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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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typedef void tskTCB;
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extern volatile tskTCB * volatile pxCurrentTCB;
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extern void vTaskSwitchContext( void );
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/*
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* Saves the stack pointer for one task into its TCB, calls
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* vTaskSwitchContext() to update the TCB being used, then restores the stack
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* from the new TCB read to run the task.
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*/
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void portSWITCH_CONTEXT( void );
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/*
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* Load the stack pointer from the TCB of the task which is going to be first
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* to execute. Then force an IRET so the registers and IP are popped off the
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* stack.
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*/
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void portFIRST_CONTEXT( void );
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/* There are slightly different versions depending on whether you are building
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to include debugger information. If debugger information is used then there
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are a couple of extra bytes left of the ISR stack (presumably for use by the
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debugger). The true stack pointer is then stored in the bp register. We add
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2 to the stack pointer to remove the extra bytes before we restore our context. */
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#ifdef DEBUG_BUILD
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#pragma aux portSWITCH_CONTEXT = "mov ax, seg pxCurrentTCB" \
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"mov ds, ax" \
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"les bx, pxCurrentTCB" /* Save the stack pointer into the TCB. */ \
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"mov es:0x2[ bx ], ss" \
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"mov es:[ bx ], sp" \
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"call vTaskSwitchContext" /* Perform the switch. */ \
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"mov ax, seg pxCurrentTCB" /* Restore the stack pointer from the TCB. */ \
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"mov ds, ax" \
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"les bx, dword ptr pxCurrentTCB" \
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"mov ss, es:[ bx + 2 ]" \
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"mov sp, es:[ bx ]" \
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"mov bp, sp" /* Prepair the bp register for the restoration of the SP in the compiler generated portion of the ISR */ \
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"add bp, 0x0002"
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#pragma aux portFIRST_CONTEXT = "mov ax, seg pxCurrentTCB" \
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"mov ds, ax" \
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"les bx, dword ptr pxCurrentTCB" \
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"mov ss, es:[ bx + 2 ]" \
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"mov sp, es:[ bx ]" \
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"add sp, 0x0002" /* Remove the extra bytes that exist in debug builds before restoring the context. */ \
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"pop ax" \
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"pop ax" \
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"pop es" \
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"pop ds" \
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"popa" \
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"iret"
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#else
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#pragma aux portSWITCH_CONTEXT = "mov ax, seg pxCurrentTCB" \
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"mov ds, ax" \
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"les bx, pxCurrentTCB" /* Save the stack pointer into the TCB. */ \
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"mov es:0x2[ bx ], ss" \
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"mov es:[ bx ], sp" \
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"call vTaskSwitchContext" /* Perform the switch. */ \
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"mov ax, seg pxCurrentTCB" /* Restore the stack pointer from the TCB. */ \
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"mov ds, ax" \
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"les bx, dword ptr pxCurrentTCB" \
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"mov ss, es:[ bx + 2 ]" \
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"mov sp, es:[ bx ]"
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#pragma aux portFIRST_CONTEXT = "mov ax, seg pxCurrentTCB" \
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"mov ds, ax" \
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"les bx, dword ptr pxCurrentTCB" \
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"mov ss, es:[ bx + 2 ]" \
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"mov sp, es:[ bx ]" \
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"pop ax" \
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"pop ax" \
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"pop es" \
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"pop ds" \
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"popa" \
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"iret"
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#endif
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