[修改] 增加freeRTOS

1. 版本FreeRTOSv202212.01，命名为kernel；

kernel/FreeRTOS/Demo/RISC-V-Qemu-sifive_e-Eclipse-GCC/main.c

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+/*
+ * 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://github.com/FreeRTOS
+ *
+ */
+
+/* FreeRTOS kernel includes. */
+#include <FreeRTOS.h>
+#include <task.h>
+
+/******************************************************************************
+ * This project provides two demo applications.  A simple blinky style project,
+ * and a more comprehensive test and demo application.  The
+ * mainCREATE_SIMPLE_BLINKY_DEMO_ONLY setting (defined in this file) is used to
+ * select between the two.  The simply blinky demo is implemented and described
+ * in main_blinky.c.  The more comprehensive test and demo application is
+ * implemented and described in main_full.c.
+ *
+ * This file implements the code that is not demo specific, including the
+ * hardware setup and standard FreeRTOS hook functions.
+ *
+ * ENSURE TO READ THE DOCUMENTATION PAGE FOR THIS PORT AND DEMO APPLICATION ON
+ * THE http://www.FreeRTOS.org WEB SITE FOR FULL INFORMATION ON USING THIS DEMO
+ * APPLICATION, AND ITS ASSOCIATE FreeRTOS ARCHITECTURE PORT!
+ *
+ *
+ * NOTE 1:
+ *
+ * This project has only been tested in the QEMU emulation of the HiFive board
+ * from SiFive.
+ *
+ * NOTE - Requires QEMU 1908xx or higher.  Start QEMU using the following command
+ * line:
+ *
+ * [your_path_1]\qemu-system-riscv32 -kernel [your_path_2]\FreeRTOS\Demo\RISC-V-Qemu-sifive_e-FreedomStudio\Debug\RTOSDemo.elf -S -s -machine sifive_e
+ *
+ * Where [your_path_1] must be replaced with the correct path to your QEMU
+ * installation and the elf file generated by this project respectively.
+ *
+ *
+ * NOTE 2:
+ *
+ * Start GDB using the following command line (this can be entered in the
+ * Eclipse Debug Launch Configuration dialogue):
+ *
+ * riscv64-unknown-elf-gdb.exe -iex "set mem inaccessible-by-default off" -iex "set arch riscv:rv32" -iex "set riscv use_compressed_breakpoint off"
+ *
+ *
+ * Note 3:
+ *
+ * Status information is sent to the QEMU serial console.
+ */
+
+/* Set mainCREATE_SIMPLE_BLINKY_DEMO_ONLY to one to run the simple blinky demo,
+or 0 to run the more comprehensive test and demo application. */
+#define mainCREATE_SIMPLE_BLINKY_DEMO_ONLY	1
+
+/*
+ * main_blinky() is used when mainCREATE_SIMPLE_BLINKY_DEMO_ONLY is set to 1.
+ * main_full() is used when mainCREATE_SIMPLE_BLINKY_DEMO_ONLY is set to 0.
+ */
+#if mainCREATE_SIMPLE_BLINKY_DEMO_ONLY == 1
+	extern void main_blinky( void );
+#else
+	#warning At the time of writing the QEMU MTIME behaviour is erratic, resulting in test failures.
+	extern void main_full( void );
+#endif /* #if mainCREATE_SIMPLE_BLINKY_DEMO_ONLY == 1 */
+
+/*
+ * Prototypes for the standard FreeRTOS callback/hook functions implemented
+ * within this file.  See https://www.freertos.org/a00016.html
+ */
+void vApplicationMallocFailedHook( void );
+void vApplicationIdleHook( void );
+void vApplicationStackOverflowHook( TaskHandle_t pxTask, char *pcTaskName );
+void vApplicationTickHook( void );
+
+/*
+ * Very simply polling write to the UART.  The full demo only writes single
+ * characters at a time so as not to disrupt the timing of the test and demo
+ * tasks.
+ */
+void vSendString( const char * pcString );
+
+/*-----------------------------------------------------------*/
+
+int main( void )
+{
+	vSendString( "Starting" );
+
+	/* The mainCREATE_SIMPLE_BLINKY_DEMO_ONLY setting is described at the top
+	of this file. */
+	#if( mainCREATE_SIMPLE_BLINKY_DEMO_ONLY == 1 )
+	{
+		main_blinky();
+	}
+	#else
+	{
+		main_full();
+	}
+	#endif
+}
+/*-----------------------------------------------------------*/
+
+void vApplicationMallocFailedHook( void )
+{
+	/* vApplicationMallocFailedHook() will only be called if
+	configUSE_MALLOC_FAILED_HOOK is set to 1 in FreeRTOSConfig.h.  It is a hook
+	function that will get called if a call to pvPortMalloc() fails.
+	pvPortMalloc() is called internally by the kernel whenever a task, queue,
+	timer or semaphore is created.  It is also called by various parts of the
+	demo application.  If heap_1.c or heap_2.c are used, then the size of the
+	heap available to pvPortMalloc() is defined by configTOTAL_HEAP_SIZE in
+	FreeRTOSConfig.h, and the xPortGetFreeHeapSize() API function can be used
+	to query the size of free heap space that remains (although it does not
+	provide information on how the remaining heap might be fragmented). */
+	taskDISABLE_INTERRUPTS();
+	for( ;; );
+}
+/*-----------------------------------------------------------*/
+
+void vApplicationIdleHook( void )
+{
+	/* vApplicationIdleHook() will only be called if configUSE_IDLE_HOOK is set
+	to 1 in FreeRTOSConfig.h.  It will be called on each iteration of the idle
+	task.  It is essential that code added to this hook function never attempts
+	to block in any way (for example, call xQueueReceive() with a block time
+	specified, or call vTaskDelay()).  If the application makes use of the
+	vTaskDelete() API function (as this demo application does) then it is also
+	important that vApplicationIdleHook() is permitted to return to its calling
+	function, because it is the responsibility of the idle task to clean up
+	memory allocated by the kernel to any task that has since been deleted. */
+}
+/*-----------------------------------------------------------*/
+
+void vApplicationStackOverflowHook( TaskHandle_t pxTask, char *pcTaskName )
+{
+	( void ) pcTaskName;
+	( void ) pxTask;
+
+	/* Run time stack overflow checking is performed if
+	configCHECK_FOR_STACK_OVERFLOW is defined to 1 or 2.  This hook
+	function is called if a stack overflow is detected. */
+	taskDISABLE_INTERRUPTS();
+	for( ;; );
+}
+/*-----------------------------------------------------------*/
+
+void vApplicationTickHook( void )
+{
+	/* The tests in the full demo expect some interaction with interrupts. */
+	#if( mainCREATE_SIMPLE_BLINKY_DEMO_ONLY != 1 )
+	{
+		extern void vFullDemoTickHook( void );
+		vFullDemoTickHook();
+	}
+	#endif
+}
+/*-----------------------------------------------------------*/
+
+void vAssertCalled( void )
+{
+volatile uint32_t ulSetTo1ToExitFunction = 0;
+
+	taskDISABLE_INTERRUPTS();
+	while( ulSetTo1ToExitFunction != 1 )
+	{
+		__asm volatile( "NOP" );
+	}
+}
+/*-----------------------------------------------------------*/
+
+void vSendString( const char * pcString )
+{
+const uint32_t ulTxFifoFullBit = 0x80000000UL;
+
+	while( *pcString != 0x00 )
+	{
+		while( ( UART0_REG( UART_REG_TXFIFO ) & ulTxFifoFullBit ) != 0UL );
+		UART0_REG( UART_REG_TXFIFO ) = *pcString;
+		pcString++;
+	}
+}
+