[修改] 增加freeRTOS

1. 版本FreeRTOSv202212.01，命名为kernel；

kernel/FreeRTOS/Demo/RISC-V-Qemu-virt_GCC/main_blinky.c

@@ -0,0 +1,159 @@
+/*
+ * FreeRTOS V202212.01
+ * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * https://www.FreeRTOS.org
+ * https://www.github.com/FreeRTOS
+ *
+ */
+
+/* FreeRTOS kernel includes. */
+#include <FreeRTOS.h>
+#include <task.h>
+#include <queue.h>
+
+#include <stdio.h>
+
+#include "riscv-virt.h"
+#include "ns16550.h"
+
+/* Priorities used by the tasks. */
+#define mainQUEUE_RECEIVE_TASK_PRIORITY		( tskIDLE_PRIORITY + 2 )
+#define	mainQUEUE_SEND_TASK_PRIORITY		( tskIDLE_PRIORITY + 1 )
+
+/* The rate at which data is sent to the queue.  The 200ms value is converted
+to ticks using the pdMS_TO_TICKS() macro. */
+#define mainQUEUE_SEND_FREQUENCY_MS			pdMS_TO_TICKS( 1000 )
+
+/* The maximum number items the queue can hold.  The priority of the receiving
+task is above the priority of the sending task, so the receiving task will
+preempt the sending task and remove the queue items each time the sending task
+writes to the queue.  Therefore the queue will never have more than one item in
+it at any time, and even with a queue length of 1, the sending task will never
+find the queue full. */
+#define mainQUEUE_LENGTH					( 1 )
+
+/*-----------------------------------------------------------*/
+
+/* The queue used by both tasks. */
+static QueueHandle_t xQueue = NULL;
+
+/*-----------------------------------------------------------*/
+
+static void prvQueueSendTask( void *pvParameters )
+{
+TickType_t xNextWakeTime;
+const unsigned long ulValueToSend = 100UL;
+const char * const pcMessage1 = "Transfer1";
+const char * const pcMessage2 = "Transfer2";
+int f = 1;
+
+	/* Remove compiler warning about unused parameter. */
+	( void ) pvParameters;
+
+	/* Initialise xNextWakeTime - this only needs to be done once. */
+	xNextWakeTime = xTaskGetTickCount();
+
+	for( ;; )
+	{
+		char buf[40];
+
+		sprintf( buf, "%d: %s: %s", xGetCoreID(),
+				pcTaskGetName( xTaskGetCurrentTaskHandle() ),
+				( f ) ? pcMessage1 : pcMessage2 );
+		vSendString( buf );
+		f = !f;
+
+		/* Place this task in the blocked state until it is time to run again. */
+		vTaskDelayUntil( &xNextWakeTime, mainQUEUE_SEND_FREQUENCY_MS );
+
+		/* Send to the queue - causing the queue receive task to unblock and
+		toggle the LED.  0 is used as the block time so the sending operation
+		will not block - it shouldn't need to block as the queue should always
+		be empty at this point in the code. */
+		xQueueSend( xQueue, &ulValueToSend, 0U );
+	}
+}
+
+/*-----------------------------------------------------------*/
+
+static void prvQueueReceiveTask( void *pvParameters )
+{
+unsigned long ulReceivedValue;
+const unsigned long ulExpectedValue = 100UL;
+const char * const pcMessage1 = "Blink1";
+const char * const pcMessage2 = "Blink2";
+const char * const pcFailMessage = "Unexpected value received\r\n";
+int f = 1;
+
+	/* Remove compiler warning about unused parameter. */
+	( void ) pvParameters;
+
+	for( ;; )
+	{
+		char buf[40];
+
+		/* Wait until something arrives in the queue - this task will block
+		indefinitely provided INCLUDE_vTaskSuspend is set to 1 in
+		FreeRTOSConfig.h. */
+		xQueueReceive( xQueue, &ulReceivedValue, portMAX_DELAY );
+
+		/*  To get here something must have been received from the queue, but
+		is it the expected value?  If it is, toggle the LED. */
+		if( ulReceivedValue == ulExpectedValue )
+		{
+			sprintf( buf, "%d: %s: %s", xGetCoreID(),
+					pcTaskGetName( xTaskGetCurrentTaskHandle() ),
+					( f ) ? pcMessage1 : pcMessage2 );
+			vSendString( buf );
+			f = !f;
+
+			ulReceivedValue = 0U;
+		}
+		else
+		{
+			vSendString( pcFailMessage );
+		}
+	}
+}
+
+/*-----------------------------------------------------------*/
+
+int main_blinky( void )
+{
+	vSendString( "Hello FreeRTOS!" );
+
+	/* Create the queue. */
+	xQueue = xQueueCreate( mainQUEUE_LENGTH, sizeof( uint32_t ) );
+
+	if( xQueue != NULL )
+	{
+		/* Start the two tasks as described in the comments at the top of this
+		file. */
+		xTaskCreate( prvQueueReceiveTask, "Rx", configMINIMAL_STACK_SIZE * 2U, NULL,
+					mainQUEUE_RECEIVE_TASK_PRIORITY, NULL );
+		xTaskCreate( prvQueueSendTask, "Tx", configMINIMAL_STACK_SIZE * 2U, NULL,
+					mainQUEUE_SEND_TASK_PRIORITY, NULL );
+	}
+
+	vTaskStartScheduler();
+
+	return 0;
+}