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jeremybenn |
/*
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FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* If you are: *
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* *
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* + New to FreeRTOS, *
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* + Wanting to learn FreeRTOS or multitasking in general quickly *
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* + Looking for basic training, *
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* + Wanting to improve your FreeRTOS skills and productivity *
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* *
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* then take a look at the FreeRTOS books - available as PDF or paperback *
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* *
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* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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* http://www.FreeRTOS.org/Documentation *
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* *
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* A pdf reference manual is also available. Both are usually delivered *
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* to your inbox within 20 minutes to two hours when purchased between 8am *
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* and 8pm GMT (although please allow up to 24 hours in case of *
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* exceptional circumstances). 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 exception to the GPL is included to allow you to distribute
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a combined work that includes FreeRTOS without being obliged to provide the
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source code for proprietary components outside of the FreeRTOS kernel.
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details. You should have received a copy of the GNU General Public
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License and the FreeRTOS license exception along with FreeRTOS; if not it
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can be viewed here: http://www.freertos.org/a00114.html and also obtained
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by writing to Richard Barry, contact details for whom are available on the
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FreeRTOS WEB site.
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1 tab == 4 spaces!
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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#include "PriorityDefinitions.h"
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PUBLIC _prvStartFirstTask
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PUBLIC ___interrupt_27
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EXTERN _pxCurrentTCB
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EXTERN _vTaskSwitchContext
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RSEG CODE:CODE(4)
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_prvStartFirstTask:
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/* When starting the scheduler there is nothing that needs moving to the
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interrupt stack because the function is not called from an interrupt.
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Just ensure the current stack is the user stack. */
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SETPSW U
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/* Obtain the location of the stack associated with which ever task
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pxCurrentTCB is currently pointing to. */
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MOV.L #_pxCurrentTCB, R15
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MOV.L [R15], R15
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MOV.L [R15], R0
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/* Restore the registers from the stack of the task pointed to by
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pxCurrentTCB. */
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POP R15
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/* Accumulator low 32 bits. */
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MVTACLO R15
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POP R15
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/* Accumulator high 32 bits. */
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MVTACHI R15
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POP R15
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/* Floating point status word. */
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MVTC R15, FPSW
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/* R1 to R15 - R0 is not included as it is the SP. */
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POPM R1-R15
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/* This pops the remaining registers. */
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RTE
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NOP
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NOP
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/*-----------------------------------------------------------*/
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/* The software interrupt - overwrite the default 'weak' definition. */
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___interrupt_27:
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/* Re-enable interrupts. */
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SETPSW I
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/* Move the data that was automatically pushed onto the interrupt stack when
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the interrupt occurred from the interrupt stack to the user stack.
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R15 is saved before it is clobbered. */
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PUSH.L R15
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/* Read the user stack pointer. */
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MVFC USP, R15
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/* Move the address down to the data being moved. */
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SUB #12, R15
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MVTC R15, USP
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/* Copy the data across, R15, then PC, then PSW. */
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MOV.L [ R0 ], [ R15 ]
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MOV.L 4[ R0 ], 4[ R15 ]
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MOV.L 8[ R0 ], 8[ R15 ]
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/* Move the interrupt stack pointer to its new correct position. */
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ADD #12, R0
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/* All the rest of the registers are saved directly to the user stack. */
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SETPSW U
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/* Save the rest of the general registers (R15 has been saved already). */
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PUSHM R1-R14
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/* Save the FPSW and accumulator. */
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MVFC FPSW, R15
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PUSH.L R15
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MVFACHI R15
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PUSH.L R15
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/* Middle word. */
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MVFACMI R15
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/* Shifted left as it is restored to the low order word. */
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SHLL #16, R15
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PUSH.L R15
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/* Save the stack pointer to the TCB. */
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MOV.L #_pxCurrentTCB, R15
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MOV.L [ R15 ], R15
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MOV.L R0, [ R15 ]
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/* Ensure the interrupt mask is set to the syscall priority while the kernel
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structures are being accessed. */
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MVTIPL #configMAX_SYSCALL_INTERRUPT_PRIORITY
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/* Select the next task to run. */
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BSR.A _vTaskSwitchContext
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/* Reset the interrupt mask as no more data structure access is required. */
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MVTIPL #configKERNEL_INTERRUPT_PRIORITY
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/* Load the stack pointer of the task that is now selected as the Running
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state task from its TCB. */
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MOV.L #_pxCurrentTCB,R15
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MOV.L [ R15 ], R15
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MOV.L [ R15 ], R0
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/* Restore the context of the new task. The PSW (Program Status Word) and
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PC will be popped by the RTE instruction. */
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POP R15
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MVTACLO R15
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POP R15
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MVTACHI R15
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POP R15
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MVTC R15, FPSW
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POPM R1-R15
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RTE
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NOP
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NOP
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/*-----------------------------------------------------------*/
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END
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