FREE";
+        case RELAY_CHN_STATE_STOPPED:
+            return "STOPPED";
+        case RELAY_CHN_STATE_FORWARD:
+            return "FORWARD";
+        case RELAY_CHN_STATE_REVERSE:
+            return "REVERSE";
+        case RELAY_CHN_STATE_FORWARD_PENDING:
+            return "FORWARD_PENDING";
+        case RELAY_CHN_STATE_REVERSE_PENDING:
+            return "REVERSE_PENDING";
+        default:
+            return "UNKNOWN";
+    }
+}
+
 /// @}