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472 lines
16 KiB
C
472 lines
16 KiB
C
/*
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FreeRTOS V7.4.2 - Copyright (C) 2013 Real Time Engineers Ltd.
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FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
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http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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***************************************************************************
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* *
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* FreeRTOS tutorial books are available in pdf and paperback. *
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* Complete, revised, and edited pdf reference manuals are also *
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* available. *
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* *
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* Purchasing FreeRTOS documentation will not only help you, by *
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* ensuring you get running as quickly as possible and with an *
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* in-depth knowledge of how to use FreeRTOS, it will also help *
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* the FreeRTOS project to continue with its mission of providing *
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* professional grade, cross platform, de facto standard solutions *
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* for microcontrollers - completely free of charge! *
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* *
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* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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* *
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* Thank you for using FreeRTOS, and thank you for your support! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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>>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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distribute a combined work that includes FreeRTOS without being obliged to
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provide the source code for proprietary components outside of the FreeRTOS
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kernel.
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details. You should have received a copy of the GNU General Public License
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and the FreeRTOS license exception along with FreeRTOS; if not it can be
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viewed here: http://www.freertos.org/a00114.html and also obtained by
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writing to Real Time Engineers Ltd., contact details for whom are available
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on the FreeRTOS WEB site.
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1 tab == 4 spaces!
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***************************************************************************
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* *
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* Having a problem? Start by reading the FAQ "My application does *
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* not run, what could be wrong?" *
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* *
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* http://www.FreeRTOS.org/FAQHelp.html *
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* *
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***************************************************************************
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http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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license and Real Time Engineers Ltd. contact details.
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http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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including FreeRTOS+Trace - an indispensable productivity tool, and our new
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fully thread aware and reentrant UDP/IP stack.
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http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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Integrity Systems, who sell the code with commercial support,
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indemnification and middleware, under the OpenRTOS brand.
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http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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engineered and independently SIL3 certified version for use in safety and
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mission critical applications that require provable dependability.
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*/
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/*
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Changes from V2.6.0
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+ AVR port - Replaced the inb() and outb() functions with direct memory
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access. This allows the port to be built with the 20050414 build of
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WinAVR.
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*/
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#include <stdlib.h>
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#include <avr/interrupt.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 ( ( portSTACK_TYPE ) 0x80 )
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/* Hardware constants for timer 1. */
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#define portCLEAR_COUNTER_ON_MATCH ( ( unsigned char ) 0x08 )
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#define portPRESCALE_64 ( ( unsigned char ) 0x03 )
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#define portCLOCK_PRESCALER ( ( unsigned long ) 64 )
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#define portCOMPARE_MATCH_A_INTERRUPT_ENABLE ( ( unsigned char ) 0x10 )
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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 tskTCB;
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extern volatile tskTCB * 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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"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, 0x3d \n\t" \
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"st x+, r0 \n\t" \
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"in r0, 0x3e \n\t" \
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"st x+, r0 \n\t" \
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);
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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 __SREG__, r0 \n\t" \
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"pop r0 \n\t" \
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);
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/*-----------------------------------------------------------*/
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/*
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* Perform hardware setup to enable ticks from timer 1, compare match A.
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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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portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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{
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unsigned short usAddress;
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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. */
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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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/* Simulate how the stack would look after a call to vPortYield() generated by
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the compiler. */
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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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/* 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 = ( unsigned short ) pxCode;
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*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned short ) 0x00ff );
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pxTopOfStack--;
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usAddress >>= 8;
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*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned short ) 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 = ( portSTACK_TYPE ) 0x00; /* R0 */
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pxTopOfStack--;
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*pxTopOfStack = portFLAGS_INT_ENABLED;
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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 = ( portSTACK_TYPE ) 0x00; /* R1 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x02; /* R2 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x03; /* R3 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x04; /* R4 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x05; /* R5 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x06; /* R6 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x07; /* R7 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x08; /* R8 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x09; /* R9 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x10; /* R10 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x11; /* R11 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x12; /* R12 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x13; /* R13 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x14; /* R14 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x15; /* R15 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x16; /* R16 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x17; /* R17 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x18; /* R18 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x19; /* R19 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x20; /* R20 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x21; /* R21 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x22; /* R22 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x23; /* R23 */
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pxTopOfStack--;
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/* Place the parameter on the stack in the expected location. */
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usAddress = ( unsigned short ) pvParameters;
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*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned short ) 0x00ff );
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pxTopOfStack--;
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usAddress >>= 8;
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*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned short ) 0x00ff );
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x26; /* R26 X */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x27; /* R27 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x28; /* R28 Y */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x29; /* R29 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x30; /* R30 Z */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x031; /* R31 */
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pxTopOfStack--;
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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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portBASE_TYPE 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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/* It is unlikely that the AVR port will get stopped. If required simply
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disable the tick interrupt here. */
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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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* 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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vTaskIncrementTick();
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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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* Setup timer 1 compare match A 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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unsigned long ulCompareMatch;
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unsigned char ucHighByte, ucLowByte;
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/* Using 16bit timer 1 to generate the tick. Correct fuses must be
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selected for the configCPU_CLOCK_HZ clock. */
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ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
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/* We only have 16 bits so have to scale to get our required tick rate. */
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ulCompareMatch /= portCLOCK_PRESCALER;
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/* Adjust for correct value. */
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ulCompareMatch -= ( unsigned long ) 1;
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/* Setup compare match value for compare match A. Interrupts are disabled
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before this is called so we need not worry here. */
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ucLowByte = ( unsigned char ) ( ulCompareMatch & ( unsigned long ) 0xff );
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ulCompareMatch >>= 8;
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ucHighByte = ( unsigned char ) ( ulCompareMatch & ( unsigned long ) 0xff );
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OCR1AH = ucHighByte;
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OCR1AL = ucLowByte;
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/* Setup clock source and compare match behaviour. */
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ucLowByte = portCLEAR_COUNTER_ON_MATCH | portPRESCALE_64;
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TCCR1B = ucLowByte;
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/* Enable the interrupt - this is okay as interrupt are currently globally
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disabled. */
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ucLowByte = TIMSK;
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ucLowByte |= portCOMPARE_MATCH_A_INTERRUPT_ENABLE;
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TIMSK = ucLowByte;
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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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void SIG_OUTPUT_COMPARE1A( void ) __attribute__ ( ( signal, naked ) );
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void SIG_OUTPUT_COMPARE1A( void )
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{
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vPortYieldFromTick();
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asm volatile ( "reti" );
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}
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#else
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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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void SIG_OUTPUT_COMPARE1A( void ) __attribute__ ( ( signal ) );
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void SIG_OUTPUT_COMPARE1A( void )
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{
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vTaskIncrementTick();
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}
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#endif
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