/*
    FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd.

    ***************************************************************************
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    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under
    the terms of the GNU General Public License (version 2) as published by the
    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
    ***NOTE*** The exception to the GPL is included to allow you to distribute
    a combined work that includes FreeRTOS without being obliged to provide the
    source code for proprietary components outside of the FreeRTOS kernel.
    FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
    more details. You should have received a copy of the GNU General Public 
    License and the FreeRTOS license exception along with FreeRTOS; if not it 
    can be viewed here: http://www.freertos.org/a00114.html and also obtained 
    by writing to Richard Barry, contact details for whom are available on the
    FreeRTOS WEB site.

    1 tab == 4 spaces!

    http://www.FreeRTOS.org - Documentation, latest information, license and
    contact details.

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*/

/*-----------------------------------------------------------
 * 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			( ( portSTACK_TYPE ) 0x3f ) /* System mode, THUMB mode, interrupts enabled. */
#else
	#define portINITIAL_SPSR 			( ( portSTACK_TYPE ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
#endif

#define portINSTRUCTION_SIZE			( ( portSTACK_TYPE ) 4 )

/* Constants required to handle critical sections. */
#define portNO_CRITICAL_NESTING 		( ( unsigned long ) 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. */
unsigned long ulCriticalNesting = ( unsigned long ) 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.
 */
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
	portSTACK_TYPE *pxOriginalTOS;

	pxOriginalTOS = 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 = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE;		
	pxTopOfStack--;

	*pxTopOfStack = ( portSTACK_TYPE ) 0xaaaaaaaa;	/* R14 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x12121212;	/* R12 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x11111111;	/* R11 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x10101010;	/* R10 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x09090909;	/* R9 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x08080808;	/* R8 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x07070707;	/* R7 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x06060606;	/* R6 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x05050505;	/* R5 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x04040404;	/* R4 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x03030303;	/* R3 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x02020202;	/* R2 */
	pxTopOfStack--;	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x01010101;	/* R1 */
	pxTopOfStack--;	

	/* When the task starts is will expect to find the function parameter in
	R0. */
	*pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
	pxTopOfStack--;

	/* The status register is set for system mode, with interrupts enabled. */
	*pxTopOfStack = ( portSTACK_TYPE ) 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;	
}
/*-----------------------------------------------------------*/

portBASE_TYPE 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;
		long err, err_min=n;
	
		*a = a0 = ((n-1)/65536ul) + 1;
		*b = b0 = n / *a;
	
		for (; *a <= 256; (*a)++)
		{
			*b = n / *a;
			err = (long)*a * (long)*b - (long)n;
			if (abs(err) > (*a / 2))
			{
				(*b)++;
				err = (long)*a * (long)*b - (long)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;
	unsigned short a;
	unsigned long 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 = ( unsigned long ) prvDefaultHandler;
		VIC1->DVAR = ( unsigned long ) prvDefaultHandler;
		
		WDG_Cmd(ENABLE);
	}
	/*-----------------------------------------------------------*/

	void WDG_IRQHandler( void )
	{
		{
			/* Increment the tick counter. */
			vTaskIncrementTick();
		
			#if configUSE_PREEMPTION == 1
			{
				/* The new tick value might unblock a task.  Ensure the highest task that
				is ready to execute is the task that will execute when the tick ISR
				exits. */
				vTaskSwitchContext();
			}
			#endif /* configUSE_PREEMPTION. */
		
			/* 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;
		long err, err_min=n;
	
	
		*a = a0 = ((n-1)/256) + 1;
		*b = b0 = n / *a;
	
		for (; *a <= 256; (*a)++)
		{
			*b = n / *a;
			err = (long)*a * (long)*b - (long)n;
			if (abs(err) > (*a / 2))
			{
				(*b)++;
				err = (long)*a * (long)*b - (long)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 )
	{
		unsigned char a;
		unsigned short b;
		unsigned long 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 = ( unsigned long ) prvDefaultHandler;
		VIC1->DVAR = ( unsigned long ) 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. */
		vTaskIncrementTick();
		
		#if configUSE_PREEMPTION == 1
		{
			/* The new tick value might unblock a task.  Ensure the highest task that
			is ready to execute is the task that will execute when the tick ISR
			exits. */
			vTaskSwitchContext();
		}
		#endif
		
		/* 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 )
{
}