329 lines
11 KiB
C
329 lines
11 KiB
C
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/*
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* FreeRTOS Kernel V10.2.1
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* Copyright (C) 2019 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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* http://www.FreeRTOS.org
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* http://aws.amazon.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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Changes from V2.5.2
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+ usCriticalNesting now has a volatile qualifier.
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*/
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/* Standard includes. */
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#include <stdlib.h>
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#include <signal.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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/*-----------------------------------------------------------
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* Implementation of functions defined in portable.h for the MSP430 port.
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*----------------------------------------------------------*/
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/* Constants required for hardware setup. The tick ISR runs off the ACLK,
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not the MCLK. */
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#define portACLK_FREQUENCY_HZ ( ( TickType_t ) 32768 )
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#define portINITIAL_CRITICAL_NESTING ( ( uint16_t ) 10 )
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#define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x08 )
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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 TCB_t;
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extern volatile TCB_t * volatile pxCurrentTCB;
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/* Most ports implement critical sections by placing the interrupt flags on
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the stack before disabling interrupts. Exiting the critical section is then
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simply a case of popping the flags from the stack. As mspgcc does not use
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a frame pointer this cannot be done as modifying the stack will clobber all
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the stack variables. Instead each task maintains a count of the critical
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section nesting depth. Each time a critical section is entered the count is
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incremented. Each time a critical section is left the count is decremented -
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with interrupts only being re-enabled if the count is zero.
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usCriticalNesting will get set to zero when the scheduler starts, but must
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not be initialised to zero as this will cause problems during the startup
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sequence. */
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volatile uint16_t usCriticalNesting = portINITIAL_CRITICAL_NESTING;
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/*-----------------------------------------------------------*/
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/*
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* Macro to save a task context to the task stack. This simply pushes all the
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* general purpose msp430 registers onto the stack, followed by the
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* usCriticalNesting value used by the task. Finally the resultant stack
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* pointer value is saved into the task control block so it can be retrieved
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* the next time the task executes.
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*/
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#define portSAVE_CONTEXT() \
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asm volatile ( "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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"mov.w usCriticalNesting, r14 \n\t" \
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"push r14 \n\t" \
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"mov.w pxCurrentTCB, r12 \n\t" \
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"mov.w r1, @r12 \n\t" \
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);
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/*
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* Macro to restore a task context from the task stack. This is effectively
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* the reverse of portSAVE_CONTEXT(). First the stack pointer value is
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* loaded from the task control block. Next the value for usCriticalNesting
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* used by the task is retrieved from the stack - followed by the value of all
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* the general purpose msp430 registers.
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*
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* The bic instruction ensures there are no low power bits set in the status
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* register that is about to be popped from the stack.
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*/
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#define portRESTORE_CONTEXT() \
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asm volatile ( "mov.w pxCurrentTCB, r12 \n\t" \
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"mov.w @r12, r1 \n\t" \
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"pop r15 \n\t" \
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"mov.w r15, usCriticalNesting \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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"bic #(0xf0),0(r1) \n\t" \
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"reti \n\t" \
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);
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/*-----------------------------------------------------------*/
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/*
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* Sets up the periodic ISR used for the RTOS tick. This uses timer 0, but
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* could have alternatively used the watchdog timer or timer 1.
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*/
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static void prvSetupTimerInterrupt( 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 the header file portable.h.
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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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/*
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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 and can be included if required.
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*pxTopOfStack = ( StackType_t ) 0x1111;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x2222;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x3333;
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pxTopOfStack--;
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*/
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/* The msp430 automatically pushes the PC then SR onto the stack before
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executing an ISR. We want the stack to look just as if this has happened
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so place a pointer to the start of the task on the stack first - followed
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by the flags we want the task to use when it starts up. */
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*pxTopOfStack = ( StackType_t ) pxCode;
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pxTopOfStack--;
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*pxTopOfStack = portFLAGS_INT_ENABLED;
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pxTopOfStack--;
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/* Next the general purpose registers. */
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*pxTopOfStack = ( StackType_t ) 0x4444;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x5555;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x6666;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x7777;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x8888;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0x9999;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0xaaaa;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0xbbbb;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0xcccc;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0xdddd;
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pxTopOfStack--;
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*pxTopOfStack = ( StackType_t ) 0xeeee;
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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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R15. */
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*pxTopOfStack = ( StackType_t ) pvParameters;
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pxTopOfStack--;
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/* The code generated by the mspgcc compiler does not maintain separate
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stack and frame pointers. The portENTER_CRITICAL macro cannot therefore
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use the stack as per other ports. Instead a variable is used to keep
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track of the critical section nesting. This variable has to be stored
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as part of the task context and is initially set to zero. */
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*pxTopOfStack = ( StackType_t ) portNO_CRITICAL_SECTION_NESTING;
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/* Return a pointer to the top of the stack we have generated so this can
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be stored in the task control block for the task. */
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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. Interrupts are disabled when
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this function is called. */
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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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/* Should not get here as the tasks are now running! */
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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 MSP430 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 called by portYIELD or taskYIELD.
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*
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* The first thing we do is save the registers so we 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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/* We want the stack of the task being saved to look exactly as if the task
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was saved during a pre-emptive RTOS tick ISR. Before calling an ISR the
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msp430 places the status register onto the stack. As this is a function
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call and not an ISR we have to do this manually. */
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asm volatile ( "push r2" );
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_DINT();
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/* Save the context of the current task. */
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portSAVE_CONTEXT();
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/* Switch to the highest priority task that is ready to run. */
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vTaskSwitchContext();
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/* Restore the context of the new task. */
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portRESTORE_CONTEXT();
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}
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/*-----------------------------------------------------------*/
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/*
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* Hardware initialisation to generate the RTOS tick. This uses timer 0
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* but could alternatively use the watchdog timer or timer 1.
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*/
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static void prvSetupTimerInterrupt( void )
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{
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/* Ensure the timer is stopped. */
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TACTL = 0;
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/* Run the timer of the ACLK. */
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TACTL = TASSEL_1;
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/* Clear everything to start with. */
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TACTL |= TACLR;
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/* Set the compare match value according to the tick rate we want. */
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TACCR0 = portACLK_FREQUENCY_HZ / configTICK_RATE_HZ;
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/* Enable the interrupts. */
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TACCTL0 = CCIE;
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/* Start up clean. */
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TACTL |= TACLR;
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/* Up mode. */
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TACTL |= MC_1;
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}
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/*-----------------------------------------------------------*/
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/*
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* The interrupt service routine used depends on whether the pre-emptive
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* scheduler is being used or not.
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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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interrupt (TIMERA0_VECTOR) prvTickISR( void ) __attribute__ ( ( naked ) );
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interrupt (TIMERA0_VECTOR) prvTickISR( void )
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{
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/* Save the context of the interrupted task. */
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portSAVE_CONTEXT();
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/* Increment the tick count then switch to the highest priority task
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that is ready to run. */
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if( xTaskIncrementTick() != pdFALSE )
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{
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vTaskSwitchContext();
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}
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/* Restore the context of the new task. */
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portRESTORE_CONTEXT();
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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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interrupt (TIMERA0_VECTOR) prvTickISR( void );
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interrupt (TIMERA0_VECTOR) prvTickISR( void )
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{
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xTaskIncrementTick();
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}
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#endif
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