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FreeRTOS-Kernel/FreeRTOS/Source/portable/GCC/ARM_CA9/portASM.S

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/*
FreeRTOS V8.0.0 - 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
.set SYS_MODE, 0x1f
.set SVC_MODE, 0x13
.set IRQ_MODE, 0x12
/* Hardware registers. */
.extern ulICCIAR
.extern ulICCEOIR
.extern ulICCPMR
/* Variables and functions. */
.extern ulMaxAPIPriorityMask
.extern _freertos_vector_table
.extern pxCurrentTCB
.extern vTaskSwitchContext
.extern vApplicationIRQHandler
.extern ulPortInterruptNesting
.extern ulPortTaskHasFPUContext
.global FreeRTOS_IRQ_Handler
.global FreeRTOS_SWI_Handler
.global vPortRestoreTaskContext
.global vPortInstallFreeRTOSVectorTable
.macro portSAVE_CONTEXT
/* Save the LR and SPSR onto the system mode stack before switching to
system mode to save the remaining system mode registers. */
SRSDB sp!, #SYS_MODE
CPS #SYS_MODE
PUSH {R0-R12, R14}
/* Push the critical nesting count. */
LDR R2, ulCriticalNestingConst
LDR R1, [R2]
PUSH {R1}
/* Does the task have a floating point context that needs saving? If
ulPortTaskHasFPUContext is 0 then no. */
LDR R2, ulPortTaskHasFPUContextConst
LDR R3, [R2]
CMP R3, #0
/* Save the floating point context, if any. */
FMRXNE R1, FPSCR
VPUSHNE {D0-D15}
VPUSHNE {D16-D31}
PUSHNE {R1}
/* Save ulPortTaskHasFPUContext itself. */
PUSH {R3}
/* Save the stack pointer in the TCB. */
LDR R0, pxCurrentTCBConst
LDR R1, [R0]
STR SP, [R1]
.endm
; /**********************************************************************/
.macro portRESTORE_CONTEXT
/* Switch to system mode. */
CPS #SYS_MODE
/* Set the SP to point to the stack of the task being restored. */
LDR R0, pxCurrentTCBConst
LDR R1, [R0]
LDR SP, [R1]
/* Is there a floating point context to restore? If the restored
ulPortTaskHasFPUContext is zero then no. */
LDR R0, ulPortTaskHasFPUContextConst
POP {R1}
STR R1, [R0]
CMP R1, #0
/* Restore the floating point context, if any. */
POPNE {R0}
VPOPNE {D16-D31}
VPOPNE {D0-D15}
VMSRNE FPSCR, R0
/* Restore the critical section nesting depth. */
LDR R0, ulCriticalNestingConst
POP {R1}
STR R1, [R0]
/* Ensure the priority mask is correct for the critical nesting depth. */
LDR R2, ulICCPMRConst
LDR R2, [R2]
CMP R1, #0
MOVEQ R4, #255
LDRNE R4, ulMaxAPIPriorityMaskConst
LDRNE R4, [R4]
STR R4, [R2]
/* Restore all system mode registers other than the SP (which is already
being used). */
POP {R0-R12, R14}
/* Return to the task code, loading CPSR on the way. */
RFEIA sp!
.endm
/******************************************************************************
* SVC handler is used to start the scheduler and yield a task.
*****************************************************************************/
.align 4
.type FreeRTOS_SWI_Handler, %function
FreeRTOS_SWI_Handler:
/* Save the context of the current task and select a new task to run. */
portSAVE_CONTEXT
LDR R0, vTaskSwitchContextConst
BLX R0
.type vPortRestoreTaskContext, %function
vPortRestoreTaskContext:
portRESTORE_CONTEXT
.align 4
.type FreeRTOS_IRQ_Handler, %function
FreeRTOS_IRQ_Handler:
/* Return to the interrupted instruction. */
SUB lr, lr, #4
/* Push the return address and SPSR. */
PUSH {lr}
MRS lr, SPSR
PUSH {lr}
/* Change to supervisor mode to allow reentry. */
CPS #SVC_MODE
/* Push used registers. */
PUSH {r0-r4, r12}
/* Increment nesting count. r3 holds the address of ulPortInterruptNesting
for future use. r1 holds the original ulPortInterruptNesting value for
future use. */
LDR r3, ulPortInterruptNestingConst
LDR r1, [r3]
ADD r4, r1, #1
STR r4, [r3]
/* Read value from the interrupt acknowledge register, which is stored in r0
for future parameter and interrupt clearing use. */
LDR r2, ulICCIARConst
LDR r2, [r2]
LDR r0, [r2]
/* Ensure bit 2 of the stack pointer is clear. r2 holds the bit 2 value for
future use. */
MOV r2, sp
AND r2, r2, #4
SUB sp, sp, r2
/* Call the interrupt handler. */
PUSH {r0-r3, lr}
LDR r1, vApplicationIRQHandlerConst
BLX r1
POP {r0-r3, lr}
ADD sp, sp, r2
CPSID i
DSB
ISB
/* Write the value read from ICCIAR to ICCEOIR. */
LDR r4, ulICCEOIRConst
LDR r4, [r4]
STR r0, [r4]
/* Restore the old nesting count. */
STR r1, [r3]
/* A context switch is never performed if the nesting count is not 0. */
CMP r1, #0
BNE exit_without_switch
/* Did the interrupt request a context switch? r1 holds the address of
ulPortYieldRequired and r0 the value of ulPortYieldRequired for future
use. */
LDR r1, =ulPortYieldRequired
LDR r0, [r1]
CMP r0, #0
BNE switch_before_exit
exit_without_switch:
/* No context switch. Restore used registers, LR_irq and SPSR before
returning. */
POP {r0-r4, r12}
CPS #IRQ_MODE
POP {LR}
MSR SPSR_cxsf, LR
POP {LR}
MOVS PC, LR
switch_before_exit:
/* A context swtich is to be performed. Clear the context switch pending
flag. */
MOV r0, #0
STR r0, [r1]
/* Restore used registers, LR-irq and SPSR before saving the context
to the task stack. */
POP {r0-r4, r12}
CPS #IRQ_MODE
POP {LR}
MSR SPSR_cxsf, LR
POP {LR}
portSAVE_CONTEXT
/* Call the function that selects the new task to execute.
vTaskSwitchContext() if vTaskSwitchContext() uses LDRD or STRD
instructions, or 8 byte aligned stack allocated data. LR does not need
saving as a new LR will be loaded by portRESTORE_CONTEXT anyway. */
LDR R0, vTaskSwitchContextConst
BLX R0
/* Restore the context of, and branch to, the task selected to execute
next. */
portRESTORE_CONTEXT
ulICCIARConst: .word ulICCIAR
ulICCEOIRConst: .word ulICCEOIR
ulICCPMRConst: .word ulICCPMR
pxCurrentTCBConst: .word pxCurrentTCB
ulCriticalNestingConst: .word ulCriticalNesting
ulPortTaskHasFPUContextConst: .word ulPortTaskHasFPUContext
ulMaxAPIPriorityMaskConst: .word ulMaxAPIPriorityMask
vTaskSwitchContextConst: .word vTaskSwitchContext
vApplicationIRQHandlerConst: .word vApplicationIRQHandler
ulPortInterruptNestingConst: .word ulPortInterruptNesting
.end
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