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; * *
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;*/
INCLUDE portmacro.inc
IMPORT vTaskSwitchContext
IMPORT vTaskIncrementTick
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, =vTaskIncrementTick ; Increment the tick count.
MOV LR, PC ; This may make a delayed task ready
BX R0 ; to run.
LDR R0, =vTaskSwitchContext ; Find the highest priority task that
MOV LR, PC ; is ready to run.
BX R0
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