text: /*
   * FreeRTOS Kernel V10.1.0
   * Copyright (C) 2018 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.
   *
   * http://www.FreeRTOS.org
   * http://aws.amazon.com/freertos
   *
   * 1 tab == 4 spaces!
   */
  
  /*-----------------------------------------------------------
   * Implementation of functions defined in portable.h for the ST STR91x ARM9
   * port.
   *----------------------------------------------------------*/
  
  /* Library includes. */
  #include "91x_lib.h"
  
  /* Standard includes. */
  #include <stdlib.h>
  #include <assert.h>
  
  /* Scheduler includes. */
  #include "FreeRTOS.h"
  #include "task.h"
  
  #ifndef configUSE_WATCHDOG_TICK
  	#error configUSE_WATCHDOG_TICK must be set to either 1 or 0 in FreeRTOSConfig.h to use either the Watchdog or timer 2 to generate the tick interrupt respectively.
  #endif
  
  /* Constants required to setup the initial stack. */
  #ifndef _RUN_TASK_IN_ARM_MODE_
  	#define portINITIAL_SPSR			( ( StackType_t ) 0x3f ) /* System mode, THUMB mode, interrupts enabled. */
  #else
  	#define portINITIAL_SPSR 			( ( StackType_t ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
  #endif
  
  #define portINSTRUCTION_SIZE			( ( StackType_t ) 4 )
  
  /* Constants required to handle critical sections. */
  #define portNO_CRITICAL_NESTING 		( ( uint32_t ) 0 )
  
  #ifndef abs
  	#define abs(x) ((x)>0 ? (x) : -(x))
  #endif
  
  /**
   * Toggle a led using the following algorithm:
   * if ( GPIO_ReadBit(GPIO9, GPIO_Pin_2) )
   * {
   *   GPIO_WriteBit( GPIO9, GPIO_Pin_2, Bit_RESET );
   * }
   * else
   * {
   *   GPIO_WriteBit( GPIO9, GPIO_Pin_2, Bit_RESET );
   * }
   *
   */
  #define TOGGLE_LED(port,pin) 									\
  	if ( ((((port)->DR[(pin)<<2])) & (pin)) != Bit_RESET ) 		\
  	{															\
      	(port)->DR[(pin) <<2] = 0x00;							\
    	}															\
    	else														\
  	{															\
      	(port)->DR[(pin) <<2] = (pin);							\
    	}
  
  
  /*-----------------------------------------------------------*/
  
  /* Setup the watchdog to generate the tick interrupts. */
  static void prvSetupTimerInterrupt( void );
  
  /* ulCriticalNesting will get set to zero when the first task starts.  It
  cannot be initialised to 0 as this will cause interrupts to be enabled
  during the kernel initialisation process. */
  uint32_t ulCriticalNesting = ( uint32_t ) 9999;
  
  /* Tick interrupt routines for cooperative and preemptive operation
  respectively.  The preemptive version is not defined as __irq as it is called
  from an asm wrapper function. */
  void WDG_IRQHandler( void );
  
  /* VIC interrupt default handler. */
  static void prvDefaultHandler( void );
  
  #if configUSE_WATCHDOG_TICK == 0
  	/* Used to update the OCR timer register */
  	static u16 s_nPulseLength;
  #endif
  
  /*-----------------------------------------------------------*/
  
  /*
   * Initialise the stack of a task to look exactly as if a call to
   * portSAVE_CONTEXT had been called.
   *
   * See header file for description.
   */
  StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
  {
  	StackType_t *pxOriginalTOS;
  
  	pxOriginalTOS = pxTopOfStack;
  
  	/* To ensure asserts in tasks.c don't fail, although in this case the assert
  	is not really required. */
  	pxTopOfStack--;
  
  	/* Setup the initial stack of the task.  The stack is set exactly as
  	expected by the portRESTORE_CONTEXT() macro. */
  
  	/* First on the stack is the return address - which in this case is the
  	start of the task.  The offset is added to make the return address appear
  	as it would within an IRQ ISR. */
  	*pxTopOfStack = ( StackType_t ) pxCode + portINSTRUCTION_SIZE;		
  	pxTopOfStack--;
  
  	*pxTopOfStack = ( StackType_t ) 0xaaaaaaaa;	/* R14 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
  	pxTopOfStack--;
  	*pxTopOfStack = ( StackType_t ) 0x12121212;	/* R12 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) 0x11111111;	/* R11 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) 0x10101010;	/* R10 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) 0x09090909;	/* R9 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) 0x08080808;	/* R8 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) 0x07070707;	/* R7 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) 0x06060606;	/* R6 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) 0x05050505;	/* R5 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) 0x04040404;	/* R4 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) 0x03030303;	/* R3 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) 0x02020202;	/* R2 */
  	pxTopOfStack--;	
  	*pxTopOfStack = ( StackType_t ) 0x01010101;	/* R1 */
  	pxTopOfStack--;	
  
  	/* When the task starts is will expect to find the function parameter in
  	R0. */
  	*pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
  	pxTopOfStack--;
  
  	/* The status register is set for system mode, with interrupts enabled. */
  	*pxTopOfStack = ( StackType_t ) portINITIAL_SPSR;
  	pxTopOfStack--;
  
  	/* Interrupt flags cannot always be stored on the stack and will
  	instead be stored in a variable, which is then saved as part of the
  	tasks context. */
  	*pxTopOfStack = portNO_CRITICAL_NESTING;
  
  	return pxTopOfStack;	
  }
  /*-----------------------------------------------------------*/
  
  BaseType_t xPortStartScheduler( void )
  {
  extern void vPortStartFirstTask( void );
  
  	/* Start the timer that generates the tick ISR.  Interrupts are disabled
  	here already. */
  	prvSetupTimerInterrupt();
  
  	/* Start the first task. */
  	vPortStartFirstTask();	
  
  	/* Should not get here! */
  	return 0;
  }
  /*-----------------------------------------------------------*/
  
  void vPortEndScheduler( void )
  {
  	/* It is unlikely that the ARM port will require this function as there
  	is nothing to return to.  */
  }
  /*-----------------------------------------------------------*/
  
  /* This function is called from an asm wrapper, so does not require the __irq
  keyword. */
  #if configUSE_WATCHDOG_TICK == 1
  
  	static void prvFindFactors(u32 n, u16 *a, u32 *b)
  	{
  		/* This function is copied from the ST STR7 library and is
  		copyright STMicroelectronics.  Reproduced with permission. */
  	
  		u32 b0;
  		u16 a0;
  		int32_t err, err_min=n;
  	
  		*a = a0 = ((n-1)/65536ul) + 1;
  		*b = b0 = n / *a;
  	
  		for (; *a <= 256; (*a)++)
  		{
  			*b = n / *a;
  			err = (int32_t)*a * (int32_t)*b - (int32_t)n;
  			if (abs(err) > (*a / 2))
  			{
  				(*b)++;
  				err = (int32_t)*a * (int32_t)*b - (int32_t)n;
  			}
  			if (abs(err) < abs(err_min))
  			{
  				err_min = err;
  				a0 = *a;
  				b0 = *b;
  				if (err == 0) break;
  			}
  		}
  	
  		*a = a0;
  		*b = b0;
  	}
  	/*-----------------------------------------------------------*/
  
  	static void prvSetupTimerInterrupt( void )
  	{
  	WDG_InitTypeDef xWdg;
  	uint16_t a;
  	uint32_t n = configCPU_PERIPH_HZ / configTICK_RATE_HZ, b;
  	
  		/* Configure the watchdog as a free running timer that generates a
  		periodic interrupt. */
  	
  		SCU_APBPeriphClockConfig( __WDG, ENABLE );
  		WDG_DeInit();
  		WDG_StructInit(&xWdg);
  		prvFindFactors( n, &a, &b );
  		xWdg.WDG_Prescaler = a - 1;
  		xWdg.WDG_Preload = b - 1;
  		WDG_Init( &xWdg );
  		WDG_ITConfig(ENABLE);
  		
  		/* Configure the VIC for the WDG interrupt. */
  		VIC_Config( WDG_ITLine, VIC_IRQ, 10 );
  		VIC_ITCmd( WDG_ITLine, ENABLE );
  		
  		/* Install the default handlers for both VIC's. */
  		VIC0->DVAR = ( uint32_t ) prvDefaultHandler;
  		VIC1->DVAR = ( uint32_t ) prvDefaultHandler;
  		
  		WDG_Cmd(ENABLE);
  	}
  	/*-----------------------------------------------------------*/
  
  	void WDG_IRQHandler( void )
  	{
  		{
  			/* Increment the tick counter. */
  			if( xTaskIncrementTick() != pdFALSE )
  			{		
  				/* Select a new task to execute. */
  				vTaskSwitchContext();
  			}
  		
  			/* Clear the interrupt in the watchdog. */
  			WDG->SR &= ~0x0001;
  		}
  	}
  
  #else
  
  	static void prvFindFactors(u32 n, u8 *a, u16 *b)
  	{
  		/* This function is copied from the ST STR7 library and is
  		copyright STMicroelectronics.  Reproduced with permission. */
  	
  		u16 b0;
  		u8 a0;
  		int32_t err, err_min=n;
  	
  	
  		*a = a0 = ((n-1)/256) + 1;
  		*b = b0 = n / *a;
  	
  		for (; *a <= 256; (*a)++)
  		{
  			*b = n / *a;
  			err = (int32_t)*a * (int32_t)*b - (int32_t)n;
  			if (abs(err) > (*a / 2))
  			{
  				(*b)++;
  				err = (int32_t)*a * (int32_t)*b - (int32_t)n;
  			}
  			if (abs(err) < abs(err_min))
  			{
  				err_min = err;
  				a0 = *a;
  				b0 = *b;
  				if (err == 0) break;
  			}
  		}
  	
  		*a = a0;
  		*b = b0;
  	}
  	/*-----------------------------------------------------------*/
  
  	static void prvSetupTimerInterrupt( void )
  	{
  		uint8_t a;
  		uint16_t b;
  		uint32_t n = configCPU_PERIPH_HZ / configTICK_RATE_HZ;
  		
  		TIM_InitTypeDef timer;
  		
  		SCU_APBPeriphClockConfig( __TIM23, ENABLE );
  		TIM_DeInit(TIM2);
  		TIM_StructInit(&timer);
  		prvFindFactors( n, &a, &b );
  		
  		timer.TIM_Mode           = TIM_OCM_CHANNEL_1;
  		timer.TIM_OC1_Modes      = TIM_TIMING;
  		timer.TIM_Clock_Source   = TIM_CLK_APB;
  		timer.TIM_Clock_Edge     = TIM_CLK_EDGE_RISING;
  		timer.TIM_Prescaler      = a-1;
  		timer.TIM_Pulse_Level_1  = TIM_HIGH;
  		timer.TIM_Pulse_Length_1 = s_nPulseLength  = b-1;
  		
  		TIM_Init (TIM2, &timer);
  		TIM_ITConfig(TIM2, TIM_IT_OC1, ENABLE);
  		/* Configure the VIC for the WDG interrupt. */
  		VIC_Config( TIM2_ITLine, VIC_IRQ, 10 );
  		VIC_ITCmd( TIM2_ITLine, ENABLE );
  		
  		/* Install the default handlers for both VIC's. */
  		VIC0->DVAR = ( uint32_t ) prvDefaultHandler;
  		VIC1->DVAR = ( uint32_t ) prvDefaultHandler;
  		
  		TIM_CounterCmd(TIM2, TIM_CLEAR);
  		TIM_CounterCmd(TIM2, TIM_START);
  	}
  	/*-----------------------------------------------------------*/
  
  	void TIM2_IRQHandler( void )
  	{
  		/* Reset the timer counter to avioid overflow. */
  		TIM2->OC1R += s_nPulseLength;
  		
  		/* Increment the tick counter. */
  		if( xTaskIncrementTick() != pdFALSE )
  		{
  			/* Select a new task to run. */
  			vTaskSwitchContext();
  		}
  		
  		/* Clear the interrupt in the watchdog. */
  		TIM2->SR &= ~TIM_FLAG_OC1;
  	}
  
  #endif /* USE_WATCHDOG_TICK */
  
  /*-----------------------------------------------------------*/
  
  __arm __interwork void vPortEnterCritical( void )
  {
  	/* Disable interrupts first! */
  	portDISABLE_INTERRUPTS();
  
  	/* Now interrupts are disabled ulCriticalNesting can be accessed
  	directly.  Increment ulCriticalNesting to keep a count of how many times
  	portENTER_CRITICAL() has been called. */
  	ulCriticalNesting++;
  }
  /*-----------------------------------------------------------*/
  
  __arm __interwork void vPortExitCritical( void )
  {
  	if( ulCriticalNesting > portNO_CRITICAL_NESTING )
  	{
  		/* Decrement the nesting count as we are leaving a critical section. */
  		ulCriticalNesting--;
  
  		/* If the nesting level has reached zero then interrupts should be
  		re-enabled. */
  		if( ulCriticalNesting == portNO_CRITICAL_NESTING )
  		{
  			portENABLE_INTERRUPTS();
  		}
  	}
  }
  /*-----------------------------------------------------------*/
  
  static void prvDefaultHandler( void )
  {
  }
  
  
  
  
  
  