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/*
FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
***************************************************************************
* *
* If you are: *
* *
* + New to FreeRTOS, *
* + Wanting to learn FreeRTOS or multitasking in general quickly *
* + Looking for basic training, *
* + Wanting to improve your FreeRTOS skills and productivity *
* *
* then take a look at the FreeRTOS books - available as PDF or paperback *
* *
* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
* http://www.FreeRTOS.org/Documentation *
* *
* A pdf reference manual is also available. Both are usually delivered *
* to your inbox within 20 minutes to two hours when purchased between 8am *
* and 8pm GMT (although please allow up to 24 hours in case of *
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***************************************************************************
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 exception 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.
*/
#include <p32xxxx.h>
#include <sys/asm.h>
#include "ISR_Support.h"
.set nomips16
.set noreorder
.extern pxCurrentTCB
.extern vTaskSwitchContext
.extern vPortIncrementTick
.extern xISRStackTop
.global vPortStartFirstTask
.global vPortYieldISR
.global vT1InterruptHandler
/******************************************************************/
.section .FreeRTOS, "ax", @progbits
.set noreorder
.set noat
.ent vT1InterruptHandler
vT1InterruptHandler:
portSAVE_CONTEXT
jal vPortIncrementTick
nop
portRESTORE_CONTEXT
.end vT1InterruptHandler
/******************************************************************/
.section .FreeRTOS, "ax", @progbits
.set noreorder
.set noat
.ent xPortStartScheduler
vPortStartFirstTask:
/* Simply restore the context of the highest priority task that has been
created so far. */
portRESTORE_CONTEXT
.end xPortStartScheduler
/*******************************************************************/
.section .FreeRTOS, "ax", @progbits
.set noreorder
.set noat
.ent vPortYieldISR
vPortYieldISR:
/* Make room for the context. First save the current status so we can
manipulate it, and the cause and EPC registers so we capture their
original values in case of interrupt nesting. */
mfc0 k0, _CP0_CAUSE
addiu sp, sp, -portCONTEXT_SIZE
mfc0 k1, _CP0_STATUS
/* Also save s6 and s5 so we can use them during this interrupt. Any
nesting interrupts should maintain the values of these registers
across the ISR. */
sw s6, 44(sp)
sw s5, 40(sp)
sw k1, portSTATUS_STACK_LOCATION(sp)
/* Enable interrupts above the current priority. */
srl k0, k0, 0xa
ins k1, k0, 10, 6
ins k1, zero, 1, 4
/* s5 is used as the frame pointer. */
add s5, zero, sp
/* Swap to the system stack. This is not conditional on the nesting
count as this interrupt is always the lowest priority and therefore
the nesting is always 0. */
la sp, xISRStackTop
lw sp, (sp)
/* Set the nesting count. */
la k0, uxInterruptNesting
addiu s6, zero, 1
sw s6, 0(k0)
/* s6 holds the EPC value, this is saved with the rest of the context
after interrupts are enabled. */
mfc0 s6, _CP0_EPC
/* Re-enable interrupts. */
mtc0 k1, _CP0_STATUS
/* Save the context into the space just created. s6 is saved again
here as it now contains the EPC value. */
sw ra, 120(s5)
sw s8, 116(s5)
sw t9, 112(s5)
sw t8, 108(s5)
sw t7, 104(s5)
sw t6, 100(s5)
sw t5, 96(s5)
sw t4, 92(s5)
sw t3, 88(s5)
sw t2, 84(s5)
sw t1, 80(s5)
sw t0, 76(s5)
sw a3, 72(s5)
sw a2, 68(s5)
sw a1, 64(s5)
sw a0, 60(s5)
sw v1, 56(s5)
sw v0, 52(s5)
sw s7, 48(s5)
sw s6, portEPC_STACK_LOCATION(s5)
/* s5 and s6 has already been saved. */
sw s4, 36(s5)
sw s3, 32(s5)
sw s2, 28(s5)
sw s1, 24(s5)
sw s0, 20(s5)
sw $1, 16(s5)
/* s7 is used as a scratch register as this should always be saved across
nesting interrupts. */
mfhi s7
sw s7, 12(s5)
mflo s7
sw s7, 8(s5)
/* Save the stack pointer to the task. */
la s7, pxCurrentTCB
lw s7, (s7)
sw s5, (s7)
/* Set the interrupt mask to the max priority that can use the API. */
di
mfc0 s7, _CP0_STATUS
ori s7, s7, 1
ori s6, s7, configMAX_SYSCALL_INTERRUPT_PRIORITY << 10
/* This mtc0 re-enables interrupts, but only above
configMAX_SYSCALL_INTERRUPT_PRIORITY. */
mtc0 s6, _CP0_STATUS
/* Clear the software interrupt in the core. */
mfc0 s6, _CP0_CAUSE
addiu s4,zero,-257
and s6, s6, s4
mtc0 s6, _CP0_CAUSE
/* Clear the interrupt in the interrupt controller. */
la s6, IFS0CLR
addiu s4, zero, 2
sw s4, (s6)
jal vTaskSwitchContext
nop
/* Clear the interrupt mask again. The saved status value is still in s7. */
mtc0 s7, _CP0_STATUS
/* Restore the stack pointer from the TCB. */
la s0, pxCurrentTCB
lw s0, (s0)
lw s5, (s0)
/* Restore the rest of the context. */
lw s0, 8(s5)
mtlo s0
lw s0, 12(s5)
mthi s0
lw $1, 16(s5)
lw s0, 20(s5)
lw s1, 24(s5)
lw s2, 28(s5)
lw s3, 32(s5)
lw s4, 36(s5)
/* s5 is loaded later. */
lw s6, 44(s5)
lw s7, 48(s5)
lw v0, 52(s5)
lw v1, 56(s5)
lw a0, 60(s5)
lw a1, 64(s5)
lw a2, 68(s5)
lw a3, 72(s5)
lw t0, 76(s5)
lw t1, 80(s5)
lw t2, 84(s5)
lw t3, 88(s5)
lw t4, 92(s5)
lw t5, 96(s5)
lw t6, 100(s5)
lw t7, 104(s5)
lw t8, 108(s5)
lw t9, 112(s5)
lw s8, 116(s5)
lw ra, 120(s5)
/* Protect access to the k registers, and others. */
di
/* Set nesting back to zero. As the lowest priority interrupt this
interrupt cannot have nested. */
la k0, uxInterruptNesting
sw zero, 0(k0)
/* Switch back to use the real stack pointer. */
add sp, zero, s5
/* Restore the real s5 value. */
lw s5, 40(sp)
/* Pop the status and epc values. */
lw k1, portSTATUS_STACK_LOCATION(sp)
lw k0, portEPC_STACK_LOCATION(sp)
/* Remove stack frame. */
addiu sp, sp, portCONTEXT_SIZE
mtc0 k1, _CP0_STATUS
ehb
mtc0 k0, _CP0_EPC
eret
nop
.end vPortYieldISR