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152 lines
3.0 KiB
C
152 lines
3.0 KiB
C
; /*
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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
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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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* ; */
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EXTERN pxCurrentTCB
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EXTERN ulCriticalNesting
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;
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Context save and restore macro definitions
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;
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portSAVE_CONTEXT MACRO
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;
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Push R0 as we are going to use the register.
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STMDB SP !, {
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R0
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}
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Set R0 to point to the task stack pointer.
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STMDB SP, {
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SP
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}
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^
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NOP
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SUB SP, SP, # 4
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LDMIA SP !, {
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R0
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}
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;
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Push the return address onto the stack.
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STMDB R0 !, {
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LR
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}
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Now we have saved LR we can use it instead of R0.
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MOV LR, R0
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;
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Pop R0 so we can save it onto the system mode stack.
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LDMIA SP !, {
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R0
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}
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Push all the system mode registers onto the task stack.
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STMDB LR, {
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R0 - LR
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}
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^
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NOP
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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 !, {
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R0
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}
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LDR R0, = ulCriticalNesting
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LDR R0, [ R0 ]
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STMDB LR !, {
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R0
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}
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Store the new top of stack
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for the task.
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LDR R1, = pxCurrentTCB
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LDR R0, [ R1 ]
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STR LR, [ R0 ]
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ENDM
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portRESTORE_CONTEXT MACRO
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;
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Set the LR to the task stack.
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LDR R1, = pxCurrentTCB
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LDR R0, [ R1 ]
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LDR LR, [ R0 ]
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;
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The critical nesting depth is the first item on the stack.
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;
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Load it into the ulCriticalNesting variable.
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LDR R0, = ulCriticalNesting
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LDMFD LR !, {
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R1
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}
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STR R1, [ R0 ]
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;
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Get the SPSR from the stack.
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LDMFD LR !, {
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R0
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}
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MSR SPSR_cxsf, R0
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;
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Restore all system mode registers
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for the task.
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LDMFD LR, {
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R0 - R14
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}
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^
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NOP
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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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;
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correct address.
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SUBS PC, LR, # 4
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ENDM
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