portable/IAR/AtmelSAM7S64/portasm.s79

;/*
; * FreeRTOS Kernel <DEVELOPMENT BRANCH>
; * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
; *
; * SPDX-License-Identifier: MIT
; *
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; *
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        RSEG ICODE:CODE
        CODE32

    EXTERN vTaskSwitchContext
    EXTERN xTaskIncrementTick

    PUBLIC vPortYieldProcessor
    PUBLIC vPortPreemptiveTick
    PUBLIC vPortStartFirstTask

#include "AT91SAM7S64_inc.h"
#include "ISR_Support.h"

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Starting the first task is just a matter of restoring the context that
; was created by pxPortInitialiseStack().
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
vPortStartFirstTask:
    portRESTORE_CONTEXT

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Manual context switch function.  This is the SWI hander.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
vPortYieldProcessor:
    ADD     LR, LR, #4          ; Add 4 to the LR to make the LR appear exactly
                                ; as if the context was saved during and IRQ
                                ; handler.

    portSAVE_CONTEXT            ; Save the context of the current task...
    LDR R0, =vTaskSwitchContext ; before selecting the next task to execute.
    mov     lr, pc
    BX R0
    portRESTORE_CONTEXT         ; Restore the context of the selected task.

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Preemptive context switch function.  This will only ever get installed if
; portUSE_PREEMPTION is set to 1 in portmacro.h.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
vPortPreemptiveTick:
    portSAVE_CONTEXT            ; Save the context of the current task.

    LDR R0, =xTaskIncrementTick ; Increment the tick count - this may wake a task.
    mov lr, pc
    BX R0

    CMP R0, #0
    BEQ SkipContextSwitch
    LDR R0, =vTaskSwitchContext ; Select the next task to execute.
    mov lr, pc
    BX R0
SkipContextSwitch
    LDR R14, =AT91C_BASE_PITC   ; Clear the PIT interrupt
    LDR R0, [R14, #PITC_PIVR ]

    LDR R14, =AT91C_BASE_AIC    ; Mark the End of Interrupt on the AIC
    STR R14, [R14, #AIC_EOICR]

    portRESTORE_CONTEXT         ; Restore the context of the selected task.


    END