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|
;/*
; FreeRTOS V8.2.0 - Copyright (C) 2014 Real Time Engineers Ltd.
; All rights reserved
;
;
; ***************************************************************************
; * *
; * FreeRTOS tutorial books are available in pdf and paperback. *
; * Complete, revised, and edited pdf reference manuals are also *
; * available. *
; * *
; * Purchasing FreeRTOS documentation will not only help you, by *
; * ensuring you get running as quickly as possible and with an *
; * in-depth knowledge of how to use FreeRTOS, it will also help *
; * the FreeRTOS project to continue with its mission of providing *
; * professional grade, cross platform, de facto standard solutions *
; * for microcontrollers - completely free of charge! *
; * *
; * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
; * *
; * Thank you for using FreeRTOS, and thank you for your support! *
; * *
; ***************************************************************************
;
;
; This file is part of the FreeRTOS distribution.
;
; FreeRTOS is free software; you can redistribute it and/or modify it under
; the terms of the GNU General Public License (version 2) as published by the
; Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
; >>>NOTE<<< The modification to the GPL is included to allow you to
; distribute a combined work that includes FreeRTOS without being obliged to
; provide the source code for proprietary components outside of the FreeRTOS
; kernel. FreeRTOS is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
; or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
; more details. You should have received a copy of the GNU General Public
; License and the FreeRTOS license exception along with FreeRTOS; if not it
; can be viewed here: http://www.freertos.org/a00114.html and also obtained
; by writing to Richard Barry, contact details for whom are available on the
; FreeRTOS WEB site.
;
; 1 tab == 4 spaces!
;
; http://www.FreeRTOS.org - Documentation, latest information, license and
; contact details.
;
; http://www.SafeRTOS.com - A version that is certified for use in safety
; critical systems.
;
; http://www.OpenRTOS.com - Commercial support, development, porting,
; licensing and training services.
;*/
.text
.arm
.ref vTaskSwitchContext
.ref xTaskIncrementTick
.ref ulTaskHasFPUContext
.ref pxCurrentTCB
;/*-----------------------------------------------------------*/
;
; Save Task Context
;
portSAVE_CONTEXT .macro
DSB
; Push R0 as we are going to use it
STMDB SP!, {R0}
; Set R0 to point to the task stack pointer.
STMDB SP,{SP}^
SUB SP, SP, #4
LDMIA SP!,{R0}
; Push the return address onto the stack.
STMDB R0!, {LR}
; Now LR has been saved, it can be used instead of R0.
MOV LR, R0
; Pop R0 so it can be saved onto the task stack.
LDMIA SP!, {R0}
; Push all the system mode registers onto the task stack.
STMDB LR,{R0-LR}^
SUB LR, LR, #60
; Push the SPSR onto the task stack.
MRS R0, SPSR
STMDB LR!, {R0}
.if (__TI_VFP_SUPPORT__)
;Determine if the task maintains an FPU context.
LDR R0, ulFPUContextConst
LDR R0, [R0]
; Test the flag
CMP R0, #0
; If the task is not using a floating point context then skip the
; saving of the FPU registers.
BEQ $+16
FSTMDBD LR!, {D0-D15}
FMRX R1, FPSCR
STMFD LR!, {R1}
; Save the flag
STMDB LR!, {R0}
.endif
; Store the new top of stack for the task.
LDR R0, pxCurrentTCBConst
LDR R0, [R0]
STR LR, [R0]
.endm
;/*-----------------------------------------------------------*/
;
; Restore Task Context
;
portRESTORE_CONTEXT .macro
LDR R0, pxCurrentTCBConst
LDR R0, [R0]
LDR LR, [R0]
.if (__TI_VFP_SUPPORT__)
; The floating point context flag is the first thing on the stack.
LDR R0, ulFPUContextConst
LDMFD LR!, {R1}
STR R1, [R0]
; Test the flag
CMP R1, #0
; If the task is not using a floating point context then skip the
; VFP register loads.
BEQ $+16
; Restore the floating point context.
LDMFD LR!, {R0}
FLDMIAD LR!, {D0-D15}
FMXR FPSCR, R0
.endif
; Get the SPSR from the stack.
LDMFD LR!, {R0}
MSR SPSR_CSXF, R0
; Restore all system mode registers for the task.
LDMFD LR, {R0-R14}^
; Restore the return address.
LDR LR, [LR, #+60]
; And return - correcting the offset in the LR to obtain the
; correct address.
SUBS PC, LR, #4
.endm
;/*-----------------------------------------------------------*/
; Start the first task by restoring its context.
.def vPortStartFirstTask
vPortStartFirstTask:
portRESTORE_CONTEXT
;/*-----------------------------------------------------------*/
; Yield to another task.
.def vPortYieldProcessor
vPortYieldProcessor:
; Within an IRQ ISR the link register has an offset from the true return
; address. SWI doesn't do this. Add the offset manually so the ISR
; return code can be used.
ADD LR, LR, #4
; First save the context of the current task.
portSAVE_CONTEXT
; Select the next task to execute. */
BL vTaskSwitchContext
; Restore the context of the task selected to execute.
portRESTORE_CONTEXT
;/*-----------------------------------------------------------*/
; Yield to another task from within the FreeRTOS API
.def vPortYeildWithinAPI
vPortYeildWithinAPI:
; Save the context of the current task.
portSAVE_CONTEXT
; Clear SSI flag.
MOVW R0, #0xFFF4
MOVT R0, #0xFFFF
LDR R0, [R0]
; Select the next task to execute. */
BL vTaskSwitchContext
; Restore the context of the task selected to execute.
portRESTORE_CONTEXT
;/*-----------------------------------------------------------*/
; Preemptive Tick
.def vPortPreemptiveTick
vPortPreemptiveTick:
; Save the context of the current task.
portSAVE_CONTEXT
; Clear interrupt flag
MOVW R0, #0xFC88
MOVT R0, #0xFFFF
MOV R1, #1
STR R1, [R0]
; Increment the tick count, making any adjustments to the blocked lists
; that may be necessary.
BL xTaskIncrementTick
; Select the next task to execute.
CMP R0, #0
BLNE vTaskSwitchContext
; Restore the context of the task selected to execute.
portRESTORE_CONTEXT
;-------------------------------------------------------------------------------
.if (__TI_VFP_SUPPORT__)
.def vPortInitialiseFPSCR
vPortInitialiseFPSCR:
MOV R0, #0
FMXR FPSCR, R0
BX LR
.endif ;__TI_VFP_SUPPORT__
pxCurrentTCBConst .word pxCurrentTCB
ulFPUContextConst .word ulTaskHasFPUContext
;-------------------------------------------------------------------------------
|
