text: /*
   * FreeRTOS Kernel <DEVELOPMENT BRANCH>
   * Copyright (C) 2021 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
   *
   * SPDX-License-Identifier: MIT
   *
   * 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
   *
   */
  
  /*
  	Changes from V4.2.1
  
  	+ Introduced the configKERNEL_INTERRUPT_PRIORITY definition.
  */
  
  /*-----------------------------------------------------------
   * Implementation of functions defined in portable.h for the PIC24 port.
   *----------------------------------------------------------*/
  
  /* Scheduler include files. */
  #include "FreeRTOS.h"
  #include "task.h"
  
  /* Hardware specifics. */
  #define portBIT_SET 1
  #define portTIMER_PRESCALE 8
  #define portINITIAL_SR	0
  
  /* Defined for backward compatability with project created prior to
  FreeRTOS.org V4.3.0. */
  #ifndef configKERNEL_INTERRUPT_PRIORITY
  	#define configKERNEL_INTERRUPT_PRIORITY 1
  #endif
  
  /* Use _T1Interrupt as the interrupt handler name if the application writer has
  not provided their own. */
  #ifndef configTICK_INTERRUPT_HANDLER
  	#define configTICK_INTERRUPT_HANDLER _T1Interrupt
  #endif /* configTICK_INTERRUPT_HANDLER */
  
  /* The program counter is only 23 bits. */
  #define portUNUSED_PR_BITS	0x7f
  
  /* Records the nesting depth of calls to portENTER_CRITICAL(). */
  UBaseType_t uxCriticalNesting = 0xef;
  
  #if configKERNEL_INTERRUPT_PRIORITY != 1
  	#error If configKERNEL_INTERRUPT_PRIORITY is not 1 then the #32 in the following macros needs changing to equal the portINTERRUPT_BITS value, which is ( configKERNEL_INTERRUPT_PRIORITY << 5 )
  #endif
  
  #if defined( __PIC24E__ ) || defined ( __PIC24F__ ) || defined( __PIC24FK__ ) || defined( __PIC24H__ )
  
  	#ifdef __HAS_EDS__
  		#define portRESTORE_CONTEXT()																						\
  					asm volatile(	"MOV	_pxCurrentTCB, W0		\n"	/* Restore the stack pointer for the task. */		\
  							"MOV	[W0], W15				\n"																\
  							"POP	W0						\n"	/* Restore the critical nesting counter for the task. */	\
  							"MOV	W0, _uxCriticalNesting	\n"																\
  							"POP	DSWPAG					\n"																\
  							"POP    DSRPAG					\n"																\
  							"POP	CORCON					\n"																\
  							"POP	TBLPAG					\n"																\
  							"POP	RCOUNT					\n"	/* Restore the registers from the stack. */					\
  							"POP	W14						\n"																\
  							"POP.D	W12						\n"																\
  							"POP.D	W10						\n"																\
  							"POP.D	W8						\n"																\
  							"POP.D	W6						\n"																\
  							"POP.D	W4						\n"																\
  							"POP.D	W2						\n"																\
  							"POP.D	W0						\n"																\
  							"POP	SR						  " );
  	#else /* __HAS_EDS__ */
  		#define portRESTORE_CONTEXT()																						\
  			asm volatile(	"MOV	_pxCurrentTCB, W0		\n"	/* Restore the stack pointer for the task. */				\
  							"MOV	[W0], W15				\n"																\
  							"POP	W0						\n"	/* Restore the critical nesting counter for the task. */	\
  							"MOV	W0, _uxCriticalNesting	\n"																\
  							"POP	PSVPAG					\n"																\
  							"POP	CORCON					\n"																\
  							"POP	TBLPAG					\n"																\
  							"POP	RCOUNT					\n"	/* Restore the registers from the stack. */					\
  							"POP	W14						\n"																\
  							"POP.D	W12						\n"																\
  							"POP.D	W10						\n"																\
  							"POP.D	W8						\n"																\
  							"POP.D	W6						\n"																\
  							"POP.D	W4						\n"																\
  							"POP.D	W2						\n"																\
  							"POP.D	W0						\n"																\
  							"POP	SR						  " );
  		#endif /* __HAS_EDS__ */
  #endif /* defined( __PIC24E__ ) || defined ( __PIC24F__ ) || defined( __PIC24FK__ ) || defined( __PIC24H__ ) */
  
  #if defined( __dsPIC30F__ ) || defined( __dsPIC33F__ )
  
  	#define portRESTORE_CONTEXT()																						\
  		asm volatile(	"MOV	_pxCurrentTCB, W0		\n"	/* Restore the stack pointer for the task. */				\
  						"MOV	[W0], W15				\n"																\
  						"POP	W0						\n"	/* Restore the critical nesting counter for the task. */	\
  						"MOV	W0, _uxCriticalNesting	\n"																\
  						"POP	PSVPAG					\n"																\
  						"POP	CORCON					\n"																\
  						"POP	DOENDH					\n"																\
  						"POP	DOENDL					\n"																\
  						"POP	DOSTARTH				\n"																\
  						"POP	DOSTARTL				\n"																\
  						"POP	DCOUNT					\n"																\
  						"POP	ACCBU					\n"																\
  						"POP	ACCBH					\n"																\
  						"POP	ACCBL					\n"																\
  						"POP	ACCAU					\n"																\
  						"POP	ACCAH					\n"																\
  						"POP	ACCAL					\n"																\
  						"POP	TBLPAG					\n"																\
  						"POP	RCOUNT					\n"	/* Restore the registers from the stack. */					\
  						"POP	W14						\n"																\
  						"POP.D	W12						\n"																\
  						"POP.D	W10						\n"																\
  						"POP.D	W8						\n"																\
  						"POP.D	W6						\n"																\
  						"POP.D	W4						\n"																\
  						"POP.D	W2						\n"																\
  						"POP.D	W0						\n"																\
  						"POP	SR						  " );
  
  #endif /* defined( __dsPIC30F__ ) || defined( __dsPIC33F__ ) */
  
  #ifndef portRESTORE_CONTEXT
  	#error Unrecognised device selected
  
  	/* Note:  dsPIC parts with EDS are not supported as there is no easy way to
  	recover the hardware stacked copies for DOCOUNT, DOHIGH, DOLOW. */
  #endif
  
  /*
   * Setup the timer used to generate the tick interrupt.
   */
  void vApplicationSetupTickTimerInterrupt( void );
  
  /*
   * See header file for description.
   */
  StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
  {
  uint16_t usCode;
  UBaseType_t i;
  
  const StackType_t xInitialStack[] =
  {
  	0x1111,	/* W1 */
  	0x2222, /* W2 */
  	0x3333, /* W3 */
  	0x4444, /* W4 */
  	0x5555, /* W5 */
  	0x6666, /* W6 */
  	0x7777, /* W7 */
  	0x8888, /* W8 */
  	0x9999, /* W9 */
  	0xaaaa, /* W10 */
  	0xbbbb, /* W11 */
  	0xcccc, /* W12 */
  	0xdddd, /* W13 */
  	0xeeee, /* W14 */
  	0xcdce, /* RCOUNT */
  	0xabac, /* TBLPAG */
  
  	/* dsPIC specific registers. */
  	#if defined( __dsPIC30F__ ) || defined( __dsPIC33F__ )
  		0x0202, /* ACCAL */
  		0x0303, /* ACCAH */
  		0x0404, /* ACCAU */
  		0x0505, /* ACCBL */
  		0x0606, /* ACCBH */
  		0x0707, /* ACCBU */
  		0x0808, /* DCOUNT */
  		0x090a, /* DOSTARTL */
  		0x1010, /* DOSTARTH */
  		0x1110, /* DOENDL */
  		0x1212, /* DOENDH */
  	#endif
  };
  
  	/* Setup the stack as if a yield had occurred.
  
  	Save the low bytes of the program counter. */
  	usCode = ( uint16_t ) pxCode;
  	*pxTopOfStack = ( StackType_t ) usCode;
  	pxTopOfStack++;
  
  	/* Save the high byte of the program counter.  This will always be zero
  	here as it is passed in a 16bit pointer.  If the address is greater than
  	16 bits then the pointer will point to a jump table. */
  	*pxTopOfStack = ( StackType_t ) 0;
  	pxTopOfStack++;
  
  	/* Status register with interrupts enabled. */
  	*pxTopOfStack = portINITIAL_SR;
  	pxTopOfStack++;
  
  	/* Parameters are passed in W0. */
  	*pxTopOfStack = ( StackType_t ) pvParameters;
  	pxTopOfStack++;
  
  	for( i = 0; i < ( sizeof( xInitialStack ) / sizeof( StackType_t ) ); i++ )
  	{
  		*pxTopOfStack = xInitialStack[ i ];
  		pxTopOfStack++;
  	}
  
  	*pxTopOfStack = CORCON;
  	pxTopOfStack++;
  
  	#if defined(__HAS_EDS__)
  		*pxTopOfStack = DSRPAG;
  		pxTopOfStack++;
  		*pxTopOfStack = DSWPAG;
  		pxTopOfStack++;
  	#else /* __HAS_EDS__ */
  		*pxTopOfStack = PSVPAG;
  		pxTopOfStack++;
  	#endif /* __HAS_EDS__ */
  
  	/* Finally the critical nesting depth. */
  	*pxTopOfStack = 0x00;
  	pxTopOfStack++;
  
  	return pxTopOfStack;
  }
  /*-----------------------------------------------------------*/
  
  BaseType_t xPortStartScheduler( void )
  {
  	/* Setup a timer for the tick ISR. */
  	vApplicationSetupTickTimerInterrupt();
  
  	/* Restore the context of the first task to run. */
  	portRESTORE_CONTEXT();
  
  	/* Simulate the end of the yield function. */
  	asm volatile ( "return" );
  
  	/* Should not reach here. */
  	return pdTRUE;
  }
  /*-----------------------------------------------------------*/
  
  void vPortEndScheduler( void )
  {
  	/* Not implemented in ports where there is nothing to return to.
  	Artificially force an assert. */
  	configASSERT( uxCriticalNesting == 1000UL );
  }
  /*-----------------------------------------------------------*/
  
  /*
   * Setup a timer for a regular tick.
   */
  __attribute__(( weak )) void vApplicationSetupTickTimerInterrupt( void )
  {
  const uint32_t ulCompareMatch = ( ( configCPU_CLOCK_HZ / portTIMER_PRESCALE ) / configTICK_RATE_HZ ) - 1;
  
  	/* Prescale of 8. */
  	T1CON = 0;
  	TMR1 = 0;
  
  	PR1 = ( uint16_t ) ulCompareMatch;
  
  	/* Setup timer 1 interrupt priority. */
  	IPC0bits.T1IP = configKERNEL_INTERRUPT_PRIORITY;
  
  	/* Clear the interrupt as a starting condition. */
  	IFS0bits.T1IF = 0;
  
  	/* Enable the interrupt. */
  	IEC0bits.T1IE = 1;
  
  	/* Setup the prescale value. */
  	T1CONbits.TCKPS0 = 1;
  	T1CONbits.TCKPS1 = 0;
  
  	/* Start the timer. */
  	T1CONbits.TON = 1;
  }
  /*-----------------------------------------------------------*/
  
  void vPortEnterCritical( void )
  {
  	portDISABLE_INTERRUPTS();
  	uxCriticalNesting++;
  }
  /*-----------------------------------------------------------*/
  
  void vPortExitCritical( void )
  {
  	configASSERT( uxCriticalNesting );
  	uxCriticalNesting--;
  	if( uxCriticalNesting == 0 )
  	{
  		portENABLE_INTERRUPTS();
  	}
  }
  /*-----------------------------------------------------------*/
  
  void __attribute__((__interrupt__, auto_psv)) configTICK_INTERRUPT_HANDLER( void )
  {
  	/* Clear the timer interrupt. */
  	IFS0bits.T1IF = 0;
  
  	if( xTaskIncrementTick() != pdFALSE )
  	{
  		portYIELD();
  	}
  }
  /*-----------------------------------------------------------*/
  