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88 lines
4.4 KiB
C
88 lines
4.4 KiB
C
/*
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* FreeRTOS Kernel <DEVELOPMENT BRANCH>
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* Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* SPDX-License-Identifier: MIT
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* https://www.FreeRTOS.org
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* https://github.com/FreeRTOS
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*
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*/
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#ifndef PORT_ASM_H
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#define PORT_ASM_H
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typedef void TCB_t;
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extern volatile TCB_t * 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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#define portSWITCH_CONTEXT() \
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asm { mov ax, seg pxCurrentTCB } \
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asm { mov ds, ax } \
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asm { les bx, pxCurrentTCB } /* Save the stack pointer into the TCB. */ \
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asm { mov es:0x2[ bx ], ss } \
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asm { mov es:[ bx ], sp } \
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asm { call far ptr vTaskSwitchContext } /* Perform the switch. */ \
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asm { mov ax, seg pxCurrentTCB } /* Restore the stack pointer from the TCB. */ \
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asm { mov ds, ax } \
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asm { les bx, dword ptr pxCurrentTCB } \
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asm { mov ss, es:[ bx + 2 ] } \
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asm { mov sp, es:[ bx ] }
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#define portFIRST_CONTEXT() \
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__asm { mov ax, seg pxCurrentTCB } \
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__asm { mov ds, ax } \
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__asm { les bx, dword ptr pxCurrentTCB } \
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__asm { mov ss, es:[ bx + 2 ] } \
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__asm { mov sp, es:[ bx ] } \
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__asm { pop bp } \
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__asm { pop di } \
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__asm { pop si } \
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__asm { pop ds } \
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__asm { pop es } \
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__asm { pop dx } \
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__asm { pop cx } \
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__asm { pop bx } \
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__asm { pop ax } \
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__asm { iret }
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#endif
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