freeRTOS 平台差异部分代码定义（一）

protmaro.h代码解析

类型重定义

/* Type definitions. */
#define portCHAR		char
#define portFLOAT		float
#define portDOUBLE		double
#define portLONG		long
#define portSHORT		short
#define portSTACK_TYPE	uint32_t
#define portBASE_TYPE	long

typedef portSTACK_TYPE StackType_t;
typedef long BaseType_t;
typedef unsigned long UBaseType_t;

#if( configUSE_16_BIT_TICKS == 1 )
	typedef uint16_t TickType_t;
	#define portMAX_DELAY ( TickType_t ) 0xffff
#else
	typedef uint32_t TickType_t;
	#define portMAX_DELAY ( TickType_t ) 0xffffffffUL

	/* 32-bit tick type on a 32-bit architecture, so reads of the tick count do
	not need to be guarded with a critical section. */
	#define portTICK_TYPE_IS_ATOMIC 1			
#endif

如果定义 configUSE_16_BIT_TICKS 为 1 则表示TickType_t配置最大计数值为16 bit。 portTICK_TYPE_IS_ATOMIC 为1 表示32位数操作是否为原子操作。否则需要进入临界区才能对32位数进行操作。

构架指定

/* Architecture specifics. */
#define portSTACK_GROWTH			( -1 )		//定义堆栈生长的方向
#define portTICK_PERIOD_MS			( ( TickType_t ) 1000 / configTICK_RATE_HZ )		//调度时间片的大小
#define portBYTE_ALIGNMENT			8		//内存对齐方式，不知道为什么是8byte 猜测与AAPCS 要求堆栈必须8字节对齐 有关

/* Constants used with memory barrier intrinsics. */
#define portSY_FULL_READ_WRITE		( 15 )		//与内存隔离指令一起使用的条件参数

其中隔离指令的参数为指令的option，为确保完成所有操作必须将值设置为0xF

定义临界区相关的函数

/*-----------------------------------------------------------*/
//设置屏蔽中断有消极
static portFORCE_INLINE void vPortSetBASEPRI( uint32_t ulBASEPRI )
{
	__asm
	{
		/* Barrier instructions are not used as this function is only used to
		lower the BASEPRI value. */
		msr basepri, ulBASEPRI
	}
}
/*-----------------------------------------------------------*/
//设置关闭屏蔽优先级为0及大于0的中断
static portFORCE_INLINE void vPortRaiseBASEPRI( void )
{
uint32_t ulNewBASEPRI = configMAX_SYSCALL_INTERRUPT_PRIORITY;

	__asm
	{
		/* Set BASEPRI to the max syscall priority to effect a critical
		section. */
		msr basepri, ulNewBASEPRI
		dsb
		isb
	}
}
/*-----------------------------------------------------------*/
//开启所有的中断
static portFORCE_INLINE void vPortClearBASEPRIFromISR( void )
{
	__asm
	{
		/* Set BASEPRI to 0 so no interrupts are masked.  This function is only
		used to lower the mask in an interrupt, so memory barriers are not 
		used. */
		msr basepri, #0
	}
}
/*-----------------------------------------------------------*/
//设置关闭屏蔽优先级为0及大于0的中断，并返回更改之前的中断优先级
static portFORCE_INLINE uint32_t ulPortRaiseBASEPRI( void )
{
uint32_t ulReturn, ulNewBASEPRI = configMAX_SYSCALL_INTERRUPT_PRIORITY;

	__asm
	{
		/* Set BASEPRI to the max syscall priority to effect a critical
		section. */
		mrs ulReturn, basepri
		msr basepri, ulNewBASEPRI
		dsb
		isb
	}

	return ulReturn;
}
/*-----------------------------------------------------------*/
//检查当前是否在中断状态，通过ipsr获取中断异常号来实现
static portFORCE_INLINE BaseType_t xPortIsInsideInterrupt( void )
{
uint32_t ulCurrentInterrupt;
BaseType_t xReturn;

	/* Obtain the number of the currently executing interrupt. */
	__asm
	{
		mrs ulCurrentInterrupt, ipsr
	}

	if( ulCurrentInterrupt == 0 )
	{
		xReturn = pdFALSE;
	}
	else
	{
		xReturn = pdTRUE;
	}

	return xReturn;
}