| ;/*
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| ; * FreeRTOS Kernel <DEVELOPMENT BRANCH>
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| ; * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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| ; *
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| ; * SPDX-License-Identifier: MIT |
| ; * |
| ; * 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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| ; */
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|
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| .text
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| .arm
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| .ref vTaskSwitchContext
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| .ref xTaskIncrementTick
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| .ref ulTaskHasFPUContext
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| .ref pxCurrentTCB
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|
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| ;/*-----------------------------------------------------------*/
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| ;
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| ; Save Task Context
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| ;
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| portSAVE_CONTEXT .macro
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| DSB
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|
|
| ; Push R0 as we are going to use it
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| STMDB SP!, {R0}
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|
|
| ; Set R0 to point to the task stack pointer.
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| STMDB SP,{SP}^
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| SUB SP, SP, #4
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| LDMIA SP!,{R0}
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|
|
| ; Push the return address onto the stack.
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| STMDB R0!, {LR}
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|
|
| ; Now LR has been saved, it can be used instead of R0.
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| MOV LR, R0
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|
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| ; Pop R0 so it can be saved onto the task stack.
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| LDMIA SP!, {R0}
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|
|
| ; Push all the system mode registers onto the task stack.
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| STMDB LR,{R0-LR}^
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| SUB LR, LR, #60
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|
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| ; Push the SPSR onto the task stack.
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| MRS R0, SPSR
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| STMDB LR!, {R0}
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|
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| .if (__TI_VFP_SUPPORT__)
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| ;Determine if the task maintains an FPU context.
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| LDR R0, ulFPUContextConst
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| LDR R0, [R0]
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|
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| ; Test the flag
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| CMP R0, #0
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|
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| ; If the task is not using a floating point context then skip the
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| ; saving of the FPU registers.
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| BEQ $+16
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| FSTMDBD LR!, {D0-D15}
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| FMRX R1, FPSCR
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| STMFD LR!, {R1}
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| ; Save the flag
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| STMDB LR!, {R0}
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| .endif
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|
|
| ; Store the new top of stack for the task.
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| LDR R0, pxCurrentTCBConst
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| LDR R0, [R0]
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| STR LR, [R0]
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|
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| .endm
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|
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| ;/*-----------------------------------------------------------*/
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| ;
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| ; Restore Task Context
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| ;
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| portRESTORE_CONTEXT .macro
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| LDR R0, pxCurrentTCBConst
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| LDR R0, [R0]
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| LDR LR, [R0]
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|
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| .if (__TI_VFP_SUPPORT__)
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| ; The floating point context flag is the first thing on the stack.
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| LDR R0, ulFPUContextConst
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| LDMFD LR!, {R1}
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| STR R1, [R0]
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|
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| ; Test the flag
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| CMP R1, #0
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|
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| ; If the task is not using a floating point context then skip the
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| ; VFP register loads.
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| BEQ $+16
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| ; Restore the floating point context.
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| LDMFD LR!, {R0}
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| FLDMIAD LR!, {D0-D15}
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| FMXR FPSCR, R0
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| .endif
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|
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| ; Get the SPSR from the stack.
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| LDMFD LR!, {R0}
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| MSR SPSR_CSXF, R0
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|
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| ; Restore all system mode registers for the task.
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| LDMFD LR, {R0-R14}^
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|
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| ; Restore the return address.
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| LDR LR, [LR, #+60]
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|
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| ; And return - correcting the offset in the LR to obtain the
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| ; correct address.
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| SUBS PC, LR, #4
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| .endm
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|
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| ;/*-----------------------------------------------------------*/
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| ; Start the first task by restoring its context.
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|
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| .def vPortStartFirstTask
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|
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| vPortStartFirstTask:
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| portRESTORE_CONTEXT
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|
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| ;/*-----------------------------------------------------------*/
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| ; Yield to another task.
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|
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| .def vPortYieldProcessor
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|
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| vPortYieldProcessor:
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| ; Within an IRQ ISR the link register has an offset from the true return
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| ; address. SWI doesn't do this. Add the offset manually so the ISR
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| ; return code can be used.
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| ADD LR, LR, #4
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|
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| ; First save the context of the current task.
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| portSAVE_CONTEXT
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|
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| ; Select the next task to execute. */
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| BL vTaskSwitchContext
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|
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| ; Restore the context of the task selected to execute.
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| portRESTORE_CONTEXT
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|
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| ;/*-----------------------------------------------------------*/
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| ; Yield to another task from within the FreeRTOS API
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|
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| .def vPortYeildWithinAPI
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|
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| vPortYeildWithinAPI:
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| ; Save the context of the current task.
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|
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| portSAVE_CONTEXT
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| ; Clear SSI flag.
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| MOVW R0, #0xFFF4
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| MOVT R0, #0xFFFF
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| LDR R0, [R0]
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|
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| ; Select the next task to execute. */
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| BL vTaskSwitchContext
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|
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| ; Restore the context of the task selected to execute.
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| portRESTORE_CONTEXT
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|
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| ;/*-----------------------------------------------------------*/
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| ; Preemptive Tick
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|
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| .def vPortPreemptiveTick
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|
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| vPortPreemptiveTick:
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|
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| ; Save the context of the current task.
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| portSAVE_CONTEXT
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|
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| ; Clear interrupt flag
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| MOVW R0, #0xFC88
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| MOVT R0, #0xFFFF
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| MOV R1, #1
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| STR R1, [R0]
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|
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| ; Increment the tick count, making any adjustments to the blocked lists
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| ; that may be necessary.
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| BL xTaskIncrementTick
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|
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| ; Select the next task to execute.
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| CMP R0, #0
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| BLNE vTaskSwitchContext
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|
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| ; Restore the context of the task selected to execute.
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| portRESTORE_CONTEXT
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|
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| ;-------------------------------------------------------------------------------
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|
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| .if (__TI_VFP_SUPPORT__)
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|
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| .def vPortInitialiseFPSCR
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|
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| vPortInitialiseFPSCR:
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|
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| MOV R0, #0
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| FMXR FPSCR, R0
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| BX LR
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|
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| .endif ;__TI_VFP_SUPPORT__
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|
|
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| pxCurrentTCBConst .word pxCurrentTCB
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| ulFPUContextConst .word ulTaskHasFPUContext
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| ;-------------------------------------------------------------------------------
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|
|