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269 lines
6.5 KiB
ArmAsm
269 lines
6.5 KiB
ArmAsm
/*
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* FreeRTOS Kernel V10.3.1
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* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* https://www.FreeRTOS.org
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* https://github.com/FreeRTOS
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*
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* 1 tab == 4 spaces!
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*/
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#include <xc.h>
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#include <sys/asm.h>
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#include "ISR_Support.h"
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.set nomips16
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.set noreorder
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.extern pxCurrentTCB
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.extern vTaskSwitchContext
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.extern vPortIncrementTick
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.extern xISRStackTop
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.global vPortStartFirstTask
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.global vPortYieldISR
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.global vPortTickInterruptHandler
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/******************************************************************/
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.set noreorder
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.set noat
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.ent vPortTickInterruptHandler
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vPortTickInterruptHandler:
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portSAVE_CONTEXT
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jal vPortIncrementTick
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nop
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portRESTORE_CONTEXT
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.end vPortTickInterruptHandler
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/******************************************************************/
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.set noreorder
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.set noat
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.ent vPortStartFirstTask
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vPortStartFirstTask:
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/* Simply restore the context of the highest priority task that has been
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created so far. */
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portRESTORE_CONTEXT
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.end vPortStartFirstTask
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/*******************************************************************/
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.set noreorder
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.set noat
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.ent vPortYieldISR
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vPortYieldISR:
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/* Make room for the context. First save the current status so it can be
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manipulated. */
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addiu sp, sp, -portCONTEXT_SIZE
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mfc0 k1, _CP0_STATUS
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/* Also save s6 and s5 so they can be used. Any nesting interrupts should
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maintain the values of these registers across the ISR. */
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sw s6, 44(sp)
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sw s5, 40(sp)
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sw k1, portSTATUS_STACK_LOCATION(sp)
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/* Prepare to re-enabled interrupt above the kernel priority. */
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ins k1, zero, 10, 6
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ori k1, k1, ( configMAX_SYSCALL_INTERRUPT_PRIORITY << 10 )
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ins k1, zero, 1, 4
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/* s5 is used as the frame pointer. */
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add s5, zero, sp
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/* Swap to the system stack. This is not conditional on the nesting
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count as this interrupt is always the lowest priority and therefore
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the nesting is always 0. */
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la sp, xISRStackTop
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lw sp, (sp)
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/* Set the nesting count. */
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la k0, uxInterruptNesting
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addiu s6, zero, 1
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sw s6, 0(k0)
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/* s6 holds the EPC value, this is saved with the rest of the context
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after interrupts are enabled. */
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mfc0 s6, _CP0_EPC
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/* Re-enable interrupts above configMAX_SYSCALL_INTERRUPT_PRIORITY. */
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mtc0 k1, _CP0_STATUS
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/* Save the context into the space just created. s6 is saved again
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here as it now contains the EPC value. */
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sw ra, 120(s5)
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sw s8, 116(s5)
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sw t9, 112(s5)
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sw t8, 108(s5)
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sw t7, 104(s5)
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sw t6, 100(s5)
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sw t5, 96(s5)
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sw t4, 92(s5)
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sw t3, 88(s5)
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sw t2, 84(s5)
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sw t1, 80(s5)
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sw t0, 76(s5)
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sw a3, 72(s5)
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sw a2, 68(s5)
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sw a1, 64(s5)
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sw a0, 60(s5)
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sw v1, 56(s5)
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sw v0, 52(s5)
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sw s7, 48(s5)
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sw s6, portEPC_STACK_LOCATION(s5)
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/* s5 and s6 has already been saved. */
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sw s4, 36(s5)
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sw s3, 32(s5)
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sw s2, 28(s5)
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sw s1, 24(s5)
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sw s0, 20(s5)
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sw $1, 16(s5)
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/* s7 is used as a scratch register as this should always be saved across
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nesting interrupts. */
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mfhi s7
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sw s7, 12(s5)
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mflo s7
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sw s7, 8(s5)
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/* Save the stack pointer to the task. */
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la s7, pxCurrentTCB
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lw s7, (s7)
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sw s5, (s7)
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/* Set the interrupt mask to the max priority that can use the API. The
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yield handler will only be called at configKERNEL_INTERRUPT_PRIORITY which
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is below configMAX_SYSCALL_INTERRUPT_PRIORITY - so this can only ever
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raise the IPL value and never lower it. */
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di
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ehb
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mfc0 s7, _CP0_STATUS
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ins s7, zero, 10, 6
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ori s6, s7, ( configMAX_SYSCALL_INTERRUPT_PRIORITY << 10 ) | 1
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/* This mtc0 re-enables interrupts, but only above
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configMAX_SYSCALL_INTERRUPT_PRIORITY. */
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mtc0 s6, _CP0_STATUS
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ehb
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/* Clear the software interrupt in the core. */
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mfc0 s6, _CP0_CAUSE
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ins s6, zero, 8, 1
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mtc0 s6, _CP0_CAUSE
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ehb
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/* Clear the interrupt in the interrupt controller. */
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la s6, IFS0CLR
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addiu s4, zero, 2
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sw s4, (s6)
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jal vTaskSwitchContext
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nop
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/* Clear the interrupt mask again. The saved status value is still in s7. */
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mtc0 s7, _CP0_STATUS
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ehb
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/* Restore the stack pointer from the TCB. */
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la s0, pxCurrentTCB
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lw s0, (s0)
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lw s5, (s0)
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/* Restore the rest of the context. */
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lw s0, 8(s5)
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mtlo s0
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lw s0, 12(s5)
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mthi s0
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lw $1, 16(s5)
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lw s0, 20(s5)
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lw s1, 24(s5)
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lw s2, 28(s5)
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lw s3, 32(s5)
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lw s4, 36(s5)
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/* s5 is loaded later. */
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lw s6, 44(s5)
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lw s7, 48(s5)
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lw v0, 52(s5)
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lw v1, 56(s5)
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lw a0, 60(s5)
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lw a1, 64(s5)
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lw a2, 68(s5)
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lw a3, 72(s5)
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lw t0, 76(s5)
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lw t1, 80(s5)
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lw t2, 84(s5)
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lw t3, 88(s5)
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lw t4, 92(s5)
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lw t5, 96(s5)
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lw t6, 100(s5)
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lw t7, 104(s5)
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lw t8, 108(s5)
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lw t9, 112(s5)
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lw s8, 116(s5)
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lw ra, 120(s5)
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/* Protect access to the k registers, and others. */
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di
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ehb
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/* Set nesting back to zero. As the lowest priority interrupt this
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interrupt cannot have nested. */
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la k0, uxInterruptNesting
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sw zero, 0(k0)
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/* Switch back to use the real stack pointer. */
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add sp, zero, s5
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/* Restore the real s5 value. */
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lw s5, 40(sp)
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/* Pop the status and epc values. */
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lw k1, portSTATUS_STACK_LOCATION(sp)
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lw k0, portEPC_STACK_LOCATION(sp)
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/* Remove stack frame. */
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addiu sp, sp, portCONTEXT_SIZE
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mtc0 k1, _CP0_STATUS
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mtc0 k0, _CP0_EPC
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ehb
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eret
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nop
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.end vPortYieldISR
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