| ;/* |
| ; * 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 |
| ; * |
| ; */ |
| |
| INCLUDE portmacro.inc |
| |
| IMPORT vTaskSwitchContext |
| IMPORT xTaskIncrementTick |
| |
| EXPORT vPortYieldProcessor |
| EXPORT vPortStartFirstTask |
| EXPORT vPreemptiveTick |
| EXPORT vPortYield |
| |
| |
| VICVECTADDR EQU 0xFFFFF030 |
| T0IR EQU 0xE0004000 |
| T0MATCHBIT EQU 0x00000001 |
| |
| ARM |
| AREA PORT_ASM, CODE, READONLY |
| |
| |
| |
| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
| ; Starting the first task is done by just restoring the context |
| ; setup by pxPortInitialiseStack |
| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
| vPortStartFirstTask |
| |
| PRESERVE8 |
| |
| portRESTORE_CONTEXT |
| |
| vPortYield |
| |
| PRESERVE8 |
| |
| SVC 0 |
| bx lr |
| |
| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
| ; Interrupt service routine for the SWI interrupt. The vector table is |
| ; configured in the startup.s file. |
| ; |
| ; vPortYieldProcessor() is used to manually force a context switch. The |
| ; SWI interrupt is generated by a call to taskYIELD() or portYIELD(). |
| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
| |
| vPortYieldProcessor |
| |
| PRESERVE8 |
| |
| ; Within an IRQ ISR the link register has an offset from the true return |
| ; address, but an SWI ISR does not. Add the offset manually so the same |
| ; ISR return code can be used in both cases. |
| ADD LR, LR, #4 |
| |
| ; Perform the context switch. |
| portSAVE_CONTEXT ; Save current task context |
| LDR R0, =vTaskSwitchContext ; Get the address of the context switch function |
| MOV LR, PC ; Store the return address |
| BX R0 ; Call the contedxt switch function |
| portRESTORE_CONTEXT ; restore the context of the selected task |
| |
| |
| |
| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
| ; Interrupt service routine for preemptive scheduler tick timer |
| ; Only used if portUSE_PREEMPTION is set to 1 in portmacro.h |
| ; |
| ; Uses timer 0 of LPC21XX Family |
| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
| |
| vPreemptiveTick |
| |
| PRESERVE8 |
| |
| portSAVE_CONTEXT ; Save the context of the current task. |
| |
| LDR R0, =xTaskIncrementTick ; Increment the tick count. |
| MOV LR, PC ; This may make a delayed task ready |
| BX R0 ; to run. |
| |
| CMP R0, #0 |
| BEQ SkipContextSwitch |
| LDR R0, =vTaskSwitchContext ; Find the highest priority task that |
| MOV LR, PC ; is ready to run. |
| BX R0 |
| SkipContextSwitch |
| MOV R0, #T0MATCHBIT ; Clear the timer event |
| LDR R1, =T0IR |
| STR R0, [R1] |
| |
| LDR R0, =VICVECTADDR ; Acknowledge the interrupt |
| STR R0,[R0] |
| |
| portRESTORE_CONTEXT ; Restore the context of the highest |
| ; priority task that is ready to run. |
| END |