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346 lines
13 KiB
C
346 lines
13 KiB
C
/*
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* FreeRTOS Kernel V10.0.0
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* Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software. If you wish to use our Amazon
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* FreeRTOS name, please do so in a fair use way that does not cause confusion.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* https://www.FreeRTOS.org
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* https://github.com/FreeRTOS
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*
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*/
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#include <stdlib.h>
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#include <avr/interrupt.h>
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#include "porthardware.h"
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#include "FreeRTOS.h"
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#include "task.h"
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/*-----------------------------------------------------------
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* Implementation of functions defined in portable.h for the AVR port.
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*----------------------------------------------------------*/
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/* Start tasks with interrupts enables. */
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#define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x80 )
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/*-----------------------------------------------------------*/
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/* We require the address of the pxCurrentTCB variable, but don't want to know
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* any details of its type. */
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typedef void RTOS_TCB_t;
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extern volatile RTOS_TCB_t * volatile pxCurrentTCB;
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/*-----------------------------------------------------------*/
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/*
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* Macro to save all the general purpose registers, the save the stack pointer
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* into the TCB.
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*
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* The first thing we do is save the flags then disable interrupts. This is to
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* guard our stack against having a context switch interrupt after we have already
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* pushed the registers onto the stack - causing the 32 registers to be on the
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* stack twice.
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*
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* r1 is set to zero as the compiler expects it to be thus, however some
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* of the math routines make use of R1.
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*
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* The interrupts will have been disabled during the call to portSAVE_CONTEXT()
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* so we need not worry about reading/writing to the stack pointer.
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*/
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#define portSAVE_CONTEXT() \
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asm volatile ( "push r0 \n\t" \
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"in r0, __SREG__ \n\t" \
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"cli \n\t" \
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"push r0 \n\t" \
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"in r0, __RAMPZ__ \n\t" \
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"push r0 \n\t" \
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"push r1 \n\t" \
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"clr r1 \n\t" \
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"push r2 \n\t" \
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"push r3 \n\t" \
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"push r4 \n\t" \
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"push r5 \n\t" \
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"push r6 \n\t" \
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"push r7 \n\t" \
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"push r8 \n\t" \
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"push r9 \n\t" \
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"push r10 \n\t" \
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"push r11 \n\t" \
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"push r12 \n\t" \
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"push r13 \n\t" \
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"push r14 \n\t" \
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"push r15 \n\t" \
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"push r16 \n\t" \
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"push r17 \n\t" \
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"push r18 \n\t" \
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"push r19 \n\t" \
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"push r20 \n\t" \
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"push r21 \n\t" \
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"push r22 \n\t" \
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"push r23 \n\t" \
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"push r24 \n\t" \
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"push r25 \n\t" \
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"push r26 \n\t" \
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"push r27 \n\t" \
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"push r28 \n\t" \
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"push r29 \n\t" \
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"push r30 \n\t" \
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"push r31 \n\t" \
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"lds r26, pxCurrentTCB \n\t" \
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"lds r27, pxCurrentTCB + 1 \n\t" \
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"in r0, __SP_L__ \n\t" \
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"st x+, r0 \n\t" \
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"in r0, __SP_H__ \n\t" \
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"st x+, r0 \n\t" );
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/*
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* Opposite to portSAVE_CONTEXT(). Interrupts will have been disabled during
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* the context save so we can write to the stack pointer.
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*/
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#define portRESTORE_CONTEXT() \
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asm volatile ( "lds r26, pxCurrentTCB \n\t" \
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"lds r27, pxCurrentTCB + 1 \n\t" \
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"ld r28, x+ \n\t" \
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"out __SP_L__, r28 \n\t" \
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"ld r29, x+ \n\t" \
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"out __SP_H__, r29 \n\t" \
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"pop r31 \n\t" \
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"pop r30 \n\t" \
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"pop r29 \n\t" \
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"pop r28 \n\t" \
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"pop r27 \n\t" \
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"pop r26 \n\t" \
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"pop r25 \n\t" \
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"pop r24 \n\t" \
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"pop r23 \n\t" \
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"pop r22 \n\t" \
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"pop r21 \n\t" \
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"pop r20 \n\t" \
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"pop r19 \n\t" \
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"pop r18 \n\t" \
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"pop r17 \n\t" \
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"pop r16 \n\t" \
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"pop r15 \n\t" \
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"pop r14 \n\t" \
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"pop r13 \n\t" \
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"pop r12 \n\t" \
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"pop r11 \n\t" \
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"pop r10 \n\t" \
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"pop r9 \n\t" \
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"pop r8 \n\t" \
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"pop r7 \n\t" \
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"pop r6 \n\t" \
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"pop r5 \n\t" \
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"pop r4 \n\t" \
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"pop r3 \n\t" \
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"pop r2 \n\t" \
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"pop r1 \n\t" \
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"pop r0 \n\t" \
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"out __RAMPZ__, r0 \n\t" \
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"pop r0 \n\t" \
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"out __SREG__, r0 \n\t" \
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"pop r0 \n\t" );
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/*-----------------------------------------------------------*/
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/*
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* Perform hardware setup to enable ticks from timer.
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*/
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static void prvSetupTimerInterrupt( void );
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/*-----------------------------------------------------------*/
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/*
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* See header file for description.
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*/
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StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
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TaskFunction_t pxCode,
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void * pvParameters )
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{
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uint16_t usAddress;
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/*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */
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/* Place a few bytes of known values on the bottom of the stack.
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* This is just useful for debugging. Uncomment if needed. */
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/* *pxTopOfStack = 0x11; */
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/* pxTopOfStack--; */
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/* *pxTopOfStack = 0x22; */
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/* pxTopOfStack--; */
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/* *pxTopOfStack = 0x33; */
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/* pxTopOfStack--; */
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/* The start of the task code will be popped off the stack last, so place
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* it on first. */
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usAddress = ( uint16_t ) pxCode;
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*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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pxTopOfStack--;
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usAddress >>= 8;
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*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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pxTopOfStack--;
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/* Next simulate the stack as if after a call to portSAVE_CONTEXT().
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* portSAVE_CONTEXT places the flags on the stack immediately after r0
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* to ensure the interrupts get disabled as soon as possible, and so ensuring
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* the stack use is minimal should a context switch interrupt occur. */
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*pxTopOfStack = ( StackType_t ) 0x00; /* R0 */
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pxTopOfStack--;
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*pxTopOfStack = portFLAGS_INT_ENABLED;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x00; /* RAMPZ */
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pxTopOfStack--;
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/* Now the remaining registers. The compiler expects R1 to be 0. */
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*pxTopOfStack = ( StackType_t ) 0x00; /* R1 */
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/* Leave R2 - R23 untouched */
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pxTopOfStack -= 23;
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/* Place the parameter on the stack in the expected location. */
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usAddress = ( uint16_t ) pvParameters;
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*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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pxTopOfStack--;
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usAddress >>= 8;
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*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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/* Leave register R26 - R31 untouched */
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pxTopOfStack -= 7;
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/*lint +e950 +e611 +e923 */
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return pxTopOfStack;
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}
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/*-----------------------------------------------------------*/
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BaseType_t xPortStartScheduler( void )
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{
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/* Setup the hardware to generate the tick. */
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prvSetupTimerInterrupt();
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/* Restore the context of the first task that is going to run. */
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portRESTORE_CONTEXT();
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/* Simulate a function call end as generated by the compiler. We will now
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* jump to the start of the task the context of which we have just restored. */
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asm volatile ( "ret" );
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/* Should not get here. */
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return pdTRUE;
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}
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/*-----------------------------------------------------------*/
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void vPortEndScheduler( void )
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{
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/* vPortEndScheduler is not implemented in this port. */
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}
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/*-----------------------------------------------------------*/
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/*
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* Manual context switch. The first thing we do is save the registers so we
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* can use a naked attribute.
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*/
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void vPortYield( void ) __attribute__( ( naked ) );
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void vPortYield( void )
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{
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portSAVE_CONTEXT();
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vTaskSwitchContext();
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portRESTORE_CONTEXT();
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asm volatile ( "ret" );
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}
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/*-----------------------------------------------------------*/
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/*
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* Manual context switch callable from ISRs. The first thing
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* we do is save the registers so we can use a naked attribute.
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*/
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void vPortYieldFromISR( void ) __attribute__( ( naked ) );
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void vPortYieldFromISR( void )
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{
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portSAVE_CONTEXT();
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vTaskSwitchContext();
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portRESTORE_CONTEXT();
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asm volatile ( "reti" );
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}
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/*-----------------------------------------------------------*/
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/*
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* Context switch function used by the tick. This must be identical to
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* vPortYield() from the call to vTaskSwitchContext() onwards. The only
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* difference from vPortYield() is the tick count is incremented as the
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* call comes from the tick ISR.
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*/
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void vPortYieldFromTick( void ) __attribute__( ( naked ) );
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void vPortYieldFromTick( void )
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{
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portSAVE_CONTEXT();
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if( xTaskIncrementTick() != pdFALSE )
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{
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vTaskSwitchContext();
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}
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portRESTORE_CONTEXT();
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asm volatile ( "reti" );
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}
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/*-----------------------------------------------------------*/
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/*
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* Setup timer to generate a tick interrupt.
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*/
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static void prvSetupTimerInterrupt( void )
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{
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TICK_init();
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}
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/*-----------------------------------------------------------*/
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#if configUSE_PREEMPTION == 1
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/*
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* Tick ISR for preemptive scheduler. We can use a naked attribute as
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* the context is saved at the start of vPortYieldFromTick(). The tick
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* count is incremented after the context is saved.
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*/
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ISR( TICK_INT_vect, ISR_NAKED )
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{
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/* Clear tick interrupt flag. */
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CLR_INT( INT_FLAGS, INT_MASK );
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vPortYieldFromTick();
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asm volatile ( "reti" );
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}
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#else /* if configUSE_PREEMPTION == 1 */
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/*
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* Tick ISR for the cooperative scheduler. All this does is increment the
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* tick count. We don't need to switch context, this can only be done by
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* manual calls to taskYIELD();
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*/
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ISR( TICK_INT_vect )
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{
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/* Clear tick interrupt flag. */
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INT_FLAGS = INT_MASK;
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xTaskIncrementTick();
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}
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#endif /* if configUSE_PREEMPTION == 1 */
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