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/*
FreeRTOS.org V5.2.0 - Copyright (C) 2003-2009 Richard Barry.
This file is part of the FreeRTOS.org distribution.
FreeRTOS.org is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License (version 2) as published
by the Free Software Foundation and modified by the FreeRTOS exception.
FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.
You should have received a copy of the GNU General Public License along
with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
Temple Place, Suite 330, Boston, MA 02111-1307 USA.
A special exception to the GPL is included to allow you to distribute a
combined work that includes FreeRTOS.org without being obliged to provide
the source code for any proprietary components. See the licensing section
of http://www.FreeRTOS.org for full details.
***************************************************************************
* *
* Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
* *
* This is a concise, step by step, 'hands on' guide that describes both *
* general multitasking concepts and FreeRTOS specifics. It presents and *
* explains numerous examples that are written using the FreeRTOS API. *
* Full source code for all the examples is provided in an accompanying *
* .zip file. *
* *
***************************************************************************
1 tab == 4 spaces!
Please ensure to read the configuration and relevant port sections of the
online documentation.
http://www.FreeRTOS.org - Documentation, latest information, license and
contact details.
http://www.SafeRTOS.com - A version that is certified for use in safety
critical systems.
http://www.OpenRTOS.com - Commercial support, development, porting,
licensing and training services.
*/
typedef void tskTCB;
extern volatile tskTCB * volatile pxCurrentTCB;
extern void vTaskSwitchContext( void );
/*
* Saves the stack pointer for one task into its TCB, calls
* vTaskSwitchContext() to update the TCB being used, then restores the stack
* from the new TCB read to run the task.
*/
void portSWITCH_CONTEXT( void );
/*
* Load the stack pointer from the TCB of the task which is going to be first
* to execute. Then force an IRET so the registers and IP are popped off the
* stack.
*/
void portFIRST_CONTEXT( void );
/* There are slightly different versions depending on whether you are building
to include debugger information. If debugger information is used then there
are a couple of extra bytes left of the ISR stack (presumably for use by the
debugger). The true stack pointer is then stored in the bp register. We add
2 to the stack pointer to remove the extra bytes before we restore our context. */
#ifdef DEBUG_BUILD
#pragma aux portSWITCH_CONTEXT = "mov ax, seg pxCurrentTCB" \
"mov ds, ax" \
"les bx, pxCurrentTCB" /* Save the stack pointer into the TCB. */ \
"mov es:0x2[ bx ], ss" \
"mov es:[ bx ], sp" \
"call vTaskSwitchContext" /* Perform the switch. */ \
"mov ax, seg pxCurrentTCB" /* Restore the stack pointer from the TCB. */ \
"mov ds, ax" \
"les bx, dword ptr pxCurrentTCB" \
"mov ss, es:[ bx + 2 ]" \
"mov sp, es:[ bx ]" \
"mov bp, sp" /* Prepair the bp register for the restoration of the SP in the compiler generated portion of the ISR */ \
"add bp, 0x0002"
#pragma aux portFIRST_CONTEXT = "mov ax, seg pxCurrentTCB" \
"mov ds, ax" \
"les bx, dword ptr pxCurrentTCB" \
"mov ss, es:[ bx + 2 ]" \
"mov sp, es:[ bx ]" \
"add sp, 0x0002" /* Remove the extra bytes that exist in debug builds before restoring the context. */ \
"pop ax" \
"pop ax" \
"pop es" \
"pop ds" \
"popa" \
"iret"
#else
#pragma aux portSWITCH_CONTEXT = "mov ax, seg pxCurrentTCB" \
"mov ds, ax" \
"les bx, pxCurrentTCB" /* Save the stack pointer into the TCB. */ \
"mov es:0x2[ bx ], ss" \
"mov es:[ bx ], sp" \
"call vTaskSwitchContext" /* Perform the switch. */ \
"mov ax, seg pxCurrentTCB" /* Restore the stack pointer from the TCB. */ \
"mov ds, ax" \
"les bx, dword ptr pxCurrentTCB" \
"mov ss, es:[ bx + 2 ]" \
"mov sp, es:[ bx ]"
#pragma aux portFIRST_CONTEXT = "mov ax, seg pxCurrentTCB" \
"mov ds, ax" \
"les bx, dword ptr pxCurrentTCB" \
"mov ss, es:[ bx + 2 ]" \
"mov sp, es:[ bx ]" \
"pop ax" \
"pop ax" \
"pop es" \
"pop ds" \
"popa" \
"iret"
#endif
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