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239 lines
8.2 KiB
C
239 lines
8.2 KiB
C
/*
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* FreeRTOS Kernel V10.3.1
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* Copyright (C) 2020 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.
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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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* 1 tab == 4 spaces!
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*/
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/*-----------------------------------------------------------
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* Implementation of functions defined in portable.h for the Atmel AT91R40008
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* port.
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*
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* Components that can be compiled to either ARM or THUMB mode are
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* contained in this file. The ISR routines, which can only be compiled
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* to ARM mode are contained in portISR.c.
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*----------------------------------------------------------*/
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/* Standard includes. */
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#include <stdlib.h>
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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#include "task.h"
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/* Hardware specific definitions. */
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#include "AT91R40008.h"
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#include "pio.h"
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#include "aic.h"
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#include "tc.h"
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/* Constants required to setup the task context. */
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#define portINITIAL_SPSR ( ( StackType_t ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
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#define portTHUMB_MODE_BIT ( ( StackType_t ) 0x20 )
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#define portINSTRUCTION_SIZE ( ( StackType_t ) 4 )
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#define portNO_CRITICAL_SECTION_NESTING ( ( StackType_t ) 0 )
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#define portTICK_PRIORITY_6 ( 6 )
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/*-----------------------------------------------------------*/
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/* Setup the timer to generate the tick interrupts. */
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static void prvSetupTimerInterrupt( void );
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/*
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* The scheduler can only be started from ARM mode, so
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* vPortISRStartFirstSTask() is defined in portISR.c.
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*/
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extern void vPortISRStartFirstTask( void );
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/*-----------------------------------------------------------*/
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/*
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* Initialise the stack of a task to look exactly as if a call to
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* portSAVE_CONTEXT had been called.
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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, TaskFunction_t pxCode, void *pvParameters )
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{
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StackType_t *pxOriginalTOS;
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pxOriginalTOS = pxTopOfStack;
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/* To ensure asserts in tasks.c don't fail, although in this case the assert
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is not really required. */
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pxTopOfStack--;
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/* Setup the initial stack of the task. The stack is set exactly as
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expected by the portRESTORE_CONTEXT() macro. */
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/* First on the stack is the return address - which in this case is the
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start of the task. The offset is added to make the return address appear
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as it would within an IRQ ISR. */
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*pxTopOfStack = ( StackType_t ) pxCode + portINSTRUCTION_SIZE;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0xaaaaaaaa; /* R14 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x12121212; /* R12 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x11111111; /* R11 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x10101010; /* R10 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x09090909; /* R9 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x08080808; /* R8 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x07070707; /* R7 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x06060606; /* R6 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x05050505; /* R5 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x04040404; /* R4 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x03030303; /* R3 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x02020202; /* R2 */
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x01010101; /* R1 */
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pxTopOfStack--;
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/* When the task starts is will expect to find the function parameter in
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R0. */
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*pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
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pxTopOfStack--;
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/* The last thing onto the stack is the status register, which is set for
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system mode, with interrupts enabled. */
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*pxTopOfStack = ( StackType_t ) portINITIAL_SPSR;
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#ifdef THUMB_INTERWORK
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{
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/* We want the task to start in thumb mode. */
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*pxTopOfStack |= portTHUMB_MODE_BIT;
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}
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#endif
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pxTopOfStack--;
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/* Some optimisation levels use the stack differently to others. This
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means the interrupt flags cannot always be stored on the stack and will
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instead be stored in a variable, which is then saved as part of the
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tasks context. */
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*pxTopOfStack = portNO_CRITICAL_SECTION_NESTING;
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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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/* Start the timer that generates the tick ISR. Interrupts are disabled
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here already. */
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prvSetupTimerInterrupt();
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/* Start the first task. */
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vPortISRStartFirstTask();
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/* Should not get here! */
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return 0;
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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 ARM port will require this function as there
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is nothing to return to. */
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}
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/*-----------------------------------------------------------*/
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/*
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* Setup the tick timer to generate the tick interrupts at the required frequency.
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*/
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static void prvSetupTimerInterrupt( void )
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{
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volatile uint32_t ulDummy;
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/* Enable clock to the tick timer... */
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AT91C_BASE_PS->PS_PCER = portTIMER_CLK_ENABLE_BIT;
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/* Stop the tick timer... */
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portTIMER_REG_BASE_PTR->TC_CCR = TC_CLKDIS;
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/* Start with tick timer interrupts disabled... */
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portTIMER_REG_BASE_PTR->TC_IDR = 0xFFFFFFFF;
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/* Clear any pending tick timer interrupts... */
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ulDummy = portTIMER_REG_BASE_PTR->TC_SR;
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/* Store interrupt handler function address in tick timer vector register...
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The ISR installed depends on whether the preemptive or cooperative
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scheduler is being used. */
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#if configUSE_PREEMPTION == 1
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{
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extern void ( vPreemptiveTick )( void );
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AT91C_BASE_AIC->AIC_SVR[portTIMER_AIC_CHANNEL] = ( uint32_t ) vPreemptiveTick;
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}
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#else // else use cooperative scheduler
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{
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extern void ( vNonPreemptiveTick )( void );
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AT91C_BASE_AIC->AIC_SVR[portTIMER_AIC_CHANNEL] = ( uint32_t ) vNonPreemptiveTick;
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}
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#endif
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/* Tick timer interrupt level-sensitive, priority 6... */
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AT91C_BASE_AIC->AIC_SMR[ portTIMER_AIC_CHANNEL ] = AIC_SRCTYPE_INT_LEVEL_SENSITIVE | portTICK_PRIORITY_6;
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/* Enable the tick timer interrupt...
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First at timer level */
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portTIMER_REG_BASE_PTR->TC_IER = TC_CPCS;
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/* Then at the AIC level. */
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AT91C_BASE_AIC->AIC_IECR = (1 << portTIMER_AIC_CHANNEL);
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/* Calculate timer compare value to achieve the desired tick rate... */
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if( (configCPU_CLOCK_HZ / (configTICK_RATE_HZ * 2) ) <= 0xFFFF )
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{
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/* The tick rate is fast enough for us to use the faster timer input
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clock (main clock / 2). */
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portTIMER_REG_BASE_PTR->TC_CMR = TC_WAVE | TC_CLKS_MCK2 | TC_BURST_NONE | TC_CPCTRG;
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portTIMER_REG_BASE_PTR->TC_RC = configCPU_CLOCK_HZ / (configTICK_RATE_HZ * 2);
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}
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else
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{
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/* We must use a slower timer input clock (main clock / 8) because the
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tick rate is too slow for the faster input clock. */
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portTIMER_REG_BASE_PTR->TC_CMR = TC_WAVE | TC_CLKS_MCK8 | TC_BURST_NONE | TC_CPCTRG;
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portTIMER_REG_BASE_PTR->TC_RC = configCPU_CLOCK_HZ / (configTICK_RATE_HZ * 8);
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}
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/* Start tick timer... */
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portTIMER_REG_BASE_PTR->TC_CCR = TC_SWTRG | TC_CLKEN;
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}
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/*-----------------------------------------------------------*/
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