;/* ; * FreeRTOS Kernel V10.2.0 ; * Copyright (C) 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved. ; * ; * Permission is hereby granted, free of charge, to any person obtaining a copy of ; * this software and associated documentation files (the "Software"), to deal in ; * the Software without restriction, including without limitation the rights to ; * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of ; * the Software, and to permit persons to whom the Software is furnished to do so, ; * subject to the following conditions: ; * ; * The above copyright notice and this permission notice shall be included in all ; * copies or substantial portions of the Software. ; * ; * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR ; * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS ; * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR ; * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER ; * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN ; * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. ; * ; * http://www.FreeRTOS.org ; * http://aws.amazon.com/freertos ; * ; * 1 tab == 4 spaces! ; */ IMPORT ulCriticalNesting ; IMPORT pxCurrentTCB ; MACRO portRESTORE_CONTEXT LDR R0, =pxCurrentTCB ; Set the LR to the task stack. The location was... LDR R0, [R0] ; ... stored in pxCurrentTCB LDR LR, [R0] LDR R0, =ulCriticalNesting ; The critical nesting depth is the first item on... LDMFD LR!, {R1} ; ...the stack. Load it into the ulCriticalNesting var. STR R1, [R0] ; LDMFD LR!, {R0} ; Get the SPSR from the stack. MSR SPSR_cxsf, R0 ; LDMFD LR, {R0-R14}^ ; Restore all system mode registers for the task. NOP ; LDR LR, [LR, #+60] ; Restore the return address ; And return - correcting the offset in the LR to obtain ... SUBS PC, LR, #4 ; ...the correct address. MEND ; /**********************************************************************/ MACRO portSAVE_CONTEXT STMDB SP!, {R0} ; Store R0 first as we need to use it. STMDB SP,{SP}^ ; Set R0 to point to the task stack pointer. NOP ; SUB SP, SP, #4 ; LDMIA SP!,{R0} ; STMDB R0!, {LR} ; Push the return address onto the stack. MOV LR, R0 ; Now we have saved LR we can use it instead of R0. LDMIA SP!, {R0} ; Pop R0 so we can save it onto the system mode stack. STMDB LR,{R0-LR}^ ; Push all the system mode registers onto the task stack. NOP ; SUB LR, LR, #60 ; MRS R0, SPSR ; Push the SPSR onto the task stack. STMDB LR!, {R0} ; LDR R0, =ulCriticalNesting ; LDR R0, [R0] ; STMDB LR!, {R0} ; LDR R0, =pxCurrentTCB ; Store the new top of stack for the task. LDR R1, [R0] ; STR LR, [R1] ; MEND END