feat(esp_ringbuf): Add vRingbufferReset

Function has similar behavior to xQueueReset() where...
    - Buffer is emptied
    - Blocked sender is unblocked

Aslo added associated unit test cases.

components/esp_ringbuf/include/freertos/ringbuf.h

@@ -386,6 +386,15 @@ void vRingbufferReturnItem(RingbufHandle_t xRingbuffer, void *pvItem);
  */
 void vRingbufferReturnItemFromISR(RingbufHandle_t xRingbuffer, void *pvItem, BaseType_t *pxHigherPriorityTaskWoken);
 
+/**
+ * @brief   Reset a ring buffer back to its original empty state
+ *
+ * @param[in]   xRingbuffer     Ring buffer to reset
+ *
+ * @note    Users must ensure that all buffers are returned before calling this function
+ */
+void vRingbufferReset(RingbufHandle_t xRingbuffer);
+
 /**
  * @brief   Delete a ring buffer
  *

components/esp_ringbuf/ringbuf.c

@@ -1252,6 +1252,32 @@ void vRingbufferReturnItemFromISR(RingbufHandle_t xRingbuffer, void *pvItem, Bas
     portEXIT_CRITICAL_ISR(&pxRingbuffer->mux);
 }
 
+void vRingbufferReset(RingbufHandle_t xRingbuffer)
+{
+    Ringbuffer_t *pxRingbuffer = (Ringbuffer_t *)xRingbuffer;
+    configASSERT(pxRingbuffer);
+
+    portENTER_CRITICAL(&pxRingbuffer->mux);
+    // Check for unreturned buffers
+    configASSERT(pxRingbuffer->pucAcquire == pxRingbuffer->pucWrite);
+    configASSERT(pxRingbuffer->pucRead == pxRingbuffer->pucFree);
+    // Reset state
+    pxRingbuffer->pucAcquire = pxRingbuffer->pucHead;
+    pxRingbuffer->pucWrite = pxRingbuffer->pucHead;
+    pxRingbuffer->pucRead = pxRingbuffer->pucHead;
+    pxRingbuffer->pucFree = pxRingbuffer->pucHead;
+    pxRingbuffer->xItemsWaiting = 0;
+    pxRingbuffer->uxRingbufferFlags &= ~rbBUFFER_FULL_FLAG;
+
+    // If there's a task waiting to transmit, unblock it
+    if (listLIST_IS_EMPTY(&pxRingbuffer->xTasksWaitingToSend) == pdFALSE) {
+        if (xTaskRemoveFromEventList(&pxRingbuffer->xTasksWaitingToSend) == pdTRUE) {
+            portYIELD_WITHIN_API();
+        }
+    }
+    portEXIT_CRITICAL(&pxRingbuffer->mux);
+}
+
 void vRingbufferDelete(RingbufHandle_t xRingbuffer)
 {
     Ringbuffer_t *pxRingbuffer = (Ringbuffer_t *)xRingbuffer;

components/esp_ringbuf/test_apps/main/test_ringbuf_common.c

@@ -20,6 +20,7 @@
 #include "freertos/ringbuf.h"
 #include "unity.h"
 #include "esp_rom_sys.h"
+#include "esp_task.h"
 
 #include "test_functions.h"
 
@@ -1318,3 +1319,62 @@ TEST_CASE("Test no-split full buffer becomes empty when oldest is returned last"
     TEST_ASSERT_NOT_NULL(slot);
     vRingbufferDelete(buffer_handle);
 }
+
+/* ----------------------------------- Test ring buffer reset --------------------------------------
+ * Reset Case: Test that vRingbufferReset() empties the ring buffer
+ * Reset unblocks sender: Test that vRingbufferReset() will unblock a previously blocked sender
+ */
+
+static uint8_t item[SMALL_ITEM_SIZE] = {0};
+
+TEST_CASE("Test ring buffer reset", "[esp_ringbuf][linux]")
+{
+    // Create buffer
+    RingbufHandle_t rb = xRingbufferCreate(SMALL_ITEM_SIZE, RINGBUF_TYPE_BYTEBUF);
+    TEST_ASSERT_MESSAGE(rb != NULL, "Failed to create ring buffer");
+    // Fill buffer
+    TEST_ASSERT_EQUAL(pdTRUE, xRingbufferSend(rb, item, SMALL_ITEM_SIZE, 0));
+    // Confirm buffer is full
+    TEST_ASSERT_EQUAL(0, xRingbufferGetCurFreeSize(rb));
+    // Reset ring buffer
+    vRingbufferReset(rb);
+    // Confirm buffer is empty
+    TEST_ASSERT_EQUAL(SMALL_ITEM_SIZE, xRingbufferGetCurFreeSize(rb));
+    // Cleanup
+    vRingbufferDelete(rb);
+}
+
+static volatile bool post_reset_send = false;
+
+static void post_reset_send_task(void *arg)
+{
+    RingbufHandle_t rb = (RingbufHandle_t)arg;
+    TEST_ASSERT_EQUAL(pdTRUE, xRingbufferSend(rb, item, SMALL_ITEM_SIZE, portMAX_DELAY));
+    post_reset_send = true;
+    vTaskDelete(NULL);
+}
+
+TEST_CASE("Test ring buffer reset unblocks sender ", "[esp_ringbuf][linux]")
+{
+    // Create buffer
+    RingbufHandle_t rb = xRingbufferCreate(SMALL_ITEM_SIZE, RINGBUF_TYPE_BYTEBUF);
+    TEST_ASSERT_MESSAGE(rb != NULL, "Failed to create ring buffer");
+    // Fill buffer
+    TEST_ASSERT_EQUAL(pdTRUE, xRingbufferSend(rb, item, SMALL_ITEM_SIZE, 0));
+    // Confirm buffer is full
+    TEST_ASSERT_EQUAL(0, xRingbufferGetCurFreeSize(rb));
+    // Launch task to block on sending to full ring buffer
+    post_reset_send = false;
+    xTaskCreatePinnedToCore(post_reset_send_task, "send tsk", 2048, (void*)rb, ESP_TASK_MAIN_PRIO + 1, NULL, 0);
+    vTaskDelay(10);
+    // Confirm blocked task has not sent
+    TEST_ASSERT_EQUAL(false, post_reset_send);
+    // Reset the ring buffer
+    vRingbufferReset(rb);
+    // Check task has unblocked and sent
+    vTaskDelay(1);
+    TEST_ASSERT_EQUAL(true, post_reset_send);
+    // Cleanup
+    vRingbufferDelete(rb);
+    vTaskDelay(1);
+}