/*
    FreeRTOS V8.0.0:rc1 - 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.
*/


	.org 0
	.text

	.set SYS_MODE,	0x1f
	.set SVC_MODE,	0x13
	.set IRQ_MODE,	0x12

	.extern _boot
	.extern vTaskSwitchContext
	.extern ulICCIAR
	.extern ulICCEOIR

	.global _vector_table
	.global FIQInterrupt
	.global Undefined
	.global PrefetchAbortHandler
	.global DataAbortInterrupt
	.global FreeRTOS_IRQ_Handler
	.global FreeRTOS_SWI_Handler

	.section .vectors

_vector_table:
	B	  _boot
	B	  Undefined
	ldr   pc, _swi
	B	  PrefetchAbortHandler
	B	  DataAbortHandler
	NOP	  /* Placeholder for address exception vector*/
	LDR   PC, _irq
	B	  FIQHandler

_irq:   .word FreeRTOS_IRQ_Handler
_swi:   .word FreeRTOS_SWI_Handler

/******************************************************************************
 * SVC handler is used to start the scheduler and yield a task.
 *****************************************************************************/
FreeRTOS_SWI_Handler:

	/* Save the context of the current task and select a new task to run. */
//	portSAVE_CONTEXT
	LDR R0, =vTaskSwitchContext
	BLX	R0

vPortRestoreTaskContext:
//	portRESTORE_CONTEXT

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, =ulPortInterruptNesting
	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		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}
	BL		vApplicationIRQHandler
	POP		{r0-r3, lr}
	ADD		sp, sp, r2

	CPSID	i

	/* Write the value read from ICCIAR to ICCEOIR. */
	LDR 	r4, ulICCEOIRConst
	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. */
	BL		vTaskSwitchContext

	/* Restore the context of, and branch to, the task selected to execute
	next. */
//	portRESTORE_CONTEXT

ulICCIARConst:	.word ulICCIAR
ulICCEOIRConst:	.word ulICCEOIR


Undefined:
	B		.

PrefetchAbortHandler:
	B		.

FIQHandler:
	B		.

DataAbortHandler:
	B		.

.end