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/*
FreeRTOS.org V5.1.2 - 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 as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
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 can be applied should you wish 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 of how and when the exception
can be applied.
***************************************************************************
***************************************************************************
* *
* 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. *
* *
***************************************************************************
***************************************************************************
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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