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135 lines
5.7 KiB
C
135 lines
5.7 KiB
C
/*
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FreeRTOS.org V5.3.1 - Copyright (C) 2003-2009 Richard Barry.
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This file is part of the FreeRTOS.org distribution.
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FreeRTOS.org is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License (version 2) as published
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by the 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 a
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combined work that includes FreeRTOS.org without being obliged to provide
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the source code for any proprietary components. Alternative commercial
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license and support terms are also available upon request. See the
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licensing section of http://www.FreeRTOS.org for full details.
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FreeRTOS.org 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.
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You should have received a copy of the GNU General Public License along
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with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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***************************************************************************
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* *
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* Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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* *
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* This is a concise, step by step, 'hands on' guide that describes both *
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* general multitasking concepts and FreeRTOS specifics. It presents and *
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* explains numerous examples that are written using the FreeRTOS API. *
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* Full source code for all the examples is provided in an accompanying *
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* .zip file. *
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* *
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***************************************************************************
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1 tab == 4 spaces!
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Please ensure to read the configuration and relevant port sections of the
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online documentation.
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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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