| /* |
| * FreeRTOS Kernel <DEVELOPMENT BRANCH> |
| * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved. |
| * |
| * SPDX-License-Identifier: MIT |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a copy of |
| * this software and associated documentation files (the "Software"), to deal in |
| * the Software without restriction, including without limitation the rights to |
| * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of |
| * the Software, and to permit persons to whom the Software is furnished to do so, |
| * subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included in all |
| * copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS |
| * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR |
| * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER |
| * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
| * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| * |
| * https://www.FreeRTOS.org |
| * https://github.com/FreeRTOS |
| * |
| */ |
| |
| typedef void TCB_t; |
| extern volatile TCB_t * 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 /* 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 ]" |
| |
| |
| #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 /* ifdef DEBUG_BUILD */ |