/*
* FreeRTOS Kernel V10.6.2
* 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
*
*/
#include <stdlib.h>
#include "porthardware.h"
#include "FreeRTOS.h"
#include "task.h"
/*-----------------------------------------------------------
* Implementation of functions defined in portable.h for the AVR port.
*----------------------------------------------------------*/
/* Start tasks with interrupts enables. */
#define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x80 )
/*-----------------------------------------------------------*/
#define portBYTES_USED_BY_RETURN_ADDRESS 2
#define portNO_CRITICAL_NESTING ( ( UBaseType_t ) 0 )
/* Stores the critical section nesting. This must not be initialised to 0.
* It will be initialised when a task starts. */
UBaseType_t uxCriticalNesting = 0x50;
/*
* Setup timer to generate a tick interrupt.
*/
static void prvSetupTimerInterrupt( void );
/*
* The IAR compiler does not have full support for inline assembler, so
* these are defined in the portmacro assembler file.
*/
extern void vPortYieldFromTick( void );
extern void vPortStart( void );
/*-----------------------------------------------------------*/
/*
* See header file for description.
*/
StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
TaskFunction_t pxCode,
void * pvParameters )
{
uint16_t usAddress;
StackType_t * pxTopOfHardwareStack;
/* Simulate how the stack would look after a call to vPortYield(). */
/*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */
/* The IAR compiler requires two stacks per task. First there is the
* hardware call stack which uses the AVR stack pointer. Second there is the
* software stack (local variables, parameter passing, etc.) which uses the
* AVR Y register.
* This function places both stacks within the memory block passed in as the
* first parameter. The hardware stack is placed at the bottom of the memory
* block. A gap is then left for the hardware stack to grow. Next the software
* stack is placed. The amount of space between the software and hardware
* stacks is defined by configCALL_STACK_SIZE.
* The first part of the stack is the hardware stack. Place the start
* address of the task on the hardware stack. */
/* Place a few bytes of known values on the bottom of the stack.
* This is just useful for debugging. */
/**pxTopOfStack = 0x11; */
/*pxTopOfStack--; */
/**pxTopOfStack = 0x22; */
/*pxTopOfStack--; */
/**pxTopOfStack = 0x33; */
/*pxTopOfStack--; */
/* Remember where the top of the hardware stack is - this is required
* below. */
pxTopOfHardwareStack = pxTopOfStack;
usAddress = ( uint16_t ) pxCode;
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
pxTopOfStack--;
usAddress >>= 8;
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
pxTopOfStack--;
/* Leave enough space for the hardware stack before starting the software
* stack. The '- 2' is because we have already used two spaces for the
* address of the start of the task. */
pxTopOfStack -= ( configCALL_STACK_SIZE - 2 );
/* Next simulate the stack as if after a call to portSAVE_CONTEXT().
* portSAVE_CONTEXT places the flags on the stack immediately after r0
* to ensure the interrupts get disabled as soon as possible, and so ensuring
* the stack use is minimal should a context switch interrupt occur. */
*pxTopOfStack = ( StackType_t ) 0x00; /* R0 */
pxTopOfStack--;
*pxTopOfStack = portFLAGS_INT_ENABLED;
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x00; /* RAMPZ */
pxTopOfStack--;
/* Next place the address of the hardware stack. This is required so
* the AVR stack pointer can be restored to point to the hardware stack. */
pxTopOfHardwareStack -= portBYTES_USED_BY_RETURN_ADDRESS;
usAddress = ( uint16_t ) pxTopOfHardwareStack;
/* SPL */
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
pxTopOfStack--;
/* SPH */
usAddress >>= 8;
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
pxTopOfStack--;
/* Now the remaining registers. */
*pxTopOfStack = ( StackType_t ) 0x01; /* R1 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x02; /* R2 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x03; /* R3 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x04; /* R4 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x05; /* R5 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x06; /* R6 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x07; /* R7 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x08; /* R8 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x09; /* R9 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x10; /* R10 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x11; /* R11 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x12; /* R12 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x13; /* R13 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x14; /* R14 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x15; /* R15 */
pxTopOfStack--;
/* Place the parameter on the stack in the expected location. */
usAddress = ( uint16_t ) pvParameters;
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
pxTopOfStack--;
usAddress >>= 8;
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x18; /* R18 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x19; /* R19 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x20; /* R20 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x21; /* R21 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x22; /* R22 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x23; /* R23 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x24; /* R24 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x25; /* R25 */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x26; /* R26 X */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x27; /* R27 */
pxTopOfStack--;
/* The Y register is not stored as it is used as the software stack and
* gets saved into the task control block. */
*pxTopOfStack = ( StackType_t ) 0x30; /* R30 Z */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x031; /* R31 */
pxTopOfStack--;
*pxTopOfStack = portNO_CRITICAL_NESTING; /* Critical nesting is zero when the task starts. */
/*lint +e950 +e611 +e923 */
return pxTopOfStack;
}
/*-----------------------------------------------------------*/
BaseType_t xPortStartScheduler( void )
{
/* Setup the hardware to generate the tick. */
prvSetupTimerInterrupt();
/* Restore the context of the first task that is going to run.
* Normally we would just call portRESTORE_CONTEXT() here, but as the IAR
* compiler does not fully support inline assembler we have to make a call.*/
vPortStart();
/* Should not get here. */
return pdTRUE;
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* vPortEndScheduler is not implemented in this port. */
}
/*-----------------------------------------------------------*/
/*
* Setup timer to generate a tick interrupt.
*/
static void prvSetupTimerInterrupt( void )
{
TICK_init();
}
/*-----------------------------------------------------------*/
#if configUSE_PREEMPTION == 1
/*
* Tick ISR for preemptive scheduler. We can use a naked attribute as
* the context is saved at the start of vPortYieldFromTick(). The tick
* count is incremented after the context is saved.
*/
__task void TICK_INT( void )
{
vPortYieldFromTick();
asm ( "reti" );
}
#else
/*
* Tick ISR for the cooperative scheduler. All this does is increment the
* tick count. We don't need to switch context, this can only be done by
* manual calls to taskYIELD();
*/
__interrupt void TICK_INT( void )
{
/* Clear tick interrupt flag. */
INT_FLAGS = INT_MASK;
xTaskIncrementTick();
}
#endif /* if configUSE_PREEMPTION == 1 */
/*-----------------------------------------------------------*/
void vPortEnterCritical( void )
{
portDISABLE_INTERRUPTS();
uxCriticalNesting++;
}
/*-----------------------------------------------------------*/
void vPortExitCritical( void )
{
uxCriticalNesting--;
if( uxCriticalNesting == portNO_CRITICAL_NESTING )
{
portENABLE_INTERRUPTS();
}
}